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urinalysis

(Encyclopedia)urinalysis yo͝orˌənălˈĭsĭs [key], clinical examination of urine for the purpose of medical diagnosis. Urine is initially examined for such characteristics as color, odor, and specific gravity. ...

polonium

(Encyclopedia)polonium pəlōˈnēəm [key], radioactive chemical element; symbol Po; at. no. 84; mass no. of most stable isotope 209; m.p. 254℃; b.p. 962℃; sp. gr. about 9.4; valence +2 or +4. Polonium is an e...

oxide

(Encyclopedia)oxide, chemical compound containing oxygen and one other chemical element. Oxides are widely and abundantly distributed in nature. Water is the oxide of hydrogen. Silicon dioxide is the major componen...

fuel cell

(Encyclopedia)fuel cell, electric cell in which the chemical energy from the oxidation of a gas fuel is converted directly to electrical energy in a continuous process (see oxidation and reduction). The efficiency ...

photochemistry

(Encyclopedia)photochemistry, study of chemical processes that are accompanied by or catalyzed by the emission or absorption of visible light or ultraviolet radiation. A molecule in its ground (unexcited) state can...

xenon

(Encyclopedia)xenon zēˈnŏn [key] [Gr.,=strange], gaseous chemical element; symbol Xe; at. no. 54; at. wt. 131.293; m.p. −111.9℃; b.p. −107.1℃; density 5.86 grams per liter at STP; valence usually 0. Xeno...

periodic law

(Encyclopedia)periodic law, statement of a periodic recurrence of chemical and physical properties of the elements when the elements are arranged in order of increasing atomic number. Such an arrangement in the for...

lewisite

(Encyclopedia)lewisite lo͞oˈəsītˌ [key], liquid chemical compound used as a poison gas. Like mustard gas and nitrogen mustard, it is a blistering agent; when inhaled, it is a powerful respiratory irritant. The...

Moore, Stanford

(Encyclopedia)Moore, Stanford, 1913–82, American biochemist, b. Chicago, Ph.D. Univ. of Wisconsin, Madison, 1938. Moore joined the faculty at the Rockefeller Institute for Medical Research (now Rockefeller Univ.)...

Kleve

(Encyclopedia)Kleve klēv [key], Cleve or Eng. Cleves, city (1994 pop. 44,780), North Rhine–Westphalia, W Germany, near the Dutch border. Tourism is important in the city, and its manufactures include foodstuffs,...