Funding for this research was provided by:
Tianjin Health Bureau (13KG134)
Article History
Received: 22 January 2018
Accepted: 16 May 2018
First Online: 3 July 2018
Compliance with ethical standards
:
: All authors declare that they have no conflict of interest. Ethical approval this article does not contain any studies with human participants performed by any of the authors.
: All procedures performed in 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.
: Informed consent was obtained from all individual participants included in the study.