  Let $A$ be a Noetherian ring of dimension $d$ and let $\mathcal{D}^b(A)$ be
the bounded derived category of $A$. Let $\mathcal{D}_i^b(A)$ denote the thick
subcategory of $\mathcal{D}^b(A)$ consisting of complexes $\mathbf{X}_\bullet$
with $\dim H^n(\mathbf{X}_\bullet) \leq i$ for all $n$. Set
$\mathcal{D}_{-1}^b(A) = 0$. Consider the Verdier quotients $\mathcal{C}_i(A) =
\mathcal{D}_i^b(A)/\mathcal{D}_{i-1}^b(A)$. We show for $i = 0, \ldots, d$,
$\mathcal{C}_i(A)$ is a Krull-Remak-Schmidt triangulated category with a
bounded $t$-structure. We identify its heart. We also prove that if $A$ is
regular then $\mathcal{C}_i(A)$ has AR-triangles. We also prove that $$
\mathcal{C}_i(A) \cong \bigoplus_{\stackrel{P}{\dim A/P = i}}
\mathcal{D}_0^b(A_P). $$
