js跳转新地址

<select name= "select" class= "serchtwo" onchange= "window.open(this.options[this.selectedIndex].value,'_Blank')" id= "loginSelect"    onkeydown= "enterSubmit(event)" >
          <option selected>集团相关产业网站链接</option>
          <option value= "http://www.dbn.com.cn" >大北农</option>
          <option value= "http://www.aweb.com.cn" >农博网</option>
          <option value= "http://www.agrosino.com/" >绿色农华</option>
          <option value= "http://www.zgnmdx.com" >农民大学</option>
          <option>猪育种公司</option>
        </select>