- 行业: Printing & publishing
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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.
Chemistry has been called the central science because it overlaps a number of other scientific disciplines, bridging physics and the biosciences. Published findings about modern chemistry date from the eighteenth century and have increased tremendously in volume since World War II. In 1946, Chemical Abstracts Service (CAS) included in its flagship publication, <i>Chemical Abstracts</i>, references to 49,578 documents; in 1997, the number was 716,564. Chemists pride themselves on their skill in using the literature of chemistry despite its enormous size and complexity. They have made extraordinary contributions to the organization of chemical information, which has had a major impact on the information retrieval practices in other scientific disciplines.
Industry:Science
Ecosystems are inherently complex, and despite efforts to identify and model causal chains linking ecosystem disturbances with ecosystem response, there are inevitable discrepancies between observed and predicted conditions in the natural environment. Uncertainty, variability, and change all contribute to these differences, yet they are often ignored in predicting environmental problems. Statistical modeling techniques represent a general classification of tools that can help address discrepancies between predictions and observations, and Bayesian statistics in particular has recently been demonstrated to be a novel and effective tool for forecasting environmental pollutant problems because of its unique approach to quantifying uncertainty and variability.
Industry:Science
In 1923, G. N. Lewis described electron donors as bases and electron acceptors as acids. Such Lewis acids and bases can combine to share electrons, forming a Lewis acid–base adduct. This fact leads to an understanding of the formation of main-group adducts and transition-metal coordination compounds, and it offers a rationale for many reactions in organic chemistry. In 2006, D. W. Stephan and colleagues uncovered a perturbation to this long-standing principle. By combining electron-rich and electron-poor species when the molecular structures preclude direct interaction of the electron acceptor and donor, they demonstrated that such sterically “frustrated” Lewis pairs (FLPs) provide unquenched Lewis acidity and basicity that is available for new reactivity.
Industry:Science
Biologists typically reduce a process to its simplest form in order to identify the fundamental mechanisms driving it. Cell division is one such process, and understanding the mechanisms controlling the cell division cycle is essential for understanding human growth and development. Diseases such as cancer are characterized by cell division in which these controls have gone awry. The simplest form of cell division likely to give insight to the process in humans is that occurring in unicellular eukaryotes, such as yeast. Yeast is a general term that covers a broad range of unicellular fungi. One of the most useful species is the fission yeast, <i>Schizosaccharomyces pombe</i>, which has become a model system for studies of growth control and cancer genetics.
Industry:Science
Design is a creative process of engineering synthetic solutions to satisfy human needs. In this sense, design is synonymous with engineering. Engineering design is undergoing a transition, driven by two complementary factors: the creation of the scientific basis of design, and industrial needs to shorten lead time, improve quality, and reduce the cost of new products. Many engineering problems can be solved when the basic scientific principles of design are applied. The science base enables designers of products and large engineering systems to perform their tasks on a logical, rational, and systematic basis (minimizing the trial-and-error process and empiricism). These changes have affected both design education and the practice of engineering in industry.
Industry:Science
During the last two decades, the natural ability of a common soil bacterium, <i>Agrobacterium tumefaciens</i>, to transfer deoxyribonucleic acid (DNA) to plants has been modified by scientists for use in the genetic engineering of many crop species into improved sources of food, fiber, and ornamentation. A scientific milestone in the genetic transformation of organisms occurred in recent years with the discovery that this bacterium can be manipulated to shuttle genes into fungi as well. The ease with which a rapidly increasing number and diversity of fungal species lend themselves to <i>Agrobacterium</i>-mediated transformation promises that genetically enhanced fungi will play a prominent role in a wide variety of novel industrial processes and applications.
Industry:Science
Configurations of inlets, catch basins, manholes, pipes, drains, mains, holding basins, pump stations, outfalls, controls, and special devices to move wastewaters from points of collection to discharge. Sewage collection systems must be designed and constructed to function without nuisance to the public, with a minimum of maintenance, with maximum safety for workers, without damage due to corrosion or erosion, with all components sized large enough to be capable of adequately serving the community through a justifiable design period with assured durability, and with an economically acceptable cost. The system of pipes and appurtenances is also known as the sewerage system. Wastewaters may be sanitary sewage, industrial wastes, storm runoff, or combined flows.
Industry:Science
Despite the enormous progress made in atmospheric research during the past 20 years, scientists still lack a basic understanding of a number of issues in the higher regions of the Earth's atmosphere. These issues include the reasons for the dryness of the stratosphere, whether or not there is evidence of the greenhouse effect in the upper atmosphere, and various questions connected with the air motion and transport mechanisms in the transition layer between the troposphere and lower stratosphere. The troposphere extends from the ground to altitudes of 8 km (5 mi) in polar regions and to 19 km (12 mi) at equatorial latitudes. The tropopause separates the troposphere from the stratosphere, which extends above the troposphere to altitudes of roughly 50 km (31 mi).
Industry:Science
Cicadas are a large and diverse group of insects in the family Cicadidae in the order Hemiptera. They are globally distributed, with especially high diversity in tropical regions. Most cicadas have a distinctive body form, with two pairs of wings, widely offset compound eyes on each side of the head, and three simple eyes (ocelli) on top of the head. They are generally large insects, ranging from 12 to 50 mm. At rest, the wings are held along the sides of the body, and generally extend beyond the abdomen without overlapping. Cicadas may be brightly or cryptically colored, and often have transparent wings. In many species, males produce distinctive sounds with specialized tymbal organs located on the abdomen. All cicadas are plant feeders with piercing mouthparts.
Industry:Science
Any naturally occurring inorganic salts of phosphoric acid, H<sub>3</sub>(PO<sub>4</sub>). All known phosphate minerals are orthophosphates since their anionic group is the insular tetrahedral unit (PO<sub>4</sub>)<sup>3−</sup>. Mineral salts of arsenic acid, H<sub>3</sub>(AsO<sub>4</sub>), have a similar crystal chemistry. There are over 150 species of phosphate minerals, and their crystal chemistry is often very complicated. Phosphate mineral paragenesis can be divided into three categories: primary phosphates (crystallized directly from a melt or fluid), secondary phosphates (derived from the primary phosphates by hydrothermal activity), and rock phosphates (derived from the action of water upon buried bone material, skeletons of small organisms, and so forth).
Industry:Science
