The spontaneous decay of an atom to an atom of a different element by emission of a particle from its nucleus (alpha and beta decay) or by electron capture.
Exotic particles produced at accelerators are often very short-lived, and can transform into lighter, less exotic products, such as electrons and photons. This process of ...
The middle layer of cells in embryonic development; gives rise to muscles, bones, and structures associated with reproduction. The middle embryonic tissue layer. Cells and ...
A pigment that gives the skin color and protects the underlying layers against damage by ultraviolet light; produced by melanocytes in the inner layer of the epidermis.
Cell division in which the chromosomes replicate, followed by two nuclear divisions. Each of the resulting gametes (in animals, spores in plants) receives a haploid set of ...
Four haploid cells produced by meiosis in the ovule of a þower. Usually, three of these cells degenerate, with the remaining cell becoming the female gametophyte phase of the ...
1. A term referring to the central portion of certain organs; e. G. , the medulla oblongata of the brain and the adrenal medulla, which synthesizes epinephrine and norepinephrine. ...
The combination of events associated with the origin, diversification, extinction, and interactions of organisms which produced the species that currently inhabit the Earth. Large ...
Annual or biennial plant (Raphanus sativus) of the mustard family, probably of Oriental origin, grown for its large, succulent root. Low in calories ...
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