Boston-based Beth Israel Deaconess Medical Center is about to begin a project called "open notes" in which about 100 doctors at the hospital and two other sites will allow 25,000 to 35,000 patients to read their physicians' notes for a year as part of their online medical record. Researchers hope to learn whether the notes prove more useful than objectionable. They hypothesize that access to doctors' notes will improve care partly because patients will become more knowledgeable about their treatment and about their doctors' instructions.