基金This research was partially supported by the National Natural Science Foundation of China (Grant No.10171118)Education Committee project Research Foundation of Chongqing (Grant No. 030801)National Natural Science Foundation of Chongqing (Grant No. 8904)
基金Supported by the National Natural Science Foundation of China(60773128)the Natural Science Research Funds of Education Department of Anhui Province (KJ2009A123)