Chemistry terminology · MLC-0109

Chemistry terms: P (1,381)

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• Precision limitThe smallest difference between two measurement results that can be distinguished from random variation under...
• Precision of indicationThe standard deviation of the repeated indications of an instrument, such as a balance, when the same stated...
• Preclinical candidateA chemical compound or biological entity that has demonstrated promising activity in early-stage research and...
• PreconcentrationA process that increases the concentration of an analyte in a sample prior to its analysis. This technique is...
• Preconcentration coefficientA ratio that quantifies the enrichment of an analyte during a preconcentration procedure before its final...
• PrecordialRelating to the region of the chest wall situated in front of the heart. This anatomical area is the site for...
• PrecursorA nuclide that precedes another nuclide in a radioactive decay chain. The precursor undergoes radioactive...
• Precursor complexAn intermediate complex formed between two or more molecular entities that precedes the main chemical...
• Precursor ionAn ion selected in a mass spectrometry experiment that undergoes fragmentation to produce other ions. This...
• Precursor ion spectrumA type of mass spectrum obtained in tandem mass spectrometry where a specific product ion is selected, and...
• Predatory mite testA soil toxicity test in which adult female predatory mites, usually Hypoaspis aculeifer, are exposed to a...
• Predicted environmental concentrationA calculated value representing the expected concentration of a chemical substance in a specific...
• Predicted no-effect concentrationA concentration of a substance below which adverse effects on an ecosystem or specific organisms are not...
• Prediction error sum of squaresA statistical measure used in multivariate calibration and regression analysis to assess the predictive...
• Prediction setA collection of chemical compounds or data points used to evaluate the performance of a computational model...
• Predictive risk assessmentThe process of estimating the potential for adverse effects of a substance or activity on human health or the...
• Predictive validityThe extent to which a test or measurement accurately forecasts a future outcome or behavior. This type of...
• Predictive valueA statistical measure that indicates the probability that a test result correctly reflects the true presence...
• PredissociationA process where a molecule, excited to a discrete rovibronic state, undergoes non-radiative decay to a...
• Pre-eclampsiaA serious medical condition that develops during pregnancy, characterized by high blood pressure and signs of...
• Pre-embryoThe early human conceptus from fertilization to about day 14, covering cleavage of the zygote, the morula and...
• Pre-equilibriumA preparatory step in solvent extraction in which the solvent, or one phase, is first contacted with a...
• Pre-exponential factorThe constant 'A' in the Arrhenius equation, k = A exp(-Ea/RT), which represents the frequency of collisions...
• Preferential sorptionThe phenomenon where one component of a mixed solvent system is adsorbed or absorbed by a polymer to a...
• Preferential sputteringThe phenomenon where certain atomic or molecular species are ejected from a solid surface at a higher rate...
• Preferred constitutional repeating unitThe specific constitutional repeating unit (CRU) chosen by applying a defined set of IUPAC seniority rules...
• Pre-filter effectThe reduction in the intensity of excitation radiation reaching the sample in luminescence spectroscopy due...
• PreformulationThe stage of drug development where the physical and chemical properties of a new drug substance are...
• Pre-gel regimeThe stage in a crosslinking polymerization reaction before the formation of an infinite network or gel point...
• Pre-gel stateThe condition of a polymerizing system before it reaches the gel point, where an infinite network structure...
• PregnancyThe physiological state of a female mammal from conception until birth, characterized by the presence of a...
• Preheating inductively-coupled plasma zoneThe initial region of an inductively coupled plasma (ICP) torch where the incoming sample aerosol and argon...
• Pre-implantationThe period of early embryonic development occurring after fertilization but before the embryo fully embeds...
• Pre-ionization stateAn excited electronic state of an atom or molecule that lies above the first ionization limit but is still...
• Premature birthThe birth of an infant before the completion of the normal gestation period. It is specifically defined as...
• Premature ovarian failureA condition characterized by the loss of normal ovarian function before the age of 40, resulting in irregular...
• Premium cokeA high-quality petroleum coke characterized by low levels of impurities, particularly sulfur and metals, and...
• Premix burnerA type of burner used in atomic absorption and emission spectroscopy where the fuel gas and oxidant are...
• PrenatalRelating to the period before birth, encompassing the developmental stages of an organism from conception...
• Prenatal development studyA toxicity study in which pregnant animals, usually rats or rabbits, are dosed daily through organogenesis...
• PreneoplasticDescribing a condition or lesion that precedes the development of a malignant neoplasm but is not yet...
• Prenol lipidsA class of lipids built from isoprene units, the five-carbon building blocks IPP and DMAPP (isopentenyl and...
• PrenolsAlcohols of the general formula H(CH2C(CH3)=CHCH2)nOH, whose carbon skeleton consists of one or more...
• Preoptic areaA region of the anterior hypothalamus located rostral to the optic chiasm, involved in regulating several...
• Pre-polymerA polymer of low molecular weight, or an oligomer, that is capable of further polymerization to form a higher...
• PrepolymerAn oligomeric or polymeric substance that contains reactive functional groups capable of undergoing further...
• Pre-polymer moleculeA macromolecule of intermediate molecular weight that still possesses reactive functional groups, allowing it...
