import re
p = re.compile(r'(@article.*?\n[ \t]*}[ \t]*)(?:\n|$)', re.DOTALL)
s = "@article{Fu_2007_ssr,\ndoi = {10.1016/j.surfrep.2007.07.001}\n}\n\n@article{Shibuya_2007_apl,\n doi = {10.1063/1.2816907}\n}"
print(p.findall(s))
aW1wb3J0IHJlCnAgPSByZS5jb21waWxlKHInKEBhcnRpY2xlLio/XG5bIFx0XSp9WyBcdF0qKSg/OlxufCQpJywgcmUuRE9UQUxMKQpzID0gIkBhcnRpY2xle0Z1XzIwMDdfc3NyLFxuZG9pID0gezEwLjEwMTYvai5zdXJmcmVwLjIwMDcuMDcuMDAxfVxufVxuXG5AYXJ0aWNsZXtTaGlidXlhXzIwMDdfYXBsLFxuIGRvaSA9IHsxMC4xMDYzLzEuMjgxNjkwN31cbn0iCnByaW50KHAuZmluZGFsbChzKSk=