Image
from article Regolith
Diagram showing the components of residual regolith.
Search Results
Search Results
Refine this search
Search result paging links
5,366 results
Image
from article Manganese
Image
from article Climate history
Plot of the average temperature for the contiguous United States during the month of August from 1895 to 2016. (Credit: NOAA)
Image
from article Climate history
Global temperature relative to peak Holocene temperature, based on ocean cores. (Credit: NASA)
Image
from article Animal virus
Electron micrograph of negatively stained, purified bovine papilloma virions with icosahedral symmetry. (Credit: David Hill and John P. Sundberg)
Image
from article Animal virus
Electron micrograph of a thin section of chicken cells containing crystalline inclusion bodies formed by an avian reovirus during infection. (Credit: David Hill and John P. Sundberg)
Image
from article Oscillatory reaction
Oscillatory behavior in a sulfuric acid medium containing potassium bromate, malonic acid, and cerous nitrate. The upper curve is the potential (in unspecified units) of a tungsten electrode and is related to the concentration ratio of…
Image
from article Oscillatory reaction
Rotating spiral bands of oxidation in a thin layer of solution containing the same reagents as in Fig. 1 except that the redox indicator ferrous phenanthroline has been substituted for cerous ion. (Courtesy of Prof. A. T. Winfree, University of…
Image
from article Oscillatory reaction
Layers of crystallization from an initially uniform magma in the Skaergaard Intrusion in Greenland. (From A. R. McBirney and R. M. Noyes, Crystallization and layering of the Skaergaard Intrusion, J. Petrol., 20:487–554, 1979)
Image
from article Heterodonta
Common heterodont bivalves. (Credit: Ronald V. Dimock, Jr.)
Image
from article Heterodonta
Common heterodont bivalves. (Credit: Ronald V. Dimock, Jr.)
Image
from article Restoration ecology
Restored sand dune habitat at Cape Canaveral, Florida. To help prevent erosion, 180,000 shrubs, including grasses, sunflowers, vines, sea grapes, and saw palmettos, were planted. (Credit: Dan Casper/National Aeronautics and Space Administration)
Image
from article Sol-gel process
Flow chart showing the sol-gel methods used to prepare bulk glasses, thin films of glass or ceramics, and powders; the powders are then sintered to produce ceramics.
Image
from article Weathering processes
Exchange-energy relationships between a rootlet and three minerals. (a) A potassium-bearing, primary silicate mineral. (b) A clay mineral well stocked with exchangeable metal cations. (c) A clay mineral scantily stocked with metal cations. The…
Image
from article Weathering processes
Comparison of binding energy (calories per gram-equivalent weight) on nutrient metal cation (indicated by M) by rocks and soil minerals with exchange binding energy on cation by plant roots. The relation of plant nutrition to weathering and…
Image
from article Prehnite
Prehnite in reniform aggregates, Paterson, New Jersey. (Specimen from Department of Geology, Bryn Mawr College)
Image
from article Tick virus diseases
A deer or black-legged tick (Ixodes scapularis). (Credit: U.S. Centers for Disease Control and Prevention)
Image
from article Tick virus diseases
Diagram depicting the life cycle of Ixodes scapularis. This deer tick can transmit viruses and other pathogens that cause a number of important diseases, including Lyme disease, anaplasmosis, and babesiosis. The risk of human infection is greatest…
Image
from article Tick virus diseases
World map depicting the locations of human tick-borne disease cases. Heartland, Bourbon, and Colorado tick fever virus cases are unique to North America. Powassan encephalitis cases are reported in North America and Russia. Tick-borne encephalitis…
Image
from article Tick virus diseases
Cases of Powassan encephalitis reported in the United States from 2006 to 2015. Most of the reported cases are in Minnesota, New York, and Wisconsin. (Credit: ArboNET, Arboviral Diseases Branch, U.S. Centers for Disease Control and Prevention)
Image
from article Anaerobic infection
Image
from article Degenerative neural diseases
Factors leading to degenerative neural diseases. Abbreviations: AD, Alzheimer's disease; AD/PD, Alzheimer's disease with parkinsonism; ALS, amyotrophic lateral sclerosis; DLB, dementia with Lewy bodies; FTD, frontotemporal dementia; MID,…
Image
from article Biological productivity
Image
from article Ergot and ergotism
Ergot life cycle. Parts a–d explained in text.
