- 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.
Africa offers an enormous range of natural habitats. Partly because of its abundance of forests, deserts, rivers, lakes, mountains, and savannas, Africa is the birthplace of some of the most remarkable mammals that the Earth has ever known. The familiar “safari” animals include gazelles, rhinoceroses, elephants, lions, cheetahs, giraffes, and hippos. Because they are too small, nocturnal, aquatic, or rare, aardvarks, elephant shrews, golden moles, tenrecs, and sea cows usually go unnoticed. Not all of these mammals are unique to Africa; most have been in parts of Asia, at least during recorded history.
Industry:Science
After a half century of virtually complete control over infectious diseases in the developed countries, the 1990s brought a worldwide resurgence of bacterial and viral diseases. An important part of this phenomenon is the emergence of antimicrobial-resistance genes in virtually all major disease-causing bacteria.
Industry:Science
After a large earthquake, the Earth oscillates with natural, resonant frequencies like the tones of a bell. This phenomenon was theoretically predicted in the nineteenth century and was actually discovered after the 1960 magnitude-9.5 Chilean earthquake, the largest tremor of the twentieth century. These so-called free oscillations are now commonly observed after earthquakes of about magnitude 6.5 and larger because of improved seismometers with high sensitivity.
Industry:Science
Aging is a complex, multifactorial process that is influenced by both genes and the environment. Aging occurs in almost all animals and is a major risk factor for the onset of a range of human diseases. The molecular and physiological causes of aging remain unknown. However, a number of genetic factors that help determine animal life span have been identified, and it is likely that some mechanisms may be elucidated in the near future.
Industry:Science
Aging is influenced by complex interactions between genetic and environmental parameters. Sirtuins are a family of nicotinamide adenine dinucleotide (NAD)–dependent protein deacetylases (which remove acetyl groups from protein molecules) and adenosine diphosphate (ADP)–ribosyltransferases (which catalyze the transfer of the ADP-ribose moiety from NAD<sup>+</sup> onto specific substrates) that are thought to play an important role in modulating these interactions. Mammalian sirtuins have been recently implicated in a variety of aging-related processes, and it has been suggested that these enzymes may prove to be effective therapeutic targets for treating age-associated diseases in humans.
Industry:Science
Agricultural ecology (or agroecology) uses ecological knowledge about organism distribution and abundance to enhance crop yields and protect crops from insect or disease attack. In turn, agricultural ecology is used as a model system for exploring further applied and basic ecological phenomena. Climate, soils, crop physiology and chemistry, and plant and insect population biology are critical elements of agricultural ecology.
Industry:Science
Agricultural materials used as feedstocks for industrial processes. For many centuries agricultural products were the main sources of raw material for the manufacturing of soap, paint, ink, lubricants, grease, paper, cloth, drugs, and a host of other nonfood products. During the early 1900s, the advances in organic synthesis in western Europe and the United States led to the use of coal as an alternative resource; in the 1940s, oil and natural gas were added as starting materials as a result of great advances in catalysis and polymer sciences. Since then the petrochemical industry has grown rapidly as the result of the abundance and low price of the starting materials as well as the development of new products, such as nylon and other polymers, water-based paints, and detergents. However, with the rapidly increasing economies of the nations of the world, these developments did not ever result in reduction in the utilization of agricultural products as industrial materials. Although specific nonfood crops, such as linseed or cotton, may have suffered from these developments, animal fats, vegetable oils, starch, cellulose, and other renewable agricultural resources still are used extensively in industry, and many new uses have been developed since the 1950s.
Industry:Science
Agronomic production, the growing of plants for food and fiber, is undergoing a technological revolution. Farmers and ranchers are using many of the same advanced and elaborate tools used in industry. Computer technology is driving this revolution. For the food and fiber producer, a significant development is real-time positioning capability, which means that a portable computer is able to determine its position on Earth almost instantaneously. The primary method of position acquisition used by agriculture is the Global Positioning System (GPS). This system is composed of computerized ground receivers and 24 satellites in orbit around the Earth. The satellites emit signals that allow a receiver on Earth (or in space, for that matter) to precisely determine its location (latitude, longitude, and elevation) through a mathematical method known as triangulation. GPS receivers mounted on tractors, sprayers, or combines or carried by hand allow farmers or ranchers to know their location in a field or pasture or rangeland to an accuracy of 10–16 ft (3–5 m) at present and a future accuracy of 1–2 in. (3–5 cm). This real-time positioning capability is resulting in a significant increase in the intensity of farm and ranch management. This intense management is referred to as site-specific farming or precision farming.
Industry:Science
Air and water are the media in which humans and all other living organisms spend their lives, the media by which heating and cooling are accomplished, and the media through which all means of transportation must pass. Fluid-dominated phenomena are critical for the operation of aircraft, sailboats, cars, and trucks, and they play an important role in energy efficiency and combustion.
Industry:Science
Air temperatures adjusted to represent human comfort or discomfort under prevailing conditions of temperature, humidity, radiation, and wind. Theoretical formulas attempt to compare the rate of heat loss to surroundings with rate of heat production by work and metabolism. Most modern empirical relations, based on relative comfort expressed by human subjects under differing atmospheric combinations, attempt to indicate the temperature at which air at some standard humidity, air motion, and radiation load would be just as uncomfortable (or comfortable). Many former indices, however, had arbitrary scales.
Industry:Science
