  The internal conversion of nuclear transition in the ${}^{235}U$ atom is
considered. The low-energy $\gamma-$quanta ($E_{\gamma} \approx$ 76.8 $eV$) are
emitted during the $E3-$transition from the excited state ($I = (\frac12)^+$)
of the ${}^{235}U$ nucleus to its ground state ($I = (\frac72)^-$). The decay
rate of this ${}^{235m}U$ isomer ($E \approx 76.8$ $eV$) noticeably depends
upon the chemical composition and actual physical conditions (i.e. temperature
$T$ and pressure $p$). By varying such a composition and physical conditions
one can change the life-time of the ${}^{235m}U$ isomer to relatively
large/small values. A specific attention is given to the fullerene molecules
containing the central ${}^{235}U$ atom. It is shown that the decay rate
$\lambda$ of the ${}^{235m}U$ isomer in the ${}^{235m}U@C_{60-n}X_n$ molecules
and related compounds can differ significantly from the values obtained for
isolated ${}^{235}U$ atoms. Some applications of this effect are considered.
