Text and Data Mining valid from 2019-03-06
First Online: 6 March 2019
Compliance with Ethical Standards
: This study was supported by a grant from National Key R&D Program of China (grant number: 2016YFC1301500) and National Science and Technology Major Project of China (grant number: 2015BAI12B02 and 2017YFC1310901).
: Ming Yang, Xiaochuan Huo, Zhongrong Miao and Yongjun Wang have no conflicts of interest that are directly relevant to the contents of this article.