web content not showing in source file

Dear all,
There are some web pages, if I use "View Souce File" in the right key menu, I can
only see some of the content. Some content, probably generated from scripts,
cannot be seen in source file. Now I want to do some processing of these source
files, is there a C# api, which can view the full html content? (I tried webclient,
it downloads source file just as that in the browser.) Or, there is another way to
get the full html file?
 
Thanks in advance.
 
Alex