  We present a kinetic equation approach to investigate dc transport properties
of graphene in the diffusive regime considering long-range electron-impurity
scattering. In our study, the effects of interband correlation (or
polarization) on conductivity are taken into account. We find that the
conductivity contains not only the usual term inversely proportional to
impurity density $N_i$, but also an anomalous term that is linear in $N_i$.
This leads to a minimum in the density dependence of conductivity when the
electron density $N_{\rm e}$ is equal to a critical value, $N_c$. For $N_{\rm
e}>N_c$ the conductivity varies almost linearly with the electron density,
while it is approximately inversely proportional to $N_{\rm e}$ when $N_{\rm
e}<N_c$ in the diffusive regime. The effects of various scattering potentials
on the conductivity minimum are also analyzed. Using typical experimental
parameters, we find that for RPA screened electron-impurity scattering the
minimum conductivity is about $5.1 e^2/h$ when $N_{\rm e}\approx 0.32N_i$.
