作者机构:[1]Department of Mathematics, Xi'an Electric Power College, Xi'an 710032, China, [2]Jiangsu Qingjiang Middle School, Huai'an 223001, China, [3]Department of Mathematics, Henan Normal University, Xinx- iang 453007, China
相关基金:Supported by the NNSF of China(10871042); Supported by the Foster Foundation of Henan Normal University(2010PL01); Supported by the Research Fund of PhD(1005)