supported by the National Natural Science Foundation of China(No.30370571);Science and Technology Program of Hebei Province,China(No.09276102D-4);the Research Project of Education Department,Hebei Province,China(No.ZD2014001)
This work was supported by the National Natural Science Foundation of China (No. 30370571);the Natural Science Foundation of Hebei Province (No. 200400628);the Program for New Century Excellent Scholars; Ministry of Eduction; China (No. 04-0253)