| 释义 |
extinction
ex·tinc·tion E0298000 (ĭk-stĭngk′shən)n.1. a. The act of extinguishing: The extinction of the fire took several hours.b. The condition of being extinguished: mourned the extinction of her dreams.2. The fact of being extinct or the process of becoming extinct: the extinction of the passenger pigeon; languages that are in danger of extinction.3. Psychology A reduction or a loss in the strength or rate of a conditioned response when the unconditioned stimulus or reinforcement is withheld.4. Physiology A gradual decrease in the excitability of a nerve to a previously adequate stimulus, usually resulting in total loss of excitability.5. Astronomy The dimming of celestial objects, usually measured in magnitudes, due to scattering and absorption of their light as it passes through interstellar dust clouds and the earth's atmosphere.extinction (ɪkˈstɪŋkʃən) or extincturen1. the act of making extinct or the state of being extinct2. the act of extinguishing or the state of being extinguished3. complete destruction; annihilation4. (General Physics) physics reduction of the intensity of radiation as a result of absorption or scattering by matter5. (Astronomy) astronomy the dimming of light from a celestial body as it passes through an absorbing or scattering medium, such as the earth's atmosphere or interstellar dust6. (Psychology) psychol a process in which the frequency or intensity of a learned response is decreased as a result of reinforcement being withdrawn. Compare habituationex•tinc•tion (ɪkˈstɪŋk ʃən)
n. 1. the act of extinguishing. 2. the state of being extinguished or extinct. 3. the act or process of becoming extinct: the extinction of a species. 4. the reduction or loss of a conditioned response as a result of the absence or withdrawal of reinforcement. 5. the darkness that results from rotation of a thin section to an angle (extinc′tion an`gle) at which plane-polarized light is absorbed by the polarizer. [1375–1425; late Middle English < Latin] Thesaurus| Noun | 1. | extinction - no longer active; extinguished; "the extinction of the volcano"inaction, inactiveness, inactivity - the state of being inactive | | 2. |  extinction - no longer in existence; "the extinction of a species"defunctnessdeath - the absence of life or state of being dead; "he seemed more content in death than he had ever been in life" | | 3. | extinction - the reduction of the intensity of radiation as a consequence of absorption and radiationabsorption - (physics) the process in which incident radiated energy is retained without reflection or transmission on passing through a medium; "the absorption of photons by atoms or molecules"natural action, natural process, action, activity - a process existing in or produced by nature (rather than by the intent of human beings); "the action of natural forces"; "volcanic activity"scattering - the physical process in which particles are deflected haphazardly as a result of collisions | | 4. |  extinction - complete annihilation; "they think a meteor cause the extinction of the dinosaurs"exterminationannihilation, disintegration - total destruction; "bomb tests resulted in the annihilation of the atoll" | | 5. | extinction - a conditioning process in which the reinforcer is removed and a conditioned response becomes independent of the conditioned stimulusexperimental extinctionconditioning - a learning process in which an organism's behavior becomes dependent on the occurrence of a stimulus in its environment | | 6. |  extinction - the act of extinguishing; causing to stop burning; "the extinction of the lights"extinguishing, quenchingending, termination, conclusion - the act of ending something; "the termination of the agreement" |
extinctionnoun dying out, death, destruction, abolition, oblivion, extermination, annihilation, eradication, obliteration, excision, extirpation Many species have been hunted to the point of extinction.extinctionnoun1. Utter destruction:annihilation, eradication, extermination, extinguishment, extirpation, liquidation, obliteration.2. The act or fact of dying:death, decease, demise, dissolution, passing, quietus, rest.Slang: curtain (used in plural).Translationsextinct (ikˈstiŋkt) adjective1. (of a type of animal etc) no longer in existence. Mammoths became extinct in prehistoric times. 絕種的，滅絕的 绝种的，灭绝的 2. (of a volcano) no longer active. That volcano was thought to be extinct until it suddenly erupted ten years ago. 不再活動的(火山) 已熄灭的（火山） extinction (ikˈstiŋkʃən) noun1. making or becoming extinct. the extinction of the species. 滅絕 灭绝2. the act of putting out or extinguishing (fire, hope etc). 撲滅(火勢)，(希望)破滅 扑灭extinction
extinction, in biology, disappearance of species of living organisms. Extinction usually occurs as a result of changed conditions to which the species is not suited. If no member of the affected species survives and reproduces, the entire line dies out, leaving no descendants. This was the case with the saber-toothed cat (Smilodon) of North America, which is not ancestral to any living species. However, a species may also become extinct through its gradual evolutionevolution,
concept that embodies the belief that existing animals and plants developed by a process of gradual, continuous change from previously existing forms. This theory, also known as descent with modification, constitutes organic evolution.
