This research was partially supported by the National Natural Science Foundation of China(Grant No.10171118,10471159);the key project of the Chinese Ministry of Education,Supported by Program for New Century Excellent Talents in University.
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)