• PrepregA composite material consisting of a fibrous reinforcement, such as carbon or glass fibers, that has been...
• PrepubertalRelating to the period of development before the onset of puberty, characterized by the absence of secondary...
• PrepubescenceThe period of late childhood just before puberty, when the gonads are still largely inactive and secondary...
• PrepuceA retractable fold of skin and mucous membrane that covers and protects the glans of the penis in males or...
• Preputial separationA developmental event in male mammals where the prepuce, or foreskin, detaches from the glans penis to which...
• Pre-reactive complexesTransient molecular assemblies formed by reactants prior to the actual chemical reaction, held together by...
• PresaturationA technique in nuclear magnetic resonance (NMR) spectroscopy that selectively reduces the signal intensity of...
• Presenile dementiaA progressive loss of cognitive function that begins before the age of 65. The condition involves memory...
• PressureThe force exerted perpendicularly per unit area on a surface. In chemistry, it is a fundamental thermodynamic...
• Pressure broadeningThe widening of spectral lines in absorption or emission spectroscopy due to collisions between the radiating...
• Pressure gradient correction factorA factor applied in gas chromatography to account for the compressibility of the carrier gas as it flows...
• Pressure-induced transitionA phase transformation in a solid material that occurs solely due to changes in applied external pressure...
• Pressure-sensitive detectorA device that detects radiation by measuring the pressure change in a gas-filled chamber caused by the...
• Pressurized hot-water extractionAn extraction technique that uses water at elevated temperatures and pressures to extract analytes from a...
• Pressurized-liquid extractionAn extraction technique that uses organic solvents or water at elevated temperatures and pressures to extract...
• PresynapticRelating to the neuron that transmits a signal across a synapse to another neuron or an effector cell. This...
• pre-T cellAn immature T lymphocyte that has successfully rearranged its T cell receptor beta chain gene and expresses a...
• PretreatmentA preparatory step applied to a material or system before a main chemical or physical process. This can...
• PrevalenceThe proportion of a population that has a specific characteristic or disease at a given point in time or over...
• Prevalence rateThe proportion of individuals in a population who have a particular disease or condition at a specific time...
• Prick testA diagnostic procedure used to identify immediate hypersensitivity reactions to specific allergens. A small...
• Primary aerosolThe aerosol generated directly by a nebulizer when a liquid sample is converted into droplets for...
• Primary beamA directed flux of particles or photons incident on a sample in a surface analysis technique, which excites...
• Primary biliary cirrhosisA chronic autoimmune liver disease characterized by the progressive destruction of small bile ducts within...
• Primary crystallizationThe initial phase of crystallization in a polymer melt or solution, where the first ordered structures begin...
• Primary dataThe set of original, unprocessed experimental values obtained directly from a measurement process before any...
• Primary electronsElectrons originating directly from an electron source, such as an electron gun in an electron microscope or...
• Primary examination standardThe top-ranking examination standard for a nominal property, a qualitative characteristic such as a blood...
• Primary immune responseThe initial immune reaction that occurs upon the first exposure of the immune system to a specific antigen...
• Primary immunizationThe initial administration of an antigen to an individual to induce a primary immune response and establish...
• Primary ionAn ion generated externally and directed at a sample surface to induce sputtering or ionization of the sample...
• Primary isotope effectThe change in reaction rate or equilibrium constant when an atom directly involved in the bond-breaking or...
• Primary lamellaeThe gill filaments of a fish, the structures that project outward from each branchial arch and carry the...
• Primary lymphoid follicleA dense, spherical aggregation of B lymphocytes found in lymphoid organs such as lymph nodes and the spleen...
• Primary lymphoid organAn anatomical site where lymphocytes originate and mature into immunocompetent cells. These organs are...
• Primary metaboliteA compound that is directly involved in the normal growth, development, and reproduction of an organism...
• Primary mixtureA gas mixture prepared by a gravimetric method, where the mass of each component is precisely weighed to...
• Primary myxedemaA condition characterized by severe hypothyroidism resulting from a dysfunction of the thyroid gland itself...
• Primary nucleusA stable, microscopic region of ordered polymer chains that forms spontaneously from a disordered melt or...
• Primary oocyteA diploid germ cell in the ovary that undergoes meiosis I to produce a secondary oocyte and a polar body...
• Primary pH standardsAqueous solutions of precisely defined composition and known pH values, used for calibrating pH meters and...
• Primary photochemical processAn elementary chemical step undergone by an electronically excited molecule that converts it into the first...
• Primary photoproductThe molecular entity formed directly from the primary photochemical process, which is the immediate...
• Primary pollutantA harmful substance that is emitted directly into the atmosphere from a source, without undergoing any...
• Primary producerAn organism that creates its own food from inorganic sources of energy and nutrients. These autotrophs form...
• Primary protection standardA limit on the burden of a pollutant, or a marker substance for it, that an exposed organism or one of its...
• Primary radicalA highly reactive species, typically an atom or molecule with an unpaired electron, generated from the...
• Primary reference examination procedureThe procedure that gives an examination result for a nominal property, such as a blood group or a base...
• Primary sampleA portion of material taken directly from a larger quantity, such as a batch, lot, or environment, at a...
