Sun, Wenshou
Liu, Jingchun
Wang, Lichao
Yi, Yanqing
Funding for this research was provided by:
Shandong Provincial Natural Science Foundation, China (Y2006B06)
Qingdao Municipal Science and Technology Program, China (07-2-3-13-jch)
Shandong Province Higher Educational Science and Technology Program, China (J08LC57)