Image
from article Electrolysis
Electrolysis cell in which the electrolyte is a solution of sodium chloride.
Search Results
Search Results
Refine this search
Search result paging links
7,415 results
Image
from article Learning
Lateral view of the human brain, including the primary areas of the frontal, temporal, parietal, and occipital lobes. (Copyright © McGraw-Hill Education)
Image
from article Learning
Brain activity can be recorded in various ways, from single-cell activity (top tracing) to the familiar electrical patterns ("brain waves") of an electroencephalogram (bottom tracing). (Credit: Based on an original drawing by C. Cotman and J.…
Image
from article Ultracentrifuge
Diagram of an electrically driven analytical ultracentrifuge. (Beckman Instruments)
Image
from article Ultracentrifuge
Analytical rotor. (Beckman Instruments)
Image
from article Ultracentrifuge
Fixed-angle preparative rotor and tubes. (Beckman Instruments)
Image
from article Biofilm
Biofilms are highly structured communities of microorganisms that are surface-associated or attached to one another, and are enclosed within a self-produced protective extracellular matrix. Biofilm formation and actions involve a number of stages:…
Image
from article Ctenothrissiformes
A Cretaceous ctenothrissiform fossil, Ctenothrissa sp. (order Ctenothrissiformes), on a limestone matrix found in Lebanon. Size: 90 mm (3.5 in.). (Photo courtesy of The Virtual Fossil Museum)
Image
from article Pyroclastic rock
Pyroclastic rock. Bombs from Mauna Kea, Hawai'i, USA. (Credit: J. P. Lockwood/USGS Photo Library, Denver, CO)
Image
from article Pyroclastic rock
Distribution downwind of the pyroclastic fall deposit from the climactic eruption of Mount St. Helens, Washington, on May 18, 1980. The contours (isopachs) are drawn through points of measured equal thickness (in centimeters) of this ash layer.…
Image
from article Pyroclastic rock
Aerial view in March 1998 of the fan-shaped pyroclastic delta formed by repeated entries of pyroclastic flows and surges into the Caribbean Sea during the Soufrière Hills Volcano eruption in 1996–1997. (Credit: R.P. Hoblitt, USGS)
Image
from article Pyroclastic rock
Observed or postulated mechanisms for the generation of pyroclastic flow and surge deposits. (a, b) Mechanisms that commonly produce block-and-ash flow deposits. (b, c) Mechanisms that trigger laterally directed blasts. (d–f) Mechanisms that…
Image
from article Pyroclastic rock
Some variations in pyroclastic rock formations. (a) Layers of pyroclastic fall deposits from the eruption plume of the June 15, 1991, explosive eruption of Mount Pinatubo (Luzon, Philippines). This exposure, located about 9 km (5.5 mi) southeast of…
Image
from article Animal testing
Mice are the most commonly used vertebrate species in animal testing and research. (Credit: Dolores Bonaparte)
Image
from article Animal testing
The use of animals in biomedical research remains essential, but the handling of these sentient beings must be done humanely to minimize and prevent animal harm. (Credit: U.S. Department of Agriculture)
Image
from article Common cold
Adenovirus structure. An adenovirus binds to the host cell via its fiber through the knob at the end of the fiber "spikes" on the capsid (protein coat) surface. (Credit: M. K. Cowan and H. Smith; copyright © McGraw Hill)
Image
from article Common cold
Human respiratory system. Common cold viruses enter through the nose, mouth, or eyes, infecting epithelial cells of the oropharynx. (Credit: M. K. Cowan and H. Smith; copyright © McGraw Hill)
Image
from article Common cold
Life cycle of a double-stranded DNA virus, such as an adenovirus. The virus attaches to specific receptors, after which it is taken up by the cell. Following entry into the cell, the viral capsid (protein coat) is digested, releasing DNA, which…
Image
from article Common cold