• Primary sclerosing cholangitisA chronic liver disease where the bile ducts inside and outside the liver become inflamed and scarred...
• Primary screenThe initial high-throughput screening experiment conducted to identify compounds or agents with a desired...
• Primary sex organAn organ that produces gametes, the reproductive cells of an organism. In vertebrates, these organs are the...
• Primary speciesThe initial radical or ionic species formed directly from the decomposition or activation of an initiator...
• Primary structureThe linear sequence of monomer units in a polymer, specifically referring to the order of amino acids in a...
• Primary successionThe ecological process of community development that occurs in an area previously devoid of life, such as...
• Primary-radical terminationThe termination of a growing polymer chain by reaction with a primary radical, which is a radical derived...
• PrimeTo prepare an immune system for a stronger, more rapid response to a subsequent exposure to an antigen. This...
• PrimerA short nucleic acid strand, typically an oligonucleotide of RNA or DNA, that serves as a starting point for...
• Primitive axisThe longitudinal axis that defines the initial body plan of an embryo during early development. This axis is...
• Primitive chainA conceptual representation of a polymer chain's trajectory within a dense polymeric melt or solution, where...
• Primitive changeA fundamental alteration in the geometry of a reacting system, such as a change in bond length or bond angle...
• Primitive grooveA longitudinal depression that forms within the primitive streak during gastrulation in early embryonic...
• Primitive nodeA knot of cells at the front end of the primitive streak in an amniote embryo that serves as the organizer of...
• Primitive pitA small depression at the centre of the primitive node, at the cranial end of the primitive streak, in the...
• Primitive streakA transient structure that forms in the early embryo during gastrulation, marking the beginning of germ layer...
• Primordial follicleThe most immature stage of an ovarian follicle, consisting of a primary oocyte arrested in prophase I of...
• Primordial germ cellPrecursor cells that are set aside early in embryonic development and eventually differentiate into gametes...
• PrimordiumThe earliest stage of development of an organ or tissue in an embryo or fetus, before it has taken on its...
• Principal component loadingA measure of the correlation between an original variable and a principal component in principal component...
• Principal component scoreA value representing the position of an observation along a principal component axis in multivariate data...
• Principal component-discriminant analysisA chemometric technique that combines principal component analysis with discriminant analysis to classify...
• Principal components regressionA multivariate statistical method that combines principal component analysis with multiple linear regression...
• Principal groupThe functional group chosen as the basis for naming an organic compound according to IUPAC nomenclature...
• Principal ionA molecular or fragment ion built from the most abundant isotope of each of its atoms, such as 12C, 1H, 16O...
• Principal moments of inertiaThe moments of inertia of a body about its three mutually perpendicular principal axes, chosen so that all...
• Principal-component analysisA statistical procedure that transforms a set of possibly correlated variables into a smaller set of...
• Principal-component factorA latent variable obtained in principal-component analysis as a linear combination of the original measured...
• Principle of allocationA concept in ecotoxicology stating that an organism has a finite amount of energy and resources to allocate...
• Principle of least nuclear motionA qualitative rule stating that chemical reactions tend to proceed in a way that involves the minimum...
• Principle of microscopic reversibilityA principle stating that at equilibrium, the rate of every elementary process is equal to the rate of its...
• Prior distributionThe distribution of product molecules among energy states that a model of the reaction predicts, evaluated at...
• Prior informed consentA formal agreement obtained from an individual or community before engaging in an activity that may affect...
• Prior probabilityThe probability assigned to a parameter or a hypothesis before any empirical evidence is taken into account...
• Privileged structureA molecular scaffold or core structure that is capable of binding to multiple biological targets with high...
• ProbabilityA numerical measure of the likelihood that a specific event will occur, expressed as a value between 0 and 1...
• Probability densityA function whose integral over a given range gives the probability that a continuous random variable falls...
• Probability-based matchingA method used in mass spectrometry for identifying unknown compounds by comparing their experimental mass...
• ProbeA molecule, often a nucleic acid or protein, that is labeled with a detectable marker and used to identify or...
• Probe ionAn ion directed at a sample surface to induce sputtering or ionization of the sample material for analysis...
• ProbitA unit of measurement for the probability of a quantal response, derived from the normal distribution. It...
• Probit log transformA statistical transformation applied to dose-response data to linearize the relationship between the...
• Problem formulationThe initial phase of an ecological risk assessment, where the scope, objectives, and assessment endpoints are...
• ProcarcinogenA chemical substance that is not carcinogenic in its original form but is converted into an active carcinogen...
• Procedure validationThe process of confirming by examination and objective evidence that a specific analytical procedure is fit...
• Procedure verificationThe process of confirming that a measurement procedure, previously validated or standardized, is suitable for...
• ProcessA sequence of chemical or physical changes that transforms one or more entities into a different state or...
• Process in a state of statistical controlA process operating with only random, common-cause variation, where all observed variations are within...
• ProchiralityA geometric property of an achiral molecule or center that can be converted into a chiral one in a single...
• Prochirality centreAn atom in a molecule that is not chiral but can become a chirality center by the replacement of one of its...
• Procrustes analysisA statistical method used to compare the shapes of two or more configurations of points by optimally...
