Chemistry terminology · MLC-0109

Chemistry terms: A (1,115)

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• Amino sugarsMonosaccharides in which a non-anomeric hydroxyl group has been replaced by an amino group or a substituted...
• Amino-acid residueThe portion of an amino acid that remains after it has been incorporated into a polypeptide chain through...
• AminoxidesAnions of the type R2N-O with the negative charge on oxygen, where R may be hydrogen or a hydrocarbyl group...
• Aminoxyl radicalsStable free radicals containing the N-O• functional group, where the unpaired electron is primarily localized...
• Aminyl radicalsReactive intermediates of the general structure R₂N•, where an uncharged nitrogen atom bears an unpaired...
• AmnesiaA partial or total loss of memory, often resulting from brain injury, disease, or psychological trauma. It...
• Amnesic shellfish poisoningA human illness caused by consuming shellfish contaminated with domoic acid, a neurotoxin produced by certain...
• AmniocentesisA prenatal diagnostic procedure in which a small amount of amniotic fluid is withdrawn from the amniotic sac...
• Amniochorionic membraneA composite fetal membrane formed by the fusion of the amnion and chorion, which encloses the amniotic fluid...
• AmnionThe innermost fetal membrane that forms a fluid-filled sac, the amniotic cavity, directly surrounding and...
• AmnioteA vertebrate animal whose embryo develops within an amnion, a protective membrane that forms a fluid-filled...
• Amniotic cavityThe fluid-filled sac enclosed by the amnion, which surrounds and protects the developing embryo or fetus...
• Amniotic fluidThe protective liquid contained within the amniotic sac that surrounds the fetus during pregnancy. This fluid...
• Amniotic sacA fluid-filled membrane that surrounds and protects a developing embryo or fetus within the uterus. This sac...
• Amorphous carbonA form of carbon that lacks a long-range crystalline structure, unlike graphite or diamond. Its atoms are...
• Amorphous domainA region within a semicrystalline polymer where the polymer chains lack long-range order and are randomly...
• Amorphous material transmitting infrared radiationA non-crystalline glass composed of elements from groups 14, 15 and 16, such as germanium, arsenic and...
• Amorphous polymerA polymer that lacks the ordered, repeating structure of a crystalline solid. Its molecular chains are...
• Amorphous stateA solid state of matter characterized by a disordered arrangement of molecules, lacking the long-range...
• Amount concentrationThe quantity obtained by dividing the amount of a component of a mixture, in moles, by the total volume of...
• Amount fractionA dimensionless quantity representing the ratio of the amount of substance of a specific constituent to the...
• Amount of substanceA measure of the quantity of elementary entities (such as atoms, molecules, ions, or electrons) present in a...
• Amount-of-substance concentrationA measure of the concentration of a specific chemical species in a solution, defined as the amount of...
• Amount-of-substance fractionA dimensionless quantity that expresses the ratio of the amount of substance of a particular component to the...
• AmpereThe SI base unit of electric current, symbol A, fixed since the 2019 redefinition by giving the elementary...
• Amperometric detection methodAn electrochemical analytical technique that measures the current generated by an oxidation or reduction...
• AmperometryAn electrochemical analytical technique where the current flowing through an electrochemical cell is measured...
• Amphibian metamorphosis assayA standardized ecotoxicological test used to evaluate the potential of chemical substances to disrupt the...
• AmphipathicDescribing a chemical entity possessing both a polar, water-attracting (hydrophilic) group and a nonpolar...
• AmphiphileA chemical compound possessing two distinct regions within the same molecule: one that is solvophilic...
• AmphiphilicDescribing a molecule or compound that possesses both hydrophilic (water-loving) and lipophilic (fat-loving)...
• Amphiprotic solventA solvent that possesses both acidic and basic properties, allowing it to act as a proton donor (Brønsted...
• Ampholytic polymerA polymer that contains both acidic and basic ionizable groups along its chain. These polymers can act as...
• AmphotericDescribing a chemical species that can react as both an acid and a base. This behavior can manifest as acting...
• Amplification of deoxyribonucleic acidThe production of multiple copies of a specific sequence of deoxyribonucleic acid (DNA), starting from a...
• Amplification reactionA reaction substituted for the conventional reaction of a determination in order to give a more favourable...
• Amplitude modulationA technique where the amplitude of a high-frequency carrier wave is varied in proportion to the instantaneous...
• Amplitude of alternating currentThe maximum absolute value reached by an alternating current during one cycle of its oscillation. This value...
• Amplitude of alternating voltageThe maximum value or peak magnitude of an alternating voltage, measured from the zero level to the crest of...
• AmpullaA flask-shaped or dilated part of a tube, duct, or canal in an anatomical structure. This expanded region...
• AmygdalaA pair of almond-shaped clusters of nuclei located deep within the medial temporal lobes of the brain. As a...
• AmyloidAn insoluble fibrous protein aggregate that can accumulate abnormally in tissues and organs, a condition...
• Amyloid plaqueExtracellular deposits of aggregated beta-amyloid (β-amyloid) peptides that accumulate in the brain tissue of...
• Amyotrophic lateral sclerosisA progressive neurodegenerative disease that affects motor neurons in the brain and spinal cord, leading to...
• AnabolismThe set of metabolic pathways that construct molecules from smaller units, requiring energy in the process...
• AnadromousDescribing fish species that migrate from saltwater environments to freshwater to spawn. These organisms...
• AnadromyA migratory life history strategy in which fish spend the majority of their adult lives in marine...
• AnaerobeA microorganism that does not require oxygen for growth and can even be harmed by its presence. These...
• AnaerobicRelating to processes or organisms that occur or live in the absence of molecular oxygen. Anaerobic...
• Anaerobic biodegradationThe biological degradation of organic materials, including polymers, by microorganisms in the absence of...
• AnaestheticA substance that causes a reversible loss of sensation, either locally or throughout the entire body. These...
• Anal canalThe terminal segment of the large intestine, extending from the rectum to the anus. This structure is...
• Anal membraneA temporary embryonic structure that separates the hindgut from the exterior during early development. This...
• AnalgesicA substance that relieves pain without causing a loss of consciousness. Analgesics act on the peripheral or...
• AnalogueA chemical compound that is structurally similar to another but differs by a certain component, such as the...
• Analogue metabolismA biodegradation process in which a compound that is normally not degraded by microorganisms is broken down...
• Analogue to digital converter (pulse)An electronic device that transforms a continuous analog electrical signal, such as a voltage pulse, into a...
• Analogue-based drug discoveryA strategy in medicinal chemistry where new drug candidates are developed by chemically modifying existing...
• Analyser blankingAn action in secondary ion mass spectrometry that stops chosen secondary ions from passing through the mass...
• Analysis areaThe specific region on a sample surface from which analytical data is collected during a measurement. This...
• Analysis planA predetermined scheme detailing the statistical methods and procedures for processing and interpreting data...
