基金This work was sponsored by the National Natural Science Foundation of China （51364037）, the Landed Plan of Science and Technology in Colleges and Universities of Jiangxi Province （KJLD12074）, the Aerospace Science Foundation of China （20111156004）.
基金Acknowledgement This research is supported by the National Natural Science Foundation of China （grant No. 50575114 and No. 50635050） and by Beijing Natural Science Foundation （grant No. 3052010） and by China Postdoctoral Science Foundation （ grant No. 20080430360）.