基金Supported by the National Natural Science Foundation of China under Grant Nos.9041201190612004+2 种基金60673180(国家自然科学基金)the International Science and Technology Cooperative Program of China under Grant No.2006DFA11080(科技部国际科技合作计划项目)the Research Program of Federal Ministry of Education and Research of Germany under Grant No.01BU0680(德国教研部资助项目)