42,772 articles
Medium and large ring conformations
Medium and large ring conformations are the three-dimensional shapes of rings with seven or more atoms, where transannular interactions between inward-facing hydrogens dominate from cyclooctane to cycloundecane.
Medium-energy ion scattering
Medium-energy ion scattering (MEIS) is an ion beam analysis technique, typically using 100–200 keV protons, that determines the composition and structure of a solid's outermost atomic layers.
Medium-entropy alloy
A medium-entropy alloy (MEA) is a metallic alloy of three or four principal elements in near-equiatomic fractions, whose mixing entropy falls between conventional alloys and high-entropy alloys.
Medronic acid
Medronic acid (methylenediphosphonic acid, medronate, MDP), CAS 1984-15-2, is the simplest bisphosphonate, a pyrophosphate analogue with a P-C-P core that binds hydroxyapatite and is used complexed with technetium-99m for bone scanning.
Medroxyprogesterone acetate
Medroxyprogesterone acetate, sold as Depo-Provera, is a synthetic progestin in clinical use since the 1960s, given by injection every 3 months as a contraceptive and in oral tablets.
medRxiv
medRxiv is a free preprint server for medical and health sciences research, launched in June 2019 by Cold Spring Harbor Laboratory, Yale University, and BMJ.
Meenakari
Meenakari (Persian: میناکاری) is a craft of vitreous enameling where colored glass is fused to metal. The tradition is strongest in Persian minakari, centered on Isfahan, and Indian minakari, centered on Jaipur.
MeerKAT Galactic Center bubbles
The MeerKAT Galactic Center bubbles are a pair of radio-emitting cavities above and below the Milky Way's center, discovered in 2019 in images from South Africa's MeerKAT telescope.
Meerwein arylation
Meerwein arylation is a copper-catalyzed radical reaction adding an aryl diazonium salt across an alkene, reported by Hans Meerwein in 1939 and widely used in synthesis.
Meerwein salts
Meerwein salts are trialkyloxonium tetrafluoroborates, principally trimethyloxonium and triethyloxonium tetrafluoroborate, crystalline reagents used to alkylate weakly nucleophilic or sensitive functional groups; the trimethyl salt is the strongest commercially available methylating reagent.
Meerwein–Ponndorf–Verley reduction
The Meerwein–Ponndorf–Verley (MPV) reduction is a transfer hydrogenation reducing aldehydes and ketones to alcohols, typically with isopropanol as hydrogen donor and aluminum isopropoxide as catalyst.
Mefenorex
Mefenorex (Rondimen), N-(3-chloropropyl)-alpha-methylphenethylamine, a racemic amphetamine-derivative anorectic for obesity, metabolized to amphetamine; withdrawn from the EU market in 2000 and now controlled.
MEG experiment
MEG, the Muon to Electron and Gamma experiment at the Paul Scherrer Institut in Switzerland, searches for the rare decay of a muon into a positron and a photon.
MEG II
MEG II is a particle physics experiment at the Paul Scherrer Institut in Switzerland searching for the rare muon decay into a positron and a gamma ray.
Megamaser Cosmology Project
The Megamaser Cosmology Project is an NRAO Key Science Project that measures the Hubble constant through geometric distances to water megamasers, independent of the distance ladder and the CMB.
Megan Cleveland
Megan Cleveland is an American research biologist at NIST's Applied Genetics Group who develops reference materials for clinical diagnostics and won a 2025 PECASE award.
Megan Thielges
Megan Thielges is an American analytical chemist at Indiana University Bloomington who develops two-dimensional infrared spectroscopy to study protein dynamics and received a PECASE award.
Megaphone
A megaphone, also called a loudhailer or bull horn, is a cone-shaped acoustic horn that directs sound into a narrow beam to extend the human voice's range.
Megathrust earthquake
A megathrust earthquake is a great earthquake of moment magnitude 8 or more that ruptures the plate-boundary fault of a subduction zone, including the largest recorded quakes.
Megatsunami
A megatsunami, also known as an iminami, is an unusually large tsunami generated by giant landslides, volcanic flank collapses, or asteroid impacts instead of ordinary earthquakes, with run-ups exceeding 100 m.
Megestrol acetate
Megestrol acetate, sold as Megace, is a synthetic progestin derived from progesterone, used as an appetite stimulant in AIDS-related wasting and as palliative treatment for advanced breast and endometrial cancer.
Meghnad Saha (মেঘনাদ সাহা)
Meghnad Saha (মেঘনাদ সাহা) was an Indian astrophysicist whose Saha ionization equation, published in 1920, relates a hot gas's ionization to its temperature and pressure and became a basic tool for interpreting stellar spectra.
Meglumine antimoniate
Meglumine antimoniate, marketed as Glucantime, is a pentavalent antimonial drug, a complex of antimony with N-methyl-D-glucamine, used since the 1940s as a standard treatment for leishmaniasis.
Meglumine diatrizoate
Meglumine diatrizoate, also called diatrizoate meglumine or meglumine amidotrizoate, is a water-soluble iodinated X-ray contrast medium used for retrograde bladder studies and in oral gastrointestinal products such as Gastrografin.
Mehran Kardar
Mehran Kardar, born in Tehran, is a theoretical physicist and Francis Friedman Professor at MIT, co-originator of the Kardar-Parisi-Zhang equation and winner of the 2025 Boltzmann Medal.
Mei Hong
Mei Hong is an American biophysical chemist and MIT professor who uses solid-state NMR spectroscopy to study membrane proteins, including the influenza M2 proton channel and tau fibrils.
Meidob Volcanic Field
Meidob Volcanic Field (Meidob Hills), alkaline volcanic field in western Sudan at the NE end of the Darfur volcanic province; 5,000 km2, nearly 700 vents, 7 Ma to 5 ka activity, last eruption 2950 BCE.
Meiji era (明治時代)
The Meiji era (明治時代), also known as the Meiji period, spans Emperor Meiji's reign over Japan from 1868 to 1912, beginning with the Meiji Restoration.
Meir Lahav
Meir Lahav (born 1936, Sofia, Bulgaria) is an Israeli chemist at the Weizmann Institute known for his work, with Leslie Leiserowitz, on the crystal forms of organic molecules.
Meissner effect
The Meissner effect, also called superdiamagnetism, is the expulsion of magnetic field from a superconductor's interior, first observed by Walther Meissner and Robert Ochsenfeld in 1933.