作者机构:[1]College of Physics and Electronics Engineering, Northwest Normal University, Lanzhou 730070, China
相关基金:Project supported by the National Natural Science Foundation of China (Grant Nos. 10774120 and 10975114), the Natural Science Foundation of Gansu Province of China (Grant No. 3ZS051-A25-013), and the Natural Science Foundation of Northwest Normal University of China (Grant Nos. NWNU-KJCXGC-03-48 and NWNU-KJCXGC-03-17).