• ProctodeumAn external invagination of the ectoderm at the caudal end of a developing embryo that contributes to the...
• Prodromal stageThe early phase of an illness in which vague or non-specific symptoms, such as fatigue, mood change, malaise...
• ProdromeAn early symptom or set of symptoms that indicates the onset of a disease or condition before the...
• ProdrugA pharmacologically inactive compound that undergoes a metabolic or chemical transformation within the body...
• Prodrug conjugateA macromolecular construct where a prodrug is covalently linked to a polymer or another substrate. This...
• ProductA molecular entity formed from reactants as a result of a chemical reaction. Products appear on the...
• Product development controlA type of reaction control where the structure of the transition state resembles the product more than the...
• Product ionAn ion formed as a result of the fragmentation or reaction of a precursor ion within a mass spectrometer...
• Product ion analysisA mass spectrometry technique where a selected precursor ion is fragmented, and the resulting product ions...
• Product ion spectrumA mass spectrum obtained by mass-analyzing the fragment ions generated from a selected precursor ion. This...
• Product state distributionThe distribution of product molecules among their possible quantum states (electronic, vibrational...
• Product-determining stepA step in a multi-step reaction sequence that determines the final product distribution, especially when...
• ProductivityThe rate at which biomass or a specific product is generated by a biological system, such as a microbial...
• Product-limit methodA non-parametric statistical method used to estimate the survival function from time-to-event data, even when...
• pro-E, pro-ZStereodescriptors used to distinguish between two identical ligands on a trigonal carbon atom that, if...
• Professional antigen-presenting cellA specialized immune cell that processes and presents antigens to naive T lymphocytes, initiating an adaptive...
• Proficiency test itemA sample, material, or artifact provided to participating laboratories in a proficiency testing scheme for...
• Proficiency testingThe evaluation of a laboratory's performance against pre-established criteria by means of interlaboratory...
• Proficiency testing providerA body that carries responsibility for every task involved in setting up and running a proficiency testing...
• Proficiency testing roundA complete cycle of a proficiency testing scheme, from the distribution of proficiency test items to...
• Proficiency testing schemeA structured program of interlaboratory comparisons designed to evaluate the performance of participating...
• Profile modeA data acquisition mode in mass spectrometry where the full intensity distribution of each ion peak is...
• Profile of mood state testA psychological assessment tool designed to measure transient mood states and changes in mood over time. It...
• Progenitor ionAn ion that undergoes fragmentation to produce other ions in a mass spectrometry experiment. It is the parent...
• ProgesteroneA steroid hormone primarily produced by the corpus luteum in the ovary, and by the placenta during pregnancy...
• ProgestinA synthetic progestogen that mimics the actions of natural progesterone in the body. These compounds bind to...
• ProgestogenA class of C21 steroid hormones that regulate female reproductive functions by activating progesterone...
• ProgramA sequence of instructions or operations that directs an automated analytical instrument or system to perform...
• Programmable flow extractionA flow-based extraction approach in which a pump controls multi-directional flow, including stopped flow, of...
• Programmed-flow chromatographyA chromatographic technique where the mobile phase flow rate is varied systematically during a separation to...
• Programmed-pressure chromatographyA chromatographic technique in which the pressure at the column inlet is deliberately changed according to a...
• Programmed-temperature chromatographyA chromatographic technique where the temperature of the column is systematically increased during a...
• ProgressionThe advancement or worsening of a disease or pathological condition over time. This involves an increase in...
• Progressive systemic sclerosisA chronic autoimmune disease characterized by widespread fibrosis of the skin and internal organs, as well as...
• Proinflammatory cytokineA signaling protein secreted by immune cells that promotes inflammation and immune cell activation. These...
• Projected rangeThe average distance an ion travels into a material along its initial direction of incidence before coming to...
• Projection formulaA flat drawing of a three-dimensional molecule that conveys its stereochemistry by convention rather than by...
• ProkaryoteA single-celled organism that lacks a membrane-bound nucleus and other membrane-bound organelles. Its genetic...
• ProlactinA peptide hormone synthesized and secreted by the anterior pituitary gland that primarily stimulates milk...
• ProlapseThe downward displacement or protrusion of an organ or tissue from its normal anatomical position. This...
• Prolate trochoidal mass spectrometerA type of mass analyzer where ions travel in a prolate trochoidal path under the influence of crossed...
• ProliferationThe rapid increase in the number of cells as a result of cell growth and division. In the context of...
• Proliferation assayA laboratory method used to measure the rate of cell division or growth in a cell population. These assays...
• PromoterA region of deoxyribonucleic acid (DNA) that initiates transcription of a particular gene. It serves as a...
• Prompt coincidenceThe simultaneous detection of two or more radiation events that originate from the same nuclear decay or...
• Prompt gamma radiationGamma rays emitted almost instantaneously, within approximately 10^-12 seconds, following a nuclear reaction...
• Prompt gamma-ray analysisA nuclear analytical technique that measures the gamma rays emitted almost instantaneously when atomic nuclei...
• Prompt neutronsNeutrons emitted directly from the fission process within an extremely short time, typically less than 10^-14...
