基金This study was supported by the NKBRSF (G1999043407-1) Tackle Key Problem of Science and technology of China (2001BA510B-07) Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-406SCXZD0101)NKTRDP (2001BA510B
基金This study was supported by the NKBRSF (G1999043407-1) Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-406+3 种基金 SCXZD0101) NKTRDP (2001BA510B-07 2002BA516A20) and Education Committee Projects of Liaong Province (990121400