国家自然科学基金61571453;湖南省自然科学基金14JJ3010;湖南省教育厅重点项目批准号: 15A020资助的课题.Project supported by the National Natural Science Foundation of ChinaGrant 61571453;the Natural Science Foundation of Hunan Province, ChinaGrant 14JJ3010;the Research Foundation of Education Bureau of Hunan Province, ChinaGrant 15A020