Funding for this research was provided by:
National Natural Science Foundation of China (31470885)
National Natural Science Foundation of China (31300752)
National Natural Science Foundation of China (31270971)
National Natural Science Foundation of China (81502615)
Article History
Received: 10 December 2016
Accepted: 14 February 2017
First Online: 28 February 2017
Compliance with ethical standards
:
: All authors declared no conflict of interest.
: This study was approved by hospital medical ethics committee of the Tai’an City Central Hospital and Qilu Hospital of Shandong University.