答案1
您可以尝试以下操作:
\documentclass{article}
\usepackage{amsmath, amsthm, amssymb}
\newtheoremstyle{dotless}{}{}{\itshape}{}{\bfseries}{}{ }{} %get rid of the
%dot after the thm number
\theoremstyle{dotless}
\newtheorem{numb}{}[section]
\renewcommand{\thenumb}{(\thesection.\arabic{numb})}
\begin{document}
\section{First Section}
\begin{numb}
F\"ur alle $k\in\mathbb{Z}$ gilt $\exp(k)=e^k$.
\end{numb}
\end{document}