a positively charged particle that is the nucleus of the helium atom; emitted from natural or radioactive isotopes

a positively charged particle that is the nucleus of the helium atom; emitted from natural or radioactive isotopes

the radiation of alpha particles during radioactive decay

the radiation of alpha particles during radioactive decay

the radiation of alpha particles during radioactive decay

the radiation of alpha particles during radioactive decay

receptors postulated to exist on nerve cell membranes of the sympathetic nervous system in order to explain the specificity of certain agents that affect only some sympathetic activities (such as vasoconstriction and relaxation of intestinal muscles and contraction of smooth muscles)

receptors postulated to exist on nerve cell membranes of the sympathetic nervous system in order to explain the specificity of certain agents that affect only some sympathetic activities (such as vasoconstriction and relaxation of intestinal muscles and contraction of smooth muscles)

the normal brainwave in the electroencephalogram of a person who is awake but relaxed; occurs with a frequency of 8-12 hertz

the normal brainwave in the electroencephalogram of a person who is awake but relaxed; occurs with a frequency of 8-12 hertz