  We study effects of electron correlation on the transport through a small
interacting system connected to reservoirs using an effective Hamiltonian which
describes the free quasi-particles of a Fermi liquid. The effective Hamiltonian
is defined microscopically with the value of the self-energy at $\omega=0$.
Specifically, we apply the method to a Hubbard chain of finite size $N$ ($=1,
2, 3, ...$), and calculate the self-energy within the second order in $U$ in
the electron-hole symmetric case. When the couplings between the chain and the
reservoirs on the left and right are small, the conductance for even $N$
decreases with increasing $N$ showing a tendency toward a Mott-Hubbard
insulator. This is caused by the off-diagonal element of the self-energy, and
this behavior is qualitatively different from that in the special case examined
in the previous work. We also study the effects of the asymmetry in the two
couplings. While the perfect transmission due to the Kondo resonance occurs for
any odd $N$ in the symmetric coupling, the conductance for odd $N$ decreases
with increasing $N$ in the case of the asymmetric coupling.
