I got a request for R package "entrez" I wrote quite some time ago. I did upload the package to my old webpage, but I have not yet finnished the movement completely to the new webpage. I decided to make a sloopy move i.e. move files when I need them or when I will have more time, ... Anyway, I am glad that entrez package still works. I uploaded the source of the package as well as the ZIP packlage for easy installation on MS Windows (note that these two links will change with the new versions - if I publish them ever; however permanent link is this one).
What does the entrez package? It is a simple function that performs search for primary IDs in PubMed via Entrez utility
esearchat NCBI. Examples:
## Are there any articles about Bioconductor in PubMed?
(search <- entrezSearch("Bioconductor[tiab]"))
## Get counts by year in the period 2000:2008
count <- entrezCountByYear(term="Bioconductor[tiab]", dp=2000:2008)
## Plot counts
plot(count, typ="l", xlab="Year",
ylab="Number of publications in PubMed")