Electron micrograph (tinted green) of human coronavirus 229E particles. Coronaviruses are named for the corona, or halo, surrounding the capsid (protein coat). The crown-like corona results from the presence of viral spikes protruding from the viral…
Image
from article Earth's interior
Speculative models of the interiors of the terrestrial planets. All are rocky, divided into a crust (not shown here), mantle, and metallic core. (After R. T. Merrill and M. W. McElhinny, The Earth's Magnetic Field, Academic Press, 1983)
Image
from article Earth's interior
Preliminary Reference Earth Model (PREM) for P- and S-wave velocities, vp and vs, and density ρ. In the part of the upper mantle where the model is anisotropic, velocities are given in both the vertical and horizontal direction. The broken lines…
Image
from article Earth's interior
Variations of gravity and pressure inside the Earth. 1 m = 3.3 ft. 1 megabar = 100 GPa. (After P. Melchior, The Physics of the Earth's Core, Pergamon Press, 1986)
Image
from article Earth's interior
Density versus depth for several mantle constituents along the 1400°C (2552°F) adiabat. Data points show the density variation of PREM. All three constituents shown here contain magnesium-rich silicates. (After D. L. Anderson, Where on Earth is the…
Image
from article Earth's interior
P-wave velocity anomalies above the core–mantle boundary in terms of spherical harmonics up to degree and order 6, obtained by inverting P-wave travel time data. Positive perturbations indicate faster-than-average material. Contour interval = 25…
Image
from article Earth's interior
Speculative, schematic model of the core–mantle boundary layer. A heterogeneous chemical boundary layer is embedded in a thermal boundary layer. Large-scale mantle circulation transports chemical heterogeneity to the base of the mantle as well as…
Image
from article Earth's interior
Schematic temperature profile of the mantle. Subsequent estimates of core temperature are higher than suggested in the figure; the temperature jump across the thermal boundary layer at the base of the mantle will then be correspondingly higher. °F =…
Image
from article Earth's interior
Schematic temperature profile of the core. The melting-point curve for the core is substantially below the melting point of pure iron. All temperatures may have to be raised to correspond with further estimates of the melting point of iron. °F = (K…
Image
from article Earth's interior
Contour plots of the radial component of the magnetic field at the core–mantle boundary (a) for the year 1715 and (b) for 1980. The contour interval is 100 microteslas; solid-line contours represent flux into the core, and broken-line contours…
Image
from article Acari
Parasitiformes body plan. Lateral view of a predatory adult female Mesostigmata showing major body regions and important structures. Scale bar = 0.1 mm (0.004 in.). (Scanning electron micrograph by D. E. Walter)
Image
from article Acari
Acariformes body plan. (a) Adult female Oribatida (Sarcoptiformes) in lateral view showing major body regions and important structures. (b) Hexapod larva (Trombidiformes): dorsal view of a chigger, a parasite of vertebrates. (c) Octopod deutonymph…
Image
from article Anthrax
A color-enhanced scanning electron micrograph showing splenic tissue from a monkey with inhalation anthrax. Rod-shaped bacilli of Bacillus anthracis (yellow) and an erythrocyte (red) are shown. (Credit: Arthur Friedlander/National Institute of…
Image
from article Anthrax
Micrograph (stained with hematoxylin and eosin) showing submucosal hemorrhage in the small intestine of a person fatally affected by gastrointestinal anthrax. (Credit: Marshal Fox/Centers for Disease Control and Prevention)
Image
from article Triple point
Phase diagram for water, showing gas, liquid, and several solid (ice) phases; triple points at A, B, and C. The pressure scale changes at 101 kilopascals from logarithmic scale at low pressure to linear at high pressure.
