作者机构:[1]School of Mathematics and Statistics, Guizhou University of Finance and Economics, Guiyang, 550025, [2]College of Mathematics and Information Science, Henan Normal University, Xinxiang, Henan, 453007
相关基金:The NSF (11101128) of China; the NSF (102300410049) of Henan Province; the NSF (BK2012736) of Jiangsu Province