基金Supported by National Natural Science Foundation of China (60674036), the Science and Technique Development Plan of Shandong Province of China (2004GG4204014), the Program for New Century Excellent Talents in University of China (NCET-07-0513), the Key Science and Technique Foundation of Ministry of Education of China (108079), and the Excellent Young and Middle-Aged Scientist Award Grant of Shandong Province of China (2007BS01010)