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collagen

(Encyclopedia)collagen kŏlˈəjən [key], any of a group of proteins found in skin, ligaments, tendons, bone and cartilage, and other connective tissue. Cells called fibroblasts form the various fibers in connecti...

histology

(Encyclopedia)histology hĭstŏlˈəjē [key], study of the groups of specialized cells called tissues that are found in most multicellular plants and animals. Histologists study the organization of tissues at all ...

hafnium

(Encyclopedia)hafnium hăfˈnēəm [key], metallic chemical element; symbol Hf; at. no. 72; at. wt. 178.49; m.p. about 2,227℃; b.p. 4,602℃; sp. gr. 13.31 at 20℃; valence +4. Hafnium is a lustrous, ductile, si...

Watson, James Dewey

(Encyclopedia)Watson, James Dewey, 1928–, American biologist and educator, b. Chicago, Ill., grad. Univ. of Chicago, 1947, Ph.D. Univ. of Indiana, 1950. With F. H. C. Crick he began (1951) research on the molecul...

Chordata

(Encyclopedia)CE5 Common features in representative groups of the phylum Chordata Chordata kôrdāˈtə, –däˈ– [key], phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal ...

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;...

Perot, H. Ross

(Encyclopedia)Perot, H. Ross (Henry Ross Perot), 1930–2019, American business executive and political leader, b. Texarkana, Tex., as Henry Ray Perot, grad. Annapolis, 1953. In 1957 he resigned his naval commissio...

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...

Carver, Raymond

(Encyclopedia)Carver, Raymond, 1938–88, American short-story writer, b. Clatskanie, Oreg. He was raised in the Pacific Northwest, where he often set his sparely written tales of everyday blue-collar life. His per...

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...