42,772 articles
Nitrosourea
Nitrosourea is a compound containing both a nitroso group and a urea group, a class best known for alkylating anticancer drugs such as carmustine and lomustine.
Nitrotoluene
Nitrotoluene, also called methylnitrobenzene, is any of three isomeric nitroaromatic compounds with formula C₇H₇NO₂, produced by nitrating toluene; the ortho and para isomers are important dye intermediates.
Nitrous acid
Nitrous acid (HNO₂, HONO) is a weak, unstable nitrogen acid that exists only in solution or gas, used in diazotization and driving atmospheric hydroxyl radical formation.
Nitrous oxide
Nitrous oxide, also known as laughing gas, is a colorless gas used as a dental anesthetic, a food propellant, and the third most important greenhouse gas.
Nitrous oxide emissions
Nitrous oxide emissions are the release of nitrous oxide, a long-lived greenhouse gas, from natural sources such as soils and the ocean and from human activities dominated by agriculture.
Nitroxide-mediated polymerization
Nitroxide-mediated polymerization (NMP), also called nitroxide mediated radical polymerization, is a controlled radical polymerization in which stable nitroxide radicals reversibly cap growing chains, enabling well-defined polymers with low polydispersity.
Nitroxyl
Nitroxyl (HNO), also called nitrosyl hydride or hydrogen oxonitrate, is a highly reactive, ephemeral molecule related to nitric oxide that exists only transiently in solution.
Niveen M. Khashab
Niveen M. Khashab is a Lebanese supramolecular chemist and founding professor at KAUST in Saudi Arabia since 2009, known for smart hybrid nanomaterials for drug delivery and porous materials for separations.
Nivôse
Nivôse, from the Latin nivosus meaning "snowy", was the fourth month of the French Republican calendar, first of the three winter months, running from 21 December to 19 January until the calendar was abolished in 1805.
Nixie tube
A Nixie tube is a cold-cathode, neon-filled display tube whose wire cathodes shaped as digits glow, standard on test equipment from the mid-1950s to the 1970s.
Niyazi Serdar Sariçiftçi
Niyazi Serdar Sariçiftçi, born 1961 in Konya, Turkey, is an Austrian-Turkish chemist at Johannes Kepler University Linz credited with inventing bulk heterojunction plastic solar cells.
NLDAS
NLDAS, the North American Land Data Assimilation System, is a multi-model land modeling system producing quality-controlled datasets of soil moisture, snow, and surface fluxes across the continental United States.
NLTS conjecture
The NLTS conjecture (No Low-Energy Trivial States), posed by Freedman and Hastings in 2014, says some low-energy quantum states need super-constant circuit depth; it was proved in 2022.
NMDA
NMDA (N-methyl-D-aspartic acid) is a synthetic acidic amino acid, first synthesized in the early 1960s, that serves as the selective agonist for the NMDA glutamate receptor named after it.
NML Cygni
NML Cygni (NML Cyg) is an extreme red supergiant, or cool hypergiant, in Cygnus, discovered in 1965 and one of the most massive M-type stars known.
NMR crystallography
NMR crystallography combines experimental solid-state NMR spectroscopy with density-functional theory calculations to determine, refine, or validate crystal structures of molecular solids, especially microcrystalline powders unsuitable for single-crystal diffraction.
NMR relaxometry
NMR relaxometry, or nuclear magnetic resonance relaxometry, is a technique measuring spin relaxation times T1 and T2 to characterize molecular motion, usually via field-dependent NMRD profiles.
NMR titration
NMR titration is an analytical chemistry method that records NMR spectra while a binding partner's concentration or pH changes stepwise, best suited to weak interactions other methods struggle to measure.
NN Ser
NN Ser (NN Serpentis), an eclipsing pre-cataclysmic white dwarf plus M4 dwarf binary with a 3.12-hour period, hosts controversial circumbinary planet candidates NN Ser c and d inferred from eclipse timing variations.
NNK
NNK, or nicotine-derived nitrosamine ketone, is a tobacco-specific nitrosamine formed during curing and one of the principal carcinogens in tobacco smoke, classified by IARC as carcinogenic to humans.
No-boundary proposal
The no-boundary proposal, or Hartle-Hawking proposal, is a candidate law for the quantum state of the universe, formulated by James Hartle and Stephen Hawking in 1983.
No-broadcasting theorem
The no-broadcasting theorem is a result of quantum information theory stating that a set of quantum states can be broadcast, or copied, if and only if the states commute pairwise.
No-cloning theorem
The no-cloning theorem is a result of quantum information theory stating that no physical process can produce a perfect copy of an unknown quantum state, established in 1982.
No-communication theorem
The no-communication theorem, also called the no-signaling principle, is a result in quantum information theory stating that entanglement cannot be used to transmit information between observers.
No-hair theorem
The no-hair theorem, also called the no-hair conjecture, states that a stationary black hole is completely characterized by just its mass, angular momentum, and electric charge.
No-miracles argument
The no-miracles argument is a philosophy-of-science argument for scientific realism holding that science's success would be a miracle unless theories are approximately true; Putnam introduced it in 1975.
No-slip condition
The no-slip condition is a fluid mechanics boundary condition stating that a viscous fluid in contact with a solid surface moves with the same velocity as that surface.
No-U-Turn Sampler
The No-U-Turn Sampler (NUTS) is a Markov chain Monte Carlo algorithm extending Hamiltonian Monte Carlo, which sets trajectory length automatically so no hand-tuning is needed.
NOAA Commissioned Officer Corps
The NOAA Commissioned Officer Corps (NOAA Corps) is one of the eight US uniformed services, whose roughly 360 officers operate NOAA's research ships and hurricane hunter aircraft.
NOAA Hazardous Weather Testbed
The NOAA Hazardous Weather Testbed is a facility in Norman, Oklahoma, where National Weather Service forecasters and NOAA researchers test experimental severe weather forecasting tools.