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autoimmune disease

(Encyclopedia)autoimmune disease, any of a number of abnormal conditions caused when the body produces antibodies to its own substances. In rheumatoid arthritis, a group of antibody molecules called collectively RF...

tropical medicine

(Encyclopedia)tropical medicine, study, diagnosis, treatment, and prevention of certain diseases prevalent in the tropics. The warmth and humidity of the tropics and the often unsanitary conditions under which so m...

pediatrics

(Encyclopedia)pediatrics pēdēăˈtrĭks [key], branch of medicine dedicated to the attainment of the best physical, emotional, and social health for infants, children, and young people generally. Pediatrics becam...

eugenics

(Encyclopedia)eugenics yo͞ojĕnˈĭks [key], study of human genetics and of methods to improve the inherited characteristics, physical and mental, of the human race. Efforts to improve the human race through bette...

rotation of crops

(Encyclopedia)rotation of crops, agricultural practice of varying the crops on a piece of land in a planned series, to save or increase the mineral or organic content of the soil, to increase crop yields, and to er...

Rhyniophyta

(Encyclopedia)Rhyniophyta rīˌnēŏfˈətə [key], division of plants known only from fossils, of which the genus Rhynia was perhaps the most important. These plants date from the Silurian and Devonian age. Relati...

Duchenne, Guillaume Benjamin Amand

(Encyclopedia)Duchenne, Guillaume Benjamin Amand gēyōmˈ bäNzhämăNˈ ämäNˈ düshĕnˈ [key], 1806–75, French physician. He is noted for researches on diseases of the muscular and nervous systems and for h...

alkaloid

(Encyclopedia)alkaloid, any of a class of organic compounds composed of carbon, hydrogen, nitrogen, and usually oxygen that are often derived from plants. Although the name means alkalilike, some alkaloids do not e...

nursery

(Encyclopedia)nursery, in horticulture, an establishment or area for the propagation, breeding, and early cultivation of plants. In North America the term nursery originally specified a place where hardy woody plan...

chloroplast

(Encyclopedia)chloroplast klōrˈəplăstˌ, klôrˈ– [key], a complex, discrete green structure, or organelle, contained in the cytoplasm of plant cells. Chloroplasts are reponsible for the green color of almost...