  The $Q^2$ dependence of the ratios of the cross sections of deep inelastic
lepton--nucleus scattering is studied in the framework of leading twist, lowest
order perturbative QCD. The $\log Q^2$ slope of the ratio $F_2^{\rm
Sn}/F_2^{\rm C}$ is computed by using the DGLAP evolution equations, and shown
to be sensitive to the nuclear gluon distribution functions. Four different
parametrizations for the nuclear effects of parton distributions are studied.
We show that the NMC data on the $Q^2$ dependence of $F_2^{\rm Sn}/F_2^{\rm C}$
rule out the case where nuclear shadowing (suppression) of gluons at $x\sim
0.01$ is much larger than the shadowing observed in the ratio $F_2^A/F_2^{\rm
D}$. We also show that the possible nonlinear correction terms due to gluon
fusion in the evolution equations do not change this conclusion. Some
consequences for computation of RHIC multiplicities, which probe the region
$x\gsim0.01$, are also discussed.
