Funding for this research was provided by:
National Natural Science Foundation of China (81872708, 81502886, 81530087)
Natural Science Foundation of Beijing Municipality (Z160002)
Received: 18 December 2018
Accepted: 24 April 2019
First Online: 22 May 2019
Ethics approval and consent to participate
: The Ethics Committee of Capital Medical University approved the study (2015SY33). Informed written consent was obtained from all participants included in the present study.
: Not applicable.
: The authors declare that they have no competing interests.
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