Chemistry terminology · MLC-0109
Chemistry terms: R (726)
- Resonance-enhanced multiphoton ionizationA technique for ionizing atoms or molecules by simultaneously absorbing multiple photons, where at least one...
- Resonant inelastic X-ray scatteringA spectroscopic technique that probes electronic excitations by measuring the energy and momentum transfer of...
- ResorptionThe complete or partial breakdown and assimilation of embryonic or fetal tissue during gestation, leading to...
- Resorptive effectThe systemic action of a substance after it has been absorbed from the gastrointestinal tract into the blood...
- Respirable dustThe fraction of airborne dust small enough to reach the gas-exchange region (alveoli) of the lung, defined by...
- Respiratory burstA rapid increase in the production of reactive oxygen species, such as superoxide radicals and hydrogen...
- Respiratory hypersensitivity assayA laboratory test designed to detect substances that induce allergic reactions in the respiratory system...
- ResponseThe measured outcome or result observed from an experimental unit after a treatment or intervention has been...
- Response constantA proportionality constant that relates the magnitude of an analytical signal to the concentration or amount...
- Response scramblingA validation procedure for QSAR and classification models in which the target property values are randomly...
- Response surface methodologyA collection of statistical and mathematical techniques for developing and analyzing empirical models that...
- Response timeThe time required for an analytical system or sensor to reach a specified percentage of its final...
- Responsive gelA gel that undergoes a reversible, discrete volume change or a sol-gel transition in response to a small...
- ResponsivityA measure of the efficiency of a detector or sensor in converting incident radiant energy into an electrical...
- Rest pointThe reading on the pointer scale of a balance at the instant the swinging beam has come to a halt. It may be...
- Resting potentialThe electrical potential difference across the plasma membrane of an excitable cell when it is not actively...
- Restricted-access sorbentA type of chromatographic sorbent designed to allow small molecules to access the stationary phase while...
- Restriction enzymesEnzymes that recognize and cleave deoxyribonucleic acid (DNA) at specific nucleotide sequences, known as...
- Restriction fragment length polymorphismA variation in the length of DNA fragments produced by digestion with a specific restriction endonuclease...
- Restriction siteA short DNA sequence, usually 4 to 8 base pairs long, that a restriction enzyme recognizes and cuts at or...
- ResultThe value assigned to the quantity being determined once the analysis and all the calculations based on the...
- Retainer and eluterA pair of chemical species, a retainer acid or base and an eluter base or acid, used in pH-zone-refining...
- RetardationA decrease in the overall rate of polymerization due to the presence of species that react with propagating...
- Retardation factorA dimensionless quantity in planar chromatography that expresses the migration of a solute relative to the...
- RetarderA substance that lowers the rate of a reaction, chiefly in polymerization kinetics, where it slows chain...
- ReteA network of interconnected small vessels or tubules within an organ, serving to collect or distribute...
- Rete testisAn anastomosing network of tubules located in the mediastinum testis, connecting the seminiferous tubules to...
- Retentate streamThe portion of a feed solution that does not pass through a membrane or filter in a separation process, thus...
- RetentionThe share of atoms that stay in, or go back to, their original chemical form after undergoing nuclear decay...
- Retention effectThe tendency of highly lipophilic persistent organic pollutants to be held more firmly by soil and vegetation...
- Retention efficiencyThe fraction of the particles entering a separator, such as a filter, impactor, or cyclone, that the device...
- Retention factorA dimensionless measure of how strongly a sample component is retained, equal to the ratio of its adjusted...
- Retention indexAn index that places the retention of a sample component between those of two standard compounds that elute...
- Retention temperatureThe temperature at which a specific analyte elutes from a chromatographic column in temperature-programmed...
- Retention timeThe characteristic time elapsed between the injection of a sample into a chromatographic system and the...
- Retention time of an unretained compoundThe time it takes for a compound that does not interact with the stationary phase to pass through a...
- Retention volumeThe volume of mobile phase that passes through a chromatographic column from the point of sample injection...
- Retention volume of an unretained compoundThe volume of mobile phase required to elute a compound that does not interact with the stationary phase from...
