作者机构:[1]Foundation Department, Wuxi City College of Vocational Technology, Jiangsu 214153, P. R. China, [2]Department of Mathematics, Shanghai University, Shanghai 200444, P. R. China, [3]Department of Mathematics and Physics, Bengbu College, Anhui 233030, P. R. China
相关基金:Supported by the National Natural Science Foundation of China (Grant No. 60773078) and the Natural Science Foundation of Anhui Provincial Education Department (No. KJ2011B090).