  Quantum Monte Carlo is used to calculate various pairing correlations of the
2D Hubbard model possessing band features experimentally observed in the
cuprates. In the hole-doped case, where the Fermi level lies close to the van
Hove singularities around $(0,\pi)$, the d$_{x^2-y^2}$ pairing correlation is
selectively enhanced, while in the electron-doped case, where the singularities
are far below the Fermi level and the Fermi surface runs through $(\pm
\pi/2,\pm \pi/2)$, both d$_{x^2-y^2}$ and d$_{xy}$ correlations are enhanced
with the latter having a $\sqrt{2}\times \sqrt{2}$ structure. The two pairing
symmetries can mix to result in a nodeless gap.
