Search Results

Search Results

Refine this search

4,534 results

Image

from article Nearshore processes

Result thumbnail
Longshore currents, generated when waves approach the beach at an angle. At Oceanside, California, the longshore current is flowing toward the observer. (Photo courtesy of Department of Engineering, University of California, Berkeley)

Image

from article Nearshore processes

Result thumbnail
Definition sketches for nearshore circulation cells. (a) Asymmetrical cell for breakers oblique to the shore. (b) Symmetrical cell for breakers parallel to the shore.

Image

from article Nearshore processes

Result thumbnail
Effect of headlands on the accretion of beach sand at Point Mugu, California. The point forms a natural obstruction that interrupts the longshore transport of sand, causing accretion and a wide beach to form (foreground). The regularly spaced…

Image

from article Nearshore processes

Result thumbnail
Sand delta at Rio de la Concepción on the arid coast of the Gulf of California. Such deltas are important sources of sand for beaches. (Courtesy of D. L. Inman)

Image

from article Aspidorhynchiformes

Result thumbnail
Aspidorhynchus acutirostris, Upper Jurassic, Bavaria; a typical fish of the order Aspidorhynchiformes.

Image

from article Paleobotany

Result thumbnail
Compression specimen of the Triassic leaf type Dicroidium.

Image

from article Paleobotany

Result thumbnail
Permian pollen grain macerated from Antarctic coal.

Image

from article Paleobotany

Result thumbnail
Cross section of a permineralized stem from a Carboniferous coal ball.

Image

from article Paleobotany

Result thumbnail
Thin section of a petrified Rhynie chert stem.

Image

from article Paleobotany

Result thumbnail
Several coprolites found within the tissues of a Carboniferous plant.

Image

from article Paleobotany

Result thumbnail
Cuticle of a fossil (Eocene) leaf showing the outline of the epidermal cells and fungus with specialized hyphae.

Image

from article Paleobotany

Result thumbnail
Several Glossopteris leaves from the Permian of Antarctica. Leaves of this type were some of the first evidence that at one time the southern continents were all physically linked into a major continental plate called Gondwana.

Image

from article Paleobotany

Result thumbnail
Section showing tree rings from a temperate plant, showing change in cell size and wall thickness.

Image

from article Paleobotany

Result thumbnail
Section showing rings from a tree with uniform cell size and wall thickness, but growing at approximately 82° South during the Triassic.

Image

from article Osteolepiformes

Result thumbnail
Schematic phylogeny (family tree) of the osteolepiforms, based on arguments presented by P. Ahlberg and Z. Johanson (1998). The fishes within the gray zone are conventionally designated as Osteolepiformes (the formal group name), but they actually…

Image

from article Osteolepiformes

Result thumbnail
The tristichopterid Eusthenopteron foordi. (a) A close-up of its pectoral fin skeleton. (b) An illustration of the full specimen. Eusthenopteron reached approximately 50–70 cm in length. Its pectoral fin skeleton contains structures equivalent to…

Image

from article Coronoidea

Result thumbnail
Stephanocrinus gemmiformis, Middle Silurian, Tennessee; side view of the theca.

Image

from article Enzyme inhibition

Result thumbnail
Enzyme inhibition often works by preventing a substrate from attaching to an active enzyme. In this example, E1 is one of three sequential enzymes that will convert a substrate (S) into a product (P). However, the product that is created can then…

Image

from article Enzyme inhibition

Result thumbnail
Two types of reversible enzyme inhibition. (Left) In competitive inhibition, the inhibitor interferes with the active site of the enzyme, so the substrate is unable to bind to it. (Right) In noncompetitive inhibition, the inhibitor changes the…

Image

from article Docodonta

Result thumbnail
Restoration of the skull of the Late Jurassic docodont Haldanodon in lateral view. Arrow points to dentary-squamosal articulation; the articular-quadrate articulation lies directly behind it (toward the midline of the skull). (Illustration by…

Image

from article Docodonta

Result thumbnail
Upper and lower molars of Docodon, a Late Jurassic docodont. (a) Occlusal view of an upper molar. (b) Internal and (c) occlusal views of a lower molar.

Image

from article Doppler VOR

Result thumbnail
Collocation of Doppler VOR and TACAN beacons installed on 100-foot high (30-m) tower with a counterpoise of 119-ft (36-m) diameter in forest near Frankfurt, Germany. Circular array consists of 39 loop antennas fed by solid-state commutator. Center…

Image

from article Doppler VOR

Result thumbnail
Principle of Doppler VOR beacon. Reference signal R and bearing signal V which is generated by dipole d are shown as they would be measured in aircraft to the north, east, south, and west of the beacon. (a) Dipole d at 180°. (b) Dipole d at 270°.…

Image

from article Doppler VOR

Result thumbnail
Comparison of radial flight recordings. (a) From VOR installation. (b) From DVOR installation. Both experimental beacons were located at same unfavorable site. Plane is flying constant course at bearing of 133° from beacons at 4000-ft (1.2-km)…

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