42,772 articles
Imaginary unit
The imaginary unit is the number i, also known as the square root of minus one, whose square is -1; it extends the real numbers to the complex numbers.
Imaging condition
An imaging condition is the mathematical rule combining forward-propagated source and backward-propagated receiver wavefields into a subsurface reflectivity image, the final step of seismic migration.
Imaging of Dirac plasmons in graphene
Imaging of Dirac plasmons in graphene is the real-space visualization of collective charge oscillations of graphene's massless Dirac electrons, first achieved in 2012 with near-field optical microscopy.
Imaging spectroscopy
Imaging spectroscopy is an optical technique that measures a full spectrum of light for every pixel of an image, producing a three-dimensional data cube used in remote sensing.
iMatGen
iMatGen (image-based materials generator) is a 2019 variational autoencoder framework for inverse design of inorganic solid-state materials, encoding crystals as invertible 3D image grids and demonstrated on vanadium oxides.
Imbecile
Imbecile is a historical medical and legal classification for an intermediate degree of intellectual disability, placed between idiot and moron, now obsolete in diagnosis and surviving mainly as an insult.
Imbibition
Imbibition is the flow process in a porous medium in which a wetting fluid displaces a non-wetting one, driven by capillary pressure; it is the reverse of drainage.
Imidazole
Imidazole, also called 1,3-diazole, is a five-membered aromatic organic compound with two nitrogen atoms and formula C₃H₄N₂, forming the core of histidine, histamine, purines, and biotin.
Imidazolidine
Imidazolidine is a saturated five-membered heterocyclic compound with two nitrogen atoms and formula C3H8N2, the fully hydrogenated form of imidazole, used as a building block in organic synthesis and medicinal chemistry.
Imidazolium chloride
Imidazolium chloride, the monohydrochloride salt of imidazole, also names the 1-alkyl-3-methylimidazolium chloride ionic liquids, the most widely investigated ionic-liquid family, used in cellulose dissolution, electrolytes, and CO2 capture.
Imide
An imide is a functional group in which a single nitrogen atom is bonded to two carbonyl groups, known for examples such as succinimide and phthalimide, the brominating reagent N-bromosuccinimide, and polyimide polymers.
Imine
An imine is an organic compound with a carbon–nitrogen double bond, the nitrogen analog of an aldehyde or ketone, formed by condensation of a carbonyl compound with a primary amine.
Imine umpolung
Imine umpolung is a strategy in organic synthesis that reverses the normal polarity of an imine's C=N bond, letting the imine carbon react as a nucleophile with carbon electrophiles.
Iminoboronate chemistry
Iminoboronate chemistry uses imines paired with ortho arylboronic acids to form reversible covalent bonds with amines in water, a standard tool for bioconjugation and probes.
Imipenem
Imipenem is a broad-spectrum intravenous carbapenem antibiotic developed at Merck as a stable derivative of thienamycin, first FDA-approved in 1985 as Primaxin with cilastatin, and given with cilastatin to prevent breakdown in the kidney.
Imke de Pater
Imke de Pater, born 1952, is a planetary scientist at UC Berkeley known for Jupiter's radio emission, the 1994 Shoemaker–Levy 9 campaign, and the textbook Planetary Sciences.
Immanuel Bloch
Immanuel Bloch (born 1972 in Fulda) is a German experimental physicist who leads quantum simulation with ultracold atoms at the Max Planck Institute of Quantum Optics.
Immanuel Velikovsky (Иммануил Великовский)
Immanuel Velikovsky (Иммануил Великовский, 1895–1979) was a Russian-born psychiatrist and psychoanalyst whose 1950 bestseller Worlds in Collision claimed recent planetary catastrophes, igniting fierce scientific controversy.
Immersed boundary method
The immersed boundary method is a numerical technique for simulating fluid–structure interaction on a fixed grid, introduced by Charles S. Peskin in 1972 for heart valve flow.
Immirzi parameter
The Immirzi parameter, or Barbero-Immirzi parameter γ, is a free dimensionless constant in loop quantum gravity that sets the size of the quantum of area.
Immortal time bias
Immortal time bias is a systematic error in observational studies with time-to-event outcomes, arising when follow-up time during which the outcome cannot occur is misclassified or excluded, usually favoring the treatment.
Immune set
An immune set is an infinite set of natural numbers that contains no infinite recursively enumerable subset, so no algorithm can enumerate an infinite subcollection of it.
Immunosensor
An immunosensor is a biosensor that uses an antibody or antigen on a transducer to detect its binding partner and convert the binding into a measurable signal.
Imogolite
Imogolite is a poorly crystalline hydrous aluminosilicate clay mineral, first described in 1962 from volcanic ash soils in Japan, whose hollow nanotubes occur in volcanic ash soils worldwide.
Impact cratering
Impact cratering is the process by which hypervelocity collisions with asteroids or comets excavate craters in a planet's solid surface, one of the most widespread surface-shaping processes in the solar system.
Impact driver
An impact driver is a power tool that drives screws and other fasteners using rapid hammer-anvil strikes, giving higher torque and less kickback than a drill.
Impact event
An impact event, also called an Earth impact, is a collision between an asteroid or comet and Earth or another body, leaving a crater or causing an airburst.
Impact metamorphism
Impact metamorphism, also called shock metamorphism, is the irreversible deformation, melting, and vaporization of rock struck by a hypervelocity impact, producing diagnostic features like shocked quartz.
Impact of the COVID-19 pandemic on the environment
The COVID-19 pandemic caused a 6.4% drop in global carbon dioxide emissions in 2020, alongside air quality changes, rising plastic waste, and mostly negative effects on conservation.
Impact wrench
An impact wrench, also called an impact gun, is a power tool that tightens or loosens threaded fasteners by delivering torque in short hammer blows through a square socket drive.