  The nonlinear diffusion equation $\frac{\partial \rho}{\partial t}=D
\tilde{\Delta} \rho^\nu$ is analyzed here, where $\tilde{\Delta}\equiv
\frac{1}{r^{d-1}}\frac{\partial}{\partial r} r^{d-1-\theta}
\frac{\partial}{\partial r}$, and $d$, $\theta$ and $\nu$ are real parameters.
This equation unifies the anomalous diffusion equation on fractals ($\nu =1$)
and the spherical anomalous diffusion for porous media ($\theta=0$). Exact
point-source solution is obtained, enabling us to describe a large class of
subdiffusion ($\theta > (1-\nu)d$), normal diffusion ($\theta= (1-\nu)d$) and
superdiffusion ($\theta < (1-\nu)d$). Furthermore, a thermostatistical basis
for this solution is given from the maximum entropic principle applied to the
Tsallis entropy.
