作者机构:[1]Department of Mathematics,Henan University of Technology,Zhengzhou 450001,China, [2]Department of Mathematics,China University of Mining and Technology,Xuzhou 221116,China
相关基金:Supported by the Tianyuan Fund for Mathematics of NSFC(11126273);Supported by the NSF of Henan Educational Committee(2011B110011);Supported by the Doctor Foundation of Henan University of Technology(2009BS029)