Project supported by the Natural Science Foundation of Anhui Education Department(KJ2012A171);the 211 Project of Anhui University(KJTD002B);the Scientific Research of BSKY from Anhui Medical University(XJ201022);the Provincial Excellent Young Talents Foundation for Colleges and Universities of Anhui Province(2011SQRL126);the Academic Innovative Scientific Research Projects of the Postgraduates for Anhui University(yfc100020,yfc100028)