Funding for this research was provided by:
Chongqing Municipal Education Commission Foundation (KJ1601338)
National Natural Science Foundation of China (51472037)
Shenzhen Science and Technology Innovation Committee (JCYJ20170818160815002)
Article History
Received: 7 August 2018
Accepted: 21 January 2019
First Online: 25 January 2019
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
Free to read: This content has been made available to all.