国家自然科学基金61302102, 61271232;江苏省属高校自然科学研究面上项目13KJB510023;国家博士后自然科学基金2013M531390 The National Natural Science Foundation of China61302102, 61271232;The Scientific Research Foundation of the Higher Education Institutions of Jiangsu Province, China13KJB510023;The National Science Foundation for Post- doctoral Scientists of China2013M531390