Rewrite obfuscated

[Matteo Niccoli]

Hi all,

I need help with nginx rewrite. Basically, I need to write a rewrite
like this:

location /try/ {
	rewrite ^(.*)$ http://www.foo.com/index.php=?1 last;
}

But, if it's possible, without rewrite the url on browser, but simple
pass the $1 to the replacement string, without change the URL.

It's possible? thanks!