- 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 gas-mixing and burning tool that produces a hot flame for the welding or cutting of metal. The torch usually delivers acetylene and commercially pure oxygen producing a flame temperature of 5000–6000°F (2750–3300°C), sufficient to melt the metal locally. The torch thoroughly mixes the two gases and permits adjustment and regulation of the flame. Acetylene requires 2.5 times its volume of oxygen for complete combustion and, being an endothermic compound of carbon and hydrogen, can produce a higher flame temperature than other fuel gases.
Industry:Science
A geminal diether (R<sub>1</sub> = H). Ketals, considered a subclass of acetals, are also geminal diethers (R<sub>1</sub> = C, aliphatic or aromatic). Acetals are (1) independent structural units or a part of certain biological and commercial polymers, (2) blocking or protecting groups for complex molecules undergoing selective synthetic transformations, and (3) entry compounds for independent organic chemical reactions.
Industry:Science
A gene which brings about the death of the organism carrying it. Lethal genes constitute the most common class of gene changes (that is, mutations) and are reflections of the fact that the fundamental function of genes is the control of processes essential to the growth and development of organisms. In higher diploid forms lethals are usually recessive and expressed only in homozygotes. Dominant lethals, expressed in heterozygotes, are rapidly eliminated and thus rarely detected. Recessive zygotic lethals are retained with considerable frequency in natural populations of cross-fertilizing organisms, while gametic lethals (those affecting normal functioning of eggs and sperm among animals, or the pollen and ovules of plants) are subject to stringent selection and are accordingly rare.
Industry:Science
A general classification of the disorders or diseases that impact upon the nervous system. An understanding of diseases of the nervous system should include not only the type of lesion and reaction to injury, but also the site of involvement. Indeed, exquisite localization of function is a key distinguishing feature between the nervous system and other organs of the body. Further important considerations include age and sex. With regard to the sites affected, one important regional division is between the central nervous system (CNS), which includes the brain, spinal cord, and their coverings (meninges), and the peripheral nervous system (PNS), which includes the motor, sensory, and autonomic components of nerves that traverse the body.
Industry:Science
A general field of physical chemistry dealing with the various situations in which two or more phases (or states of aggregation) can coexist in thermodynamic equilibrium with each other, with the nature of the transitions between phases, and with the effects of temperature and pressure upon these equilibria. Many superficial aspects of the subject are largely qualitative, for example, the empirical classification of types of phase diagrams; but the basic problems always are susceptible to quantitative thermodynamic treatment, and in many cases, statistical thermodynamic methods can be applied to simple molecular models.
Industry:Science
A general name applied to certain species of the genus <i>Toxicodendron</i>, previously known as <i>Rhus</i>, in the sumac family (Anacardiaceae). <i>Toxicodendron radicans</i> is the poison ivy of eastern North America; <i>T. diversiloba</i> is the poison oak of California. These plants are natives of North America. Both cause ivy poisoning, an annoying and often painful dermatitis.
Industry:Science
A general name for any member of a heterogeneous group of serum proteins precipitated by 50% saturated ammonium sulfate, and thus differing from albumin, the protein present in greatest concentration in normal serum. Originally, the globulins were further subdivided on the basis of solubility (pseudoglobulin) or insolubility (“true globulins”) in salt-free pure water. However, the sharp demarcations implied by these definitions do not exist since globulins show varying degrees of solubility in water and in solutions of various ionic strengths.
Industry:Science
A general set of phenomena whereby materials suffer a marked decrease in their ability to deform (loss of ductility) or in their ability to absorb energy during fracture (loss of toughness), with little change in other mechanical properties, such as strength and hardness. Embrittlement can be induced by a variety of external or internal factors, for example, (1) a decreasing or an increasing temperature; (2) changes in the internal structure of the material, namely, changes in crystallite (grain) size, or in the presence and distribution of alloying elements and second-phase particles; (3) the introduction of an environment which is often, but not necessarily, corrosive in nature; (4) an increasing rate of application of load or extension; and (5) the presence of surface notches. This article is restricted to metals and alloys, and describes embrittlement in terms of the above factors.
Industry:Science
A general term applied to a condition of dormancy and torpor found in cold-blooded (poikilotherm) vertebrates and invertebrates. This rather universal phenomenon can be readily seen when body temperatures of poikilotherm animals drop in a parallel relation to ambient environmental temperatures. In the strict sense of the word, hibernation is a term which physiologists apply to relatively few species of mammals and birds (warm-blooded vertebrates).
Industry:Science
A general term for a genus of grasses of which the most important species is the deeply rooted perennial <i>Paspalum dilatatum</i>. Dallis grass is widely used in the southern United States, mostly for pasture, and remains productive indefinitely if well managed. Dallis grass does best on fertile soils and responds to lime and fertilizer. On heavier soils it remains green throughout the winter unless checked by heavy frosts. Seed production is hampered by infection with ergot, a fungus that invades developing seeds and produces purplish-black horny bodies. Ergot-bearing seed heads are very toxic to livestock, whether in pasture or in hay, and Dallis grass must be so managed as to prevent consumption of infected heads by livestock.
Industry:Science