• PronephrosThe earliest and most primitive kidney structure that develops in vertebrate embryos. It is a transient...
• PronucleusThe haploid nucleus of a sperm or egg cell during fertilization, before the fusion of the two nuclei to form...
• Proof of conceptThe demonstration that a particular idea, method, or product is feasible and has the potential to achieve its...
• Propagating speciesA reactive intermediate, such as a radical, anion, cation, or coordination complex, that adds monomer units...
• PropaguleAny material or structure that can be dispersed to give rise to a new organism, serving as an agent of...
• Propagule rainThe continual immigration of individuals, such as seeds, spores, or larvae, from a source population into a...
• ProperdinA plasma protein that stabilizes the C3 convertase of the alternative pathway of the complement system...
• PropertyAn attribute of a system that is observable or measurable, used in clinical laboratory sciences to describe a...
• Property value assignmentThe process of determining and documenting a specific numerical value for a characteristic of a material...
• Pro-pesticideA chemical compound that is not pesticidally active itself but is converted into an active pesticide after...
• ProphageThe genetic material of a bacteriophage (a virus that infects bacteria) that has been integrated into the...
• ProphaseThe first stage of cell division (mitosis or meiosis) during which the chromatin condenses to form visible...
• Proportional counterA gas-filled radiation detector that gives an electrical pulse whose height scales with the energy deposited...
• Proportional counter tubeA radiation detector that measures ionizing radiation by collecting the ions produced in a gas-filled tube...
• Proportional gas-scintillation counterA radiation detector that uses a gas-filled chamber where incident radiation excites the gas atoms, causing...
• Proportional mortality rateThe number of deaths from a specific cause within a defined population over a specified time period...
• ProprioceptionThe sense of the relative position of one's own parts of the body and the effort being employed in movement...
• ProprioceptorA specialized sensory receptor located in muscles, tendons, joints, and the inner ear that detects changes in...
• pro-R, pro-SStereodescriptors used to distinguish between two identical ligands on a prochiral center, typically a carbon...
• ProsA locant for the imidazole ring of histidine, from the Greek for near, marking the ring nitrogen atom closest...
• ProsencephalonThe most anterior of the three primary brain vesicles of the embryonic neural tube, which later develops into...
• ProstaglandinsA group of lipid compounds derived enzymatically from fatty acids, specifically arachidonic acid, that act as...
• ProstanoidsThe family of 20-carbon oxygenated lipid mediators formed from arachidonic acid and related polyunsaturated...
• ProstateA gland in the male reproductive system that secretes prostatic fluid, a component of semen. This fluid...
• ProsthesisAn artificial device, often constructed from biocompatible polymers, designed to replace a missing or...
• Prosthetic groupA non-protein chemical component that is tightly and stably bound to a protein, often through covalent bonds...
• ProtamineA small, arginine-rich protein that replaces histones late in spermatogenesis, condensing the DNA in the...
• ProteasomeA large, multi-subunit protein complex found in the cytoplasm and nucleus of all eukaryotic cells that...
• Protected lyophobic colloidA lyophobic colloid that has been stabilized against coagulation by the adsorption of a protective layer of a...
• ProtectinA cell surface glycoprotein, also known as CD59, that inhibits the formation of the membrane attack complex...
• Protecting groupA chemical moiety temporarily introduced into a molecule to mask or block the reactivity of a specific...
• Protection of a reactive groupThe chemical modification of a functional group within a polymer or monomer to temporarily render it...
• Protective actionThe stabilization of a lyophobic sol by the addition of a lyophilic colloid. This phenomenon prevents the...
• Protective immunityThe state of resistance to infection or disease conferred by the immune system, preventing or reducing the...
• Protein AA surface protein produced by Staphylococcus aureus bacteria that binds specifically and with high affinity...
• Protein complexA quaternary structure formed when two or more polypeptide chains, known as protein subunits, bind to each...
• Protein complex purificationThe isolation of a specific multi-protein assembly from a mixture of other cellular components, while...
• Protein data bankA public repository for the three-dimensional structural data of biological macromolecules, such as proteins...
• Protein data bank fileA standardized text file format used to store atomic coordinates and related information for macromolecular...
• Protein databaseA structured collection of information about proteins, including their amino acid sequences...
• Protein engineeringThe process of modifying the structure and function of proteins through genetic manipulation or chemical...
• Protein foldingThe physical process by which a polypeptide chain acquires its native, three-dimensional structure, a...
• Protein fractionationThe process of separating a mixture of proteins into individual components or groups of components based on...
• Protein fragmentationThe cleavage of a protein into smaller pieces. In tandem mass spectrometry of intact proteins, as in top-down...
• Protein GA bacterial cell wall protein isolated from Group G Streptococcus, which binds to the Fc region of mammalian...
• Protein identificationThe process of assigning an identity to an unknown protein or a set of proteins within a sample. This is...
• Protein kinaseAn enzyme that modifies other proteins by chemically adding phosphate groups to them in a process called...
• Protein kinase CA family of serine/threonine protein kinases that regulate the activity of other proteins by adding phosphate...
• Protein machineA large, multi-protein complex in which the constituent proteins work together in a coordinated manner to...