• AnalyteThe chemical species, substance, or component of interest whose presence, concentration, or properties are...
• Analyte transport rateThe mass of analyte delivered to the plasma in each unit of time in atomic spectrometry with liquid sample...
• Analytic studyAn epidemiological investigation designed to test a specific hypothesis about the relationship between an...
• Analytical chemistryThe branch of chemistry focused on the qualitative and quantitative characterization of chemical substances...
• Analytical functionThe function that gives the measured amount of an analyte from the instrument reading, with the...
• Analytical instrumentA device or apparatus designed to perform chemical analysis by measuring physical or chemical properties of a...
• Analytical intercomparisonA program where multiple laboratories analyze identical samples using their own methods and instruments, and...
• Analytical methodA detailed set of instructions and procedures used to perform a chemical analysis, including sample...
• Analytical pyrolysisA technique that involves the thermal decomposition of a sample in an inert atmosphere, followed by the...
• Analytical quality controlA set of procedures and practices implemented to monitor the reliability and accuracy of analytical...
• Analytical radiochemistryThe branch of analytical chemistry in which radioactivity is a necessary part of the procedure, covering both...
• Analytical runA sequence of measurements performed on a set of samples, quality control materials, and blanks under...
• Analytical selectivityThe ability of an analytical method to accurately measure a specific analyte in a complex sample matrix...
• Analytical unitA complete measuring system built from subunits: a part that brings in and removes the sample or calibration...
• AnamnesticRelating to the rapid and heightened immune response that occurs upon re-exposure to an antigen previously...
• AnamnioteAn animal whose embryo develops without an amnion, a fluid-filled sac that surrounds and protects the embryo...
• AnaphaseThe stage of mitosis or meiosis during which sister chromatids (in mitosis and meiosis II) or homologous...
• Anaphase lagThe phenomenon where one or more chromosomes or chromatids fail to move properly to the spindle poles during...
• AnaphrodisiacA substance that reduces or suppresses sexual desire, also known as libido. These agents can act through...
• Anaphylactic shockA severe, life-threatening systemic allergic reaction that occurs rapidly after exposure to an allergen. It...
• AnaphylactoidDescribing a reaction that clinically resembles anaphylaxis but is not mediated by immunoglobulin E (IgE)...
• AnaphylatoxinA peptide fragment, such as C3a, C4a, or C5a, generated during complement activation that induces...
• AnaphylaxisA rapid, severe, and potentially fatal systemic hypersensitivity reaction mediated by immunoglobulin E (IgE)...
• AnaplasiaA condition in which cells lose their specialized characteristics and revert to a more primitive...
• AnasarcaA condition of severe and generalized edema, characterized by the widespread swelling of subcutaneous...
• AnastomosisA natural or surgical connection between two tubular structures, such as blood vessels, ducts, or loops of...
• AnationA ligand substitution reaction in coordination chemistry where an anionic ligand replaces a neutral ligand...
• Anchoring villusA specialized projection of the chorion, a fetal membrane, that extends into the decidua of the maternal...
• AndroblastomaA rare type of sex cord-stromal tumor that primarily affects the gonads, most commonly the ovary, but can...
• AndrogenA class of steroid hormones that stimulate or control the development and maintenance of male characteristics...
• Androgen receptorA nuclear receptor protein that binds to androgens, such as testosterone and dihydrotestosterone, mediating...
• AndrogenicDescribing a substance or effect that promotes the development of male characteristics, such as the growth of...
• AndrostenedioneA steroid with 19 carbon atoms, secreted by the adrenal cortex and the gonads, that serves as an intermediate...
• AnemiaA condition characterized by a deficiency of red blood cells or hemoglobin in the blood, leading to reduced...
• AnencephalusA severe congenital birth defect characterized by the incomplete development of the brain and bones of the...
• AnencephalyA severe birth defect in which a baby is born without parts of the brain and skull. This condition occurs...
• AnergyA state of functional unresponsiveness in lymphocytes, such as T or B cells, following exposure to a specific...
• Aneroid barometerA device used to measure atmospheric pressure without the use of a liquid, unlike a mercury barometer. It...
• AnestheticA drug that induces a temporary and reversible loss of sensation or awareness. General anesthetics cause a...
• AnestrusA period of sexual inactivity in female mammals, occurring between cycles of estrus or breeding seasons...
• AneugenA chemical agent that causes aneuploidy, which is an abnormal number of chromosomes in a cell. This effect...
• AneuploidDescribing a cell or organism that has an abnormal number of chromosomes, meaning it does not contain an...
• AneuploidyA cellular condition characterized by an atypical count of chromosomes, deviating from the normal diploid...
• AneurysmA localized, abnormal balloon-like bulge or weakening in the wall of a blood vessel, most commonly an artery...
• Anger cameraA type of gamma camera used in nuclear medicine to image the distribution of radioactive tracers within the...
• AngioblastA precursor cell derived from the mesenchyme that gives rise to the endothelial cells lining the interior...
• AngioedemaA rapid, localized swelling of the deep layers of the skin, subcutaneous tissue, mucosa, and submucosal...
• AngiogenesisThe physiological process involving the growth of new blood vessels from pre-existing vasculature. This...
• AngiographyA medical imaging procedure that visualizes the internal structure of blood vessels and organs. This...
• Angiotensin converting enzymeA peptidase enzyme that converts angiotensin I to angiotensin II, a potent vasoconstrictor. This enzyme is a...
• AngleA measure of the rotation between two intersecting lines or planes, or the divergence between two rays...
• Angle of emissionThe angle between the direction of an emitted particle or photon and the normal to the surface from which it...
• Angle of incidenceThe angle between the normal to a surface and the direction of an incoming beam of radiation or particles...
• Angle of optical rotationThe degree to which a substance rotates the plane of plane-polarized light as the light passes through it...
• Angle of reposeThe maximum stable angle that a heap of granular material forms with a horizontal surface. This angle is...
• Angle resolved mass spectrometryA tandem mass spectrometry technique for studying the collisional excitation step, in which the angle through...
• Angle strainThe increase in potential energy of a molecule due to bond angles deviating from their ideal values. This...
• ÅngströmA non-SI unit of length used to express atomic and molecular dimensions, chemical bond lengths, and...
• Angular distributionThe probability distribution of products or scattered particles as a function of their scattering angle...
• Angular frequencyA scalar measure of the rate of rotation or oscillation, expressed in radians per unit time. It is directly...
• Angular momentumA vector quantity that measures the amount of rotational motion of a particle or body about a point, equal to...
• Angular overlap modelA semi-empirical ligand field theory used to describe the bonding in transition metal complexes. It...
• Anhydro basesNeutral compounds made from an iminium hydroxide, for instance a quaternary heterocyclic salt with a methyl...
• AnilidesA class of organic compounds derived from aniline, where the amino group's hydrogen atom is replaced by an...
