supported by NSFC(No.10901002);supported by NSFC(No.11126173);the NSF of Anhui Province Education Committee(No.KJ2011Z151);the Research Culture Funds of Anhui Normal University(No.2012xmpy009);Anhui Province Natural Science Foundation(No.1208085QA02)
Supported by the NSF of China(10901002);the Research Culture Funds of Anhui Normal University(2012xmpy009);The second author is supported by the NSF of China(11126173);Anhui Province Natural Science Foundation(1208085QA02)
Supported by the NSF of China(11126173);Anhui Province Natural Science Foundation(1208085QA02);the NSF of China(10901002);the NSF of Anhui Province Education Committee(KJ2011Z151)
Supported by National Natural Science Foundation of China(11126173);Project of Anhui Province of Excellent Young Talents in University(2011SQRL013ZD);Scientific Research Foundation for the PhDs of Anhui University and Graduate Academic Innovation Team of Anhui University(YFC100008)