基金National Natural Science Foundation of China(10705001)Foundation for the Author of National Excellent Doctoral Dissertation of China(200924)+1 种基金Doctoral Program Foundation of Institutions of Higher Education China(20090211120029)Program for New Century Excellent Talentsin University by Ministry of Education of China(NCET-10-0442)~~
基金The project supported by National Natural Science Foundation of China under Grant Nos. 90103019, 10375003 and 10421503, the Doctoral Program Foundation of Institution of Higher Education under Grant No. KJCX2-SW-N10. S.L. Zhu thanks B.A. Li for very helpful criticism and N. Kochelev and X.G. He for useful discussions.