- 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.
Cholesterol is a steroid alcohol that is essentially insoluble in aqueous solutions. In mammals it is normally solubilized by its association with other lipids, such as phospholipids or bile acids; thus, most cholesterol is found in cell membranes, plasma lipoproteins, and bile. Cholesterol can be esterified with a fatty acid to form cholesteryl esters. The latter form discrete lipid droplets in cells, especially in cells of steroidogenic tissues, and in the lipid core of low-density lipoproteins in the blood.
Industry:Science
Declines in the populations of amphibians (frogs, toads, salamanders, newts, and caecilians) were first highlighted internationally in 1989 at the First World Congress of Herpetology (the study of amphibians and reptiles) in Canterbury, U.K. Many researchers had independently noticed that the populations of frogs they studied were greatly reduced in number or had disappeared altogether from locations in which they had previously been abundant. One such location was in the Sierra Nevada mountains of California.
Industry:Science
Any apparatus which swings, because of gravity, with a natural period of 84.4 min, that is, with the same period as a hypothetical simple pendulum whose length is the Earth's radius. In 1923 Max Schuler showed that such an apparatus has the unique property that the pendulum arm will remain vertical despite any motions of its pivot. It is therefore useful as a base for navigational instruments. Schuler also showed how gyroscopes can be used to increase the period of a physical pendulum to the desired 84.4 min.
Industry:Science
Arrangements of the names of species and groups of species meant to convey how these organisms are related to one another. The purposes of biological classifications are to organize the known biodiversity, provide a framework that will incorporate newly discovered biodiversity, and provide a predictive framework for studying biodiversity. Systematics focuses on studies of biodiversity and relationships among organisms. Taxonomy is a subdiscipline of systematics that focuses on formal classifications of organisms.
Industry:Science
Chemicals obtained from wood. The practice was carried out in the past, and continues wherever technical utility and economic conditions have combined to make it feasible. Woody plants comprise the greatest part of the organic materials produced by photosynthesis on a renewable basis, and were the precursors of the fossil coal deposits. Future shortages of the fossil hydrocarbons from which most organic chemicals are derived may result in the economic feasibility of the production of these chemicals from wood.
Industry:Science
Energetic electrons ejected from atoms in matter by the passage of ionizing particles. In every primary ionizing collision between a charged particle and an atom, one or more electrons are ejected. Delta electrons are, by definition, that small fraction of these emitted electrons having energies which are large compared to the ionization potential. The name is a traditional one—comparable to alpha particles, for energetic helium nuclei, and beta particles, for energetic electrons emitted in radioactive decays.
Industry:Science
As the result of a half century of study of elementary particles, physicists today believe that all matter and energy at currently accessible energy scales consists of a small set of fundamental particles whose interactions are described by the relatively simple rules of a quantum field theory. The list of these particles and the rules for their basic interactions constitute what is now known as the standard model. At present, gravity is the only experimentally known force that does not have a place in this model.
Industry:Science
Auger electron spectroscopy (AES) is a widely used technique that detects the elements in the first atomic layers of a solid surface. Although many elements can be detected, hydrogen usually cannot be observed. Excellent spatial resolution can be achieved. Auger electron spectroscopy is important in many areas of science and technology, such as catalysis, electronics, lubrication, and new materials, and also understanding chemical bonding in the surface region. Auger spectra can be observed with gas-phase species.
Industry:Science
In 1781 the French astronomer Charles Messier published his catalog of star clusters and nebulae. Officially, the principal catalog of these objects is the <i>New General Catalogue of Clusters and Nebulae</i>, drawn up by J. L. E. Dreyer in 1888, but the Messier numbers are much more widely used by amateur astronomers. For example, the Andromeda Nebula is much more widely known as M31 than as NGC 224. Recently, the Caldwell catalog has been compiled to list notable objects that are absent from the Messier catalog.
Industry:Science
Autophagy, the destruction of the cell's components by its own enzymes, is a process of all eukaryotic cells. Various types of autophagy occur during normal development or as a response to various types of stress, including starvation. Defects in autophagy are correlated with a number of diseases in humans. Recent advances in the study of autophagy in baker's yeast (<i>Saccharomyces cerevisiae</i>) have provided insight into the molecular basis of this process in more complex eukaryotes, including animals and humans.
Industry:Science
