An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 12 Search : reaction
abstraction reaction
  واژیرش ِ آهنجش   
vâžireš-e âhanješ (#)

Fr.: réaction d'abstraction   

Chemistry: A bimolecular chemical reaction that involves removal of an atom or ion from a molecule. For example, hydrogen abstraction from methane: CH4 + Cl → CH3 + HCl.

abstraction; → reaction.

chain reaction
  واژیرش ِ زنجیری، واکنش ِ ~   
vâžireš-e zanjiri, vâkoneš-e ~

Fr.: réaction en chaîne   

A succession of → nuclear fissions when the neutrons released by previous fissions produce other nuclear fissions which themselves cause other reactions and the reactions goes on increasing exponentially.

chain; → reaction.

chemical reaction
  واژیرش ِ شیمیایی، واکنش ِ ~   
vâžireš-e šimiyâyi, vâkoneš-e ~

Fr.: réaction chimique   

A → change or → transformation in which a → substance → decomposes, → combines with other → substances, or interchanges constituents with other substances.

chemical; → reaction.

nuclear reaction
  واژیرش ِ هسته‌ای   
vâžireš-e haste-yi

Fr.: réaction nucléaire   

A process in which the energy, composition, or structure of an atomic nucleus changes.

nuclear; → reaction.

principle of action and reaction
  پَروز ِ ژیرش و واژیرش، ~ کنش و واکنش   
parvaz-e žireš va vâžireš, ~ koneš va vâkoneš

Fr.: principe d'action et de réaction   

Newton's third law of motion, which states that for every action there must be an equal and opposite reaction.

principle; → action; → reaction.

proton-proton reaction
  واژیرش ِ پروتون-پروتون   
vâžireš-e-e proton-proton

Fr.: réaction proton-proton   

A → thermonuclear reaction in which two protons collide at very high velocities and combine to form a → deuterium. See also → proton-proton chain.

proton; → reaction.

pycnonuclear reaction
  واژیرش ِ چگال‌هسته‌ای   
vâžireš-e cagâl-hasteyi

Fr.: réaction pycnonucléaire   

A nuclear reaction that takes place at high densities and relatively low temperatures. Pycnonuclear reactions are almost temperature independent and occur even at zero temperature. These reactions are extremely slow at densities typical for normal stars but intensify with increasing density. For example, carbon burns into heavier elements at densities over 1010 g cm-3.

Pycnonuclear, from pycno- a combining form meaning "dense, thick," from Gk. pyknos "dense, solid" + → nuclear; → reaction.

Vâžireš, → reaction; cagâl-hasteyi, from cagâl, → dense, + hasteyi, → nuclear.

reaction
  واژیرش، واکنش   
vâžireš, vâkoneš

Fr.: réaction   

1) General: Action in response to some influence, event, stimulus.
2) An equal and opposite force exerted by a body against a force acting upon it. → principle of action and reaction.
3) A → nuclear reaction; → chain reaction.
4) → chemical reaction.

Verbal noun of → react.

reaction rate
  نرخ ِ واژیرش   
nerx-e vâžireš

Fr.: taux de réaction   

The speed with which a → chemical reaction takes place. In other words, the change in → concentration of a → substance divided by the → time interval during which the change is observed.

reaction; → rate.

resonant reaction
  واژیرش ِ باز‌آوا   
vâžireš-e bâzâvâ

Fr.: réaction résonnante   

A nuclear reaction whose probability is enhanced at an energy corresponding to an energy level of one of the nuclei. → resonance capture.

Resonant, verbal adj. of → resonate; → reaction.

thermonuclear reaction
  واژیرش ِ گرماهسته‌ای   
vâžireš-e garmâhaste-yi (#)

Fr.: réaction thermonucléaire   

A nuclear reaction in which two or more atomic nuclei fuse into a single heavier nucleus by a collision of the interacting particles at extremely high temperatures. Chains of thermonuclear reactions, such as the → proton-proton chain and the → CNO cycle, account for the energy radiated from the Sun and more massive stars.

thermo- + → nuclear; → reaction.

threshold of reaction
  آستانه‌ی ِ واژیرش   
âstâne-ye vâžireš

Fr.: seuil de réaction   

The minimum energy, for an incident particle or photon, below which a particular reaction does not occur.

threshold; → reaction.