3Jane M,Christopher B.Manual of clinical nursing procedures[M].4th ed,Philadelphis:Blackwell Science USA,1996:559.
4King M, Zahrn J H, Pierrot D, et al. The role of mucus gel viscosity, spinnability, and adhesive properties in clearance by sireulated cough[J]. Biorheology, 1998,26 (4) : 737-745.