javascript实现文字无缝滚动

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 height: 140px; width: 400px; border: solid; 1px; overflow: hidden;" id="box">
 <ul id="ul1">
 <li><a href="#">1.学会html5 绝对的屌丝逆袭（案例）</a><span>2013-09-18</span></li>
 <li><a href="#">2.tab页面切换效果（案例）</a><span>2013-10-09</span></li>
 <li><a href="#">3.圆角水晶按钮制作（案例）</a><span>2013-10-21</span></li>
 <li><a href="#">4.HTML+CSS基础课程(系列)</a><span>2013-11-01</span></li>
 <li><a href="#">5.分页页码制作（案例）</a><span>2013-11-06</span></li>
 <li><a href="#">6.导航条菜单的制作（案例）</a><span>2013-11-08</span></li>
 <li><a href="#">7.信息列表制作(案例)</a><span>2013-11-15</span></li>
 <li><a href="#">8.下拉菜单制作(案例)</a><span>2013-11-22</span></li>
 <li><a href="#">9.如何实现“新手引导”效果</a><span>2013-12-06</span></li> 
 </ul>

 <ul id="ul2"></ul> 

 </div>

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