First of all, in case you’re not very familiar with it, PubMed Central (PMC) is the NIH repository for peer-reviewed primary research reports in the life sciences. It was developed by the U.S. National Library of Medicine (NLM)/National Institutes of Health (NIH) as an online archive of biomedical journal articles. The full text of all PMC articles is available for free. (Some participating publishers, however, delay release of their articles for a set time after paper publication (often six months)). You can get more background information here.
If available, PubMed citations are linked to the text in PMC:
In order to keep pace with the continuing advances in web technology, PMC has launched PubReader, an alternative web presentation that offers another, more reader-friendly view of the articles in the PMC archive:
Designed particularly for enhancing the readability of PMC journal articles on tablet and other small screen devices, PubReader can also be used on desktops and laptops and from multiple web browsers.