Where can I have access to research papers for free?

Answer 1

Sometimes you can get lucky with Google Scholar, ScienceDirect, or JSTOR.

Answer 2

http://arxiv.org/

Huge wealth of papers in the sciences. However, keep in mind that not all of them end up being published - although many do, you also might run into a few quacks.

Answer 3

try science direct

http://www.sciencedirect.com/

or elsevier science

http://www.elsevier.com/wps/find/homepage.cws_home

both sites contain huge amounts of published science papers