Image
from article Exotic viral diseases
A colorized negative stained transmission electron micrograph depicting a number of Marburg virus virions. Marburg virus disease is a rare, exotic viral disease that affects both humans and nonhuman primates. (Credit: Frederick A. Murphy/Centers for…
Image
from article Surface and interfacial chemistry
Scheme for reducing bacterial adhesion at an implanted biomaterial.
Image
from article Surface and interfacial chemistry
Image
from article Surface and interfacial chemistry
Microscopic surface structures. (a) Surface atoms occupying positions other than the bulk-terminated locations. The first interlayer spacing d12 is greater than the bulk interlayer spacing d34. The second interlayer spacing d23 is smaller than the…
Image
from article Surface and interfacial chemistry
Image
from article Surface and interfacial chemistry
Processes of electron spectroscopies. (a) Auger electron spectroscopy. A core-level electron is ejected by excitation from the incident high-energy electron. A second electron fills the vacancy left by the ejected electron. The third electron, the…
Image
from article Surface and interfacial chemistry
Typical configuration for application of optical spectroscopies to surface analysis. (a) Transmission. (b) External or specular reflection. (c) Internal reflection. I = reflected light intensity. I0 = initial light intensity. θi = angle of incidence…
Image
from article Surface and interfacial chemistry
Scanning tunneling microscopy and images for (a) constant-current mode and (b) constant-height mode; shown only in x dimension for simplicity.
Image
from article Ankerite
Ankerite. (a) Specimen of the mineral (specimen from Department of Geology, Bryn Mawr College). (b) Crystal habits (after C. Klein, Manual of Mineralogy, 21st ed., John Wiley & Sons, Inc., 1993).
Image
from article Lignin
Chemical formula representation of lignin, in which bold lines represent linkages between individual phenylpropane lignin monomer units, and shaded area represents the structure of a typical lignin model compound.
Image
from article Cicada
Brood IX periodical cicada in Athens, West Virginia. (Photo by Louie H. Yang)
Image
from article Cicada
Periodical cicada life cycle. Counterclockwise from lower left: Nymphal cicada feeding on plant roots belowground; ants and other detrivores feeding on dead cicada litterfall; teneral adult cicada recently emerged from the nymphal exuviae; bird…
Image
from article Cicada
Brood X periodical cicadas in Boyce, Virginia. (Photo by Louie H. Yang)
Image
from article Lava
Examples of lava. (a) Pahoehoe lava (in Kilauea, Hawaii) has a smooth and wavy surface formed by a thin layer of cooler lava at the surface. The surface layer is pushed into folds from the faster-moving, hot fluid lava beneath (photograph by J. D.…
Image
from article Tektite
Dumbbell-shaped tektite (irgizite) from the Zhamanshin meteoritic impact crater, Northern Aral Region, Russia. The glass is so dark brown that it appears black in reflected light.
