Enhancing open access in the biomedical field

This study was designed to document the state of open access (OA) in the biomedical field in 2009. PubMed was used to collect bibliographic data on target articles published in 2009. Google and PubMed were then used to establish the availability of free full-text online versions for these articles. Articles were analyzed according to the type of OA to provide insight into the characteristics of OA. The main finding was that almost half of the articles were accessible as OA articles, indicating that OA has progressed rapidly since our previous surveys reported for 2005 and 2007. More than half of the OA articles in the biomedical field are provided by Open Access Journals, the so-called 'Gold Road'. PubMed Central is used for journal publishers to archive their contents freely. The percentage of OA articles accessible via institutional repositories (IR) and authors' websites, or the 'Green Road', has consistently remained low.