Funding for this research was provided by:
National Natural Science Foundation of China (81671800)
Natural Science Foundation of Beijing Municipality (7172204)
Article History
Received: 15 March 2018
Accepted: 7 August 2018
First Online: 21 August 2018
Compliance with ethical standards
:
: All 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. For retrospective studies, this type of study formal consent is not required. This article does not contain any studies with animals performed by any of the authors.
: Informed consent was obtained from all individual participants included in the study.