• AnilsA type of organic compound characterized by a carbon-nitrogen double bond, where the nitrogen atom is...
• AnionAn atom or group of atoms that has a net negative electric charge due to an excess of one or more electrons...
• Anion exchangeA type of ion-exchange chromatography where negatively charged ions (anions) in a sample solution are...
• Anion exchangerA type of ion-exchange material, typically a resin, that possesses positively charged functional groups...
• Anion-activated-monomer polymerizationAn activated-monomer polymerization in which the activated monomer is anionic and acts as the nucleophile...
• Anionic group-transfer polymerizationA living polymerization technique where the propagating species is an anion, and the active center is...
• Anionic polymerA polyelectrolyte that carries a net negative charge due to the presence of anionic groups along its polymer...
• Anionic polymerizationA type of chain polymerization initiated by anions, which act as nucleophiles to open the double bond of a...
• Anionic ring-opening polymerizationA chain polymerization mechanism where a cyclic monomer is opened by an anionic initiator, leading to the...
• Anionized moleculeAn ion produced when an anion attaches to a neutral molecule M, for example the chloride or formate adduct of...
• Anionotropic rearrangementA rearrangement in which a migrating group moves together with its bonding electrons from one atom to a...
• AnisotropicDescribing a material whose physical properties, such as refractive index, electrical conductivity, or...
• Anisotropic Raman scatteringRaman scattering that comes from the anisotropic component of the derived polarizability tensor, as distinct...
• AnisotropyThe property of a material exhibiting different physical or chemical characteristics when measured along...
• AnkyloglossiaA congenital oral anomaly characterized by an abnormally short, thick, or tight lingual frenulum, the band of...
• Ankylosing spondylitisA chronic inflammatory disease primarily affecting the spine, leading to stiffness and pain. It can cause...
• AnnealingA heat treatment that holds a solid polymer at one temperature, or on a changing profile, short of complete...
• AnnelationA chemical reaction that results in the formation of a new ring system fused to an existing molecule. This...
• AnnihilationA process in which a particle and its antiparticle interact and both disappear, their mass being converted...
• AnnulationA chemical reaction that leads to the formation of a new ring system directly attached to an existing...
• AnnulenylidenesA class of cyclic organic compounds that are derivatives of annulenes, featuring a carbene center within the...
• AnnulusA ring-like structure, a term used in neuroanatomy to describe specific formations. In the context of the...
• AnodeThe electrode of an electrochemical cell at which oxidation takes place, so electrons pass from the species...
• Anodic stripping voltammetryAn electrochemical method for trace metal analysis that involves two steps: preconcentration and stripping...
• Anodic transfer coefficientA dimensionless parameter in electrochemistry that describes the fraction of the applied potential that...
• AnodontiaA rare congenital condition characterized by the complete absence of all teeth, including both primary...
• Anogenital distanceA body measurement taken from the anus to the base of the external genitalia, which is longer in males than...
• Anomalous dispersionThe phenomenon where the refractive index of a medium decreases with increasing frequency (decreasing...
• Anomalous liquid junction potentialAn extra potential, often far larger than an ordinary liquid junction potential, that appears between the...
• Anomalously polarized Raman bandA Raman band whose depolarization ratio exceeds 0.75, the upper limit for an ordinary depolarized band in...
• Anomeric effectThe stereoelectronic preference for an electronegative substituent at the anomeric carbon of a pyranose or...
• Anomeric hydroxy groupThe hydroxyl group attached to the anomeric carbon atom in a cyclic monosaccharide. The anomeric carbon is...
• AnomersDiastereoisomers of cyclic monosaccharides or glycosides that differ in configuration only at the anomeric...
• AnonychiaA rare congenital condition characterized by the complete absence of fingernails and toenails. This disorder...
• AnophthalmiaA congenital malformation characterized by the complete absence of one or both eyes. This condition results...
• AnorchismA congenital condition characterized by the complete absence of one or both testes in a male individual. This...
• AnorexiaA medical symptom characterized by a loss of appetite or a decreased desire to eat. This condition can stem...
• Anorexia nervosaA severe eating disorder characterized by an intense fear of gaining weight and a distorted body image...
• AnosmiaThe complete loss of the sense of smell, which is the inability to perceive odors. In neurotoxicology, it is...
• AnotiaA congenital malformation characterized by the complete absence of the external ear, also known as the pinna...
• AnovulationThe absence of ovulation, which is the release of an egg from the ovary during the menstrual cycle. This...
• AnoxiaA condition characterized by the complete absence of oxygen supply to an organ or tissue. This is a more...
• Ansa compoundsMacrocyclic compounds characterized by a bridge (ansa chain) connecting two non-adjacent positions of a...
• AntagonismA situation in which the combined toxic effect of two or more chemicals is less than the sum of their...
• AntagonistA substance that binds to a receptor but does not activate it, thereby blocking the action of an agonist. In...
• AntarafacialA stereochemical descriptor indicating that a reaction or process occurs on opposite faces of a pi system or...
• AntemortemRelating to the period before death. In toxicology and forensic chemistry, it describes events, conditions...
• AnthelminticA chemical agent or drug used to expel or destroy parasitic worms from the body, particularly from the...
• AnthocyanidinsA class of naturally occurring plant pigments that are the aglycones of anthocyanins, meaning they lack a...
• AnthocyaninsWater-soluble plant pigments belonging to the flavonoid class, responsible for the red, purple, and blue...
• AnthracosisA type of pneumoconiosis, a lung disease caused by the inhalation and accumulation of coal dust in the lungs...
• AnthropogenicOriginating from or produced by human activities, rather than from natural processes. In ecotoxicology and...
• AntiA stereochemical descriptor for groups lying on opposite faces of a reference plane, the counterpart of syn...
• Antiaromatic compoundsCyclic, planar, fully conjugated molecules that possess 4n pi electrons, where n is an integer. Unlike...
• AntiaromaticityA property of cyclic, planar, fully conjugated molecules that leads to a destabilization of the pi electron...
• AntibioticA chemical substance produced by microorganisms or synthesized that inhibits the growth of or kills other...
• AntibodyA Y-shaped protein produced by the immune system in response to the presence of a foreign substance, known as...
• Antibody therapyA medical treatment that uses antibodies to target and neutralize specific disease-causing agents or cells...
• Antibody-dependent cellular cytotoxicityA mechanism of immune defense where target cells coated with antibodies are recognized and lysed by certain...
• Antibody-forming cell assayA laboratory technique used to quantify the number of B lymphocytes that are actively producing antibodies...
• Antibonding molecular orbitalA molecular orbital formed by the out-of-phase combination of atomic orbitals, resulting in a region of zero...
• AnticholinergicA substance that blocks the action of the neurotransmitter acetylcholine at its receptors in the central and...
• Anticircular elutionA mode of radial elution in chromatography where the mobile phase flows from the outer circumference of a...
