the National Natural Science Foundation of China.21006126,21276272;the Research Funds of China University of Petroleum,BeijingBJBJRC-2010-01;Beijing Nova Program2010B069;the Research Fund for the Doctoral Program of Higher Education20100007120009;项目受国家自然科学基金.21006126,21276272;中国石油大学北京青年拔尖人才专项基金BJBJRC-2010-01;北京市科技新星计划2010B069;博士点基金新教师课题20100007120009