The font setting in mathematical environment such as the definition of theorem in latex __latex

If you want to set the font in this environment, you need to use the macro-package amsthm, according to the documents in which there are three kinds of self-contained formats? Plain:italic fonts with extra space definition:upright fonts, extra space up and down Remark:upright fonts, no extra space up and down

Change font settings according to Thmtest.tex

\newtheoremstyle{thry}%? name?
{3pt}%? Space above?
{3pt}%? Space below?
{\upshape}%? Body font?
{}% ? Indent amount?
{}% ? Theorem head font?
{:}% ? Punctuation after the theorem head?
{. 5em}%? After theorem head?
{}% ? Theorem Head spec (can is left empty, meaning ' normal ')?
\theoremstyle{thry}
\newtheorem{thry}{theorem}

Use in document

\begin{thry}
1+2=3
\end{thry}

There are several types of font type, detailed reference latex symbol corresponding table