  The influence of charging effects on time-dependent transport in small
semiconductor quantum dots with arbitrary level spectra is studied. Starting
from an explicit time-dependent tunneling Hamiltonian, a non-Markovian Master
equation is derived which is also valid in the nonlinear response regime. The
many-body nonequilibrium distribution functions of the dot are calculated and
the I-V characteristic of the structure including the displacement currents is
obtained. New resonant features show up in the Coulomb oscillations and in the
Coulomb staircase, and a new possibility to realize electronic pumps is
described.
