Funding for this research was provided by:
National Natural Science Foundation of China (71373203)
Received: 3 May 2017
Accepted: 30 April 2018
First Online: 8 May 2018
Ethics approval and consent to participate
: This research was approved by the Ethics Committee of the Xi’an Jiaotong University, and Shaanxi Provincial Institute for Tuberculosis Control and Prevention (Letter Number:2017-518), and it was conducted according to the principles of the Declaration of Helsinki. Participants were middle school and college students, written informed content was obtained from them or their parents (16>) prior to the survey.
: The authors declare that they have no competing interests.
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