In this paper, we first show that there exists a maximizer for the
non-endpoint Strichartz inequalities for the Schr\"odinger equation in all
dimensions based on the recent linear profile decomposition results. We then
present a new proof of the linear profile decomposition for the Schr\"oindger
equation with initial data in the homogeneous Sobolev space; as a consequence,
there exists a maximizer for the Sobolev-Strichartz inequality.Comment: 14 pages; Various corrections, references update