Increasingly, scholars are frustrated that their research is available only to people who have access to big libraries, so they either publish their research in journals that are free to anyone to read or they reserve the right to put copies of their research online. Try Googling the author and title of an article you need and add filetype:pdf - you might get lucky and find a free copy online.
For research in biology and biomedical sciences, the National Institutes of Health provides two nifty options. PubMed is a huge database of medical research articles. After you do a search, you can choose to limit your results to free full text articles.
Or you can go to PubMed Central, an archive of over 1,000 life science journals and articles based on research funded by the NIH to find lots of articles in biology and medicine.
When you have a source with a bibliography, you can see if a particular article from the bibliography is available by looking the journal's name up at the link below. Then you can use the volume and date information to navigate to the article. If we don't have access to that journal, we usually can get it from another library.