..... Click the link for more information. into a new species, as a result of natural selection for characteristics suited for new conditions. An example of the latter situation is the evolution of horseshorse,
hoofed, herbivorous mammal now represented by a single extant genus, Equus. The term horse commonly refers only to the domestic Equus caballus and to the wild Przewalski's horse.
..... Click the link for more information. from the eophippus (Hyracotherium) to Miohippus to Merychippus to the present-day Equus. There has been an unbroken line of descent, yet horses of the earlier types no longer exist. Human activities, such as overhunting a species or destroying its habitat, have caused the extinction of some species, such as the passenger pigeonpigeon,
common name for members of the large family Columbidae, land birds, cosmopolitan in temperate and tropical regions, characterized by stout bodies, short necks, small heads, and thick, heavy plumage.
..... Click the link for more information. and dodododo,
a flightless forest-dwelling bird of Mauritius, extinct since the late 17th cent. The dodo was closely related to the Rodrigues solitaire, extinct flightless giant found on another island in the Mascarene Islands.
..... Click the link for more information. , and threatened many others (see endangered speciesendangered species,
any plant or animal species whose ability to survive and reproduce has been jeopardized by human activities. In 1999 the U.S. government, in accordance with the U.S.
..... Click the link for more information. ). See also mass extinctionmass extinction,
the extinction of a large percentage of the earth's species, opening ecological niches for other species to fill. There have been at least ten such events.
..... Click the link for more information. . Bibliography See M. V. Barrow, Jr., Nature's Ghosts: Confronting Extinction from the Age of Jefferson to the Age of Ecology (2009); E. Fuller, Lost Animals: Extinction and the Photographic Record (2014). extinction The reduction in the amount of light or other radiation received from a celestial body as a result of absorption and scattering of the radiation by intervening dust grains in space (interstellar extinction) and in the Earth's atmosphere (atmospheric extinction). The extinction decreases with wavelength of the radiation and increases with the pathlength through the absorbing medium and with the density of the medium. The starlight is also reddened since the extinction of blue light by dust is greater than that of red light. The reddening may be given in terms of the color excess, E , E = (B –V) – (B –V )0 where (B –V) and (B –V )0 are the observed and intrinsic color indices of the star. Most stars are reddened by a few tenths of a magnitude although values of up to two magnitudes are not uncommon. Stars lying behind extremely dense matter might only be detectable at radio or infrared wavelengths. See also infrared sources. Extinction (also extinctive inhibition), in physiology, a form of internal conditioned inhibition in accordance with Pavlovian theory. The simplest form of extinction is the progressive weakening of external manifestations of the orienting reflex when the subject is repeatedly exposed to an extraneous stimulus. A more complex form of extinction is the gradual decrease in magnitude of a conditioned reflex in the absence of reinforcement by an unconditioned stimulus. The time required for any given degree of extinction, as well as its degree, depends on various factors, including the modality of the conditional signal, the type of unconditioned reflex (for example, the alimentary or defensive types), the type of registrable reaction (such as motor or secretory reactions), and the extent to which the conditioned reflex has become established. It is presumed that extinction is based on inhibitory activity in the conductive links by which signals are transmitted from the sensory (afferent) pathways to the effector (efferent) systems of the brain. extinction[ek′stiŋk·shən] (astronomy) The reduction in the apparent brightness of a celestial object due to absorption and scattering of its light by the atmosphere and by interstellar dust; it is greater at low altitudes. (evolution) The worldwide death and disappearance of a specific organism or group of organisms. (hydrology) The drying up of lake by either water loss or destruction of the lake basin. (optics) Phenomenon in which plane polarized light is almost completely absorbed by a polarizer whose axis is perpendicular to the plane of polarization. (physical chemistry) absorbance (psychology) Decrease in frequency and elimination of a conditioned response if reinforcement of the response is withheld. Extinctionbald eagleonce on verge of extinction, this bird is now protected; still an endangered species. [Ecology: Hammond, 290]dinosaurdinosaurs died out, unable to adapt to environmental change. [Ecology: Hammond, 