- Retention volume of the stationary phaseThe volume of liquid stationary phase that remains held inside the column throughout a counter-current...
- Retention volumes, see Retention volume
- Reticulate doped polymerA composite in which a small-molecule organic conductor is crystallized as a fine network on the surface of a...
- RetinaA light-sensitive layer of tissue at the back of the eye that contains photoreceptor cells, which convert...
- Retinoic acidA metabolite of vitamin A that functions as a signaling molecule in vertebrate development and cell...
- RetinopathyA non-inflammatory disease affecting the retina of the eye, leading to damage to the blood vessels or other...
- RetroA prefix with several established meanings. In carotenoid and retinoid names it shows that every single and...
- Retro Diels-Alder reactionA unimolecular fragmentation reaction in mass spectrometry where a cyclic molecule undergoes a reverse...
- Retrograde axonal transportThe movement of molecules and organelles within a neuron's axon from the axon terminal back toward the cell...
- Retrograde neurotransmissionA form of synaptic communication where a chemical messenger is released from the postsynaptic neuron and...
- Retrograde solubilityA phenomenon where the solubility of a solute in a solvent decreases as the temperature increases, contrary...
- RetroperitonealDescribing the anatomical space and the organs situated within it, located behind the peritoneum in the...
- Retrospective risk assessmentAn evaluation of the risks associated with past exposures to hazardous substances or conditions, often...
- Retrospective studyA research design that looks back in time to examine exposures or risk factors in relation to an outcome that...
- RetrosynthesisA problem-solving technique in organic chemistry used to design synthetic routes for complex molecules by...
- Returned effect of poisonsA heightened response to a poison, in which the dose-effect curve shifts so that a given dose acts more...
- ReuptakeThe process by which neurotransmitters are actively transported from the synaptic cleft back into the...
- Reverse geneticsAn experimental approach that begins with a known gene sequence and then investigates its function by...
- Reverse geometryA design for a double-focusing mass spectrometer in which the magnetic sector is placed before the...
- Reverse immunologyA strategy for finding T-cell epitopes that starts from a protein or gene sequence rather than from T cells...
- Reverse iodine-transfer polymerizationA form of iodine-transfer polymerization in which the starting mixture holds a conventional radical...
- Reverse library searchA library search in which only the peaks present in the library reference spectrum are compared with the...
- Reverse mutationA genetic mutation that restores the original wild-type sequence or function that was lost due to a previous...
- Reverse osmosisA membrane separation process that removes dissolved solids and other impurities from a fluid by applying...
- Reverse passive agglutinationA serological technique used to detect antigens by observing the agglutination of carrier particles, such as...
- Reverse transcriptasesA class of deoxyribonucleic acid (DNA) polymerases that catalyze the synthesis of DNA from an RNA template...
- Reverse transcriptionThe process by which genetic information from an RNA template is transcribed into a complementary DNA (cDNA)...
- Reversed direct-injection burnerA direct-injection burner in which the fuel gas, instead of the oxidant, is used to aspirate and nebulize the...
- Reversed isotope dilution analysisIsotope dilution analysis with the roles exchanged: a known amount of a stable isotope of the element is...
- Reversed-phase chromatographyA chromatographic technique where the stationary phase is nonpolar and the mobile phase is polar, typically...
- Reversible alterationA change in a biological system or chemical structure that can return to its original state once the...
- Reversible chain deactivationA chemical reaction in which a propagating polymer chain is converted into a dormant species that is unable...
- Reversible networkA polymer network in which the cross-links connecting the polymer chains are dynamic and not permanent. These...
- Reversible transitionA phase transition that can proceed in both forward and reverse directions under specific conditions...
- Reversible-addition-fragmentation chain-transfer agentA compound that mediates polymerization by a reversible-addition-fragmentation chain-transfer (RAFT)...
- Reversible-addition-fragmentation chain-transfer polymerizationA type of reversible-deactivation radical polymerization in which control over the molecular weight and...
- Reversible-addition-fragmentation radical polymerizationA reversible-deactivation radical polymerization whose dormant species is a persistent radical, with...
- Reversible-deactivation anionic polymerizationA controlled anionic polymerization method where the active anionic propagating species can reversibly...
