42,772 articles
Devonian
The Devonian, or Age of Fishes, is a geologic period from 419.2 to 358.9 million years ago, when jawed fishes dominated and the first tetrapods appeared.
Dew point
The dew point is the temperature to which air must be cooled at constant pressure for water vapor to condense, and a direct measure of humidity.
Dewar benzene
Dewar benzene is a highly strained colorless valence isomer of benzene with two fused cyclobutene rings, proposed by James Dewar in 1869 and first synthesized in 1962.
Dextroamphetamine
Dextroamphetamine, also known as dexamfetamine or Dexedrine, is a central nervous system stimulant prescribed mainly for ADHD and narcolepsy, and the more potent of amphetamine's two enantiomers.
DFT matrix
The DFT matrix is a complex square matrix whose entries are powers of an N-th root of unity, so multiplying it by a vector computes the discrete Fourier transform.
DFT-based microkinetic modeling
DFT-based microkinetic modeling (DFT-MKM) is a computational catalysis method that builds kinetic models from DFT-calculated elementary steps, predicting rates and selectivities for systems like CO2 hydrogenation, ammonia synthesis, and electrocatalysis.
DFT-D3
DFT-D3 is an empirical London dispersion correction for density functional theory and related quantum chemical methods, developed by Stefan Grimme and coworkers and published in the Journal of Chemical Physics in 2010.
DFTB3
DFTB3 is a semiempirical quantum-chemical method, the third-order extension of the self-consistent-charge density-functional tight-binding method (SCC-DFTB), improving hydrogen bonds and proton affinities and widely used in QM/MM biomolecular simulations.
DG Tau
DG Tau (DG Tauri) is a classical T Tauri star, a young low-mass star still accreting from its disk, in the Taurus Molecular Cloud about 120.8 parsecs away.
DGLAP evolution
DGLAP evolution, or the Altarelli-Parisi equations, is the set of perturbative QCD equations describing how parton distribution functions change with the energy scale of a scattering process.
Dhamar, Harras of
Harras of Dhamar, a volcanic field in central-western Yemen near Dhamar city (14.57°N, 44.67°E), elevation 3,500 m, extending 80 km east with stratovolcanoes, cones, and a possible unconfirmed 1937 eruption.
Dhu al-Hijja (ذو الحجة)
Dhu al-Hijja (ذو الحجة) is the twelfth and final month of the Islamic lunar calendar, when the Hajj pilgrimage is performed and Eid al-Adha falls on the 10th.
Dhu al-Hijjah
Dhu al-Hijjah (Arabic: ذو الحجة) is the twelfth and final month of the Islamic lunar calendar, the month of the Hajj pilgrimage to Mecca and of Eid al-Adha on its tenth day.
Di-n-octyl phthalate
Di-n-octyl phthalate (DnOP) is an odorless, oily phthalate ester used as a plasticizer in polyvinyl chloride, sold only as about 20% of a commercial C6–10 phthalate mixture.
Di-tert-butyl dicarbonate
Di-tert-butyl dicarbonate, commonly called Boc anhydride or Boc2O, is a colorless organic reagent used in organic synthesis to protect amines, including amino acids and peptides, with the Boc group.
Diacetone alcohol
Diacetone alcohol, or 4-hydroxy-4-methyl-2-pentanone, is a clear, water-miscible beta-hydroxy ketone solvent made by condensing two acetone molecules. A slow-evaporating solvent used mainly in paints and coatings, it is also an intermediate for mesityl oxide.
Diacetyl
Diacetyl (butane-2,3-dione) is a volatile diketone with an intense buttery aroma that occurs naturally in butter, beer, wine, and coffee and is used as a flavoring agent.
Diafiltration
Diafiltration is a pressure-driven membrane filtration method that washes out small solutes such as salts by adding water or buffer while retaining larger molecules like proteins.
Diagenesis
Diagenesis is the set of physical, chemical, and biological changes that convert deposited sediment into sedimentary rock at low temperatures and pressures, before metamorphism begins.
Diagnostic systems on major fusion devices
The diagnostic systems on major fusion devices cover how ITER, JET, and Wendelstein 7-X measure plasma, from ITER's roughly 50 systems across 26 ports to JET's interferometer.
Diagnostic test accuracy meta-analysis
Diagnostic test accuracy (DTA) meta-analysis is a systematic review method that pools studies of a diagnostic test's sensitivity and specificity, handling the threshold trade-off between them.
Diagonal
A diagonal is a line segment joining two non-adjacent vertices of a polygon or polyhedron; a polygon with n vertices has n(n−3)/2 diagonals, and a triangle has none.
Diagonal lemma
The diagonal lemma, also called the diagonalization or fixed-point lemma, is a mathematical logic theorem giving each arithmetic formula a sentence describing itself, key to Gödel's incompleteness theorems.
Diagonal matrix
A diagonal matrix is a square matrix in which every entry off the main diagonal is zero, so arithmetic, powers, determinants, and inverses reduce to operations on the diagonal entries.
Diagonalizable matrix
A diagonalizable matrix, or nondefective matrix, is a square matrix similar to a diagonal matrix, meaning it has n linearly independent eigenvectors and acts as simple scaling in the eigenbasis.
Diagonalization (linear algebra)
Diagonalization is a linear algebra method rewriting a square matrix A as A = PDP⁻¹, with D diagonal of eigenvalues and P's columns eigenvectors, making powers and functions of A easy to compute.
Dialectica interpretation
The Dialectica interpretation, also called Gödel's functional interpretation or D-interpretation, is a proof interpretation reducing Heyting arithmetic to Gödel's quantifier-free System T, published by Kurt Gödel in 1958.
Dialetheism
Dialetheism is the view that some contradictions, called dialetheias, are both true and false, developed by Graham Priest and Richard Routley in the late 1970s.
Diallyl disulfide
Diallyl disulfide (DADS) is an organosulfur compound making up 17.5 to 35.6% of garlic oil, formed when allicin breaks down and giving garlic its odor.
Diallyl sulfide
Diallyl sulfide is an organic sulfide with a strong garlic odor, formed when crushed garlic's allicin decomposes, and a standard inhibitor of the enzyme CYP2E1.