Search Results

Search Results

Refine this search

1,023 results

Image

from article Biofilm

Result thumbnail
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 Ecosystem

Result thumbnail
Levels of organization in ecosystems, which involve both biotic (living) components and abiotic (nonliving, physical) components. (Copyright © McGraw-Hill Education)

Image

from article Ecosystem

Result thumbnail
General model of energy flow through ecosystems. (Copyright © McGraw-Hill Education)

Image

from article Ecosystem

Result thumbnail
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

Result thumbnail
General model of the nitrogen cycle in ecosystems. (Copyright © McGraw-Hill Education)

Image

from article Ecosystem

Result thumbnail
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 Biodiversity

Result thumbnail
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

Result thumbnail
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

Result thumbnail
Ecosystem function (a) as a positive, linear function of biodiversity and (b) as a nonlinear, satiating function of biodiversity.

Image

from article Urodela

Result thumbnail
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

Result thumbnail
Southern dwarf siren (Pseudobranchus axanthus), which has undergone limb degeneration and retains only tiny forelimbs. (Credit: U.S. Geological Survey)

Image

from article Urodela

Result thumbnail
World distribution of salamanders (order Urodela), indicated by areas of shaded blue color. (Copyright © McGraw Hill)

Image

from article Urodela

Result thumbnail
California tiger salamander (Ambystoma californiense). (Credit: John Cleckler/U.S. Fish and Wildlife Service)

Image

from article Urodela

Result thumbnail
The two-toed amphiuma salamander (Amphiuma means). (Credit: Southeast Ecological Center, U.S. Geological Survey)

Image

from article Urodela

Result thumbnail
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 Thirst and sodium appetite

Result thumbnail
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 Environmental management

Result thumbnail
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

Result thumbnail
Without proper environmental management, economic and industrial development often lead to environmental pollution, especially in urban environments. (Credit: Simon Alvinge/123RF)

Image

from article Marine ecology

Result thumbnail
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

Result thumbnail
The snaking waterways of a mangrove estuary in northwestern Madagascar. (Credit: Michael Fay/Getty Images/National Geographic RF)

Image

from article Marine ecology

Result thumbnail
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

Result thumbnail
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 Swamp, marsh, and bog

Result thumbnail
Cross-sectional diagram representing the progressive filling by vegetation of a pit lake in recently glaciated terrain.

Image

from article Plant vulnerability to climate change

Result thumbnail
Subarctic tundra and vegetation of the Denali National Park and Preserve in Alaska. As a result of climate change and the resultant poleward and upward shift of plant ranges, plants and their ecosystems may become particularly vulnerable. (Credit:…

Image

from article Plant vulnerability to climate change

Result thumbnail
Blue grama (Bouteloua gracilis) growing in Montana. As a result of warming temperatures, this type of grass could face decreased productivity, allowing forbs to increase and making the ecosystem less tolerant of drought and grazing. (Credit: Matt…

Image

from article Plant vulnerability to climate change

Result thumbnail
Modeled distribution of suitable climate space in Europe for stiff sedge (Carex bigelowii), which is an Arctic-Alpine plant: (a) during the period 1961–1990 (green color = suitable climate space during the 1961–1990 period); (b) climate model…

Image

from article Plant vulnerability to climate change

Result thumbnail
The endangered western prairie fringed orchid (Platanthera praeclara) is declining across much of its range in North America. (Credit: U.S. Fish and Wildlife Service)

Image

from article Speech

Result thumbnail
Human head and thorax. (Courtesy of G. E. Peterson)

Image

from article Speech

Result thumbnail
Action of the glottis during speech. (a) Six successive positions of the vocal folds in one vibration cycle at 120 Hz. (b) Relation between pitch and vocal fold tension. (Courtesy of D. W. Farnsworth)

Image

from article Speech

Result thumbnail
Sound spectrograms of the utterance “speech production.” (a) Energy patterns: A, pulse; B, periodic; C, aperiodic; and D, silence. (b) The dotted lines represent the pitch pattern of the utterance.

Image

from article Speech

Result thumbnail
Computer-generated three-dimensional spectral display of the spoken syllable “yah.”