Image
from article Tumor virus
Under certain conditions, human papillomaviruses are capable of causing cancer in humans. (Credit: Laboratory of Tumor Virus Biology, National Cancer Institute)
Image
from article Ecosystem
Levels of organization in ecosystems, which involve both biotic (living) components and abiotic (nonliving, physical) components. (Copyright © McGraw-Hill Education)
Image
from article Ecosystem
General model of energy flow through ecosystems. (Copyright © McGraw-Hill Education)
Image
from article Ecosystem
Food chains are limited by energy transfer. In this illustration, energy is transferred from the Sun to a plant (producer) to a primary consumer and to a secondary consumer. Energy is used by the producer and consumer organisms and is lost to the…
Image
from article Ecosystem
General model of the nitrogen cycle in ecosystems. (Copyright © McGraw-Hill Education)
Image
from article Ecosystem
General model of the carbon cycle in ecosystems: (A) carbon dioxide (CO2) from the air; (B) carbon from decomposition; (C) carbon from fossil fuels; (D) natural events (for example, forest fires and volcanoes) release CO2 into the air. (Copyright ©…
Image
from article Macrocyclic compound
Macrocyclic structures. (a) Two crown ethers. (b) A basic structure for three cryptands. (c) A lariat ether. (d) All-aliphatic spherand. (e) All-aromatic spherand.
Image
from article Macrocyclic compound
Macrocycles with various structural features. (a) Bicyclic cryptand (ditopic receptor). (b) Calix[6]arene; R represents a functional group. (c) Cavitand. (d) Carcerand. (e) Cyclophanes.
Image
from article Macrocyclic compound
Tetramers. (a) Resorcinarene having the rctt conformation. (b) Pyrogallolarene having the rccc conformation.
Image
from article Macrocyclic compound
The metal cation is the guest and the organic structure is the host in (a) 18-crown-6 complex of potassium cation (K+) and (b) sodium (Na+) complexed by a calix[4]arene.
Image
from article Macrocyclic compound
Complexing species. (a) Dibinaphtho-22-crown-6. (b) R,R-dibinaphtho-22-crown-6 complex of phenethylammonium chloride.
Image
from article Macrocyclic compound
Affinities for anions and cations shown for (a) pyrrole and (b) furan-derived cyclic tetramers.
Image
from article Macrocyclic compound
Amphiphiles. (a) Crown ether-steroid amphiphile. (b) Crown ether bolaamphiphile.
Image
from article Salicylate
Chemical structures of (a) salicylate, the conjugate base of (b) salicylic acid, and the nonsteroidal anti-inflammatory drug (NSAID) (c) acetylsalicylic acid (aspirin).
Image
from article Meningococcus
A photomicrograph reveals the presence of the bacterium Neisseria meningitidis, which can be pathogenic, leading to meningococcal meningitis. (Credit: James Volk/Centers for Disease Control and Prevention)
Image
from article Hydrological consequences of global warming
The hydrologic cycle is characterized by evaporation and transpiration from the surfaces; transport of water vapor in the atmosphere by the wind, clouds, and precipitation; and water storage in snow, glaciers, groundwater, and oceans. Units: 1000…
Image
from article Hydrological consequences of global warming
Spatial patterns of climate model projections of (a) precipitation, (b) soil moisture, (c) runoff, and (d) evaporation for 2090–2099 under the mid-range A1B emission scenario from the Intergovernmental Panel for Climate Change 2007. (Climate Change…
Image
from article Biodiversity
Global biodiversity hotspots. There are more than 30 biodiversity hotspots located around the world. These areas have experienced severe habitat losses (at least 70%) as the result of human activities, hampering the work of conservationists in their…
Image
from article Biodiversity
A regional analysis of 25 oceanic regions shows that 92% of all known biodiversity falls into a dozen groups, of which crustaceans (for example, crabs, shrimps, and lobsters), mollusks (for example, snails, bivalves, squids, and octopus), and fish…
Image
from article Biodiversity
Ecosystem function (a) as a positive, linear function of biodiversity and (b) as a nonlinear, satiating function of biodiversity. (Copyright © McGraw Hill)
Image
from article Marcus equation
Free-energy plot for an electron-transfer reaction with zero standard free-energy change (an electron self-exchange reaction).
Image
from article Marcus equation
Free-energy plot for an electron-transfer reaction when the free-energy change (|Δ G °|) is less than the reorganization parameter (λ).
Image
from article Haplosporida
Spore of Urosporidium fuliginosum.
