Funding for this research was provided by:
National Natural Science Foundation of China (71804197)
Text and Data Mining valid from 2020-04-06
Received: 26 December 2019
Accepted: 19 March 2020
First Online: 6 April 2020
Ethics approval and consent to participate
: Ethical approval was obtained from the Institutional Review Committee of the Xiangya School of Public Health of Central South University. 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.
: Not applicable.
: The authors declare that they have no competing interests.