出典:Wiktionary
From uranium + 235 (“the atomic mass of the isotope”).
uranium-235 (uncountable)
出典:Wikipedia
出典:『Wikipedia』 (2011/06/22 14:38 UTC 版)
Uranium-235 is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238 it is fissile, i.e., it can sustain fission chain reaction. It is the only fissile isotope that is a primordial nuclide or found in significant quantity in nature.