Funding for this research was provided by:
Humanities and Social Science Talent Plan of Shaanxi Province (7121900018)
National Natural Science Foundation of China (no.71672139)
Article History
Received: 24 March 2018
Accepted: 14 March 2019
First Online: 30 March 2019
Compliance with Ethical Standards
:
: All authors declare that they no conflict of interest.
: This article does not contain any studies with animals performed by any of the authors. 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 the study.