• Protein purificationA series of processes intended to isolate a single type of protein from a complex mixture, such as cells...
• Protein quantificationThe measurement of the concentration or absolute amount of one or more specific proteins in a sample. Methods...
• Protein sequencerAn automated instrument that determines the primary structure of a protein, which is its amino acid sequence...
• Protein sequencingThe analytical process of determining the order of amino acids in a protein or peptide chain. This technique...
• Protein stainingA technique used to visualize proteins separated by electrophoresis or chromatography, or to detect proteins...
• ProteinaseAn enzyme that catalyzes the hydrolysis of peptide bonds in proteins or peptides. These enzymes are also...
• Proteinase 3A serine proteinase found primarily in the azurophilic granules of neutrophils, a type of white blood cell...
• Protein-free filtrateThe liquid portion of a biological fluid, such as blood plasma or serum, from which all or most proteins have...
• Protein-protein interactionThe specific physical contact between two or more protein molecules, driven by electrostatic forces, hydrogen...
• ProteinsMacromolecules composed of polypeptide chains, which are linear polymers of amino acids linked by peptide...
• ProteinuriaThe presence of an abnormally high concentration of protein in the urine, indicating impaired kidney...
• ProteoformAll the different molecular forms of a protein that arise from a single gene, including those resulting from...
• ProteogenomicsAn integrated approach that combines proteomics and genomics data to enhance the understanding of biological...
• ProteoglycanA type of glycoprotein consisting of a core protein covalently attached to one or more glycosaminoglycan...
• ProteoglycomicsThe large-scale study of proteoglycans, which are proteins covalently attached to one or more...
• ProteolipidsA class of proteins covalently modified with lipid or fatty acid moieties, rendering them soluble in organic...
• ProteolysisThe directed breakdown of proteins into smaller polypeptides or single amino acids. This process is mediated...
• Proteolytic digestionThe controlled enzymatic cleavage of proteins into smaller peptide fragments using specific proteases. This...
• Proteolytic enzymeAn enzyme that catalyzes the breakdown of proteins by hydrolyzing their peptide bonds, a process known as...
• Proteolytic peptideA short peptide fragment generated from a larger protein through the action of a proteolytic enzyme. These...
• ProteomeThe entire set of proteins expressed by a cell, tissue, or organism at a particular time and under specific...
• ProteomicsThe large-scale study of proteins, particularly their structures and functions, within a biological system...
• ProtiumThe most common and lightest isotope of the element hydrogen, consisting of a single proton and no neutrons...
• ProtofugalityThe kinetic tendency of a group attached to a molecule to be transferred as a proton (H+) to a base. This...
• ProtolysisA chemical reaction involving the transfer of a proton from one molecule or ion to another. This process...
• ProtonA stable subatomic particle with a positive elementary electric charge, found in the nucleus of every atom...
• Proton affinityThe negative of the enthalpy change for the gas-phase reaction of a chemical species with a proton to form...
• Proton dopingThe process of introducing protons into a polymer matrix to increase its electrical conductivity...
• Proton magnetic momentA measure of the strength and orientation of the magnetic dipole of a proton, arising from its intrinsic...
• Proton magnetogyric ratioThe ratio of the magnetic dipole moment of a proton to its spin angular momentum, symbolized γp. It fixes the...
• Proton rest massThe invariant mass of a proton when it is at rest, representing its intrinsic mass independent of its motion...
• Proton transfer reactionA chemical reaction involving the transfer of a proton (H+) from one chemical species, the Brønsted acid, to...
• Protonated moleculeA molecule that has gained a proton (H+) through an ionization process, typically in the gas phase. This...
• ProtonationThe addition of a proton (H+) to an atom, molecule, or ion, resulting in the formation of a conjugate acid...
• Protonation constantAn equilibrium constant that quantifies the affinity of a chemical species for a proton in solution. It...
• Proton-bound dimerA molecular ion formed by the association of two neutral molecules with a single proton. This species is...
• Protonic conductivityThe ability of a material to conduct electrical charge through the movement of protons (H+ ions). This...
• ProtophilicityThe kinetic tendency of a chemical species to accept a proton (H+) from a Brønsted acid. This property...
• ProtoplastA plant, bacterial, or fungal cell that has had its cell wall completely removed, leaving only the plasma...
• PrototrophsMicroorganisms, such as bacteria or yeast, capable of synthesizing all the complex organic molecules required...
• Prototype drugA representative drug within a class of pharmacological agents that exemplifies the characteristic...
• ProximalDescribing a position or location that is nearer to the center of the body or the point of attachment of a...
• Proximity effectA phenomenon in lithography where the exposure of a resist in one area is affected by the exposure of...
• Prozone effectA phenomenon observed in immunological assays, such as agglutination or precipitation tests, where high...
• P-selectinAn adhesion molecule stored in the alpha-granules of platelets and in the Weibel-Palade bodies of endothelial...
• Pseudo acidsA compound that shows ordinary acidic behaviour only after a slow structural rearrangement, usually...
• Pseudo basesCovalent hydroxy compounds that react with acids to form salts by losing water, with a rearrangement of the...
• Pseudo rate constantA rate constant determined under conditions where the concentration of one or more reactants is kept...