Image
from article Chromium
Image
from article Reproductive behavior
The mating of dragonflies encompasses a number of reproductive behaviors. Typically, the male is in front and the female is behind. If the female is willing to mate, she bends her abdomen forward to collect sperm from the male's accessory genitalia,…
Image
from article Reproductive behavior
Sage-grouse lek. Males stake out and defend territories on a traditional breeding ground. Females breed with males in selected territories. (Credit: U.S. Fish and Wildlife Service)
Image
from article Reproductive behavior
Two bull northern elephant seals fighting for dominance on the beach. (Credit: eoind/Getty Images)
Image
from article Reproductive behavior
Natterjack toad giving a mating call with its vocal sac expanded. (Credit: Bobby Bok)
Image
from article Reproductive behavior
Mating behavior of sticklebacks: (a) zigzag dance of a male, which leads a female to the nest; (b) the male stimulates the female in the nest to lay eggs; (c) schematic portrayal of the events in a courtship sequence. (Credit: Based on original…
Image
from article Reproductive behavior
Lordosis in a female rodent. When mounted, the females of many mammalian species adopt the lordotic posture, rendering copulation possible. Note the concave arching of the spine. (Credit: Based on an original drawing by L. C. Drickamer and S. H.…
Image
from article Reproductive behavior
A black-browed albatross feeding a chick. This is one example in which parental care may be extensive and prolonged. (Credit: Vetta/Getty Images)
Image
from article Toxin
Bacteria, such as Clostridium perfringens, often produce exotoxins that have deleterious effects on other organisms. Clostridium perfringens can cause foodborne disease by contamination of raw food materials. (Credit: Don Stalons/Centers for Disease…
Image
from article Toxin
Taiwan banded krait (Bungarus multicinctus). Certain elapid snakes known as kraits produce a venom that contains bungarotoxins, which are potent neurotoxins. (Credit: LiCheng Shih)
Image
from article Celiac disease
Small bowel biopsy showing villous atrophy, which is found in individuals affected by celiac disease. (Credit: Ed Uthman/National Institutes of Health)
Image
from article Celiac disease
Antigen presentation of gliadin peptide to a CD4 T cell. Gliadin peptides bind to pockets P1, P4, P6, P7, and P9 of the (a) HLA-DQ8 and (b) HLA-DQ2 molecules. (Copyright © McGraw-Hill Education)
Image
from article Concussion
A three-dimensional magnetic resonance imaging (MRI) view of a human brain. The red-colored areas indicate temporary injury to the brain's covering following a concussion. (Credit: Lawrence Latour, Center for Neuroscience and Regenerative Medicine,…
Image
from article Barium
Image
from article Deep-marine sediments
Bathymetric display of the northern Gulf of Mexico based on high-resolution bathymetric swath data. The data are displayed to give a 3-D perspective of present-day shelf, slope, and basin settings. Note the highly irregular sea-floor topography and…
Image
from article Deep-marine sediments
Map showing long-distance transport of modern slides of about 300 km (186 mi) downslope from the shelf edge (100-fathom, 183-m, or 600-ft contour line) off northwestern Africa. Thickness of slide = 25 m (82 ft). (From R. D. Jacobi, Sediment slides…
Image
from article Deep-marine sediments
Conceptual model showing interaction between channelized (axial) turbidity currents, overbank turbidity currents, and bottom currents (contour currents) in deep-sea environments. (From G. Shanmugam, T. D. Spalding, and D. H. Rofheart, Process…
Image
from article Deep-marine sediments
Amazon Fan. (a) Channel bifurcation through avulsion on the deep-sea Amazon Fan results in unchannelized sandy flows by breaching their confining levee through a crevasse and spreading out initially as unchannelized flows into a lower interchannel…
Image
from article Deep-marine sediments
Sizes of modern abyssal plains. (From P. P. E. Weaver, J. Thomson, and P. M. Hunter, Introduction, in P. P. E. Weaver and J. Thomson (eds.), Geology and Geochemistry of Abyssal Plains, Geol. Soc. London Spec. Publ., no. 31, pp. vii–xii, 1987)
Image
from article Deep-marine sediments
GLORIA long-range side-scan sonar imagery showing fingerlike patterns of debris flows in the Bear Island Fan on the continental margin of the modern Norwegian-Barents Sea. These fans are composed of cohesive debris flows. Properties of the Bear…
Image
from article Infertility
Illustration of (left) a normal ovary compared to (right) a polycystic ovary. A polycystic ovary can result from an imbalance of reproductive hormones. (Credit: Alila Medical Images)
Image
from article Infertility
Colored scanning electron micrograph of a deformed sperm cell. The cell has residual cytoplasm (denoted by the pinkish lump) below its head (top right). (Credit: Steve Gschmeissner/Science Photo Library/Alamy Stock Photo)
Image
from article Slime molds
Close-up view of slime mold on the ground. (Credit: Melinda Fawver/iStock/Getty Images)
