42,772 articles
Enumerative combinatorics
Enumerative combinatorics is the branch of mathematics that counts the elements of finite sets, seeking exact formulas, recurrences, or asymptotics for counting functions, as in Cayley's tree formula.
Envelope (mathematics)
In geometry and calculus, an envelope is a curve tangent to every member of a one-parameter family of curves, extended to surfaces; Leibniz introduced the idea in 1694.
Envelope (waves)
In wave physics, the envelope, also called the wave or signal envelope, is the slowly varying amplitude curve outlining a modulated wave's rapid oscillations, moving at the group velocity.
Envelope method (statistics)
The envelope method is a dimension-reduction technique in multivariate statistics that improves regression efficiency by separating relevant variation from immaterial variation, introduced by Cook, Li, and Chiaromonte in 2010.
Environment America
Environment America is a federation of state-based environmental advocacy organizations in the United States, founded in 2007 out of the state PIRG network and headquartered in Denver.
Environmental and toxicological effects of nitro compounds
Environmental and toxicological effects of nitro compounds: military explosives such as TNT, RDX, and HMX persist in soil and water, and microbial reduction of nitro groups produces metabolites that damage hemoglobin and DNA.
Environmental Assessment of Ogoniland
The Environmental Assessment of Ogoniland is a 2011 United Nations report assessing oil contamination in Ogoniland, Nigeria's Niger Delta, and recommending a clean-up lasting up to 25 years.
Environmental Defense Fund
The Environmental Defense Fund (EDF) is an American environmental nonprofit founded in 1967 on Long Island, known for the 1990 Clean Air Act's cap-and-trade acid rain program.
Environmental degradation
Environmental degradation, also called environmental damage or ecological degradation, is the deterioration of the natural environment through resource depletion, ecosystem destruction, and pollution, reducing the capacity of land, water, and air to sustain life.
Environmental effects of mining
The environmental effects of mining are the changes mineral extraction imposes on land, water, air, and ecosystems, including acid drainage that can persist for decades after closure.
Environmental flow
An environmental flow is the quantity, timing, and quality of water flow and level needed to sustain aquatic ecosystems, a field of assessment with some 207 methodologies recorded worldwide by 2003.
Environmental hazard
An environmental hazard, also called an environmental health hazard, is a natural or human-made condition that can harm health, ecosystems, or property, with air pollution the deadliest.
Environmental Indicators
Environmental indicators: quantitative measures communicating environmental trends, structured by the PSR/DPSIR framework, used in OECD Core Set, EEA, SDG, and EPI monitoring systems.
Environmental migrant
An environmental migrant, also known as an environmental refugee or ecomigrant, is a person who leaves home because environmental change adversely affects their living conditions.
Environmental noise
Environmental noise is unwanted community sound from road, rail, and air traffic and industry, measured with sound level meters and regulated under the EU's Environmental Noise Directive.
Environmental scanning electron microscopy
Environmental scanning electron microscopy, or ESEM, is a scanning electron microscopy technique that images uncoated, hydrated, wet, or dirty specimens at elevated chamber pressures, without conductive coating or high vacuum.
Environmental transmission electron microscopy
Environmental transmission electron microscopy (ETEM) is a type of transmission electron microscopy that images specimens at atomic resolution while surrounded by controlled gas, often at elevated temperature, chiefly to study catalysts.
Enyne
An enyne is a hydrocarbon compound containing both a carbon–carbon double bond and a triple bond in one chain, a combination that underlies signature reactions such as enyne metathesis.
Enyne metathesis
Enyne metathesis is an organic reaction joining an alkene and an alkyne under transition-metal carbene catalysis to give a conjugated 1,3-diene, including the ring-closing variant RCEYM.
Enzo Martinelli
Enzo Martinelli (1911–1999) was an Italian mathematician at the University of Rome, known for the Bochner–Martinelli formula, the first multidimensional analog of Cauchy's integral formula.
Enzymatic C–H functionalization
Enzymatic C–H functionalization uses enzymes, including P450s and engineered P411s developed by directed evolution, to convert carbon–hydrogen bonds directly into carbon–carbon and carbon–nitrogen bonds without prefunctionalizing substrates.
Enzymatic carbene transfer
Enzymatic carbene transfer is a family of artificial biocatalytic reactions first engineered at Caltech in 2012, in which heme proteins form metal-carbene intermediates from diazo compounds to make new bonds.
Enzymatic carbon dioxide reduction
Enzymatic carbon dioxide reduction uses enzymes, alone or in cascades, to convert CO2 into one-carbon products such as formate and methanol, typically in water at mild conditions.
Enzymatic cyclopropanation and cyclopropenation
Enzymatic cyclopropanation and cyclopropenation are biocatalytic carbene-transfer reactions in which engineered heme enzymes turn diazo compounds and alkenes or alkynes into highly stereoselective cyclopropane or cyclopropene rings.
Enzymatic depolymerization
Enzymatic depolymerization uses enzymes to cleave the hydrolyzable backbones of polymers such as PET and cellulose into monomers, enabling closed-loop plastic recycling and biomass conversion.
Enzymatic extraction
Enzymatic extraction, also called enzyme-assisted extraction (EAE), is a green sample-preparation method that uses cell-wall-degrading enzymes to release polyphenols, oils, and proteins from plant material under mild conditions.
Enzymatic interesterification
Enzymatic interesterification is a fats and oils modification method that uses lipase enzymes to rearrange fatty acids, changing melting behavior while preserving fatty acid composition.
Enzymatic oligonucleotide synthesis
Enzymatic oligonucleotide synthesis uses template-independent polymerases, most often TdT, to build DNA and RNA strands in water, avoiding the solvents and yield losses of phosphoramidite chemistry.
Enzymatic peptide ligation
Enzymatic peptide ligation is the use of enzymes, such as sortases and engineered proteases, to form native peptide bonds between fragments with high selectivity under mild conditions.
Enzymatic polymerization
Enzymatic polymerization is the in vitro synthesis of polymers by isolated enzymes such as lipases and peroxidases, a metal-free route to polyesters, polycarbonates, polyphenols, and polysaccharides.