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from article Set theory
Sets of points on a plane.
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from article Set theory
Vertical projection of set X onto segment Y.
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from article Polygon
Triangle ABC with nine-point circle. Symbols are explained in text.
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from article Polygon
Regular pentagon, showing approximate construction without a protractor. Symbols are explained in text.
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from article Polygon
Polar triangles A, B, C and A′, B′, C′. The center of the sphere is at O. AQ and PB are 90° arcs, so angle C′ = arc PQ is the supplement of AB.
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from article Epicycloid
Diagram of an epicycloid.
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from article Mass spectrometry
Mass spectra of creatine (molecular weight 131) obtained by (a) electron impact, (b) chemical ionization, (c) field ionization, and (d) field desorption with moderate heating. Both the molecular ion (not observed in a) and the M + 1 ion in b, c, and…
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from article Mass spectrometry
Representative gas-phase proton affinities of molecules.
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from article Mass spectrometry
Potential well of a molecule: (a) undistorted, with ionization potential I near a metal with work function ϕ in the absence of a field gradient; and (b) in a strong field gradient. Near the metal surface the external field raises the most weakly…
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from article Mass spectrometry
Use of isotope distribution to determine elemental composition. (a) Molecular ion for a compound containing one bromine atom. (b) Molecular ion for a compound containing two bromine atoms. (c) Molecular ion for a compound containing neither bromine…
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from article Mass spectrometry
Mass spectra of (a) acetophenone and (b) valerophenone, using electron impact.
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from article Mass spectrometry
Scale-expanded portion of acetophenone spectrum showing a broad metastable ion at m/e 56.5.
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from article Supramolecular chemistry
Schematic representation of the self-assembly of a tricompartmental cagelike architecture by coordination of 7 ligands of two different types and 12 Cu(I) metal ions: R groups are omitted for clarity on the assembled entity (right). (After P. N. W.…
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from article Licorice
Small cut pieces of dried licorice root (Glycyrrhiza glabra).
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from article Centrifugation
Laboratory centrifuge. (Credit: McGraw-Hill Education)
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from article Centrifugation
Centrifuge used in the development of new therapeutic molecules based on human antibodies for the treatment of infectious and inflammatory diseases, Biotherapix, Grupo Genetrix, Madrid, Spain. (Credit: Pixtal/AGE Fotostock)
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from article Sleep-dependent memory processing
The sleep cycle, memory systems, and memory stages. (a) The human sleep cycle. Across the night, rapid eye movement (REM) sleep and non-REM (NREM) sleep cycle every 90 minutes in an ultradian manner (that is, occurring in cycles that are repeated…
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from article Sleep-dependent memory processing
Sleep-dependent motor skill learning. (a) Wake first. After morning training (10 a.m., clear bar), subjects showed no significant change in performance when tested after 12 hours of wake time (10 p.m., clear bar). However, when tested again…
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from article Sleep-dependent memory processing
Sleep-dependent integration of human relational memory. (a) Delayed inference (associative) memory performance (% correct) in a relational memory task following different offline delays. Immediate testing after just a 20-min offline delay…
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from article Rape
Rape (Brassica napus). (Credit: Howard F. Schwartz)
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from article Territoriality
The tiger (Panthera tigris) is highly territorial in its behavior. (Credit: Safique Hazarika Photography/Getty Images)
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from article Boron
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from article Diamond thin films
Diamond thin films. (a) Nucleation and growth of a diamond thin film. (b) Scanning electron microscope side view image of a 400-nm-thick diamond thin film grown on a silicon substrate. (Wensha Yang, University of Wisconsin-Madison)
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from article Diamond thin films
Scanning electron microscope images of two diamond films, showing the individual diamond crystallites that agglomerate into a continuous film. (a) Very small diamond grains. (b) Film with larger diamond crystals. (Bin Sun, University of…
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from article Metallochaperones
A family of copper metallochaperones direct the trafficking of copper ions inside the cell. The schematic shows three distinct pathways of copper movement within a eukaryotic cell. Copper is first transported into the cell by the cell-surface copper…
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from article Hunger
Principles of appetite regulation by gut–brain peptides. Tissues and organs, including the pancreas, stomach, small intestine, adipose tissue, and large intestine, are sources of peptides that stimulate or inhibit appetite-regulating neurons in the…
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from article Rhenium
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from article Infrared spectroscopy
Mid-infrared absorption spectra recorded on a Fourier-transform spectrometer at a resolution of 1 cm−1. (a) Polystyrene film, 0.05 mm thick. The weak intensity fluctuations between 2000 and 2800 cm−1 are interference fringes, caused by reflections…
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from article Infrared spectroscopy
Basic single-beam recording infrared prism spectrometer. The monochromator (the portion from the entrance slit S1 to the exit slit S2) is a Littrow mounting, a common arrangement for infrared instruments.
