国家自然科学基金项目31160016,31260034、云南省应用基础研究基金资助项目KKSA201126005和教育部回国人员科研启动基金KKQA201226003资助 Supported by the National Natural Science Foundation of China 31160016,31260034,the Application and Basic Research Fund of Yunnan Province KKSA201126005,and the Scientific Research Foundation for Returned Overseas Chinese Scholars,State Education Ministry of China KKQA201226003