作者机构:[1]School of Mathematics, Jilin University, Changchun, 130012, [2]College of Mathematics, Jilin Normal University, Siping, Jilin, 136000
相关基金:The NSF (11271155, 11001105, 11071126, 10926156, 11071269) of China, the Specialized Research Fund (20110061110003, 20090061120037) for the Doctoral Program of Higher Education, the Scientific Re- search Fund (201100011, 200903278) of Jilin University, and the NSF (20101596, 20130101066JC) of Jilin Province.