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from article Infrared spectroscopy
Spectrum of the ν1 + ν5 rotation–vibration band of acetylene recorded with a grating spectrometer, resolution 0.05 cm−1; gas at 25°C and 100-torr (13.3-kPa) pressure, 25-cm (10-in.) path length. The letters indicate features that are discussed in…
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from article Xenon
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from article Distilled spirits
Flow diagram of whiskey production. (J. E. Seagram and Sons)
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from article Difference equation
Numerical solution of Eq. (32) for a = 0.05, b = 0.1, c = 0.01, and a step input. The solution uses the state-variable representation of Eq. (33) and the difference-equation approximation of Eq. (36) with h = 0.1.
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from article Cycloid
Diagram of cycloid; symbols explained in text.
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from article Dialysis
Equipment for dialysis.
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from article Field theory (mathematics)
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from article Field theory (mathematics)
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from article Carbon
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from article Carbon
Graphene, an allotrope of carbon in which carbon atoms are arranged in a monolayer and bonded covalently forming a hexagonal structure. (Copyright © Science Photo Library/Alamy Stock Photo)
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from article Carbon
Carbon nanotube. (Copyright © Science Photo Library/Alamy Stock Photo)
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from article Speech perception
The perception of speech (as well as the production of speech) involves interactive processes occurring in various regions of the brain. Researchers also have noted the important contribution that vision makes to normal speech perception. (Copyright…
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from article Speech perception
An auditory spectrogram of the word "telephone." (a) The vertical striations in the bands represent amplitude modulation at the frequency of the voice pitch. Such striations are absent from the initial noise portion corresponding to the voiceless…
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from article Sugar crops
Sugarcane (Saccharum officinarum) growing in Cuba. (Credit: Curioso Photography/Shutterstock)
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from article Sugar crops
Sugarbeets (Beta vulgaris). (Credit: Agricultural Research Service, U.S. Department of Agriculture)
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from article Information theory (biology)
Human information processing. The estimates of channel capacity are based on the number of rods in the retina of the eye and the number of hair cells in the inner ear's organ of Corti.
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from article Information theory (biology)
Flow diagram of communication.
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from article Information theory (biology)
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from article Information theory (biology)
Coupling diagram of communication.
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from article Solution
Fugacity and mole fraction. Line A, ideal. Line B, typical nonideal. Line C, Henry's law.
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from article Adsorption
Particle adsorption on polymer hydrogel surface. [Credit: N. Sato et al., Sci. Rep., 2017 (CC BY 4.0)]
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from article Adsorption
One-dimensional potential energy curves typical for hydrogen molecules (H2) and atoms (H) as they approach the surface of a metal substrate. The solid curve, which involves a crossing from the molecular curve to the atomic curve, shows the type of…
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from article Adsorption
Analogy between the bonding of (a) the ethylidyne ligand (CCH3) to a rhodium (Rh) single crystal surface and (b) to a cobalt carbonyl cluster [H3CC(Co)2(CO)7]. The bond lengths and angles, as determined by diffraction techniques, are virtually…
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from article Adsorption
Scanning tunneling micrographs of 5× 2.25 nanometer areas of (a) the basal plane of a graphite surface and (b) the same surface after being covered with a liquid drop of 1-triacontanol. The bright spots in (a) correspond to every other carbon atom…
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from article Radiation chemistry
Variation of G with linear energy transfer (LET) for the products solvated electron (e−aq), OH, H2O2, H, and H2. (After R. C. Cooper and R. W. Wood, eds., Physical Mechanisms in Radiation Biology, National Technical Information Service, 1974)
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from article Radiation chemistry
Growth and decay of the signal of naphtholate anion in the pulse irradiation of a naphthol solution. Deter- mination of the decay rate gives a spontaneous lifetime of 30 milliseconds for loss of the naphthol proton in aqueous solution.
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from article Radiation chemistry
Time dependence of the electron spin resonance signals of hydrogen atoms in the presence of 50–600-micromolar azide ion. The signal intensities and decay periods decrease with increasing azide ion concentration.
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from article Transition elements
Portion of periodic table showing transition elements, their atomic number, symbol, and electron configurations in valence shells; heavy border indicates the more restricted classification.
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from article Transition elements
Physical properties of transition elements as function of their atomic number.
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from article Toxicology
Toxicologists study the adverse effects of chemical and physical agents on living organisms. In this photograph, a turtle is covered in petroleum following an oil spill. (Credit: Getty Images)
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from article Toxicology
Fish killed by chemically contaminated waters. (Credit: National Oceanic and Atmospheric Administration)
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from article Toxicology
The movement of mercury in the environment. In nature, mercury vapor (Hg0) is a stable gas and evaporates from the Earth's surface (both soil and water). Moreover, anthropogenic sources are a significant contributor to atmospheric mercury, and these…
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from article Food
Sources of healthy fats, which are one component of a balanced diet. (Credit: Tina Larsson\Getty Images)
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from article Surface (geometry)
Part of a dihedron (the rest has been torn away), showing dihedral angle.
