Funding for this research was provided by:
the National Natural Science Foundation of China (No. 31571459)
National Natural Science Foundation of China (No. 81272908)
Article History
Received: 13 July 2018
Accepted: 17 December 2018
First Online: 2 February 2019
Compliance with ethical standards
:
: The authors have declared that no competing interest exists.
: Not applicable.
: Informed Consent is not required for this type of study.