- Reversible-deactivation cationic polymerizationA reversible-deactivation polymerization where the active chain carriers are carbocations or other cationic...
- Reversible-deactivation coordination polymerizationA reversible-deactivation polymerization whose chain carriers are coordination complexes, so propagation...
- Reversible-deactivation ionic polymerizationA chain polymerization where the propagating species are ionic and undergo reversible deactivation, creating...
- Reversible-deactivation polymerizationA class of polymerization techniques where the propagating species can reversibly interconvert between an...
- Reversible-deactivation radical polymerizationA type of radical polymerization where the concentration of active radicals is kept low through a rapid and...
- Reversing heat flowA component of the total heat flow in modulated-temperature DSC that follows the temperature modulation...
- Revolutions per minuteA unit of rotational frequency, representing the number of full rotations a body completes around a fixed...
- Rey-Osterrieth complex figure testA neuropsychological assessment tool that evaluates visual perception, nonverbal memory, and executive...
- RF-only quadrupoleA type of quadrupole mass filter operated solely with a radiofrequency (RF) voltage applied to its rods...
- R-group decompositionA computational method used in drug design to analyze the structural diversity of a chemical series by...
- RhabdomyolysisA severe medical condition characterized by the breakdown of skeletal muscle tissue, leading to the release...
- RheologyThe science studying the deformation and flow of matter, particularly liquids and soft solids that exhibit...
- Rheopexic gelA type of gel that exhibits an increase in viscosity over time when subjected to a constant shear rate, and...
- RheopexyA rare type of non-Newtonian fluid behavior where the viscosity of a fluid increases with time under constant...
- Rhesus factorAn inherited protein, specifically an antigen, found on the surface of red blood cells. Individuals who have...
- Rheumatic feverA severe inflammatory disease that develops as a complication of an untreated or inadequately treated...
- Rheumatoid arthritisA chronic autoimmune disease characterized by inflammation of the synovial lining of joints, leading to pain...
- Rheumatoid factorAn autoantibody, an antibody directed against the body's own tissues, that is present in the blood of many...
- RhinitisInflammation of the mucous membranes lining the inside of the nose, leading to symptoms such as a runny nose...
- Rhodamine dyesA family of fluorescent organic dyes belonging to the xanthene class, characterized by a xanthene core with...
- RhombencephalonThe posterior region of the embryonic vertebrate brain, also known as the hindbrain. It is one of the three...
- Rhombohedral graphiteAn allotrope of carbon with a crystal structure where the hexagonal layers of carbon atoms are stacked in an...
- RhonchusA continuous, low-pitched, rattling breath sound heard during auscultation of the lungs, resembling snoring...
- Ribbon delocalisationA specific type of electron delocalization occurring in certain conjugated systems, where the delocalized...
- Ribonucleic acidsPolymeric molecules composed of ribonucleotide units linked by phosphodiester bonds, playing central roles in...
- RibonucleotidesThe monomeric units that constitute ribonucleic acid (RNA). Each ribonucleotide is composed of three...
- Ribosomal RNAA type of ribonucleic acid (RNA) that forms a structural and catalytic component of ribosomes, the cellular...
- RibosomesComplex molecular machines found within all living cells that serve as the primary sites of biological...
- Rice-Ramsperger-Kassel theoryA statistical theory that describes the unimolecular decomposition of molecules in the gas phase. It assumes...
- Rice-Ramsperger-Kassel-Marcus theoryAn extension of the Rice-Ramsperger-Kassel theory that incorporates quantum mechanical effects and a more...
- RifflingA method of sample division that uses a riffle splitter, a device with a series of chutes that alternately...
- Right-handed helixA helical polymer chain conformation in which the chain progresses away from the observer in a clockwise...
- Righting reflexAn innate reflex observed in most animals that corrects the body's orientation when it is in an abnormal...
- Righting testA behavioral test used in toxicology and neuropharmacology to assess an animal's ability to regain an upright...
- Rigid chainA polymer chain that possesses a high resistance to bending and rotation around its backbone bonds, resulting...
- Rigid membranesIon-selective membranes with a rigid structure, made either of a thin glass membrane or of a synthetic...
