supported by the Special Foundation for High Schools Doctoral Program of Ministry of Education;China (No.20101417110001);the Scientific Research Foundation for the Returned Overseas Chinese Scholars in Shanxi Province;China (No.2010-51);the Natural Science Foundation of Shanxi Province of China (No.2010011049-3);Science and Technology Fund of Taiyuan Municipality (No.201010-1400);Scientific and Technologial Innovation Programs of Higher Education Institutions in Shanxi Province;China (No.20091111)