如何搜索和导航XML节点

I have the following XML :

我有以下XML:

<LOCALCELL_V18 ID = "0x2d100000">
  <MXPWR ID = "0x3d1003a0">100</MXPWR> 
</LOCALCELL_V18>
<LOCALCELL_V18 ID = "0x2d140000">
  <MXPWR ID = "0x3d1403a0">200</MXPWR>  
</LOCALCELL_V18>
<LOCALCELL_V18 ID = "0x2d180000">  
  <MXPWR ID = "0x3d1803a0">300</MXPWR>   
</LOCALCELL_V18> 
<LOCALC