  Let D be the ring of differential operators on a smooth irreducible affine
variety X over the complex numbers; or, more generally, the enveloping algebra
of any locally free Lie algebroid on X. The category of finitely-generated
graded modules of the Rees algebra D has a natural quotient category qgr(D)
which imitates the category of modules on Proj of a graded commutative ring. We
show that the derived category D^b(qgr(D)) is equivalent to the derived
category of finitely-generated modules of a sheaf of algebras E on X which is
coherent over X. This generalizes the usual Beilinson equivalence for
projective space, and also the Beilinson equivalence for differential operators
on a smooth curve used by Ben-Zvi and Nevins to describe the moduli space of
left ideals in D.
