国家自然科学基金项目51372160和51242007,山西省回国留学人员科研项目2011-031及山西省留学人员科技活动择优项目[2011]762资助;Supported by National Natural Science Foundation of China Nos.51372160 and 51242007,Scientific Research Foundation for Returned Overseas Chinese Scholars of Shanxi Province No.2011-031,Technology Foundation for Selected Overseas Chinese Scholar of Shanxi Province No.[2011]762