// 顶部导航效果代码
var previewObject;
function chgMemuBg(object)
{	
	var a = document.getElementById('index');
	a.className = "nocurrent";
	object.parentNode.className = "current";
	if(previewObject != null && previewObject != object.parentNode)
	{
		previewObject.className = "nocurrent";
	}
	previewObject = object.parentNode;
}