| 释义 |
ra·di·a·tion
I. \ˌrādēˈāshən\ noun
(-s)
Etymology: Latin radiation-, radiatio, from radiatus (past participle of radiare to radiate) + -ion-, -io -ion
1.
a. : the act or process of radiating
< with radiation of the pain there may be tenderness over the sciatic nerve — J.A.Key >
< radiation of a radio program >
< the radiation of their world-conquering culture — Harper's >
< his smile … is a radiation of light — Saturday Review >
b. : the process of emitting radiant energy in the form of waves or particles
< radiation is easily distinguished from other forms of heat transfer … by its speed of propagation which equals that of light, and by the fact that no intervening medium is required for its transmission — J.G.Charney >
also : the combined processes of emission, transmission, and absorption of radiant energy
2.
a. : something that is radiated
< the real apostolic radiation which goes out from a contemplative monastery springs from the interior purity of the monks' own souls — Thomas Merton >
< believe in the presence of radiations which stream to earth from mysterious realms beyond — Edward Sapir >
b. : energy radiated in the form of waves or particles (as sound waves, electromagnetic waves, and corpuscular emissions that include alpha rays, beta rays, and neutrons released in atomic nuclear changes as well as cosmic rays)
< the essential identity of light, heat, and other electromagnetic radiation — D.L.Harms >
< an antenna in free space … sends out radiation in all directions — J.C.Slater >
3. : radial arrangement; also : a radial thing or part
4.
a. : biological evolution in a group of organisms that is characterized by spreading into different environments and by divergence of structure
< adaptive radiation in which new species arise better fitted to live under new conditions than in the ancestral habitat >
b. : the totality of new species, varieties, or other groups produced by radiation
5. : a method of surveying in which the field is triangulated by lines radiating from a central point
6. : a tract of nerve fibers within the brain; especially : one concerned with the distribution of impulses arising from sensory stimuli to the relevant coordinating centers and nuclei
7. : a device for radiating heat
II. noun
: transfer of heat by radiation — compare conduction in the Dict convection in the Dict |