supported by the NNSF of China(10826059,10901092);the NSF of Shandong Province of China (Q2007A05);the China Postdoctoral Science Foundation(20090451292)
Supported by the NNSF of China(10826059,10901092);the NSF of Shandong Province of China (Q2007A05);the China Postdoctoral Science Foundation and the Scientific Research Start-up Foundation of QFNU(BSQD07028)
This work was supported by the National Natural Science Foundation of China(10571093,10671099,10771123);the Research Foundation for Doctor Programma(20050055038);the Natural Science Foundation of Shandong Province(Q2007A05);the Scien-tific Research Start-up Foundation of QFNU(bsqd07028)