Li, Huajiao
An, Haizhong
Gao, Xiangyun
Fang, Wei
Article History
Received: 26 March 2015
Accepted: 28 July 2015
First Online: 22 September 2015
Competing interests
: The authors declare that we have no competing interests as defined by the journal or any other interests that might be perceived to influence the results and/or discussion reported in this paper.