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leucine

(Encyclopedia)CE5 leucine lo͞oˈsēn [key], organic compund, one of the 20 amino acids commonly found in animal proteins. Only the l-stereooisomer appears in mammalian protein. It is one of several essential am...

osmium

(Encyclopedia)osmium ŏzˈmēəm [key], metallic chemical element; symbol Os; at. no. 76; at. wt. 190.23; m.p. 3,045±30℃; b.p. 5,027±100℃; sp. gr. 22.57 at 20℃; valence usually +0 to +8. Osmium is a very ha...

mass extinction

(Encyclopedia)mass extinction, the extinction of a large percentage of the earth's species, opening ecological niches for other species to fill. There have been at least ten such events. The five greatest were thos...

chromium

(Encyclopedia)chromium krōˈmēəm [key] [Gr.,=color], metallic chemical element; symbol Cr; at. no. 24; at. wt. 51.9961; m.p. about 1,857℃; b.p. 2,672℃; sp. gr. about 7.2 at 20℃; valence +2, +3, +6. Chromiu...

bromine

(Encyclopedia)bromine brōˈmēn, –mĭn [key] [Gr.,=stench], volatile, liquid chemical element; symbol Br; at. no. 35; at. wt. 79.904; m.p. –7.2℃; b.p. 58.78℃; sp. gr. of liquid 3.12 at 20℃; density of va...

flying lemur

(Encyclopedia)flying lemur, gliding mammal native to the tropical lowland forests of S Asia, Malaya, and the Philippines. Also called the colugo, the flying lemur is brownish or grayish above and paler below. It ra...

liana

(Encyclopedia)liana lēänˈ [key], name for any climbing plant that roots in the ground. The term is most often used for the woody vines that form a characteristic part of tropical rain-forest vegetation; they are...

Ypres, battles of

(Encyclopedia)Ypres, battles of, three major engagements of World War I fought in and around the town of Ypres in SW Belgium. The first battle of Ypres (Oct.–Nov., 1914) was the last of the series of engagements ...

addax

(Encyclopedia)addax ădˈăks [key], large, desert-dwelling antelope. It is a single species, Addax nasomaculatus. The addax is yellowish-white in color, has a brown mane and throat fringe, and may stand as high as...

umbrella

(Encyclopedia)umbrella, a small canopy used as a protection against the sun in China, Egypt, and elsewhere in remote antiquity. It was often an emblem of rank. During the Middle Ages the umbrella became almost exti...