Math & Science ⇒ newtheoremstyle

[allevo]

but how can i write in Times stile?!?! or in Courier?!?

[Stefan Kottwitz]

You could use mathptmx for a Times font:

Code: Select all

\usepackage{mathptmx}

or the courier package for Courier:

Code: Select all

\usepackage{courier}

Stefan