string(249) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E8%AE%BA%E6%96%87%E6%91%98%E8%A6%81%E4%B8%8E%E6%AD%A3%E6%96%87%E6%A0%BC%E5%BC%8F => Failed to connect to 101.89.117.144 port 38017: Connection refused"
论文摘要与正文格式
