1. Evidence-based Medicine Center, School of Basic Medical Science, Lanzhou University, Lanzhou, PR China;
2. The Second Clinical Medical College of Lanzhou University, Lanzhou, PR China;
3. Department of NICU, The General Hospital of Ningxia Medical University, Yinchuan, PR China;
4. Key Laboratory of Evidence-based Medicine and Knowledge Translation of Gansu Province, Lanzhou, PR China