Funding for this research was provided by:
National Social Science Foundation of China (15ZDB172)
Text and Data Mining valid from 2019-01-25
Received: 18 September 2018
Accepted: 9 January 2019
First Online: 25 January 2019
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of the Faculty of Sociology and Anthropology of Sun Yat-sen University. All participants fully consented to participate in the study.
: Not applicable.
: The authors declare that they have no competing interests.
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