• Anticlined stemsChain stems in a polymer crystal whose side groups face opposite ways relative to the chain axis, so...
• AnticoagulantA substance that prevents or slows the coagulation of blood. These agents interfere with the blood clotting...
• AnticodonA sequence of three nucleotides located on a molecule of transfer RNA (tRNA) that is complementary to a...
• AnticonvulsantA drug used to prevent or reduce the severity and frequency of convulsive seizures, which are characteristic...
• AnticycloneA large-scale atmospheric circulation system characterized by descending air and high atmospheric pressure at...
• AntidepressantA class of psychoactive medications used to alleviate symptoms of depression and other mood disorders. These...
• Antidirectional packingA specific arrangement of polymer chains within a crystalline structure where adjacent chains or chain...
• anti-DNA antibodyAn autoantibody that specifically targets and binds to deoxyribonucleic acid (DNA), which can be either...
• AntidoteA therapeutic substance that counteracts the toxic effects of a specified xenobiotic. Antidotes function...
• AntiemeticA drug that is effective in the prevention or treatment of nausea and vomiting (emesis). These agents act on...
• Anti-erythrocyte antibodyAn antibody that specifically targets and binds to antigens present on the surface of red blood cells...
• AntigenAny substance that elicits an immune response in an organism, leading to the production of antibodies or...
• Antigen presentationThe process by which certain immune cells, known as antigen-presenting cells (APCs), display fragments of...
• Antigen processingThe intracellular biochemical pathways by which protein antigens are degraded into smaller peptide fragments...
• Antigen receptorA specific protein molecule on the surface of a lymphocyte that binds to a particular antigen, initiating an...
• Antigen recognitionThe specific binding of an antigen by an antigen receptor on a lymphocyte, which is a fundamental step in...
• AntigenicDescribing a substance that can be specifically recognized by the adaptive immune system, particularly by...
• Antigenic determinantA specific region on an antigen molecule that is recognized and bound by an antibody or T-cell receptor...
• AntigenicityThe capacity of a chemical substance to bind specifically to components of the adaptive immune system, such...
• Antigen-presenting cellA cell that displays foreign antigens, complexed with major histocompatibility complex (MHC) molecules, on...
• Antigen-presenting grooveA specific binding cleft located on the surface of major histocompatibility complex (MHC) molecules, which...
• AntihistamineA drug that counteracts the effects of histamine, a substance released by the body during allergic reactions...
• Anti-idiotypic antibodyAn antibody that recognizes and binds to the unique antigen-binding site (idiotype) of another antibody. This...
• Anti-isotypic antibodyAn antibody that specifically binds to an isotype determinant, which is a constant region feature shared by...
• AntimetaboliteA substance that structurally resembles a natural metabolite and interferes with its normal metabolic...
• Antimitochondrial antibodyAn autoantibody directed against components of the mitochondria, the organelles responsible for cellular...
• AntimitoticDescribing a substance or agent that inhibits or disrupts cell division, specifically the process of mitosis...
• Antimony-xenon lampA high-pressure arc lamp in which an electrical discharge passes through xenon mixed with antimony vapour...
• anti-Müllerian hormoneA glycoprotein hormone produced by the Sertoli cells in males and granulosa cells in females. In male...
• AntimuscarinicDescribing a pharmacological agent that blocks the action of acetylcholine at muscarinic acetylcholine...
• AntimycoticA chemical agent or drug used to treat fungal infections by inhibiting the growth of fungi or killing them...
• AntineuralgicDescribing a substance or treatment that alleviates or suppresses neuralgic pain, which is characterized by...
• Antineutrophil cytoplasmic autoantibodyAn autoantibody that targets proteins within the cytoplasm of neutrophils, a type of white blood cell. These...
• Antineutrophil cytoplasmic autoantibody associated vasculitisA group of autoimmune diseases characterized by inflammation of small blood vessels, driven by the presence...
• AntinicotinicA pharmacological agent that blocks the action of acetylcholine at nicotinic receptors, which are a type of...
• AntinociceptionThe reduction in the perception of a noxious or painful stimulus, which can be achieved through...
• Antinuclear antibodyAn autoantibody that targets components within the nucleus of a cell. These antibodies are produced by the...
• AntiparticleA subatomic particle that has the same mass as its corresponding particle but opposite electric charge and...
• Antiphospholipid syndromeAn autoimmune disorder characterized by the presence of antiphospholipid antibodies, which target...
• Antiprismo-An affix in inorganic names for a set of eight atoms arranged as a square antiprism, a polyhedron in which...
• AntipsychoticA class of psychoactive drugs used to manage psychosis, particularly in conditions like schizophrenia and...
• AntipyreticA substance that reduces or prevents fever by lowering a raised body temperature. These agents act on the...
• Anti-reflective coatingA thin layer of material applied to a substrate to reduce the reflection of light from its surface. This...
• AntiresistantA substance added to a pesticide formulation to cut down insect resistance to that pesticide. It is a...
• AntiserumBlood serum containing antibodies against specific antigens, obtained from an animal or human that has been...
• Anti-sheep red blood cell IgM response assayA common immunotoxicological assay used to assess the functional integrity of the immune system, particularly...
• AntisolitonA type of topological defect in a polymer chain, particularly in conjugated polymers, that represents a...
• AntispasmodicA pharmaceutical agent that suppresses muscle spasms, particularly those affecting smooth muscles in the...
• anti-Stokes Raman scatteringA type of inelastic light scattering where the scattered photon gains energy from the molecule, resulting in...
• anti-Stokes type radiationElectromagnetic radiation emitted by a substance at a higher frequency (shorter wavelength) than the exciting...
• AntisymmetryA form of bilateral asymmetry in which individuals in a population differ markedly between their two sides...
• Antisymmetry principleA fundamental principle in quantum mechanics stating that the total wavefunction of a system of identical...
• Anti-thixotropyA rheological phenomenon where the viscosity of a non-Newtonian fluid increases over time when subjected to a...
• AntitoxinAn antibody produced by the immune system that neutralizes a specific toxin. These antibodies bind to and...
• AntrumA cavity or chamber of the body, frequently within bone, whose exact meaning depends on the organ, as in the...
• AnusThe external opening at the terminal end of the gastrointestinal tract, through which feces are expelled from...
• AnxiolyticA drug or other substance that reduces anxiety, tension, and agitation. These agents exert their effects...
• AortaThe principal and largest artery in the body, which conducts oxygen-rich blood from the heart's left...
• Aorta-gonad-mesonephros regionA region of embryonic mesoderm made up of the dorsal aorta, the genital ridges and the mesonephros, which...
• Aortic archThe curved part of the aorta that arises from the left ventricle of the heart and descends into the chest. It...
• Aortopulmonary septumA spiral-shaped wall of tissue that develops in the embryonic heart to partition the truncus arteriosus and...
• Α-oxo carbenesHighly reactive intermediates that possess a divalent carbon atom (carbene) directly adjacent to a carbonyl...
