Funding for this research was provided by:
National Natural Science Foundation of China (No. 81301978)
Ph.D. Programs Foundation of Ministry of Education of China (No. 20130171120105)
Young Teacher Cultivation Project of Sun Yat-sen University (No. 13YKPY39)
Article History
Received: 28 November 2017
Accepted: 20 April 2018
First Online: 24 April 2018
Compliance with Ethical Standards
:
: The authors declare that they have no conflict of interest.
: 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 this study.