In astrophysics almost all the papers are available online. Though if you're not at a University or government lab that pays a journal fee, you may be blocked from downloading some of the more recent papers. And perhaps by online you mean in html format and not pdf of a scan?
I was under the impression that almost all papers were available online for free. Maybe it's just in my field, though. Or maybe I just haven't had the need to look at enough papers yet. But from what I understand, just about anything I could want to look at is on one of these two sites (both of which are accessible to me at school as well as home where I pay no subscription fee):
(no subject)
Date: 2005-05-24 06:30 pm (UTC)(no subject)
Date: 2005-05-24 07:32 pm (UTC)(no subject)
Date: 2005-05-25 12:31 am (UTC)http://www.slac.stanford.edu/spires/hep/
http://www.arxiv.org/
(no subject)
Date: 2005-05-24 10:43 pm (UTC)(no subject)
Date: 2005-05-24 10:46 pm (UTC)