正则: 检索出中英文混排字符串中的中文

Example 1:
<script language="javascript">
var str="a45df中a545df54华df人df%民ad1f共a554df和5a4d55f国df"
str=escape(str)
alert(unescape(str.match(/%u[\w]{4}/g).join("")))
</script>

Example 2:
<script language="javascript">
var str="a45df中a545df54华df人df%民ad1f共a554df和5a4d55f国df";
alert(str.match(/[\u4e00-\u9fa5]/g).join(""));
</script>

Example 3:
<script language="javascript">
var str="a45df中a545df54华df人df%民ad1f共a554df和5a4d55f国df";
alert(str.replace(/[^\u4e00-\u9fa5]/g,""));
</script>