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tryptophan

(Encyclopedia)CE5 tryptophan trĭpˈtəfăn [key], organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein. It is one of several essent...

valerian, in botany

(Encyclopedia)CE5 Valerian, Valeriana officinalis valerian, common name for some members of the Valerianaceae, a family chiefly of herbs and shrubs of temperate and colder regions of the Northern Hemisphere; a ...

vein

(Encyclopedia)CE5 Cross section of vein showing valves vein, blood vessel that returns blood to the heart. Except for the pulmonary vein, which carries oxygenated blood from the lungs to the heart, veins carry ...

radio frequency

(Encyclopedia)radio frequency, range of electromagnetic waves with a frequency or wavelength suitable for communication uses. Some of these waves serve as carriers of the lower-frequency audio waves; others are mod...

fructose

(Encyclopedia)CE5 fructose lĕvˈyəlōsˌ [key], or fruit sugar, simple sugar found in honey and in the fruit and other parts of plants. It is much sweeter than sucrose (cane sugar). It is best obtained by hydr...

instrument-landing system

(Encyclopedia)CE5 Instrument-landing system (ILS), the most common instrument-landing approach system, uses two beams to guide an airplane. instrument-landing system (ILS), ground-based radio system designed to...

Jenghiz Khan

(Encyclopedia)CE5 Empire of Jenghiz Khan (1227) Jenghiz Khan jĕngˈgĭs, gĕngˈgĭs kän [key], Mongolian Chinggis Khaan, 1167?–1227, Mongol conqueror, originally named Temujin. He succeeded his father, Yek...

phase, in astronomy

(Encyclopedia)CE5 Phases of the moon phase, in astronomy, the measure of how much of the illuminated surface of a planet or satellite can be seen from a point at a distance from that body; the term is most ofte...

witch hazel

(Encyclopedia)CE5 Witch hazel, Hamamelis virginiana witch hazel, common name for some members of the Hamamelidaceae, a family of trees and shrubs found mostly in Asia. The family includes the large genus (Coryl...

adenosine triphosphate

(Encyclopedia)CE5 Adenosine triphosphate (ATP) adenosine triphosphate (ATP) ədĕnˈəsēn trīˌfŏsˈfāt [key], organic compound composed of adenine, the sugar ribose, and three phosphate groups. ATP serves ...