The University of Miami medical school on Monday announced that it had received a $100 million donation -- the second-largest amount ever given to a Florida university -- and that the money would be used for biomedical research.The donation, a gift from the family of the late construction magnate Leonard M. Miller, who was treated for cancer there, means the University of Miami now has $800 million toward its goal of raising $1 billion by 2007. The funds will be used to establish four professorships, to recruit the next generation of biomedical scientists and for research.