如何更改定理后数字的字体

Question

我想将数字的字体改为\itshape，例如，我想得到 Theorem {\itshape 1.1}。有没有办法在 theorem 环境中做到这一点

Answer 1

假设您仅在文档中使用该amsthm包，则可以这样做。

如果您只希望此行为适用于“简单”定理样式，请在序言中添加以下几行以重新定义简单样式：

\makeatletter
\renewcommand{\th@plain}{%
  \renewcommand\@upn{\textit}%
  \itshape%
}
\makeatother

您就完成了。

平均能量损失

\documentclass{article}
\usepackage{amsthm}

\makeatletter
\renewcommand{\th@plain}{%
  \renewcommand\@upn{\textit}%
  \itshape%
}
\makeatother

\newtheorem{thm}{Theorem}[section]

\begin{document}

\section{Test}

\begin{thm}
This is a theorem.
\end{thm}

\end{document} 

输出

相反，如果你想要所有定理样式都具有这种行为，请将上述代码替换为

\makeatletter
  \renewcommand\@upn{\textit}
\makeatother

平均能量损失

\documentclass{article}
\usepackage{amsthm}

\makeatletter
  \renewcommand\@upn{\textit}
\makeatother

\newtheorem{thm}{Theorem}[section]
\theoremstyle{remark}
\newtheorem{rmk}[thm]{Remark}

\begin{document}

\section{Test}

\begin{thm}
This is a theorem.
\end{thm}

\begin{rmk}
And this is a remark.
\end{rmk}

\end{document} 

输出

Answer 2

下面是一个带封装的方法ntheorem，我重新定义了一下plain样式：

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage[amsthm, thmmarks, thref]{ntheorem}
\usepackage{cleveref}

\makeatletter
\renewtheoremstyle{plain}%
{\item[\hskip\labelsep \theorem@headerfont ##1\ \textit{##2}\theorem@separator]}%
{\item[\hskip\labelsep \theorem@headerfont ##1\ \textit{##2}\ (##3)\theorem@separator]}
\makeatother
\newtheorem{thm}{Theorem}[section]

\begin{document}

\section{A first section}
\begin{thm}\label{testthm}
This is a test theorem.
\end{thm}
We see in \cref{testthm}…

\end{document} 

Answer 3

如果你没有使用专门用于定理的包，你可以这样做

\documentclass{article}
\usepackage{etoolbox}

\makeatletter
\patchcmd{\@opargbegintheorem}{#2}{\textit{#2}}{}{}
\patchcmd{\@begintheorem}{#2}{\textit{#2}}{}{}
\makeatother

\newtheorem{thm}{Theorem}

\begin{document}
\begin{thm}
Something
\end{thm}
\end{document}