相关基金:国家自然科学基金资助项目(50279002);国家"八六三"高技术资助项目(2001AA623010;2003AA623010);长江学者奖励计划资助项目(IRT0420).Supported by: National Natural Science Foundation of China (No.50279002); National "863" High Technology Project (No.2001AA623010, 2003AA623010); Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT)(No.IRT0420).