基金Partially supported by the National Natural Science Foundation of China(10371011 and 10071005) and the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry.
基金supported by the Chinese National Science Foundation for Distinguished Young Scholars(No.10925104)The work of Fu was supported by NSFC(No.11001219)the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.2010JK860)
