In recent years, a virtual library of medical research has concluded that, other factors being equal, complex surgery turns out better when it's done at hospitals where the procedure is done a lot.

VOA: standard.2010.07.14

One that was developed a number of years ago but has been perfected and refined in recent years with very, very good research.

该概念很多年前就已经提出了,但在近年通过高水平的研究才被改进完善

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选