supported by the Natural Science Foundation of Chongqing (Grant No.cstc2012jjA70004);the National Natural science Foundation of China (Grant No.51275551)
Project supported by the Natural Science Foundation of Chongqing(Grant No.cstc2012jjA 70004 and cstc2012 jjA 40062);the National Natural science Foundation of China(Grant No.51275551);the Graduate Innovation Fund of Chongqing University of Technology(Grant No.YCX2013206)