- Ring and double bond equivalentA value calculated from a molecular formula that indicates the degree of unsaturation in a molecule...
- Ring assemblyA compound consisting of two or more identical cyclic systems directly joined to each other by a single bond...
- Ring reversalA conformational change in a cyclic molecule where the ring undergoes a flip, interconverting between two...
- Ring testAn interlaboratory study in which several laboratories analyze identical samples to assess the performance of...
- Ringelmann chartA series of charts used to visually estimate the density of smoke emitted from industrial sources, such as...
- Ringing gelA type of gel that exhibits a characteristic oscillatory or 'ringing' behavior when subjected to mechanical...
- Ring-opening copolymerizationA polymerization process involving the opening of cyclic monomers and their subsequent incorporation into a...
- Ring-opening metathesis polymerizationA type of chain polymerization where cyclic olefins undergo ring-opening through a metathesis reaction...
- Ring-opening nucleophilic chain polymerizationA chain polymerization mechanism where a cyclic monomer undergoes ring-opening initiated by a nucleophile...
- Ring-opening polymerizationA polymerization reaction in which cyclic monomers are converted into linear polymers by the scission of a...
- Ring-sectorAn unbranched chain of ring atoms that runs between two bridgeheads or ring junctions, used in naming bridged...
- Rinse solventA weak solvent passed through a sorbent in solid-phase extraction after the sample has been loaded, so that...
- RiparianDescribing the zone of land directly adjacent to a body of fresh water, such as a river, stream, or lake...
- Rise timeThe duration required for a signal or system response to transition from a specified low amplitude to a...
- Rise velocityThe upward component of the speed of the vaporized analyte as it travels through the viewing region of a...
- RiskThe probability of an adverse effect occurring and the magnitude of that effect, often expressed as a...
- Risk analysisThe overall process for controlling situations in which people or organisms might encounter a hazard...
- Risk assessmentThe process of identifying and evaluating the potential adverse effects of exposure to a hazard, such as a...
- Risk assessment management processA structured framework that integrates risk assessment with risk management to address potential hazards...
- Risk associated with a lifetime exposureThe estimated probability of an adverse health effect occurring over an individual's entire lifespan due to...
- Risk aversionA behavioral tendency to prefer a certain outcome with a lower, but guaranteed, benefit over an uncertain...
- Risk characterisationThe final step in a risk assessment, where the results of hazard identification, dose-response assessment...
- Risk communicationThe interactive process of exchanging information and opinions about risks among risk assessors, risk...
- Risk de minimisA level of risk considered to be so small as to be negligible or trivial, and therefore not warranting...
- Risk estimationThe quantitative determination of the probability and magnitude of adverse effects occurring due to exposure...
- Risk evaluationThe process of determining the significance or acceptability of identified risks, often involving a...
- Risk hypothesesTestable statements that describe the potential relationships between stressors, exposure, and ecological...
- Risk identificationThe initial stage of risk assessment, involving the recognition and characterization of potential hazards and...
- Risk managementThe process of making decisions and implementing actions to control or reduce risks to human health or the...
- Risk markerA measurable characteristic or factor that indicates an increased probability of developing a disease or...
- Risk monitoringThe continuous or periodic surveillance of identified risks to determine if they are changing or if new risks...
- Risk perceptionThe subjective assessment that individuals or groups make regarding the probability and severity of a...
- Risk phrasesStandardized statements describing the hazards associated with dangerous substances and preparations, used...
- Risk quotientA numerical value obtained by dividing the predicted environmental concentration (PEC) of a substance by its...
- Risk ratioA comparison of the probability of an adverse outcome occurring in a group exposed to a substance against the...
- Risk reductionActions taken to lessen the probability, negative consequences, or both, associated with a particular hazard...
- Risk sourceA substance, activity, or condition that has the potential to cause harm to human health or the environment...
- Risk-specific doseA calculated dose of a chemical that corresponds to a predetermined, acceptable level of risk for a specific...
- Ritchie equationA linear free-energy relationship that correlates the rates of reaction between electrophiles and...
- Rivet popper hypothesisA concept suggesting that ecosystems can tolerate the loss of some species without immediate collapse...
- RNA interferenceA biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted...
