作者机构:[1]Business School, University of Shanghai for Science and Technology, Shanghai 200093, China., [2]Department of Computing and Information Technology, Fudan University, Shanghai 200433, China.
相关基金:This research was supported by the National Natural Science Foundation of China under Grant No. 70371070; Shanghai Leading Academic Discipline Project under Grant No. S30504; and Key Project for Fundamental Research of STCSM under Grant No. 06JC14057.