$(function(){
    $('.dxz li').height($('.dxz li').width()/4*3.5 + "px")
    var a = $('.cksx a:nth-of-type(2)').html()  //内容
    var b = $('.cksx a:last-of-type').html()
    $('.cksx a:first-of-type').hide()
    if(a.length != 0){                          //判断内容是否为空
        $('.cksx a:nth-of-type(2)').prepend("上一篇：") 
    }else{
        $('.cksx a:first-of-type').prepend("上一篇：")
        $('.cksx a:first-child').show()
    }
    if(b.length != 0){
        $('.cksx a:last-of-type').prepend("下一篇：")
    }
})