Image
from article Haplosporida
Stages in the development of Icthyosporidium giganteum.
Image
from article Lead
Image
from article Lead
Galena (lead sulfide, PbS) is an ore mined for lead. (Credit: USGS)
Image
from article Oxygen toxicity
The dual effect of oxygen on biologic activity. Organisms that avail themselves of the enormous metabolic advantages provided by dioxygen (O2) must defend themselves against its toxicity. (Copyright © McGraw Hill)
Image
from article Micrometeorology
Soundings of temperature versus height for (a) day time and (b) nighttime obtained by radiosonde measurements during the Wangara experiment near Hay, New South Wales, Australia, in 1967. Soundings are shown for 9 A.M. through 9 P.M. on day 33 of the…
Image
from article Micrometeorology
The 3 P.M. sounding from Fig. 1a showing the layers of the daytime convective boundary layer.
Image
from article Urodela
A typical member of the order Urodela: the longtail salamander (Eurycea longicauda). (Credit: Ryan Hagerty/U.S. Fish and Wildlife Service)
Image
from article Urodela
Southern dwarf siren (Pseudobranchus axanthus), which has undergone limb degeneration and retains only tiny forelimbs. (Credit: U.S. Geological Survey)
Image
from article Urodela
World distribution of salamanders (order Urodela), indicated by areas of shaded blue color. (Copyright © McGraw Hill)
Image
from article Urodela
California tiger salamander (Ambystoma californiense). (Credit: John Cleckler/U.S. Fish and Wildlife Service)
Image
from article Urodela
The two-toed amphiuma salamander (Amphiuma means). (Credit: Southeast Ecological Center, U.S. Geological Survey)
Image
from article Urodela
The northern red salamander (Pseudotriton ruber ruber) is a member of the family Plethodontidae. (Credit: Alicia Lafever/U.S. National Park Service)
Image
from article Spinal cord disorders
Human spinal cord. (Copyright © McGraw-Hill Education)
Image
from article Thirst and sodium appetite
Regulation of cellular water. ADH = antidiuretic hormone.
Image
from article Thirst and sodium appetite
Hypovolemic thirst and sodium appetite are caused by altered sensory information from an underfilled circulation, reinforced by increases in circulating angiotensin II and mineralocorticoids. Angiotensin peptides generated from components of a…
Image
from article Earth's heat flow
Geographic distribution of heat flow measurement sites. (After H. N. Pollack, S. J. Hurter, and J. R. Johnson, Heat flow from the Earth's interior: Analysis of the global data set, Rev. Geophys., 31(3):267–280, 1993)
Image
from article Earth's heat flow
Heat flow–versus–age relationships for continents and oceans. (After D. Sprague and H. N. Pollack, Heat flow in the Mesozoic and Cenozoic, Nature, 285:393–395, 1980)
Image
from article Earth's heat flow
Geographic distribution of 17 heat flow provinces where the linear relationship between measured heat flow and radiogenic heat production from near-surface rocks has been empirically determined. (After I. Vitorello and H. N. Pollack, On the…
Image
from article Earth's heat flow
Present-day global heat flow (degree 12 spherical harmonic representation). Contours are in milliwatts per square meter. (After H. N. Pollack, S. J. Hurter, and J. R. Johnson, Heat flow from the Earth's interior: Analysis of the global data set,…
Image
from article Chamois
Alpine chamois (Rupicapra rupicapra). (Photograph courtesy of Brent Huffman/Ultimate Ungulate Images)
Image
from article Environmental management
Environmental management seeks to provide solutions to the practical problems that humans encounter or create, including the production of garbage and waste. (Credit: Walter Zerla/Getty Images)
Image
from article Environmental management
Without proper environmental management, economic and industrial development often lead to environmental pollution, especially in urban environments. (Credit: Simon Alvinge/123RF)
Image
from article Chicxulub impact crater
Bouguer gravity anomaly map over the Chicxulub impact crater. The coastline is designated by a thin white line, cenotes (natural pits) and sinkholes are designated by black dots, and the city of Mérida and the town of Chicxulub Puerto are designated…
Image
from article Chicxulub impact crater
Seismic line imaging of what lies beneath the seafloor, showing the Chicxulub impact crater. The crater includes many faults that can be grouped into an exterior ring fault, a series of outer ring faults, and a series of inner ring faults. Within…
Image
from article Bioassay
In conducting bioassays, researchers often employ laboratory culture tests, which use, for example, bacteria cultured in a petri dish (usually to model an effect on the organism of interest or on some basic cellular function). (Credit:…
Image
from article Surfactant
Foam blankets typically contain less than 1% surfactant to produce a stable foam that blocks oxygen for fire suppression. (Credit: U.S. Navy)
Image
from article Amniota
Basic types of vertebrate eggs.
