  In this paper we prove a conjecture of B. Shoikhet. This conjecture states
that the tangent isomorphism on homology, between the Poisson homology
associated to a Poisson structure on $\mathbb{R}^d$ and the Hochschild homology
of its quantized star-product algebra, is an isomorphism of modules over the
(isomorphic) respective cohomology algebras. As a consequence, we obtain a
version of the Duflo isomorphism on coinvariants.
