var thisurl = document.URL;
var obj = [
	['woyaoliuxue','bn_liuxue.jpg'],
	['wenhuaguangchang','bn_guangchang.jpg']
]

for( var i = 0; i < obj.length; i++ )
{
	if( thisurl.indexOf( obj[i][0] ) > -1 )
	{ 
		$("#changeimg").html('<img src="/images/' + obj[i][1] + '" />');
	}
}