How to define a bold font style for \emph text

Question

Recently, I wanted to set all my \emphasized text to bold, because I think the default Italic of \emph is not distinctly emphasized.

But I haven't found a solution for it. Please give me some idea. Thanks.

I read a comment on '\emph or \textit', it says:

I rarely use physical font commands in my body text. I use them to define styles in the preamble and use the styles in the document afterwards, ensuring consistency and allowing changes to be easily made.

But I didn't find how to define our own styles, after searching in LaTeX Wikibook.

I have tried:

• \let\emph\textbf
• \renewcommand{\emph}[1]{\textbf{#1}}

But failed to set bold to \emph text.

I finally figured out a solution that using Bold font for ItalicFont:

% compile by `xelatex file.tex`
\documentclass{book}
% CJK
\usepackage{xltxtra, xeCJK}
\setCJKmainfont[BoldFont=Adobe Heiti Std,ItalicFont=Adobe Heiti Std]{Adobe Song Std}
% Latin
\usepackage{fontspec}
\setmainfont{Gentium Book Basic}[ItalicFont=Gentium Book Basic Bold]
\begin{document}
I want to bold \emph{emphasized} text.

% bold CJK emphasized text
我想用粗体显示 \emph{强调的} 文字
\end{document}

However, I don't think it's a wise solution.

So, any idea? Thanks again.