Gao, H
Zhang, T
Wu, Y
Wu, Y
Jiang, L
Zhan, J
Li, J
Yang, R
Article History
Received: 20 July 2013
Revised: 15 April 2014
Accepted: 22 April 2014
First Online: 2 July 2014
Competing interests
: The authors declare no conflict of interest.
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