string(276) "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%E7%9A%84%E6%A0%BC%E5%BC%8F%E8%A6%81%E6%B1%82%E6%9C%89%E5%93%AA%E4%BA%9B => Failed to connect to 101.89.159.206 port 38075: Connection refused"
论文摘要的格式要求有哪些
