  We consider the one-dimensional compressible Navier--Stokes system for a
viscous and heat-conducting ideal polytropic gas when the viscosity $\mu$ and
the heat conductivity $\kappa$ depend on the specific volume $v$ and the
temperature $\theta$ and are both proportional to $h(v)\theta^{\alpha}$ for
certain non-degenerate smooth function $h$. We prove the existence and
uniqueness of a global-in-time non-vacuum solution to its Cauchy problem under
certain assumptions on the parameter $\alpha$ and initial data, which imply
that the initial data can be large if $|\alpha|$ is sufficiently small. Our
result appears to be the first global existence result for general adiabatic
exponent and large initial data when the viscosity coefficient depends on both
the density and the temperature.
