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答案1
使用 amsthm 和 thmtools:
\documentclass{article}
\usepackage{amsthm,thmtools}
\declaretheoremstyle[
notebraces={}{},
notefont=\normalfont\itshape,
headpunct={\normalfont.},
headformat={\NAME\ \NUMBER.\NOTE},
spaceabove=\topsep,
spacebelow=\topsep,
]{noparens}
\declaretheorem[
style=noparens,
name=Hypomnema,
]{hypo}
\begin{document}
\begin{hypo}[On Seidel's product representation of the natural logarithm]
Some text
\end{hypo}
\begin{hypo}[what the theorem's about]
More text
\end{hypo}
\end{document}