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colloid
(Encyclopedia)colloid kŏlˈoid [key] [Gr.,=gluelike], a mixture in which one substance is divided into minute particles (called colloidal particles) and dispersed throughout a second substance. The mixture is also...pollution
(Encyclopedia)pollution, contamination of the environment as a result of human activities. The term pollution refers primarily to the fouling of air, water, and land by wastes (see air pollution; water pollution; s...protein
(Encyclopedia)protein, any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellu...element
(Encyclopedia) CE5 element, in chemistry, a substance that cannot be decomposed into simpler substances by chemical means. A substance such as a compound can be decomposed into its constituent elements by means o...iron
(Encyclopedia)iron, metallic chemical element; symbol Fe [Lat. ferrum]; at. no. 26; at. wt. 55.845; m.p. about 1,535℃; b.p. about 2,750℃; sp. gr. 7.87 at 20℃; valence +2, +3, +4, or +6. Iron is biologically s...dinosaur
(Encyclopedia)dinosaur dīˈnəsôr [key] [Gr., = terrible lizard], extinct land reptile of the Mesozoic era. The dinosaurs, which were egg-laying animals, ranged in length from 21⁄2 ft (91 cm) to about 127 f...Transylvania
(Encyclopedia)Transylvania trănˌsĭlvāˈnyə [key], Rom. Transilvania or Ardeal, Hung. Erdély, Ger. Siebenbürgen, historic region and province (21,292 sq mi/55,146 sq km), central Romania. A high plateau, Tran...Cretaceous period
(Encyclopedia)Cretaceous period krĭtāˈshəs [key], third and last period of the Mesozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table), lasting from approximately 144 to 65 millio...fish, in zoology
(Encyclopedia) CE5 Anatomy of a ray-finned fish fish, limbless aquatic vertebrate animal with fins and internal gills. Traditionally the living fish have been divided into three class: the primitive jawless fish...Botswana
(Encyclopedia) CE5 Botswana bŏtswäˈnə [key], officially Republic of Botswana, republic (2020 est. pop. ...Browse by Subject
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