- 行业: Printing & publishing
- Number of terms: 178089
- Number of blossaries: 0
- Company Profile:
McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
All the chemical, biochemical, and physical changes that sediments undergo from the time of deposition until the stage of metamorphism is reached. Diagenetic changes are gradational with metamorphism at elevated temperatures or pressures, and with atmospheric weathering effects when sedimentary rocks are exposed on the Earth's surface. Diagenesis commonly transforms sediments into sedimentary rocks and results in significant chemical and mineralogical changes. With increased burial, sands undergo grain rearrangement and compaction, mineral dissolution or replacement, and mineral precipitation as cements. Clays formed during weathering processes are transformed into illite, chlorite, and muscovite. Porous carbonate sediments consisting of unstable aragonite or magnesium-calcite are transformed to nonporous limestones composed of calcite. In spite of these profound changes, many features such as macroscopic sedimentary structures may be preserved in both detrital (sandstones and shale) and carbonate rocks. Diagenetic processes and products vary with original sediment composition and depositional environment, depth of burial (pressure and temperature), burial time, nature and movement of interstitial fluids, and physical, chemical, and biochemical processes.
Industry:Science
All the features of the skin and its appendages that are arranged in designs, both in humans and other animals. Examples are scales, hairs, and feathers; coloration; and epidermal ridges of the fingers, palms, and feet. In its common usage, the term applies to the configurations of epidermal ridges, collectively named dermatoglyphics. Dermatoglyphics are characteristic of primates.
Industry:Science
All the physical and chemical processes by which living, organized substance is produced and maintained and the transformations by which energy is made available for use by an organism.
Industry:Science
All the seas between Asia and Australia and the Pacific and the Indian oceans. They form a geographical and oceanographical unit because of their special structure and position, and make up an area of 3,450,000 mi<sup>2</sup> (8,940,000 km<sup>2</sup>), or about 2.5% of the surface of all oceans.
Industry:Science
Allelopathy is any direct or indirect effect, positive or negative, of one plant (including microorganisms) on another through the production of chemical compounds that pass into the environment. This type of effect apparently has been found in many ecosystems, including natural forests and plantations. More than 100 forest species have been found to produce and release allelopathic compounds (allelochemicals), although there are still few field confirmations of the phenomenon.
Industry:Science
Allergies result from immune responses to environmental compounds (allergens), which are normally harmless agents on their own, derived from sources such as pollen, animal dander, and house mites. Allergens trigger disease through activation of inflammatory pathways in sensitized individuals, initiating immune defense mechanisms that are out of proportion to the allergen threat to the individual. The inflammation pathways are thought to involve the production of the IgE class of antibodies, which develop specificity for particular allergens. The IgE antibodies on their own are incapable of activating an immune response, which requires the interaction of these antibodies with specific cells carrying a high-affinity receptor for the antibody. IgE bound to the surface of cells acts as a sensitive sentry for the presence of small amounts of allergens. The recognition of allergens triggers the cellular receptors and the activation of these cells, which release histamines, leukotrienes, and other mediators of the allergic response. Recent studies have elucidated the atomic interactions between the antibodies and their high-affinity receptors that are at the heart of this inflammatory pathway, providing new tools to develop therapeutic treatments for allergies and asthma.
Industry:Science
Almost all cancer cells have overcome the normal cellular signals that prevent continued division, and thus are immortal. Normal cells from young individuals can divide many times, but they have not accumulated all the other changes needed to make a cell malignant. In most instances, cells become senescent (aged) before they become malignant. Cellular aging and cancer appear to be linked, and the mechanisms regulating aging may act as a cancer brake. A major challenge is to find out how to make cancer cells mortal to inhibit their growth, and how to increase the lifespan of healthy cells.
Industry:Science
Alopecia or hair loss is a common problem that involves numerous potential etiologic factors. Nearly every patient consulting a physician because of hair loss should receive a diagnosis.
Industry:Science
Alteration of the Earth's climate by human activities; humans have the capacity to modify the Earth's climate in several important ways.
Industry:Science
Altered reactivity in humans and animals to allergens (substances foreign to the body that cause allergy) induced by exposure through injection, inhalation, ingestion, or skin contact. The most common clinical manifestations of allergy are hay fever, asthma, hives, atopic (endogenous) eczema, and eczematous skin lesions caused by direct contact with allergens such as poison ivy or certain chemicals.
Industry:Science
