- 行业: Printing & publishing
- Number of terms: 178089
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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 highly interdisciplinary field covering the chemical, physical, and biological features of complex chemical species held together and organized by means of intermolecular (noncovalent) bonding interactions. It is “chemistry beyond the molecule.”
Industry:Science
A highly modified integumentary gland which arises from an epithelial invagination into the dermis. It becomes cut off from its site of origin and develops into a luminous organ composed of a lens and a light-emitting gland, at the back of which is a pigmented reflector of probable dermal-cell origin. These luminous bodies occur in deep-sea teleosts and elasmobranchs which live in areas of total darkness.
Industry:Science
A highly sensitive analytic technique for determining the composition of elements in small samples. Proton-induced x-ray emission (PIXE) is a nondestructive method capable of analyzing many elements simultaneously at concentrations of parts per million in samples as small as nanograms. PIXE has gained acceptance in many disciplines; for example, it is the preferred technique for surveying the environment for trace quantities of such toxic elements as lead and arsenic. There has also been a rapid development in the use of focused proton beams for PIXE studies in order to produce two-dimensional maps of the elements at spatial resolutions of micrometers.
Industry:Science
A highly sensitive instrument which measures all or some of the following variables: current, charge, voltage, and resistance. There are two classes of electrometers, mechanical and electronic. The mechanical instruments have been largely replaced by electronic types.
Industry:Science
A highly sensitive low-noise amplifier for ultrahigh-frequency and microwave radio signals, utilizing as the active element an inductor or capacitor whose reactance is varied periodically at another microwave or ultrahigh frequency. A varactor diode is most commonly used as the variable reactor. The varactor is a semiconductor <i>pn</i> junction diode, and its junction capacitance is varied by the application of a steady signal from a local microwave oscillator, called the pump. Amplification of weak signal waves occurs through a nonlinear modulation or signal-mixing process which produces additional signal waves at other frequencies. This process may provide negative-resistance amplification for the applied signal wave and increased power in one or more of the new frequencies which are generated.
Industry:Science
A highly sulfated mucopolysaccharide isolated from mammalian (chiefly beef) tissues, with blood anticoagulant activity. Heparin was first found in abundance in the liver, hence the name, but it is present in substantial amounts in the spleen, muscle, and lung as well. Chiefly composed of <small>D</small>-glucosamine and <small>D</small>-glucuronic acid residues, it usually has a molecular weight from 6000 to 20,000. It normally occurs as the sodium or potassium salts and undergoes some degree of desulfation when the free acid is liberated. Full desulfation of heparin yields heparamine, which on treatment with carboxylic acid anhydrides furnishes heparides, that is, amides of the polysaccharide, free of anticoagulant properties but still valuable for treating hyperlipidemia. In the blood of most mammals, heparin is an antagonist to thrombin, prothrombin, and thromboplastin. It lessens the tendency of platelets to agglutinate. When it is injected, its action is almost instantaneous, but it begins to decline rapidly in 2–3 h. Heparin is only effective when injected, and the site of the injection often becomes swollen or inflamed and causes pain. It is used in the treatment of venous thrombosis, embolism, myocardial infarction, and certain types of cerebral thrombosis. Heparin is the single most important anticoagulant used in medicine.
Industry:Science
A high-performance fighter aircraft is a self-contained unit with its own energy source in the form of the fuel. However, a pilot is normally needed to take off, perform maneuvers, and land the aircraft. A pilotless vehicle that could automatically perform these tasks would be a smart aircraft. For an example of a smart structure, consider that the fighter aircraft is capable of flying and performing maneuvers at subsonic, transonic, and supersonic speeds, and different airfoil cross sections or shapes of the wing are more efficient at different speed regimes. The wing structure is a smart structure if any of the following can be achieved:
Industry:Science
A high-performance infrared telescope that is one of the four Great Observatories launched by the National Aeronautics and Space Administration (NASA) between 1990 and 2003. It takes advantage of dramatic advances in infrared detectors that have occurred over the last 20 years; it utilizes modern detector arrays in space, where they are limited only by the faint glow of the zodiacal dust cloud. Ground-based infrared telescopes can operate only at the wavelengths where the atmosphere is transparent, lying between 1 and 25 micrometers. Even within these windows, the thermal emission of the atmosphere is more than a million times greater than the dilute emission of the zodiacal cloud; there is additional foreground thermal emission from the telescope itself. High-sensitivity detectors are blinded by these bright foreground signals. Operating in space eliminates the atmospheric absorption and emission; also, a telescope in the vacuum of space can be cooled sufficiently to virtually eliminate its emission.
Industry:Science
A high-pressure discharge lamp that is enclosed in a quartz envelope containing metal halides, usually iodides, and produces high-efficacy white light. These lamps are widely used for sports stadiums, roadways, commercial interiors, and industrial applications. The singular lamp feature is the compact geometry and high efficacy of nearly white light.
Industry:Science
A high-vacuum tube designed for operation in the frequency region from approximately 3000 to 300,000 megahertz. Two considerations distinguish a microwave tube from vacuum tubes used at lower frequencies: the dimensions of the tube structure in relation to the wavelength of the signal that it generates or amplifies, and the time during which the electrons interact with the microwave field.
Industry:Science
