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aquarium
(Encyclopedia)aquarium, name for any supervised exhibit of aquatic animals and plants. Aquariums are known to have been constructed in ancient Rome, Egypt, and Asia. Goldfish have been bred in China for several hun...mortar, in building
(Encyclopedia)mortar, in building, mixture of lime or cement with sand and water, used as a bedding and adhesive between adjacent pieces of stone, brick, or other material in masonry construction. Lime mortar, a co...methane
(Encyclopedia)methane mĕthˈān [key], CH4, colorless, odorless, gaseous saturated hydrocarbon; the simplest alkane. It is less dense than air, melts at −184℃, and boils at −161.4℃. It is combustible and c...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...carboxyl group
(Encyclopedia)carboxyl group kärbŏkˈsĭl [key], in chemistry, functional group that consists of a carbon atom joined to an oxygen atom by a double bond and to a hydroxyl group, OH, by a single bond. Carboxylic a...urea
(Encyclopedia) CE5 urea yo͝oēˈə [key], organic compound that is the principal end product of nitrogen metabolism in most mammals. Urea was the first animal metabolite to be isolated in crystalline form; its c...actinium
(Encyclopedia)actinium ăktĭnˈēəm [key] [Gr.,=like a ray], radioactive chemical element; symbol Ac; at. no. 89; mass number of most stable isotope 227; m.p. about 1,050℃; b.p. 3,200℃±300℃; sp. gr. 10.07;...ruthenium
(Encyclopedia)ruthenium ro͞othēˈnēəm [key], metallic chemical element; symbol Ru; at. no. 44; at. wt. 101.07; m.p. about 2,310℃; b.p. about 3,900℃; sp. gr. 12.41 at 20℃; valence commonly +2, +3, +4, +6, ...Kuril Islands
(Encyclopedia)Kuril Islands kyo͝orˈēlz, kyo͝orēlzˈ [key], Jap. Chishima-Retto, Rus. Kurilskiye Ostrova, island chain, c.6,020 sq mi (15,590 sq km), Sakhalin region, E Russia. They stretch c.775 mi (1,250 km) ...Cyclades
(Encyclopedia)Cyclades sīˈklədēz [key], Gr. Kikládhes [Gr.,=circular], island group, c.1,000 sq mi (2,...Browse by Subject
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