  We derive a boundary condition for the Nambu Keldysh Green's function in
diffusive normal metal / unconventional superconductor junctions applicable for
mixed parity pairing. Applying this theory to a 1d model of $s+p$-wave
superconductor, we calculate LDOS in DN and charge conductance of DN /
$s+p$-wave superconductor junctions. When the $s$-wave component of the pair
potential is dominant, LDOS has a gap like structure at zero energy and the
dominant pairing in DN is even-frequency spin-singlet $s$-wave. On the other
hand, when the $p$-wave component is dominant, the resulting LDOS has a zero
energy peak and the dominant pairing in DN is odd-frequency spin-triplet
$s$-wave. We show the robustness of the quantization of the conductance when
the magnitude of $p$-wave component of the pair potential is larger than that
of $s$-wave one. These results show the robustness of the anomalous proximity
effect specific to spin-triplet superconductor junctions.
