Liu, B
Zhang, X
Deng, W
Liu, J
Li, H
Wen, M
Bao, L
Qu, J
Liu, Y
Li, F
An, Y
Qin, C
Cao, B
Wang, C
Article History
Received: 3 March 2014
Revised: 2 July 2014
Accepted: 2 July 2014
First Online: 2 October 2014
Competing interests
: The authors declare no conflict of interest.