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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...

water mold

(Encyclopedia)water mold, common name for a group of multinucleated organisms that superficially resemble fungi but are now recognized as having an independent evolutionary lineage and are placed in the kingdom Pro...

tree shrew

(Encyclopedia)tree shrew, small, arboreal mammal of the family Tupaiidae, found in S Asia. The 17 known species of tree shrews are classified as the order Tupaioidea or Scandentia. Tree shrews superficially resembl...

tenrec

(Encyclopedia)tenrec tĕnˈrĕk [key], any of the small insectivorous mammals of the family Tenrecidae, also called tendrecs or tanrecs. These animals are found on the island of Madagascar. In that closed environme...

bone marrow

(Encyclopedia)bone marrow, soft tissue filling the spongy interiors of animal bones. Red marrow is the principal organ that forms blood cells in mammals, including humans (see blood). In children, the bones contain...

bichir

(Encyclopedia)bichir bĭchˈər [key], common name for African freshwater fishes as of the family Polypteridae, and particularly for those of the genus Polypterus. Bichirs are among the most primitive of the ray-fi...

zoology

(Encyclopedia)zoology, branch of biology concerned with the study of animal life. From earliest times animals have been vitally important to man; cave art demonstrates the practical and mystical significance animal...

selenium

(Encyclopedia)selenium səlēˈnēəm [key], nonmetallic chemical element; symbol Se; at. no. 34; at. wt. 78.96; m.p. 217℃; b.p. about 685℃; sp. gr. 4.81 at 20℃; valence −2, +4, or +6. Selenium is directly ...

serotonin

(Encyclopedia)serotonin sĕrˌətōˈnĭn [key], organic compound that was first recognized as a powerful vasoconstrictor occurring in blood serum. It was partially purified, crystallized, and named in 1948, and it...

Hittite art and architecture

(Encyclopedia)Hittite art and architecture, works of art and structures created by the ancient Hittites The principal architectural remnant of the Hittite civilization is at Boğazköy, where temple structures ...