- Robertsonian translocationA specific type of chromosomal rearrangement that involves the fusion of two acrocentric chromosomes at their...
- RobotAn automated, programmable machine capable of carrying out a complex series of actions autonomously or...
- Rocket electrophoresisA quantitative immunoelectrophoretic technique used to determine the concentration of an antigen in a sample...
- Rod groupA symmetry group for atoms arranged in three dimensions but repeating regularly along only one direction...
- Rod-coil copolymerA block copolymer composed of at least one block with a rigid, rod-like conformation and at least one block...
- RodenticideA chemical substance specifically designed to kill rodents, such as rats, mice, and voles. These pesticides...
- Rod-like morphologyA structural characteristic of a material where its constituent particles or domains are elongated and...
- RöntgenA non-SI unit of exposure to X-rays or gamma rays, defined by the amount of ionization produced in air. One...
- Root mean square error of cross validationA statistical measure of the average magnitude of the errors in predictions made by a model during a...
- Root mean squared error of calibrationA statistical measure that quantifies the average magnitude of the differences between the predicted values...
- Root mean squared error of predictionA measure of the average magnitude of the errors in predictions made by a model on a set of new, unseen data...
- Root-mean-square end-to-end distanceA statistical measure of the average spatial separation between the two ends of a polymer chain, accounting...
- Root-mean-square end-to-end distance of a freely rotating chainA theoretical measure of the average separation between the ends of a polymer chain where bond angles are...
- Root-mean-square radius of gyrationA measure of the average size of a polymer coil in solution or in the melt, representing the root-mean-square...
- Root-mean-square unperturbed end-to-end distanceThe average spatial separation between the ends of a polymer chain in an ideal theta solvent, where...
- Root-mean-square unperturbed radius of gyrationThe average size of a polymer coil in an ideal theta solvent, where excluded volume effects are negligible...
- RosetteA microscopic cluster formed by a central cell, typically a lymphocyte, surrounded by and attached to other...
- RostralDescribing a direction toward the front of the body or the head, or a structure situated closer to the head...
- RotamerA conformer that arises from hindered rotation about a single bond and sits at a minimum on the potential...
- Rotarod testA behavioral assessment used in neurotoxicology and pharmacology to evaluate motor coordination, balance, and...
- Rotated Fischer projectionA projection formula for polymer chains, made by turning a standard Fischer projection through 90 degrees so...
- Rotating disc electrodeAn electrode consisting of a conductive disk embedded in an insulating cylinder, which is rotated at a...
- Rotating disk sorptive extractionA microextraction technique where a sorbent-coated disk is rotated in a sample solution to extract analytes...
- Rotating-frame NOE spectroscopyA nuclear magnetic resonance technique that measures the nuclear Overhauser effect (NOE) in a coordinate...
- Rotation per helix residueThe angle of rotation about the helix axis that relates the position of one constitutional repeating unit to...
- Rotational barrierThe energy difference between the highest and lowest energy conformations that arise from rotation around a...
- Rotational branchA family of lines within a gas-phase rovibrational band, all produced by transitions with the same change ΔJ...
- Rotational constantsThe constants A, B and C that set the spacing of a molecule's rotational energy levels, each equal to a fixed...
- Rotational correlation timeThe average time a molecule takes to rotate through an angle of one radian. This parameter reflects the rate...
- Rotational diffusionThe random reorientation of molecules or molecular segments due to thermal energy, leading to changes in...
- Rotational diffusion coefficientA measure of the rate at which a molecule reorients itself due to random thermal motions in a fluid. This...
- Rotational echo double resonanceA solid-state nuclear magnetic resonance (NMR) technique that measures heteronuclear dipolar couplings...
- Rotational frequencyThe number of complete revolutions or rotations executed per unit of time by a rotating object or system...
- Rotational frictional coefficientA measure of the resistance encountered by a molecule or molecular segment as it undergoes rotational motion...
- Rotational isomeric stateA specific conformation of a polymer chain segment defined by the fixed dihedral angles around its backbone...
- Rotational relaxation timeThe characteristic time constant for a molecule's rotational motion to return to equilibrium after a...
