I have a database of references for my site, many of the references in there are pubmed, but some many of them are from other journals. I need a way to automatically convert the URL of studies from different journals into a DOI. I also need to get the abstract from them. I have this firefox plugin called zotero, you enter the link of a journal and it automacally gets the metadata for you so theres clearly a way to do this but I don't know how they do it. With pubmed articles its easy because they have an API, and they have their PMID in the URL. But I don't know what to do with articles from other journals.
For example: http://www.sciencedirect.com/science/article/pii/S0014483502920427 http://onlinelibrary.wiley.com/doi/10.1038/sj.bjp.0702844/full http://www.ingentaconnect.com/content/ben/mrmc/2007/00000007/00000006/art00004
They all have different URL structures. Is there an API where I can feed the link into it, and it gives me back metadata such as DOI, PMID and also the abstract?