## changing math fonts temporarily

Hi,

I've ended up using

\usepackage{txfonts}

in my preamble as it gives me the best look for most of my math fonts. However, I'd like to revert back to the amsfonts version of two particular symbols (\vdash and \models). \usepackage{amsfonts} is in my preamble, so is there any way I can pick that up temporarily in the document when I want one or other of the above mentioned symbols?

thanks

ajm