From a PLOS Blogs Post by Michael Morris:
At PLoS, we’re dedicated to the tenet of Open Access, making academic literature widely available on the web. However, with an ever-growing pool of scientific literature, our goals have to consider not only making content available, but also accessible. With the breadth of articles we aggregate, you need a strong tool to find the specific information you want. Our authors have published on methods to get the most out of search engine queries and even how search engine data can yield its own important results. To help our users navigate the sea of information PLoS publishes daily, we introduced an Advanced Search function with a broad range of filters.
Read the Complete “How To” Post (With Screenshots)
See Also: Search Faster and Smarter With PLOS (via PLOS Blogs, June 2010)