Image

from article Speech

Result thumbnail
Speech flakes of vowels in the words (a) “far,” (b) “food,” and (c) “fee.” (Courtesy of Charles Wooters)

Image

from article Speech

Result thumbnail
Regions of the brain involved in speech. (a) Left hemisphere, usually more involved in speech functions than the right hemisphere. (b) A model for the neural processes involved in speaking a heard word. Arrows indicate the path of the relayed signal…

Image

from article Biological insect control

Result thumbnail
The emerald ash borer (Agrilus planipennis) is an invasive pest insect that damages ash tree species in North America and Europe. Researchers are searching for natural enemies against the borer in its native range (Asia) to use as biological control…

Image

from article Mental disorders

Result thumbnail
X-ray of a human brain (side view) against a black background. The image is transparent and detailed with soft blue swaps. (Credit: Brainmaster/Getty Images)

Image

from article Mental disorders

Result thumbnail
Colorized CT (computerized tomography) scan of a healthy brain (view from above). The axial (horizontal) scan has revealed the head and brain in cross section. The front of the head is at the top. The ventricles (dark areas, center), which lie…

Image

from article Marine conservation

Result thumbnail
A marine conservation biologist surveying marine invertebrates in a Mediterranean marine protected area in the Gulf of Gökova, Turkey. (Credit: Images & Stories/Alamy Stock Photo)

Image

from article Marine conservation

Result thumbnail
Bleached Acropora coral in shallow water, French Polynesia. Warming climates have affected marine habitats, with numerous marine species being depleted, threatened, or endangered. (Credit: Seaphotoart/Alamy Stock Photo)

Image

from article Marine conservation

Result thumbnail
An oil slick off a beach along the South Devon coast of England. Restoration efforts undertaken by marine conservationists attempt to return compromised habitats to ecologically functional, more pristine conditions. (Credit: Richard Packwood/Getty…

Image

from article Social mammals

Result thumbnail
Meerkats (Suricata suricatta) are notable social mammals. Here, they are looking for danger outside of their den. (Credit: Alta Oosthuizen/Shutterstock)

Image

from article Social mammals

Result thumbnail
An adult female African lion (Panthera leo) nurses four cubs. The early ingestive behavior (nursing) of mammals has a high degree of social significance. (Credit: Glow Images)

Image

from article Social mammals

Result thumbnail
Mexican spider monkeys (Ateles geoffroyi vellerosus) are primates that display many examples of social behavior and organization. (Credit: Oksana Kunka/123RF)

Image

from article Venus' flytrap

Result thumbnail
Dionaea muscipula (the Venus' flytrap) growing in a South Carolina nature preserve. Winged petioles and traps in various stages of the capture cycle are visible. The plant is surrounded by Sphagnum moss, which is a frequent community associate.…

Image

from article Venus' flytrap

Result thumbnail
Stages in the capture and digestion of a fly by the Venus' flytrap. A prey item is attracted to the trap margins by nectar (a). When a trigger hair on the inside leaf surface is twice stimulated (b), the trap closes rapidly (c). Complete closure is…

Image

from article Lichens

Result thumbnail
The ascolichen Teloschistes chrysophthalmus. (Credit: Jason Hollinger)

Image

from article Lichens

Result thumbnail
Cuplike lichens of the genus Cladonia. (Credit: Jacinta Lluch Valero)

Image

from article Dune vegetation

Result thumbnail
American beachgrass (Ammophila breviligulata), which dominates coastal dunes along much of the Eastern seaboard of the United States and the Great Lakes. (Photo by Rob Routledge, Sault College, Sault Ste. Marie, Ontario, Canada)

Image

from article Dune vegetation

Result thumbnail
Sea oats (Uniola paniculata) are abundant on the foredunes of the Atlantic coast of the southeastern United States. (Photo by Robert L. Anderson, USDA Forest Sevice)

Learn more about AccessScience

a female college student looking at the screen of her silver-cased laptop computer
Watch the YouTube video

flyer thumbnail

Download the flyerGet Adobe Acrobat Reader pdf icon