基金项目: | Supported by the Foundation of Beijing Information Science and Technology University (Grant No. 1025020), Scientific Research Project of Beijing Educational Committee (Grant No. SQKM201211232016), Natural Science Foundation of Beijing (Grant No. 1102018), National Natural Science Foundation of China (Grant No. 61072145), Key Project of Chinese Ministry of Education (Grant No. 106033), and National Basic Research Program of China (973 Program) (Grant No. 2005CB321901) |