BibTeX exported from scientific journals usually have all the informations you need to cite them; one of them is the url. For saving space i would prefer to hyperlink the name of the journal rather than printing the whole url. One way to do such thing would be by writing the url as an \href before the journal name in the .bib file like so
@article{Reference7,
author = "Zwicker, Judith and Lovett, Ronald",
title = "When does a pair correlation function fix the state of an equilibrium system?",
journal = "\href{http://scitation.aip.org/content/aip/journal/jcp/93/9/10.1063/1.458944}{The Journal of Chemical Physics}",
year = "1990",
volume = "93",
number = "9",
pages = "6752-6755",
url = "",
doi = "http://dx.doi.org/10.1063/1.458944"
}
which will generate a the desired form, that is

My question is: since I have a huge number of citations, is there a procedure to achieve the same result in an automated fashion, because in this case I have copied the url from its previous position (url = " here ") to where it is now.
Thanks
eprints which you can configure globally by type (so you just specify the identifier and the type in your.bibfile). Definitely space and effort efficient! – cfr Nov 27 '14 at 02:41