42,772 articles
Grubbs catalyst
Grubbs catalyst is a well-defined ruthenium carbene complex reported by Robert H. Grubbs in 1992 that catalyzes olefin metathesis, work honored with the 2005 Nobel Prize in Chemistry.
Grundlagen der Arithmetik
Die Grundlagen der Arithmetik (The Foundations of Arithmetic) is an 1884 book by the German logician Gottlob Frege, arguing that arithmetic is a development of logic.
Grundlagen der Geometrie
Grundlagen der Geometrie (Foundations of Geometry) is a monograph by the German mathematician David Hilbert, first published in Leipzig in 1899, which supplied the first complete axiom system for Euclidean geometry and shaped twentieth-century mathematics.
Grüneisen parameter
The Grüneisen parameter (γ) is a dimensionless solid-state quantity measuring how a crystal's vibrational frequencies shift with volume, named for German physicist Eduard Grüneisen and widely used in high-pressure and geophysics work.
Grunwald–Winstein equation
The Grunwald–Winstein equation, proposed by Ernest Grunwald and Saul Winstein in 1948, is a linear free-energy relationship relating solvolysis rates to solvent ionizing power, extended to include nucleophilicity.
Grus (constellation)
Grus, the crane, is a southern constellation covering 366 square degrees south of Piscis Austrinus, named by Johann Bayer in 1603 and best viewed on October evenings.
GS 1124-68
GS 1124-68, also cataloged GRS 1124-68 and X-ray Nova Muscae 1991, is a soft X-ray transient in Musca discovered on January 8, 1991, hosting a black hole of about 11 solar masses.
GS 2000+25
GS 2000+25 (QZ Vulpeculae) is a stellar-mass black hole X-ray binary in Vulpecula, discovered as a bright X-ray nova by the Ginga satellite in 1988.
GSI Helmholtz Centre for Heavy Ion Research
GSI Helmholtz Centre for Heavy Ion Research (Gesellschaft für Schwerionenforschung) is a German national laboratory in Darmstadt operating a heavy-ion accelerator, known for discovering six chemical elements including darmstadtium.
GSST (Ge2Sb2Se4Te1) phase-change material
GSST, the chalcogenide alloy Ge2Sb2Se4Te1, is an optical phase-change material developed at MIT from 2018 as a selenium-substituted GST derivative, offering low infrared loss and a large index contrast.
GTPγS
GTPγS is a non-hydrolysable analog of guanosine triphosphate in which sulfur replaces an oxygen of the terminal phosphate, locking G proteins in their active state.
Guaiacol
Guaiacol, also known as O-methoxyphenol, is a phenolic ether found in wood smoke, guaiac resin, and smoked foods, and a raw material for vanillin and guaifenesin.
Guanethidine
Guanethidine, once sold as Ismelin, is an antihypertensive drug that depletes norepinephrine in sympathetic nerve endings, a mainstay for severe hypertension after 1960 that is now discontinued.
Guangbin Dong
Guangbin Dong (董广彬) is an American-based organic chemist at the University of Chicago known for catalytic carbon–carbon bond activation and "cut & sew" ring construction.
Guanidine
Guanidine is a strong organic base with the formula CH₅N₃, the parent of the guanidines; its group appears in arginine, creatine, and drugs such as streptomycin and proguanil.
Guanidine hydrochloride
Guanidine hydrochloride, also called guanidinium chloride or GdmCl, is the hydrochloride salt of the strong organic base guanidine, used in laboratories to denature proteins and purify nucleic acids.
Guanosine diphosphate
Guanosine diphosphate (GDP) is a guanine nucleotide with two phosphate groups and formula C₁₀H₁₅N₅O₁₁P₂, the product of GTP hydrolysis and the inactive, GDP-bound state of regulatory GTP-binding proteins.
Guanosine monophosphate
Guanosine monophosphate, also called guanylic acid, is a purine ribonucleotide made of guanine, ribose, and one phosphate group, an RNA building block and umami flavor enhancer.
Guarded hot plate method
The guarded hot plate method is a primary steady-state technique for measuring the thermal conductivity of insulation, standardized as ASTM C177 and ISO 8302 since 1945.
Guenter Ahlers (engineer)
Guenter Ahlers is an experimental physicist known for critical phenomena near the superfluid transition of liquid helium and for experiments on convection, pattern formation, and turbulent heat transport.
Guerbet reaction
The Guerbet reaction, named for French chemist Marcel Guerbet, is a catalytic coupling of two alcohols with loss of water, forming a longer-chain, β-branched primary alcohol used industrially for over a century.
Guest star (客星) (astronomy)
Guest star, or 客星, is the term in traditional East Asian astronomy for a celestial body that suddenly appears and slowly fades, covering comets, novae, and supernovae.
Guglielmo Lanzani
Guglielmo Lanzani is an Italian physicist and full professor at the Politecnico di Milano who studies organic photophysics and develops light-sensitive interfaces, including a retinal prosthesis for degenerative blindness.
Guglielmo Marconi
Guglielmo Marconi was an Italian inventor of wireless telegraphy, or radio, who received the first wireless patent in 1896 and won the 1909 Nobel Prize in Physics.
Guglielmo Scovazzi
Guglielmo Scovazzi is an Italian-American computational mechanics researcher and Duke University professor, best known for developing the Shifted Boundary Method and receiving the 2017 Presidential Early Career Award.
Guiana Shield
The Guiana Shield, also called the Guayana Shield, is a Precambrian rock formation underlying Venezuela, Guyana, Suriname, French Guiana, and parts of Brazil and Colombia.
Guibin Jiang (江桂斌)
Guibin Jiang (江桂斌) is a Chinese analytical and environmental chemist at the Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, known for research on persistent organic pollutants and mercury.
Guide star
A guide star is a natural or artificial optical reference source used by telescopes and spacecraft for steady pointing, or by adaptive optics to cancel atmospheric blurring.
Guide to the Expression of Uncertainty in Measurement
The Guide to the Expression of Uncertainty in Measurement (GUM) is the international standard for evaluating and expressing uncertainty in measurement, first published by ISO in 1993.
Guiding center
The guiding center is the center of the spiral trajectory of a charged particle gyrating in a magnetic field; guiding-center theory averages out the fast gyration.