5Barrows HS. A taxonomy of problem-based learningmethods[J]. Med Educ, 1986,20(6) : 481-486.
6Srinivasan M ,Wilkes M ,Stevenson F,et al. Comparing problem-based learning with case-based learning :effects of a major curricular shift at two institutions[J]. Acad Med, 2007,82 ( 1 ) : 74-82.