  Transport through a one-dimensional wire of interacting electrons connected
to semi infinite leads is investigated using a bosonization approach. The
dynamic nonlocal conductivity is rigorously expressed in terms of the
transmission. For abrupt variations of the interaction parameters at the
junctions, an incident electron is transmitted as a sequence of partial
charges: the central wire acts as a Fabry-P\'erot resonator. The dc conductance
is shown to be given by the total transmission which turns out to be perfect.
When the wire has a tendency towards superconducting order, partial Andreev
reflection of an incident electron occurs. Finally, we study the role of a weak
barrier at one contact or inside the wire by a renormalization group method at
finite temperature. We compute the conductance in the presence of localized or
extended disorder, and compare our results to recent experiments on quantum
wires.
