我在一个双列文档中插入了一个表格。表格应该横跨两列，中间没有分页符。理想情况下，表格应该固定在页面顶部，下方有两列文本。使用 几乎可以实现我想要的效果\FloatBarrier。表格现在忽略了列，并横跨整个页面宽度。但是，这对下面的标题不起作用，它适合左列。我还注意到，在 Overleaf 中，文本会打印在表格上，表格仍然固定在一列上（当它位于右侧列时，它会延伸到页面的边框）。有没有办法得到我想要的结果（见图）
？
\documentclass[12pt,a4paper,twoside]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[left={2.5cm},right={2.5cm},top={2cm},bottom={2.5cm}]{geometry}
\usepackage{multirow}
\usepackage{tabularx,booktabs}
\usepackage{placeins}
\usepackage{calc}
\usepackage{float}
\usepackage{lipsum}
\begin{document}
\twocolumn
\lipsum[3-5]
\FloatBarrier
\begin{table}[!tbh]
\centering
\begin{tabularx}{\textwidth}{lllll}
%\toprule
\textbf{step} & \textbf{extractant} & \textbf{target phase} & \parbox{3cm}{\bfseries possible mechanism} & \textbf{reference} \\
\addlinespace[0.2cm]
\parbox[t][][t]{\widthof{digestion}}{PO\(_4\)} & \parbox[t][][t]{\widthof{1\,M NaH2PO4}}{1\,M NaH2PO4, pH\,5, 16\,h, 24\,h + water wash} & \parbox[t][][t]{\widthof{As coprecipitated}}{adsorbed As} & \parbox[t][][t]{3.2cm}{anion exchange of PO4 for AsO4 and AsO3} & \parbox[t][][t]{3.3cm}{\cite{welchFactorsControllingShallow1998}; modified by \cite{keonValidationArsenicSequential2001}}\\
\addlinespace[0.2cm]
\parbox[t][][t]{\widthof{digestion}}{HCl} & \parbox[t][][t]{\widthof{1\,M NaH2PO4}}{1\,N HCl, 2\(*\)\,1\,h + water wash} & \parbox[t][][t]{\widthof{As coprecipitated}}{As coprecipitated with Mn oxides and amorphous Fe oxides} & \multirow{3}{3.2cm}{proton dissolution; Fe-Cl complexation} & \parbox[t][][t]{3.3cm}{\cite{huerta-diazPyritizationTraceMetals1992}; \cite{cornwellCharacterizationIronSulfide1987}; \cite{wallmannNewProcedureDetermining1993}; \cite{canfieldSulfateReductionDiagenesis1988}} \\
\addlinespace[0.2cm]
\parbox[t][][t]{\widthof{digestion}}{Microwave digestion} & \parbox[t][][t]{\widthof{1\,M NaH2PO4}}{xxx} & \parbox[t][][t]{\widthof{As coprecipitated}}{xxx} & \parbox[t][][t]{3.2cm}{xxx} & \parbox[t][][t]{3.3cm}{cite{various}} \\
\bottomrule
\end{tabularx}
\caption[Single Extraction: Steps]{Single Extraction Procedure; table from \cite{keonValidationArsenicSequential2001} (modified)}
\label{extraction_steps}
\end{table}
\lipsum[6-8]
\end{document}
答案1
如果用 替换，table您table*的表格将跨越两列。在下面的 MWE 中，我还使用了mhchem和siunitx化学式和单位包。最后，我删除了所有parboxes并使用类型tabularx的X列，以便在单元格中自动换行。我还删除了单元格中的对齐方式，因为这会导致相当大的水平空白。
\documentclass[12pt,a4paper,twoside]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[left={2.5cm},right={2.5cm},top={2cm},bottom={2.5cm}]{geometry}
\usepackage{tabularx,booktabs}
\usepackage[version=4]{mhchem}
\usepackage{siunitx}
\usepackage{ragged2e}
\DeclareSIUnit\Molar{M}
\DeclareSIUnit\Normal{N}
\usepackage{lipsum}
\begin{document}
\twocolumn
\begin{table*}[htbp]
\centering
\begin{tabularx}{\textwidth}{>{\RaggedRight}p{1.75cm}*{4}{>{\RaggedRight}X}}
\toprule
\textbf{step} & \textbf{extractant} & \textbf{target phase} & \bfseries possible \newline mechanism & \textbf{reference} \\
\midrule
\ce{PO4} & \SI{1}{\Molar} \ce{NaH2PO4}, pH\,5, \SI{16}{\hour}, \SI{24}{\hour} + water wash & adsorbed As & anion exchange of \ce{PO4} for \ce{AsO4} and \ce{AsO3} & \cite{welchFactorsControllingShallow1998}; modified by \cite{keonValidationArsenicSequential2001}\\
\addlinespace[0.2cm]
HCl & \SI{1}{\Normal} HCl, 2$\cdot$\SI{1}{\hour} + water wash & As coprecipitated with Mn oxides and amorphous Fe oxides & proton dissolution; Fe-Cl complexation & \cite{huerta-diazPyritizationTraceMetals1992}; \cite{cornwellCharacterizationIronSulfide1987}; \cite{wallmannNewProcedureDetermining1993}; \cite{canfieldSulfateReductionDiagenesis1988} \\
\addlinespace[0.2cm]
Microwave digestion & xxx & xxx & xxx & \cite{various} \\
\bottomrule
\end{tabularx}
\caption[Single Extraction: Steps]{Single Extraction Procedure; table from \cite{keonValidationArsenicSequential2001} (modified)}
\label{extraction_steps}
\end{table*}
\lipsum
\end{document}
最后，对表格内容做一点小评论：似乎缺少一些电荷，特别是关于 PO4、AsO4……