• Pseudo-acceptable daily intakeAn intake value for a substance, treated as safe for daily lifelong exposure, that is derived by dividing the...
• PseudoadaptationAn apparent adaptation of an organism to a changed environment, often a chemical stressor, in which the...
• PseudoallergyA reaction that clinically resembles an allergic reaction but does not involve an immunological mechanism...
• Pseudo-asymmetric carbon atomA carbon atom in a molecule that is bonded to four different groups, two of which are enantiomeric to each...
• Pseudobulbar affectA neurological condition characterized by involuntary, sudden, and uncontrollable outbursts of crying or...
• Pseudo-bulk behaviourA kinetic regime in emulsion, miniemulsion, microemulsion, suspension or dispersion polymerization in which...
• Pseudo-catalysisThe acceleration of a reaction by an acid, base or similar species that stays at nearly constant...
• Pseudo-co-oligomerAn irregular oligomer built from a single kind of monomer that nevertheless shows several different...
• Pseudo-copolymerAn irregular polymer built from a single kind of monomer that nevertheless shows a variety of structural...
• PseudohalogensPolyatomic inorganic molecules that resemble the diatomic halogens in their chemical behavior. These species...
• PseudohermaphroditeAn individual possessing gonads of one sex but external genitalia that are ambiguous or resemble those of the...
• Pseudo-ionic polymerizationA polymerization in which each monomer is inserted into a polar bond at the active chain end without any ions...
• PseudomeningoceleAn abnormal collection of cerebrospinal fluid that communicates with the subarachnoid space but is not...
• PseudopericyclicA concerted reaction whose bonding changes occur around a cyclic array of atoms, with at least one atom where...
• PseudopolymorphA crystalline solid that exhibits different crystal structures due to the incorporation of solvent molecules...
• PseudopregnancyA state in female mammals, notably rodents, in which the body shows hormonal and uterine changes of pregnancy...
• PseudorotationA conformational change in a molecule where the atoms appear to rotate around a central atom, leading to an...
• PseudorotaxaneA supramolecular assembly consisting of a macrocyclic component threaded onto a linear threading component...
• Pseudorotaxane polymerA macromolecular pseudorotaxane where either the macrocyclic component, the threading component, or both, are...
• Pseudotumor cerebriA neurological disorder characterized by increased intracranial pressure without an identifiable cause, such...
• PsoriasisA chronic autoimmune skin condition characterized by rapid overproduction of skin cells, leading to thick...
• PsoriaticRelating to or characteristic of psoriasis, a chronic autoimmune disease affecting the skin and sometimes the...
• PsychoactiveDescribing a chemical substance that, when ingested or administered, crosses the blood-brain barrier and acts...
• Psychomotor retardationA noticeable slowing of thought processes and a reduction in physical movements, often observed as a symptom...
• PsychoneuroimmunologyThe interdisciplinary field of study that examines the interactions among the psychological processes, the...
• PsychosisA mental state characterized by a loss of contact with reality, involving symptoms such as delusions (false...
• PsychotropicDescribing a substance that affects mental activity, behavior, or perception by altering brain function...
• Psychrometric hygrometerAn instrument used to measure atmospheric humidity by comparing the temperatures of a dry-bulb thermometer...
• PsychrometryThe scientific study of the properties of moist air, specifically mixtures of water vapor and other gases. It...
• PterocarpansA group of isoflavonoid compounds characterized by a tetracyclic ring system derived from isoflavones. They...
• Ptolemaic incongruityA fallacy in ecotoxicology of treating one level of biological organisation, whether the molecule, organism...
• PubertyThe developmental stage during which an individual's body undergoes physical changes to become capable of...
• PubescentDescribing an individual who is undergoing or has recently undergone puberty, the process of sexual...
• PubicRelating to the pubis, the anterior and inferior part of the hip bone, which forms the front of the pelvis...
• Pubic symphysisA cartilaginous joint located in the midline of the body, connecting the left and right pubic bones. This...
• Public health impact assessmentA quantitative extension of risk assessment in which the estimated risk of an exposure is applied to a...
• Puffer fishA type of fish belonging to the family Tetraodontidae, known for its ability to inflate its body rapidly when...
• PuffingAn undesirable expansion and distortion phenomenon that occurs in certain carbon materials, particularly...
• Puffing inhibitorA chemical additive incorporated into carbon precursors, such as petroleum coke, to mitigate or prevent the...
• Pull-down assayA biochemical technique used to isolate and identify proteins that interact with a specific bait protein or...
• PulmonaryRelating to the lungs, and used in toxicology to describe either the route of exposure through inhalation or...
• Pulmonary arteryA large blood vessel that carries deoxygenated blood from the right ventricle of the heart to the lungs. It...
• Pulmonary surfactantA complex mixture of lipids and proteins produced by alveolar cells in the lungs, which reduces the surface...
• Pulmonary valve stenosisA congenital heart defect characterized by a narrowing of the pulmonary valve, which obstructs blood flow...
• Pulse amplitude analyserAn electronic instrument designed to measure and sort electrical pulses according to their amplitude. It...
• Pulse amplitude selectorA circuit that permits the passage of electrical pulses only if their amplitude falls within a specified...
