  In this paper we consider the initial-boundary value problem to the
one-dimensional compressible Navier-Stokes equations for idea gases. Both the
viscous and heat conductive coefficients are assumed to be positive constants,
and the initial density is allowed to have vacuum. Global existence and
uniqueness of strong solutions is established for any $H^2$ initial data, which
generalizes the well-known result of Kazhikhov--Shelukhin (Kazhikhov, A. V.;
Shelukhin, V. V.: \emph{Unique global solution with respect to time of initial
boundary value problems for one-dimensional equations of a viscous gas, J.
Appl. Math. Mech., 41 (1977), 273--282.) to the case that with nonnegative
initial density.
