My goal is to produce a graph showing the linkages (and lack there of) between several fields that share a common subproblem by showing who cites whom. There are many databases that show citations between papers: ISI Web of Knowledge, Microsoft Academic Research, and Google Scholar. However none allows me to download even part of their database. Is there some database I have overlooked? Has someone written a scrapper for one of these websites?
For reference, the fields I'm considering are Mechanics, Magnetic Resonance Imaging, Signal Processing, Geophysics, and several others.