jq过渡效果


<script type="text/javascript" src="http://www.mailuke.com/js/jquery-1.2.6.pack.js"></script>
<script type="text/javascript">
(function(){
var tit = $("#z_type>dt");
tit.each(function(){
var me = $(this);
var dd = me.next("dd");
if(dd.length<1){
me.removeClass("classfied_jia");
}else{
me.addClass("classfied_jia");
me.bind("click",function(){
var index = me.index();
if(dd.is(":hidden")) {
dd.slideDown(100).siblings("dd").slideUp(100);
me.addClass("classfied_open").siblings("dt").removeClass("classfied_open");
//$.cookie('key',index);
} else {dd.slideUp(100);
me.removeClass("classfied_open");
//$.cookie('key',null);
}
})
}
})
})() 
</script><div class="classfied_lift mt10">
         <h2></h2>
            <dl id="z_type">
                <dt><a href="javascript:void(0)">彩色隐形眼镜</a></dt>
                <dd style="display:none" class="classfied_l_c">
                    <ul>
                        <li><a href="#">保视宁保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">Bescon</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">购买清单</a></li>
                    </ul>
                </dd>
                <dt><a href="javascript:void(0)">彩色隐形眼镜</a></dt>
                <dd style="display:none" class="classfied_l_c">
                    <ul>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">Bescon</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">购买清单</a></li>
                    </ul>
                </dd>
                <dt><a href="javascript:void(0)">彩色隐形眼镜</a></dt>
                <dd style="display:none" class="classfied_l_c">
                    <ul>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视了宁</a></li>
                        <li><a href="#">Bescon</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">购买清单</a></li>
                    </ul>
                </dd>
                <dt><a href="javascript:void(0)">彩色隐形眼镜</a></dt>
                <dd style="display:none" class="classfied_l_c">
                    <ul>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">Bescon</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">保视宁</a></li>
                        <li><a href="#">购买清单</a></li>
                    </ul>
                </dd>
             </dl>
        </div>这是一个伸缩菜单,点击展开,
现在问题是,太生硬,给这个jq加上过渡效果.