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from article Surface (geometry)
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from article Surface (geometry)
Some quadric surfaces, with parameters a, b, and c. (a) Ellipsoid; 0 < c < b < a. (b) Hyperboloid of one sheet; 0 < a < b < c. (c) Elliptic paraboloid; 0 < a < b and c > 0. (d) Hyperboloid of two sheets; 0 < a < b < c. (e) Hyperbolic paraboloid; c >…
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from article Surface (geometry)
Surface of revolution. The generating curve (in the yz plane) is f(y,z) = 0. The axis of revolution is the z axis.
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from article Surface (geometry)
Sphere, with a zone and a lune.
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from article Surface (geometry)
Catenoid. The axis of revolution is the y axis.
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from article Interpolation
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from article Interpolation
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from article Interpolation
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from article Gas and atmosphere analysis
Collection devices for monitoring air in the workplace. (a) Solid sorbent (charcoal) sampling tube. (b) Midget impinger. (c) Cowled cassette and its filter. (d) Passive monitor, used for nitrogen dioxide. (e) Piston-type detector tube pump.
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from article Gas and atmosphere analysis
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from article Gas and atmosphere analysis
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from article Gas and atmosphere analysis
Evacuated-flask sampling system.
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from article Autopilot
Basic elements of an autopilot system.
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from article Autopilot
Typical longitudinal autopilot control loop.
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from article Autopilot
Typical directional autopilot control loop.
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from article Zirconium
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from article Food microbiology
Pie chart showing the 14 major foodborne pathogens according to their economic costs (shown in terms of percent and U.S. dollars). The annual cost estimates are based on disease incidences in the United States. The five most costly foodborne…
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from article Food microbiology
A colorized scanning electron micrograph (SEM) of Salmonella enterica serovar Enteritidis. This foodborne pathogen can cause enteric (intestinal) infections. (Credit: Jean Guard-Petter/U.S. Department of Agriculture)
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from article Food microbiology
A digitally colorized scanning electron micrograph (SEM) depicting a number of mustard-colored, spheroid-shaped Staphylococcus aureus bacteria that were in the process of escaping their destruction by blue-colored human white blood cells. (Credit:…
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from article Food microbiology
Low-temperature electron micrograph of a cluster of E. coli bacteria. Each individual bacterium is oblong-shaped. (Credit: Eric Erbe/U.S. Department of Agriculture; digital colorization by Christopher Pooley/U.S. Department of Agriculture)
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from article Food microbiology
Confocal light micrograph of Campylobacter jejuni cells (fluorescent green) on chicken skin. (Credit: Anna Bates/U.S. Department of Agriculture)
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from article Controlled/living radical polymerization
Free-radical polymerization.
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from article Controlled/living radical polymerization
Active and dormant radical equilibrium.
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from article Controlled/living radical polymerization
Nitroxide-mediated radical polymerization of styrene or butylacrylate.
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from article Controlled/living radical polymerization
Atom transfer radical polymerization.
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from article Controlled/living radical polymerization
RAFT polymerization.
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from article Menthol
Enantioselective synthesis of /(−) menthol.
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from article Gel permeation chromatography
Gel permeation chromatograph.
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from article Gel permeation chromatography
Typical gel permeation chromatogram with a calibration curve.
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from article Gel permeation chromatography
Typical triple chromatogram obtained by using both light scattering and viscometric detectors in addition to a concentration detector.
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from article Problem solving (psychology)
Composite view of a colorized magnetic resonance imaging (MRI) scan of a human brain blended with a cross-section illustration of a human head. Cognitive psychology attempts to understand the integral mental processes of the human brain involved in…
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from article Problem solving (psychology)
The game of chess involves many aspects of problem solving. In chess playing, a solution consists of an attempt to convert an initial state of a task (for example, a chessboard before the first move is made) into a final or goal state (checkmate)…
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from article Morphine alkaloids
Biosynthesis of thebaine.
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from article Osmoregulatory mechanisms
Various osmoregulatory mechanisms are utilized in a marine fish. The "0/00" term indicates units of parts per thousand. (Copyright © McGraw-Hill Education)
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from article Osmoregulatory mechanisms
The kidney helps to eliminate water and waste products from the body. During osmoregulation in this organ, numerous smaller functional units, called urinary tubules or nephrons, allow water to be moved across cell membranes from a lower to a higher…
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from article Carborane
Parent clusters from which carborane structures are determined. The diagonal lines define series of related closo, nido, and arachno structures.
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from article Carborane
Skeletal structures of the (a) 1,2-, (b) 1,7-, and (c) 1,12-isomers of C2B10H12.