• Apex currentThe highest value of the alternating current at a maximum, called an apex, when the alternating current is...
• AphakiaA medical condition characterized by the absence of the natural crystalline lens within the eye. This absence...
• AphasiaA neurological disorder that impairs a person's ability to communicate, affecting the production or...
• AphicideA chemical substance, a type of insecticide, specifically intended to kill aphids. These agents can act as...
• AphidA small, soft-bodied insect belonging to the superfamily Aphidoidea, known for feeding on plant sap. These...
• AphoniaThe complete loss of voice, resulting in an inability to produce vocal sounds. This condition can stem from...
• AphrodisiacA substance, food, or drug believed to stimulate sexual desire or enhance sexual performance. These agents...
• ApicalDescribing a position in a trigonal bipyramidal molecular geometry that lies along the axis perpendicular to...
• ApicophilicityThe preference of a substituent in a trigonal bipyramidal molecule to occupy an apical position rather than...
• AplasiaThe incomplete or defective development of an organ or tissue, resulting in its absence or severe...
• ApneusisA prolonged inspiratory gasp followed by a short, insufficient expiration. This abnormal breathing pattern...
• Apo-A prefix with two main chemical uses. In biochemistry it marks the protein part of a conjugated protein or...
• ApodizationThe mathematical modification of a free induction decay (FID) or interferogram by multiplying it with a...
• Apodization functionA mathematical weighting function applied to an interferogram in Fourier transform spectroscopy to minimize...
• ApoenzymeThe protein component of an enzyme that is catalytically inactive without its associated non-protein cofactor...
• ApoproteinA protein that is normally associated with a non-protein component, known as a prosthetic group, but is...
• ApoptosisA highly regulated process of programmed cell death that eliminates unwanted or damaged cells from...
• ApparentA prefix used for a measured quantity in a system where the exact molecular composition or speciation is...
• Apparent molar massA molar mass worked out directly from measurements, with no allowance for effects that distort the result...
• Apparent monomerThe constitutional unit of a polymer that is named as if it were the monomer for the purposes of source-based...
• Apparent rate constant of polymerisationA rate constant that describes the overall speed of a polymerization reaction under specific experimental...
• Apparent viscosityThe ratio of shear stress to shear rate for a non-Newtonian fluid, measured at a specific shear rate and...
• Appearance energyThe minimum energy required to form a particular fragment ion from a neutral molecule, along with any neutral...
• Appearance temperatureThe minimum temperature at which a specific analyte signal can be detected in electrothermal atomic...
• Appendicular skeletonThe portion of the vertebrate skeleton that includes the bones of the limbs, as well as the pectoral...
• AppendixA small, finger-like blind tube attached to the cecum, the first part of the large intestine, in humans and...
• AppertisationA food preservation method involving the heating of food in sealed containers to a temperature and for a...
• Applicability domainThe response and chemical structure space in which a computational model, such as a quantitative...
• Applied potentialThe electrical voltage intentionally imposed across an electrochemical cell or between an electrode and a...
• ApraxiaA neurological disorder characterized by the inability to perform learned voluntary movements despite having...
• Aprotic solventA solvent that does not have a hydrogen atom bonded to an electronegative atom like oxygen or nitrogen, and...
• AquagelA hydrogel whose network is a colloidal network, that is, a gel with water as the liquid component held in an...
• AquamolalityA measure of solute concentration in a mixed solvent, equal to the molality of the solute multiplied by the...
• AquationA chemical reaction in which a ligand in a coordination complex is replaced by a water molecule. This process...
• Arachno-A structural prefix used to describe a polyhedral cluster of atoms, particularly in boranes and their...
• ArachnodactylyA congenital physical condition characterized by abnormally long and slender fingers and toes, giving them a...
• Arachnoid membraneA delicate, web-like middle layer of the meninges, the protective membranes that surround the brain and...
• Arachnoid villusA small protrusion of the arachnoid membrane, one of the three meninges covering the central nervous system...
• ArachnoiditisAn inflammatory condition of the arachnoid membrane, one of the three layers of tissue that surround the...
• Α-ray spectrometerAn instrument designed to measure the energy distribution of alpha particles emitted from a radioactive...
• ArboricideA substance or agent specifically designed to kill trees or woody plants. These chemicals are often...
• ArborizationThe characteristic branching pattern of nerve cell extensions, such as dendrites and axons, resembling the...
• Archibald's methodA technique for determining the weight-average molar mass of macromolecules in solution using an analytical...
• Arcsine square root transformationA statistical data transformation applied to proportional data, such as percentages or fractions, to...
• AreaThe geometric or projected area of an electrode surface in contact with the solution, taken without regard to...
• Area of interfaceThe boundary region between two immiscible phases where their properties change abruptly. This area is where...
• Area sourceA diffuse source of air pollution that originates from a collection of individually small emission points...
• Area under the curveA quantitative measure derived from a plot of a variable against another, often time, representing the...
• Area under the moment curveA pharmacokinetic parameter derived from the product of time and drug concentration in the blood plasma...
• Area-related parametersQuantities expressed per unit area, such as a reaction rate or an amount adsorbed divided by the surface area...
• AreicA property of a substance or system expressed per unit of area. The term is used as a prefix or adjective to...
• Areic doseThe number of energetic particles of a stated kind, such as ions or atom clusters, that enter a solid through...
• Areic dose rateThe areic dose of energetic particles introduced into a solid during a time interval, divided by that...
• Areic surface energyThe excess energy per unit area at the surface of a material compared to the bulk. This energy arises from...
• Arene epoxidesA class of epoxy compounds in which an epoxide ring, also known as an oxirane ring, is fused to an aromatic...
• ArenesA class of aromatic hydrocarbons characterized by one or more benzene rings. These compounds exhibit enhanced...
• Arenium ionsCarbocation intermediates formed during electrophilic aromatic substitution reactions, where an electrophile...
• ArenolsA class of organic compounds characterized by a hydroxyl group directly attached to a carbon atom of an...
• AreolaA small, circular area of different coloration surrounding a central point, often referring to the pigmented...
• Argon ion laserA type of gas laser that uses ionized argon gas as the gain medium to produce coherent light. It emits light...
• ArgyriaA permanent discoloration of the skin, mucous membranes, and internal organs caused by chronic exposure to...
• Arithmetic meanA measure of central tendency calculated by summing a set of numerical values and dividing by the number of...
• Arnold-Chiari malformationA structural defect in the cerebellum, the part of the brain that controls balance, where the lower part of...
• AromataseAn enzyme, also known as estrogen synthase, that catalyzes the final step in estrogen biosynthesis from...
• AromaticDescribing a ring-shaped, fully conjugated molecule whose measured stability exceeds what would be expected...
• Aromatic photocycloadditionA photochemical reaction where two or more molecules, at least one of which is aromatic, combine to form a...
