Xu, Shuaishuai
Ruan, Shidong
Liu, Shanfeng
Xu, Jianrong
Gong, Ruozhen http://orcid.org/0000-0003-3233-8623
Article History
Received: 22 September 2017
Accepted: 22 January 2018
First Online: 7 February 2018
Compliance with ethical standards
:
: No funding was received for this study.
: The authors declare that they have no conflict of interest.
: All procedures performed in the studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: For this type of retrospective study formal consent is not required.