Image
from article Slime molds
Plasmodial slime mold (Physarum polycephalum). (Credit: Jonatha M. Gott/Case Western Reserve University)
Image
from article Soap
Soap bars. (Credit: Getty Images)
Image
from article Industrial health and safety
Woodworker wearing safety goggles and hearing protection. (Credit: Shutterstock/Robert Kneschke)
Image
from article Coral bleaching
Coral reef at Kahului Point, Maui, Hawaii. (Left) Healthy corals are mostly brown or green in color as a result of the partner algae that live in the coral tissue. (Right) Because of heat stress to the corals, the algae can release toxic chemicals…
Image
from article Coral bleaching
Increases in temperature (in °F) in the surface waters of the Great Barrier Reef in Australia during the month of March since 1960. Water temperatures of just a few degrees above normal conditions have resulted in massive bleaching of corals.…
Image
from article Coral bleaching
Coral at Lizard Island, Australia. (Left) Bleached coral. (Right) Two months later, the coral had died and been overgrown by fleshy algae. (Credit: Richard Vevers and Christophe Bailhache/The Ocean Agency/XL Catlin Seaview Survey)
Image
from article Forensic dentistry
A dental identification from a homicide case. (a) Radiograph of the decedent exposed 18 years prior to her murder. (b) Radiograph of the decedent exposed 1 month prior to death. (c) Radiograph of the skeletal remains that were thought to be her.…
Image
from article Forensic dentistry
Four human bite marks on human skin. The American Board of Forensic Odontology (ABFO) #2 scale is present in each photograph to assist in documenting the size of the injury as well as the positioning of the camera. Bite (a) exhibits a higher degree…
Image
from article Molecular structure and spectra
Diatomic molecule with nuclei at distance Re apart, built from atoms of radii r and r′.
Image
from article Molecular structure and spectra
Electric dipole moment p of typical diatomic molecule as function of internuclear distance R; pe is the dipole moment at the equilibrium distance Re.
Image
from article Molecular structure and spectra
U(R) curve of ground electronic state of H2 with vibrational levels and dissociation continuum. D indicates the dissociation energy. Maximum v here is 14. ( After G. Herzberg, Molecular Spectra and Molecular Structure, vol. 1, 2d ed., Van Nostrand,…
Image
from article Molecular structure and spectra
Lowest vibrational levels of H2, O2, and I2, numbered by vibrational quantum number v. Vibration level spacings decrease with increasing v. Where spacing reaches zero, the molecule dissociates; dissociation level D is indicated for I2. Energies are…
Image
from article Molecular structure and spectra
Lowest rotational levels of H2, O2, and I2. For H2 and I2, J is the rotational quantum number, according to Eq. (5) in the text. O2 is in a Hund's case b triplet state, and the rotational levels are designated by N, where the total angular momentum…
Image
from article Molecular structure and spectra
Normal vibration modes of H2O and CO2. Synchronized displacements of atoms occur in proportion to lengths of the arrows. Diagram corresponds to snapshot taken at one phase of vibration.
Image
from article Molecular structure and spectra
Relation of band lines (lower part) [see Eqs. (8) and (9)] to rotational levels [see Eq. (6)] for a vibration-rotation band or an electronic band. In the former case, the upper and lower sets of rotational levels belong to two vibrational levels of…
Image
from article Molecular structure and spectra
Intensity distribution at several temperatures for a diatomic absorption band. Line positions are based on Eq. (9) assuming B′ = B′ for simplicity; frequency increases toward the left (opposite to Fig. 7). (a) and (b) correspond respectively to B…
Image
from article Molecular structure and spectra
Fundamental (1,0) vibration-rotation band of DCl in absorption showing the intensity distribution of the lines. The wavenumber scale increases to the right (in contrast to Fig. 8), so the R branch is to the right of the band origin, P branch to the…
Image
from article Molecular structure and spectra
Diatomic U(R) curves for three cases to explain the vibrational intensity distribution according to the Franck-Condon principle. The asymptote of each curve for large R corresponds to dissociation into atoms, with one or both atoms excited in the…
Image
from article Molecular structure and spectra
Assignment of individual transitions in the spectrum of the S-F stretching fundamental ν3 of sulfur hexafluoride (SF6) as resolving power increases. (a) Fourier transform spectrum; resolution of 0.06 cm−1 [2 GHz]. (b) Spectrum recorded with tunable…
Image
from article Rheumatic fever
Photomicrograph of Streptococcus pyogenes illustrates its chain structure. Streptococcus pyogenes stains purple/violet after undergoing a Gram stain test. (Credit: Lisa Burgess; copyright © McGraw Hill)
Image
from article Cleft lip and cleft palate
Unilateral, incomplete cleft lip in which the notch does not extend to the nose.