• Aromatic substitution photochemical electrophile-olefin combinationA photochemical reaction involving the substitution of a group on an aromatic ring by an electrophilic...
• Aromatic substitution photochemical radical-olefin combinationA photochemical aromatic substitution that joins three separate partners, a free radical, an alkene and an...
• AromaticityA property of cyclic, planar molecules with a delocalized pi-electron system that confers enhanced stability...
• Array detectorA device consisting of multiple individual detector elements arranged in a one-dimensional or two-dimensional...
• ArresterEquipment that removes solid or liquid particles from a stream of gas, as used on stacks and exhaust ducts to...
• ArrhythmiaAn abnormality in the heart's rhythm, rate, or conduction system, causing the heart to beat too fast, too...
• ArsanesSaturated acyclic and cyclic arsenic hydrides with the general formula AsₙHₙ₊₂, or AsₙHₙ for monocycles. The...
• ArsanylidenesCarbene analogues of the form R-As:, in which a monosubstituted arsenic atom carries a lone pair and two...
• Arsanylium ionsThe arsanyl cation H2As+ and its substitution derivatives R2As+, in which a two-coordinate arsenic atom...
• ArseniasisA condition resulting from chronic exposure to arsenic, leading to a range of health effects depending on the...
• ArsenidesAnionic species formally derived by the removal of one or more hydrons from arsane, AsH₃, or its derivatives...
• Arsine oxidesOrganic compounds containing a pentavalent arsenic atom double-bonded to an oxygen atom and single-bonded to...
• ArsinesOrganic compounds containing at least one arsenic-carbon bond, formally derived from arsane (AsH3) by...
• Arsinic acidsOrganic arsenic compounds containing an arsenic atom bonded to two hydrocarbyl groups, one hydroxyl group...
• Arsinous acidsOrganoarsenic(III) compounds of the type R2AsOH, with H2AsOH as parent, in which arsenic carries two...
• Arsonic acidsOrganoarsenic(V) acids of the type RAs(=O)(OH)2, in which arsenic carries one hydrocarbyl group, one oxo...
• Arsonium compoundsOrganic compounds characterized by a positively charged arsenic atom, As+, bonded to four organic groups...
• Arsonous acidsOrganoarsenic(III) compounds of the type RAs(OH)2, formally derived from arsenous acid, As(OH)3, by replacing...
• ArsoranesPentacoordinate arsenic(V) compounds derived from the hydride AsH5, named lambda5-arsane, by replacing...
• ArteriogenesisThe process of remodeling existing small arteries into larger, more functional collateral vessels in response...
• Arteriolovenular anastomosisA direct vascular connection between an arteriole and a venule that allows blood to bypass the intervening...
• ArteriosclerosisA group of diseases characterized by the thickening, hardening, and loss of elasticity of the walls of...
• ArteriovenousRelating to or connecting both an artery and a vein. The term describes anatomical structures, physiological...
• Arteriovenous anastomosisA direct connection between an artery and a vein, allowing blood to bypass the capillary network. These...
• Arteriovenous fistulaAn abnormal connection or passageway formed directly between an artery and a vein, bypassing the capillaries...
• Arteriovenous malformationA congenital disorder characterized by an abnormal tangle of blood vessels where arteries connect directly to...
• Arteriovenous shuntA route by which blood passes straight from an artery to a vein, skipping the capillary beds and so...
• ArthralgiaPain experienced in a joint without objective signs of inflammation, such as swelling or redness. This...
• ArthritisInflammation of one or more joints, characterized by pain, swelling, stiffness, and reduced range of motion...
• ArthrosisA degenerative joint disease characterized by the breakdown of cartilage and underlying bone in a joint...
• Arthus reactionA localized type III hypersensitivity reaction characterized by tissue necrosis resulting from the formation...
• ArtifactAn observation or result that is not naturally present but arises from the experimental or observational...
• ArtificialDescribing a substance or material that is not naturally occurring but is instead synthesized or modified by...
• Artificial inseminationA reproductive technology involving the deliberate introduction of sperm into a female's reproductive tract...
• Artificial latexA colloidal dispersion of a pre-existing polymer in a continuous liquid phase, usually water. The polymer is...
• Artificial neural networksComputational models inspired by the structure and function of biological neural networks, consisting of...
• Artificial organA man-made device or tissue construct designed to replace or augment the function of a natural biological...
• Artificial photosynthesisA process that mimics natural photosynthesis to convert sunlight, water, and carbon dioxide into chemical...
• Artificial polymerAny polymer produced by people rather than by living organisms and not itself a biopolymer, which covers...
• Artificial radioactivityRadioactivity induced in a stable nuclide by bombarding it with energetic particles, such as neutrons...
• Artificial soil testA standardized ecotoxicological assay conducted in a laboratory setting using a precisely formulated soil...
• Artisol testAn earthworm toxicity test in which worms are kept in an artificial medium of silica, water and glass beads...
• Aryl cationsA carbocation obtained formally when a ring carbon of an arene loses a hydride ion, the phenyl cation C6H5+...
• Aryl groupsUnivalent organic groups derived from an arene by the removal of one hydrogen atom from a ring carbon. These...
• Aryl hydrocarbon hydroxylaseA cytochrome P450 enzyme, specifically CYP1A1, that catalyzes the hydroxylation of aryl hydrocarbons...
• Aryl hydrocarbon receptorA ligand-activated transcription factor that mediates the toxic and biological effects of certain...
• Aryl hydrocarbon receptor nucleotide translocator proteinA protein that forms a heterodimer with the ligand-bound aryl hydrocarbon receptor (AhR) in the nucleus. This...
• Arylene groupsDivalent organic groups derived from an aromatic hydrocarbon by the removal of two hydrogen atoms from ring...
• AryneA highly reactive, neutral intermediate derived from an aromatic compound by the formal removal of two...
• As low as reasonably achievableA principle in risk management, particularly in radiation protection and environmental safety, that aims to...
• AsbestosisA chronic lung disease caused by inhaling asbestos fibers, leading to scarring of lung tissue and impaired...
• AscaricideA chemical agent or drug used to kill or expel parasitic roundworms of the genus Ascaris from the...
• Ascending elutionA chromatographic technique where the mobile phase flows upwards through a stationary phase, against the...
• AshThe non-combustible solid residue remaining after the complete combustion of a substance, such as coal, wood...
• AshingA sample preparation procedure for decomposing the organic matrix of a sample to preconcentrate non-volatile...
• Aspect ratioThe ratio of the height of a feature to its width, particularly in the context of micro- or nanofabrication...
• AsphyxiaA condition characterized by a severe deficiency of oxygen in the body, accompanied by an excess of carbon...
• AsphyxiantA substance that causes suffocation by displacing oxygen from the air or by interfering with the body's...
• AspiratorA device that creates a partial vacuum by means of a high-velocity fluid jet, often water or air. The moving...
