string(284) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E5%A4%AE%E7%A5%A8%E5%88%86%E4%B8%BA%E6%99%AE%E9%80%9A%E5%A4%AE%E8%A1%8C%E7%A5%A8%E6%8D%AE%E5%92%8C%E4%B8%93%E9%A1%B9%E5%A4%AE%E7%A5%A8 => Received HTTP code 403 from proxy after CONNECT"
央票分为普通央行票据和专项央票