Image
from article Cleft lip and cleft palate
Cleft palate, resulting in a fissure in the palate connecting the nasal and oral cavities.
Image
from article Protein
Molecular model illustration of myoglobin, which is a protein found in the muscle tissue of mammals. Myoglobin is an important protein that binds to and stores oxygen for use during strenuous exercise. The structure of the globin protein protects…
Image
from article Protein
The levels of protein structure, including primary, secondary (α-helices and β-sheets), tertiary, and quaternary. (Copyright © McGraw-Hill Education)
Image
from article Protein
The α-helix of protein structure. The repeating NHCOC units form the backbone, which spirals up in a left-handed or right-handed fashion. (The right-handed configuration is adopted in natural proteins with l-amino acids.) Hydrogen bonds are…
Image
from article Protein
Illustration of the molecular structure of hemoglobin. A single molecule of hemoglobin is composed of four protein subunits, called globins, with each containing a heme group that holds a single iron ion in its center. (Copyright © McGraw-Hill…
Image
from article Fog
Fogs formed by various processes. (a) Radiation fog; appears first as shallow layers above moist ground. (b) Stratocumulus cloud, formed from lifted fog. (c) Fog bow resulting from large cloud droplets in the fog top.
Image
from article Ixodides
An argasid tick, Otobius megnini, known as the spinose ear tick, shown enlarged. (Photo by Mat Pound, Agricultural Research Service, U.S. Department of Agriculture)
Image
from article Ixodides
A female ixodid tick, Ixodes scapularis, known as the blacklegged tick or deer tick, shown enlarged. This tick spreads Lyme disease in the eastern half of the United States. (Photo by Scott Bauer, Agricultural Research Service, U.S. Department of…
Image
from article Myxozoa
Different types of myxospores, the typical myxozoan stage in the fish host. Top row: Species of the most species-rich myxozoan genus Myxobolus—M. aeglefini from the eye cornea of the gadoid fish Melanogrammus aeglefinus (left); Myxobolus species…
Image
from article Myxozoa
Life cycle of Myxozoa. The myxosporean life cycle involves an annelid definitive host and a vertebrate intermediate host. Actinospores are released from an annelid and typically infect a fish host. Myxospores are produced after the vast…
Image
from article Supercritical fluid
Typical pressure-temperature diagram of a pure material. cp = critical point.
Image
from article Supercritical fluid
Typical supercritical-fluid extraction process.
Image
from article Supercritical fluid
Simplified flow diagram of a commercial hydrothermal oxidation process (supercritical-water oxidation).
Image
from article Immunotherapy
Numerous points along the cancer immunity cycle are targeted by researchers in attempts at immunotherapy. In general, researchers seek to improve the ability of a tumor-bearing individual (the host) to reject the tumor immunologically. (Copyright ©…
Image
from article Immunotherapy
Histology slide of glioblastoma brain cancer cells. Glioblastoma is an aggressive form of malignant brain tumor. Various methods of immunotherapy attempt to stimulate the host's intrinsic immune response to the tumor. (Credit: Anna…
Image
from article Rhumb line
Example of a rhumb line.
Image
from article Polyolefin
The repeating unit of polyethylene.
