  Electronic transport in multiwall carbon nanotubes and semiconductor
nanowires was compared. In both cases, the non ohmic behavior of the
conductance, the so-called zero bias anomaly, shows a temperature dependence
that scales with the voltage dependence. This robust scaling law describes the
conductance $G(V,T)$ by a single coefficient $\alpha$. A universal behavior as
a function of $\alpha$ is found for all samples. Magnetoconductance
measurements furthermore show that the conduction regime is weak localization.
The observed behavior can be understood in terms of the coulomb blockade
theory, providing that a unique tunnel resistance on the order of 2000 $\Omega$
and a Thouless energy of about 40 meV exists for all samples.
