9Wang R, Luo O, He L, et al. Preservative-free 0. 9% sodium chloride for flushing and locking peripheral intra- venous access device: a prospective controlled trial[J]. J Evid Based Med,2012,5(4):205-208.
10Higgins J P, Green S. Cochrane handbook for systematic reviews of interventions (Version 5. 1. 0)[EB/OL].[2013-06-25]. http://www. Cochrane hand book. org.