• AssayA procedure for determining the quantity of a specific substance, such as a chemical compound or a biological...
• Assay kitA pre-packaged collection of reagents and materials designed for performing a specific analytical test or...
• Assay validationThe process of establishing the performance characteristics and limitations of an analytical method, and the...
• AssemblageA collection of organisms of phylogenetically related species that are found together in a specific habitat...
• Assessment endpointAn explicit expression of the environmental value to be protected, often stated as a measurable...
• AssessorA person assigned by an accreditation body to judge the competence of a laboratory, working alone or within...
• Assigned valueA value attributed to a particular quantity and accepted, sometimes by convention, as having an uncertainty...
• AssimilationThe process by which chemical substances are taken up by a living organism from its environment and...
• AssociationThe process by which molecules or ions combine to form larger aggregates, often through non-covalent...
• Association reactionA chemical reaction in which two or more molecules or fragments combine to form a single, larger molecule...
• Associative avoidance testA behavioral paradigm used to study learning and memory, where an animal learns to associate a neutral...
• Associative ionizationAn ionization process where two neutral atoms or molecules collide and combine to form a single molecular...
• Associative learningA type of learning where an organism learns to connect two or more stimuli or events that occur together in...
• AstheniaA medical condition characterized by a general feeling of weakness, lack of energy, and physical or mental...
• AsthmaA chronic inflammatory disease of the airways, characterized by recurrent episodes of wheezing...
• AstringentA chemical substance that causes the constriction or shrinkage of body tissues, particularly mucous membranes...
• AstrocyteA star-shaped glial cell found in the brain and spinal cord, making up a large proportion of the cells in the...
• Astrocytic scarA dense barrier formed by reactive astrocytes at the site of central nervous system injury, such as stroke or...
• AstrocytomaA type of brain tumor that originates from astrocytes, which are glial cells that support neurons in the...
• AstrogliosisA reactive process of astrocytes in response to central nervous system injury, disease, or infection...
• Asym-A nomenclature affix, short for asymmetrical, used in older names to mark the less symmetrical of two...
• AsymmetricDescribing a molecule or object that lacks any element of symmetry, meaning it cannot be superimposed on its...
• Asymmetric carbon atomA carbon atom that is covalently attached to four non-identical atoms or groups, creating a center of...
• Asymmetric enantiomer-differentiating polymerizationA polymerization in which a chiral catalyst or initiator acts on a racemic mixture of chiral monomers and...
• Asymmetric filmA thin film, usually of liquid, that is bounded on its two sides by different bulk phases, for example a...
• Asymmetric inductionThe preferential formation of one enantiomer or diastereomer over another during a chemical reaction...
• Asymmetric membraneA membrane characterized by a non-uniform structure across its cross-section, typically consisting of a...
• Asymmetric photochemistryPhotochemical reactions that produce a chiral product with an excess of one enantiomer, starting from an...
• Asymmetric polymerizationA polymerization process that yields a polymer with a preferred handedness or chirality, even when starting...
• Asymmetric synthesisA chemical reaction or sequence of reactions that converts an achiral starting material into a chiral...
• Asymmetric topA type of rigid rotor molecule in which all three principal moments of inertia are distinct. This molecular...
• Asymmetric transformationA process in which a racemic mixture is converted into a single enantiomer or diastereomer, often through a...
• Asymmetrical flow field-flow fractionationA separation technique that separates macromolecules or particles based on their diffusion coefficients. The...
• AsymmetryThe absence of symmetry elements in a molecule or object, meaning it cannot be superimposed on its mirror...
• Asymmetry factorA measure of the peak shape in chromatography, calculated as the ratio of the distance from the peak maximum...
• Asymmetry parameterThe factor β, used in X-ray photoelectron spectroscopy, that characterizes how the intensity of...
• Asymmetry potentialThe potential difference that develops across a glass electrode when identical solutions are present on both...
• Asymptotic threshold concentrationThe concentration of a chemical at which a given percentage of the test organisms stay in approximate...
• Atactic macromoleculeA macromolecule in which the pendant groups or substituent atoms are randomly distributed on either side of...
• Atactic polymerA polymer in which the substituent groups along the backbone chain are arranged randomly with respect to...
• AtaxiaA neurological sign consisting of a lack of voluntary coordination of muscle movements, which can include...
• Ataxia telangiectasiaA rare, inherited neurodegenerative disorder characterized by progressive cerebellar ataxia, oculocutaneous...
• AtelectasisA complete or partial collapse of a lung or a lobe of a lung, occurring when the alveoli within the lung...
• AtheliaA rare congenital anomaly characterized by the complete absence of one or both nipples. This condition can...
• AtherosclerosisA chronic inflammatory disease characterized by the buildup of plaque, composed of cholesterol, fats, and...
• AthetosisA neurological condition characterized by continuous, slow, involuntary, and writhing movements, particularly...
• AthymiaThe congenital absence of the thymus gland, either partially or completely. This condition results in a...
• At-line extractionA sampling technique where a portion of the sample is removed from the process stream and transferred to an...
• AtmosphereA non-SI unit of pressure, historically defined as the pressure exerted by a column of mercury 760 mm high at...
• Atmospheric depositionThe process by which airborne substances, including pollutants and nutrients, are transferred from the...
• Atmospheric pressure chemical ionizationA soft ionization technique used in mass spectrometry where analytes are ionized at atmospheric pressure...
• Atmospheric pressure ionizationA soft ionization technique used in mass spectrometry where ions are generated at atmospheric pressure before...
• Atmospheric pressure matrix-assisted laser desorption/ionizationAn ionization method in mass spectrometry where a sample, embedded in a matrix, is desorbed and ionized by a...
• Atmospheric pressure photoionizationAn ionization technique used in mass spectrometry where analytes are ionized by photons at atmospheric...
• AtomThe smallest unit of ordinary matter that forms a chemical element, consisting of a nucleus of protons and...
• Atom-atom polarizabilityA measure of how the electron density at one atom in a molecule changes in response to a perturbation, such...
• Atom-bond polarizabilityA Hückel perturbation-theory quantity measuring how much the pi electron density at one atom changes when the...
• Atomic absorption spectroscopyA spectroanalytical procedure for the quantitative determination of chemical elements, based on the...
• Atomic chargeA calculated value representing the net electric charge associated with a specific atom within a molecule. It...
• Atomic emission spectroscopyA spectroanalytical technique that measures the intensity of light emitted by excited atoms in a sample to...
• Atomic excitation sourceA device or mechanism that provides the energy necessary to promote atoms from their ground electronic state...
• Atomic fluorescenceThe emission of electromagnetic radiation by excited atoms that have absorbed radiation of a specific...
• Atomic fluorescence spectroscopyA spectroanalytical technique that measures the intensity of fluorescent radiation emitted by atoms after...
• Atomic force microscopyA high-resolution scanning probe microscopy technique that images the topography of a sample surface by...
