You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allpages apcontinue="科研项目列表" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="18" ns="0" title="Mediawiki入门" />
      <p pageid="76" ns="0" title="《夸克胶子等离子体-从大爆炸到小爆炸》erratum" />
      <p pageid="51" ns="0" title="变分计算例子" />
      <p pageid="86" ns="0" title="数学物理方法" />
      <p pageid="99" ns="0" title="早期科研动态" />
      <p pageid="77" ns="0" title="核子结构" />
      <p pageid="94" ns="0" title="核子结构、QCD与重离子物理相关会议列表" />
      <p pageid="85" ns="0" title="济南大学粒子物理" />
      <p pageid="19" ns="0" title="理论力学" />
      <p pageid="28" ns="0" title="科研笔记" />
    </allpages>
  </query>
</api>