Boston-based Beth Israel Deaconess Medical Center, which laid off about 70 workers last month and made other cuts to regain its financial footing, is now taking other steps to stem a projected $28 million loss this year in its biomedical research operations. The expected deficit is forcing the teaching hospital to give up lab space in two buildings and consolidate its research at a single site. Hospital officials blame the projected loss on lower-than-expected funding from the National Institutes of Health and a costly lease arrangement it made about five years ago at a new research building.