• Atomic laserA gas laser whose lasing medium is a vapour of free atoms, excited by energy handed over from other atomic or...
• Atomic massThe mass of an atom, typically expressed in unified atomic mass units (u). This value represents the total...
• Atomic mass constantA constant with the dimension of mass, equal to one twelfth of the mass of a free carbon-12 atom at rest in...
• Atomic mixingThe intermingling of different atomic species within a material, typically induced by energetic particle...
• Atomic numberThe quantity of protons present within the nucleus of an atom of a particular chemical element. This number...
• Atomic orbitalA mathematical function that describes the wave-like behavior of an electron or a pair of electrons in an...
• Atomic polar tensorA 3 by 3 tensor, one per atom, whose elements are the derivatives of the molecular dipole moment components...
• Atomic spectral linesNarrow, discrete wavelengths of electromagnetic radiation emitted or absorbed by atoms as their electrons...
• Atomic spectroscopyA broad category of analytical techniques that study the interaction of electromagnetic radiation with atoms...
• Atomic symbolA one- or two-letter abbreviation used to represent a chemical element, derived from its name, often in Latin...
• Atomic unitsA system of natural units used in atomic physics and quantum chemistry, where fundamental physical constants...
• Atomic vapourA gaseous phase consisting of individual, neutral atoms of an element, distinct from a molecular gas where...
• AtomizationThe process of converting a sample from a solid, liquid, or gaseous state into a population of free...
• Atomization curveA graph of the absorbance of an analyte against the atomization temperature in electrothermal atomic...
• Atomization surface temperatureThe temperature of the interior surface of an electrothermal atomizer at the moment of maximum absorbance...
• AtomizeTo break a liquid into a fine spray of very small droplets, often by forcing it through a small orifice or by...
• AtomizerAny system that converts an analyte into atomic vapour, such as a flame, a graphite furnace, an inductively...
• Atom-molecule complex mechanismA reaction mechanism in chemical kinetics where an atom and a molecule first form a transient, weakly bound...
• Atom-transfer radical polymerizationA controlled radical polymerization technique that uses a reversible halogen atom transfer between a dormant...
• AtonyA physiological state characterized by the loss of normal muscular tone or strength, resulting in muscles...
• Atopic allergyA hypersensitivity reaction mediated by immunoglobulin E (IgE) antibodies, leading to symptoms such as...
• Atopic dermatitisA chronic inflammatory skin condition characterized by intensely itchy, red, and scaly rashes, often...
• Atopic eczemaA chronic inflammatory skin disorder characterized by recurrent itchy, erythematous, and scaly lesions...
• AtopyA genetic predisposition to develop allergic diseases, such as asthma, allergic rhinitis (hay fever), or...
• ATP binding cassette proteinA large family of transmembrane proteins that transport a wide variety of substrates across cellular...
• AtresiaThe congenital absence or abnormal narrowing of a body opening or tubular structure, such as a duct or canal...
• Atrial-septal defectA congenital heart defect characterized by a hole in the septum, the wall separating the two upper chambers...
• Atrichia congenitaA rare genetic disorder characterized by the complete absence of hair from birth, affecting the scalp and...
• AtrioventricularRelating to the structures, functions, or region between the atria and the ventricles of the heart. This...
• AtriumA chamber of the heart that receives blood from the body or lungs and pumps it into a ventricle. Humans and...
• AtrophyA reduction in the size of a cell, tissue, organ, or part of the body, resulting from a decrease in cell size...
• AtropisomersStereoisomers produced by hindered rotation about a single bond, where the energy barrier is large enough for...
• AttachmentA transformation in which a substrate is converted into a larger molecular entity by forming exactly one...
• Attention deficit hyperactivity disorderA neurodevelopmental disorder characterized by persistent patterns of inattention, hyperactivity, and...
• AttenuanceA measure of the reduction in radiant power of an electromagnetic wave as it passes through a medium...
• Attenuance filterAn optical filter designed to reduce the intensity of incident radiation over a specific range of wavelengths...
• Attenuated total reflectionA phenomenon where an electromagnetic wave, typically infrared light, undergoes total internal reflection at...
• Attenuated total reflection infrared spectroscopyA spectroscopic technique that uses attenuated total reflection to obtain infrared spectra of samples...
• Attenuated total reflection spectroscopyA spectroscopic technique that involves placing a sample in contact with an internal reflection element...
• Attenuated vaccineA type of vaccine that contains a weakened, live form of the pathogen, which has been modified to lose its...
• AttenuationThe reduction in the intensity of radiation as it passes through a medium, resulting from absorption and...
• Attenuation coefficientA quantitative measure of how strongly a substance or medium impedes the passage of radiation, such as light...
• AttoThe standard SI prefix for a factor of one quintillionth, or 10⁻¹⁸. It is assigned the symbol 'a' and is...
• AttractantA substance that induces an organism to move towards its source. These chemical signals can be volatile...
• Attractive potential-energy surfaceA region on a potential-energy surface where the energy decreases as reactants approach each other...
• Attractive-mixed-repulsive classificationA system for categorizing the dynamics of a chemical reaction based on the location of the energy barrier...
• Attributable riskThe part of the risk of disease in an exposed group that is due to the exposure, calculated as the incidence...
• Attrition rateThe rate at which drug candidates are lost as they progress through the development stages on the way to the...
• Atypical interstitial pneumoniaAn acute or chronic respiratory distress of cattle that occurs without the toxemia or other systemic signs...
• AuditA planned, impartial and recorded examination in which evidence is gathered and judged against a set of...
• Auditory tubeA narrow passage connecting the middle ear to the nasopharynx, also known as the Eustachian tube. Its primary...
• Aufbau principleA rule that dictates the filling of atomic orbitals with electrons in an atom or ion. It states that...
• AufwuchsA complex community of microorganisms, algae, fungi, and detritus that grows on submerged surfaces in aquatic...
• Auger effectA process in which an atom with an inner-shell vacancy relaxes by ejecting an outer-shell electron, known as...
• Auger electronAn electron emitted from an atom during the Auger effect, which is a non-radiative process where an...
• Auger electron spectroscopyA surface-sensitive analytical technique that identifies elements present in the top few atomic layers of a...
• Auger electron spectrumA plot of the number of emitted Auger electrons as a function of their kinetic energy. The spectrum is...
• Auger electron yieldThe probability that an inner-shell vacancy in an atom will be filled by an electron transition that results...
• Auger neutralizationA process where an ion approaching a surface captures an electron from the surface, leading to the emission...
• Auger parameterA quantity in X-ray photoelectron spectroscopy equal to the kinetic energy of a sharp Auger line minus the...
• Auger photoelectron coincidence spectroscopyAn analytical technique in which an Auger electron and a photoelectron, both originating from the same atom...

1,115 of 13,676 terms in Chemistry terminology (MLC-0109). Request the full dataset.