supported by the National Natural Science Foundation of China(11161006,11171142);the Guangxi Natural Science Foundation(2011GXNSFA018139);Guangxi"new century 1000talents pleject"
supported by the National Natural Science Foundation of China(11161006,11171142);the Guangxi Natural Science Foundation(2011GXNSFA018139);Guangxi"new century 1000 talents project"
supported by the National Natural Science Foundation of China(11161006,11171142);the Guangxi Natural Science Foundation(2011GXNSFA018139);Guangxi New Century 1000 Talents Project;Guangxi graduate student education innovation project(2011106030701M06)