• Pulse durationThe time interval during which a potential or current pulse is applied to the working electrode in pulse...
• Pulse energyThe total energy contained within a single pulse of electromagnetic radiation, such as from a laser. It is...
• Pulse pile-upAn artifact in radiation detection systems where two or more closely spaced electrical pulses from individual...
• Pulse rateThe frequency at which discrete packets of ions or electrons are generated or detected in an analytical...
• Pulse reactorA type of chemical reactor where reactants are introduced in discrete, short bursts or pulses, rather than...
• Pulse sequenceA precisely timed series of radiofrequency pulses, magnetic field gradients, and delays applied to a sample...
• Pulse widthThe time duration of a primary ion pulse used in techniques like time-of-flight secondary-ion mass...
• Pulsed extraction fieldAn electric field applied intermittently between a sample and the extraction optics of a mass spectrometer...
• Pulsed laserA laser system that emits light in discrete bursts or pulses, rather than as a continuous wave. These pulses...
• Pulsed-field gradientA magnetic field gradient that is rapidly switched on and off during a nuclear magnetic resonance (NMR)...
• Pulsed-laser polymerisationA method for determining propagation rate coefficients in free-radical polymerization by using intermittent...
• Pump-dump-probe techniqueA spectroscopic method used to investigate ultrafast chemical dynamics by sequentially exciting, waiting, and...
• Pump-probe techniqueA time-resolved spectroscopic method employing two sequential laser pulses to investigate ultrafast processes...
• Pure shift yielded by chirp excitationA method in nuclear magnetic resonance (NMR) spectroscopy that separates chemical shift information from...
• Pure-element relative sensitivity factorA quantitative parameter used in surface analysis techniques, such as X-ray photoelectron spectroscopy (XPS)...
• Purified protein derivativeA complex mixture of proteins derived from the culture filtrate of Mycobacterium tuberculosis, used as an...
• PurineA heterocyclic aromatic organic compound consisting of a pyrimidine ring fused to an imidazole ring. It forms...
• Purine basesNitrogen-containing heterocyclic organic compounds characterized by a fused pyrimidine and imidazole ring...
• Purkinje cellA large, flask-shaped neuron located in the cerebellar cortex, characterized by an extensive dendritic tree...
• PurpuraThe appearance of purple-colored spots on the skin, mucous membranes, or internal organs, caused by bleeding...
• Pursuit aiming testA paper-and-pencil test of eye-hand coordination and motor speed in which the subject marks a dot in each of...
• Push-pull conjugationA molecular arrangement where an electron-donating group and an electron-withdrawing group are connected...
• PutamenA large, round structure located at the base of the forebrain, forming part of the basal ganglia. It is...
• PyknosisA morphological change in the nucleus of a cell characterized by the irreversible condensation of chromatin...
• Pyloric stenosisA condition in which the pylorus, the muscular valve between the stomach and the duodenum, thickens and...
• Pyramidal cellA type of multipolar neuron with a pyramid-shaped cell body, a single long axon, and multiple dendrites...
• Pyramidal inversionA dynamic process where a trigonal pyramidal molecule or a chiral center with a lone pair rapidly...
• PyranosesMonosaccharides that exist in a six-membered ring form, consisting of five carbon atoms and one oxygen atom...
• PyrethroidA class of synthetic organic compounds structurally related to the natural pyrethrins, which are insecticides...
• PyrexiaAn elevation of core body temperature above the normal homeostatic range, also known as fever. This condition...
• PyrimidineA heterocyclic aromatic organic compound containing two nitrogen atoms at positions 1 and 3 of a six-membered...
• Pyrimidine basesNitrogen-containing heterocyclic organic compounds characterized by a six-membered ring containing two...
• PyroA prefix for a compound formed by heating another compound, usually with loss of water or another small...
• Pyroelectric detectorA type of thermal detector that measures changes in temperature by sensing the electric charge generated on...
• PyrogenAny substance that induces fever when introduced into the body. These substances can be exogenous, such as...
• Pyrogen testA biological assay performed to detect the presence of pyrogenic substances in pharmaceutical products...
• PyrogenicRelating to a substance or agent that induces pyrexia, or fever, upon introduction into the body. Pyrogenic...
• PyrolysisThe thermal decomposition of organic materials, including polymers, in the absence of oxygen or other...
• Pyrolysis curveA plot of the atomic absorbance of an analyte against the pyrolysis (ashing) temperature in electrothermal...
• Pyrolysis mass spectrometryA technique that involves the thermal decomposition of a sample in an inert atmosphere, followed by the...
• Pyrolysis-gas chromatographyAn analytical technique where a sample is thermally decomposed in an inert atmosphere (pyrolysis) to produce...
• Pyrolytic carbonA form of carbon laid down from gaseous hydrocarbons by chemical vapour deposition on a heated substrate, at...
• Pyrolytic graphiteA highly ordered form of graphite produced by the thermal decomposition of hydrocarbon gases at high...
• PyrromethenesOrganic compounds characterized by a methine bridge connecting two pyrrole rings, forming a conjugated...

1,381 of 13,676 terms in Chemistry terminology (MLC-0109). Request the full dataset.