国家自然科学基金批准号:2117108、辽宁省科技厅自然科学基金20082050;辽宁省教育厅高等学校科研基金批准号:L2010152资助的课题.*Project supported by the National Natural Science Foundation of China Grant No.2117108, the Natural Science Foundation of Liaonning Province, ChinaGrant 20082050;the Liaoning Province Education Department Research Project, ChinaGrant L2010152