- Rotational termA component of the total energy of a molecule that arises from its rotation around its center of mass. These...
- Rotation-vibration spectrumA type of molecular spectrum that arises from simultaneous changes in both the rotational and vibrational...
- Rotator phase transitionA type of phase transition in which molecules or molecular groups within a solid crystal gain rotational...
- Rotatory powerThe ability of a chiral substance to rotate the plane of plane-polarized light, a phenomenon known as optical...
- Rotaxane constitutional repeating unitA constitutional repeating unit of a macromolecular rotaxane that itself has a rotaxane structure, so every...
- Rotaxane constitutional unitA molecular entity within a rotaxane that retains the characteristic interlocked structure, comprising a...
- Rotaxane end-unitA unit at the chain end of a macromolecular rotaxane, pairing the terminal group of the polymer chain with...
- Rotaxane monomerA monomer whose molecule is itself a rotaxane, with a macrocycle threaded on an axle that carries bulky end...
- Rotaxane monomeric unitThe smallest constitutional unit of a macromolecular rotaxane that is derived from a rotaxane monomer and is...
- Rotaxane polymerA macromolecule in which multiple rotaxane units are incorporated into the polymer backbone or as side...
- RotaxanesMechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule threaded through a...
- RotenoidsA class of naturally occurring isoflavonoid compounds characterized by a specific tetracyclic ring system...
- RotometerA device for measuring the flow rate of a fluid in a closed tube, also known as a variable area flowmeter. It...
- Roughness factorThe ratio of the true surface area of a material to its apparent or geometric surface area. This factor...
- Rouse chainA theoretical model of a polymer chain that treats the chain as a series of beads connected by entropic...
- Rouse theoryA theoretical framework that describes the dynamics of polymer chains in dilute solutions or melts by...
- Route of exposureThe pathway by which a chemical substance enters a biological system or comes into contact with a target...
- Rovibronic stateA quantum mechanical state of a molecule that simultaneously describes its rotational, vibrational, and...
- Row structureA specific type of polymer morphology characterized by a lamellar crystal structure that forms on a fibrous...
- r-strategyA reproductive strategy characterized by the production of many offspring with a high growth rate, short...
- RubredoxinA small, non-heme iron protein found in anaerobic bacteria and archaea, characterized by a single iron atom...
- Ruby laserA type of solid-state laser that employs a synthetic ruby crystal, consisting of aluminum oxide doped with...
- Ruggedness of a measurement procedureThe capacity of an analytical method to keep giving acceptable results when small variations creep into the...
- Rule of fiveA set of four property limits, formulated by Christopher Lipinski, used to flag compounds likely to have poor...
- Rule of threeA set of guidelines used in fragment-based lead discovery to define a chemical fragment suitable for...
- Rules of practical causal inferenceA set of guidelines used to establish a cause-and-effect relationship between an exposure and an observed...
- Run biasA systematic error that affects all measurements performed within a single analytical run, causing them to...
- Run-offThe portion of precipitation or irrigation water that flows over the land surface, eventually reaching...
- RuntAn individual animal within a litter that is noticeably smaller and weaker than its littermates at birth or...
- RuptureThe process of breaking or bursting, often referring to the failure of a material under stress or the...
- Rutherford backscatteringA surface analysis technique that involves directing a beam of high-energy ions, typically helium ions, at a...
- Rutherford backscattering spectrometryAn analytical technique that uses the elastic scattering of high-energy ions, typically helium ions, from a...
- Rutherford cross sectionA theoretical value describing the probability of elastic scattering of charged particles by a Coulomb...
- Ρ-valueA quantitative measure in physical organic chemistry that describes the sensitivity of a reaction series to...
- Rydberg constantA fundamental physical constant that relates to the electromagnetic spectra of atoms. It represents the...
- Rydberg orbitalAn atomic or molecular orbital characterized by a very large principal quantum number, causing the electron...
- Rydberg stateAn electronically excited state of an atom or molecule in which an electron is promoted to an orbital with a...
- Rydberg transitionAn electronic transition in an atom or molecule where an electron moves from a valence orbital to a Rydberg...
726 of 13,676 terms in Chemistry terminology (MLC-0109). Request the full dataset.