  The transport properties of a tunnel barrier in a one-dimensional wire are
investigated at finite voltages and temperatures. We generalize the Luttinger
model to account for finite ranges of the interaction. This leads to deviations
from the power law behaviour first derived by Kane and Fisher. At high energies
the influence of the interaction disappears and the Coulomb blockade is
suppressed. The crossover in the voltage or in the temperature dependence can
provide a direct measure for the range of the interaction.
