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blood groups

(Encyclopedia)blood groups, differentiation of blood by type, classified according to immunological (antigenic) properties, which are determined by specific substances on the surface of red blood cells. Blood group...

quasicrystal

(Encyclopedia)quasicrystal kwāˈzīkrĭsˌtəl, kwäzˈē– [key] or quasiperiodic solid, solid body that exhibits such crystalline features as symmetry and repeating patterns of unit cells (regular arrangements ...

radiation sickness

(Encyclopedia)radiation sickness, harmful effect produced on body tissues by exposure to radioactive substances. The biological action of radiation is not fully understood, but it is believed that a disturbance in ...

eye

(Encyclopedia)CE5 Cross section of human eye eye, organ of vision and light perception. In humans the eye is of the camera type, with an iris diaphragm and variable focusing, or accommodation. Other types of ey...

cycad

(Encyclopedia)cycad sīˈkăd [key], any plant of the order Cycadales, tropical and subtropical palmlike evergreens. The cycads, ginkgoes, and conifers comprise the three major orders of gymnosperms, or cone-bearin...

banana

(Encyclopedia)banana, name for several species of the genus Musa and for the fruits these produce. The banana plant—one of the largest herbaceous plants—is native to tropical Asia but now cultivated throughout ...

Horvitz, H. Robert

(Encyclopedia)Horvitz, H. Robert (Howard Robert Horivtz), 1947–, American geneticist, b. Chicago, Ill., Ph.D. Harvard, 1974. Horvitz has been a professor at the Massachusetts Institute of Technology since 1978. W...

Furchgott, Robert Francis

(Encyclopedia)Furchgott, Robert Francis, 1916–2009, American biochemist, b. Charleston, S.C., Ph.D. Northwestern Univ., 1940. Furchgott spent his entire career as a professor (1956–89) at the State Univ. of New...

Murad, Ferid

(Encyclopedia)Murad, Ferid, 1936–, American pharmacologist, b. Whiting, Ind., M.D., Ph.D. Western Reserve Univ. (now Case Western Reserve Univ.), 1965. Murad taught at the Univ. of Virginia (1975–81), Stanford ...

acetylcholine

(Encyclopedia)acetylcholine əsētˌəlkōˈlēn [key], a small organic molecule liberated at nerve endings as a neurotransmitter. It is particularly important in the stimulation of muscle tissue. The transmission ...