Funding for this research was provided by:
China Scholarship Council (201506990016)
Text and Data Mining valid from 2018-02-17
First Online: 17 February 2018
Compliance with Ethical Standards
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the local ethics committee in the Southwest University 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.
: The authors declare that they have no conflict of interest.