Liang, H
Gu, Y
Li, T
Zhang, Y
Huangfu, L
Hu, M
Zhao, D
Chen, Y
Liu, S
Dong, Y
Li, X
Lu, Y
Yang, B
Shan, H
Article History
Received: 6 December 2013
Revised: 4 April 2014
Accepted: 8 April 2014
First Online: 22 May 2014
Competing interests
: The authors declare no conflict of interest.