Funding for this research was provided by:
Shanghai Municipal Commission of Health and Family Planning (15GWZK1001&2013SY006)
Text and Data Mining valid from 2018-04-05
Received: 6 June 2017
Accepted: 22 March 2018
First Online: 5 April 2018
Ethics approval and consent to participate
: Written informed consent statement forms were obtained from participants. The right to withdraw and autonomy of responses were also explained. This study received approval from the ethics committee of the Fudan University School of Public Health, China (IRB00002408 & FWA00002399).
: Not applicable
: The authors declare that they have no competing interests.
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