作者机构:[1]Department of Mathematics and Computer Science, Fujian Normal University, Fuqing 350300, Fujian, China
相关基金:Supported by the National Natural Science Foundation of China (40676016 and 10471039), the National Program for Basic Science Researches of China (2003CB415101-03 and 2004CB418304), the Key Project of the Chinese Academy of Sciences (KZCX3-SW-221) and E-Insitutes of Shanghai Municipal Education Commission (N.E03004)