From American Association for the Advancement of Science’s “The Effects of Patenting in the AAAS Scientific Community” [250 kb PDF] (2006):
Forty percent of respondents who had acquired patented technologies since January 2001 reported difficulties in obtaining those technologies. Industry bioscience respondents reported the most problems, with 76 percent reporting that their research had been affected by such difficulties. In contrast, only 35 percent of academic bioscience respondents reported difficulties that affected their research.
Of the 72 respondents who reported that their work had been affected by the technology acquisition process, 58 percent of those reported that their work was delayed. Fifty percent reported that they had to change their research, and 28 percent reported abandoning their research project as acquisition of the necessary technologies involved overly complex licensing negotiations.