290]dodolarge, flightless bird exterminated on Mauritius. [Ecology: Wallechinsky, 131]great aukhunters killed such large numbers, these birds became extinct in 1840s. [Ecology: Hammond, 290]heath henhuman settlement of U.S. Atlantic Coast contributed to the extinction of these birds. [Ecology: Hammond, 290]Last of the Mohicans, Thenovel foreseeing the extinction of various Indian tribes. [Am. Lit.: The Last of the Mohicans]mastodonsimilar to the elephant, the mastodon is now extinct. [Ecology: Hammond, 290]moalarge ostrichlike bird, hunted chiefly for its food; it died out in 1914. [Ecology: Hammond, 290]passenger pigeonhunted to extinction by 1914; vast numbers once darkened American skies during migratory flights. [Ecology: EB, VII: 786]saber-toothed tigerwild cat that died out about 12,000 years ago. [Ecology: Hammond, 290]Last of the Barons, Theportrays England’s brilliant aristocracy as dying breed (1470s). [Br. Lit.: The Last of the Barons, Magill I, 492–494]whalemany species in danger of extinction, owing to massive hunting. [Ecology: Hammond, 290]extinction1. Physics reduction of the intensity of radiation as a result of absorption or scattering by matter 2. Astronomy the dimming of light from a celestial body as it passes through an absorbing or scattering medium, such as the earth's atmosphere or interstellar dust 3. Psychol a process in which the frequency or intensity of a learned response is decreased as a result of reinforcement being withdrawn extinction
extinction [eks-ting´shun] in psychology, the disappearance of a conditioned response as a result of its not being reinforced; also, the process by which the disappearance is accomplished. See also conditioning.ex·tinc·tion (eks-tingk'shŭn), 1. In behavior modification or in classical or operant conditioning, a progressive decrease in the frequency of a response that is not positively reinforced; the withdrawal of reinforcers known to maintain an undesirable behavior. 2. Synonym(s): absorbance [L. extinguo, to quench] extinction (ĭk-stĭngk′shən)n.1. a. The act of extinguishing: The extinction of the fire took several hours.b. The condition of being extinguished: mourned the extinction of her dreams.2. The fact of being extinct or the process of becoming extinct: the extinction of the passenger pigeon; languages that are in danger of extinction.3. Psychology A reduction or a loss in the strength or rate of a conditioned response when the unconditioned stimulus or reinforcement is withheld.4. Physiology A gradual decrease in the excitability of a nerve to a previously adequate stimulus, usually resulting in total loss of excitability.extinction Psychiatry A facet of operant–classical conditioning, in which the conditioned response is weakened and eventually disappears by nonreinforcement. See Operant conditioning, Respondent conditioning, Sensory extinction. ex·tinc·tion (eks-tingk'shŭn) 1. In behavior modification or classical or operant conditioning, a progressive decrease in the frequency of a response that is not positively reinforced.
See: conditioning2. Synonym(s): absorbance. [L. extinguo, to quench]extinction - the act of making EXTINCT or the state of being extinct.
- the elimination of an allele of a gene in a population, due to RANDOM GENETIC DRIFT or to adverse SELECTION pressures.
- any periodical, catastrophic event resulting in a species or larger taxonomic group dying out abruptly at a particular point in geological history. Such extinctions are thought to be cyclical, occurring every 28.4 million years, and have been attributed to cosmic activity such as showers of large asteroids or comets, though neither the periodicity nor its causes are at present universally accepted.
LegalSeeAdemptionextinction
Related to extinction: Mass extinction, Extinction of SpeciesSynonyms for extinctionnoun dying outSynonyms- dying out
- death
- destruction
- abolition
- oblivion
- extermination
- annihilation
- eradication
- obliteration
- excision
- extirpation
Synonyms for extinctionnoun utter destructionSynonyms- annihilation
- eradication
- extermination
- extinguishment
- extirpation
- liquidation
- obliteration
noun the act or fact of dyingSynonyms- death
- decease
- demise
- dissolution
- passing
- quietus
- rest
- curtain
Synonyms for extinctionnoun no longer activeRelated Words- inaction
- inactiveness
- inactivity
noun no longer in existenceSynonymsRelated Wordsnoun the reduction of the intensity of radiation as a consequence of absorption and radiationRelated Words- absorption
- natural action
- natural process
- action
- activity
- scattering
noun complete annihilationSynonymsRelated Words- annihilation
- disintegration
noun a conditioning process in which the reinforcer is removed and a conditioned response becomes independent of the conditioned stimulusSynonymsRelated Wordsnoun the act of extinguishingSynonymsRelated Words- ending
- termination
- conclusion
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