- 行业: Printing & publishing
- Number of terms: 178089
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- 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.
A binding agent used in construction of clay brick, concrete masonry, and natural stone masonry walls and, to much less extent, landscape pavements. Modern mortars are improved versions of the lime and sand mixtures historically used in building masonry walls.
Industry:Science
A binding or structural agent used in construction and engineering applications. Grout is typically a mixture of hydraulic cement and water, with or without fine aggregate; however, chemical grouts are also produced.
Industry:Science
A biochemical reaction involving the transfer of a negatively charged electron from one organic compound to another organic compound or to oxygen. When a compound loses an electron, or is oxidized, another compound gains the electron, or is reduced. Oxidation-reduction (redox) reactions represent the main source of biological energy. Redox reactions occur simultaneously, and one does not occur without the other. The principal sources of reductants for animals are the numerous breakdown products of the major foodstuffs: carbohydrates, fats, and proteins. Energy release from these substances occurs in a stepwise series of hydrogen and electron transfers to molecular oxygen.
Industry:Science
A Biological community that contains few trees or shrubs, is characterized by mixed herbaceous (nonwoody) vegetation cover, and is dominated by grasses or grasslike plants. Grassland ecosystems range from the dense bamboo of the Amazonian tropics to the cool northern steppes of Russia, and from dry plains in the western United States to Canadian arctic grasslands. Mixtures of trees and grasslands occur as savannas at transition zones with forests, as in the east-central United States, or where rainfall is marginal for trees, such as in south-central Africa and Australia. About 1.2 × 10<sup>8</sup> mi<sup>2</sup> (4.6 × 10<sup>7</sup> km<sup>2</sup>) of the Earth's surface is covered with grasslands, which make up about 32% of the plant cover of the world. The proportion of original grasslands varies widely among continents with about 44% remaining in Europe and less than 10% in Australia, although the latter has vast expanses of savannas. In North America, grasslands include the Great Plains, which extend from southern Texas into Canada. The European meadows cross the subcontinent, and the Eurasian steppe ranges from Hungary eastward through Russia to Mongolia; the pampas cover much of the interior of Argentina and Uruguay. Vast and varied savannas and velds can be found in central and southern Africa and throughout much of Australia.
Industry:Science
A biological community, essentially a grassland, covering extensive high areas in equatorial mountains of the Western Hemisphere. Paramos occur in alpine regions above timberline and are controlled by a complex of climatic and soil factors peculiar to mountains near the Equator. The richly diverse flora and the fauna of the paramos are adapted to severely cold, mostly wet conditions. Humans have found some paramos suitable for living and use. Since paramos were defined originally in Spanish-speaking countries, no English equivalent has been given to the term.
Industry:Science
A biological discipline embracing the general principles of pathology (disease in the broadest sense) as applied to insects. It refers to human observations and actions concerning the cause, symptomatology, gross pathology, histopathology, pathogenesis, and epizootiology of the diseases of insects; it is concerned with whatever can go wrong or become abnormal in an insect. A diseased insect may be suffering from an infectious disease caused by a microorganism or a noninfectious disease, such as metabolic disturbance, a genetic abnormality, a fetal malformation, a nutritional deficiency, a physical or chemical injury, or an injury caused by parasites or predators.
Industry:Science
A biological molecule that is a tripeptide comprising the three amino acids glutamate, cysteine, and glycine, and is involved in multiple metabolic processes. While the cysteine residue is linked to the glycine residue through a normal α-amide bond, the glutamate residue is linked to the cysteine residue through an unusual γ-amide bond. Glutathione is found in reduced and oxidized forms (<b>Fig. 1</b>). The reduced form (GSH) contains only a single glutathione unit with the side chain of cysteine in the sulfhydryl form. The oxidized form (glutathione disulfide, GSSG) contains two glutathione units covalently attached through a disulfide bridge between the cysteine residues.
Industry:Science
A biologically active amine that is formed by the decarboxylation of the amino acid histidine. It is widely distributed in nature and is found in plant and animal tissues as well as in insect venoms. In humans, histamine is a mediator of inflammatory reactions, and it functions as a stimulant of hydrochloric acid secretion in the stomach.
Industry:Science
A biologically active substance produced by bacteria and consisting of lipopolysaccharide, a complex macromolecule containing a polysaccharide covalently linked to a unique lipid structure, termed lipid A. All gram-negative bacteria synthesize lipopolysaccharide, which is a major constituent of their outer cell membrane. One major function of lipopolysaccharide is to serve as a selectively permeable barrier for organic molecules in the external environment. Different types of gram-negative bacteria synthesize lipopolysaccharide with very different polysaccharide structures.
Industry:Science
A black, infusible carbonaceous substance occurring in Uinta County, Utah. It is insoluble in carbon disulfide, has a density of about 1.05, and consists of 79–80% carbon, 10.5–12.5% hydrogen, 4–6% sulfur, 1.8–2.2% nitrogen, and some oxygen.
Industry:Science
