基金Supported by the Teaching and Research Award Program for Outstanding Young Teachersin Higher Educations of MOE,P.R.C(TRAPOYT,No.2002-40),the Science Fund for Distinguished Overseas Chinese Scholars of MOP,P.R.C(SFDOCS,No.2003-50)and the Guizhou Governor’s Foundation for Outstanding Scientistsin Science,Technology and Education(GFOSTE,No.2003-04)