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.
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.
vâžireš-e šimiyâyi, vâkoneš-e ~
Fr.: réaction chimique
Fr.: réaction nucléaire
A process in which the energy, composition, or structure of an atomic nucleus changes.
principle of action and reaction
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.
Fr.: réaction proton-proton
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.
1) General: Action in response to some influence, event, stimulus.
Verbal noun of → react.
Fr.: taux de réaction
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.
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.
threshold of reaction
Fr.: seuil de réaction
The minimum energy, for an incident particle or photon, below which a particular reaction does not occur.