Image
from article Amniota
Embryo developing in amniote eggs.
Image
from article Mecoptera
Male scorpion fly (Panorpa), order Mecoptera.
Image
from article Marine ecology
Marine ecology investigates the basic structural and functional relationships within and among living populations and their physical–chemical environments in marine ecosystems. In this photograph, a cold water reef in California is host to a…
Image
from article Marine ecology
The snaking waterways of a mangrove estuary in northwestern Madagascar. (Credit: Michael Fay/Getty Images/National Geographic RF)
Image
from article Marine ecology
Estuary salt marshes in the Grand Bay National Estuarine Research Reserve, Mississippi. (Credit: P. R. Hoar/National Oceanic and Atmospheric Administration)
Image
from article Marine ecology
Coral bleaching in the lagoon of Huahine Island, French Polynesia. Coral bleaching is the response of corals to environmental stress in which they eject the single-cell algae that live within the transparent coral tissue, making the white coral…
Image
from article Matrix isolation
Vacuum-vessel base cross section for matrix photoionization experiments. 10 K = −263°C or −442°F.
Image
from article Matrix isolation
Schematic plan view of the matrix assembly for pulsed-laser ablation.
Image
from article Matrix isolation
Infrared and Raman spectra of lithium superoxide, Li+O2−, using lithium-7 and 30% 18O2, 50% 16O18O, and 20% 16O2 at concentrations of Ar/O2 = 100. The Raman spectrum was recorded by using 200 mW of 488-nm excitation at the sample.
Image
from article Matrix isolation
Visible and ultraviolet absorption spectra of naphthalene samples in solid argon at 20 K. Upper curves show Ar/CCl4/N = 3000/4/1, and lower curves show the same sample after 15 s of irradiation at 220–1000 nm from a high-pressure mercury arc.
Image
from article Matrix isolation
Infrared spectra in the 2000–1200 cm−1 region for the products of the reactions of laser-ablated Al atoms with pure hydrogen co-deposited at 3.5 K. (a) Spectrum obtained from initial deposited sample. (b) Spectrum after >290 nm irradiation. (c)…
Image
from article Dental caries
The disease of dental caries or tooth decay is largely preventable. Bacteria colonize the tooth surface and often produce sufficient acids to demineralize the tooth's enamel. Then, dental plaque can build up on the tooth's surface, creating…
Image
from article Dental caries
Early caries (cavity) lesion of a primary first molar (indicated by the arrow). (Copyright © McGraw Hill)
Image
from article Swamp, marsh, and bog
Young cypress trees growing out of a swamp located in the Florida Everglades. (Credit: Getty Images)
Image
from article Platinum
Image
from article Medical control systems
Diagram of selected portions of the human motor control system. (After G. L. Gottlieb, D. M. Corcos, and G. C. Agarwal, Strategies for the control of voluntary movements with one mechanical degree of freedom, Behav. Brain Sci., 12:189–250, 1989)
Image
from article Medical control systems
Electric hand, a myoelectric prosthesis. (a) Two views of the hand, 2.5 in. (6 cm) across the knuckles, with the cover removed in one view to show the electric motor drive circuit. (b) Child using the electric hand. (Hugh Steeper Ltd.)
