作者机构:[1]School of Mathematics and Statistics, Minnan Normal University, Fujian 363000, P. R. China, [2]Institute of Mathematics, Ningde Teachers' College, Fujian 352100, P. R. China
相关基金:Supported by National Natural Science Foundation of China (Grant Nos.11201414;10971185;11171162);; the Natural Science Foundation of Fujian Province (Grant No.2012J05013);; Training Programme Foundation for Excellent Youth Researching Talents of Fujian’s Universities (Grant No.JA13190)