国家自然科学基金重点项目(30330640),国家自然科学基金(30170901),国家科技部重大科技专项基金(2002AA2Z3130).
Supported by the Key Program of National Natural Science Foundation of China(30330640),National Natural Science Foundation of China(30170901) and the grant from the National Sciences and Technologies R&D Program (2002AA2Z3130).