limit_req for a url

I like to limit_req for a url ex. http://mysite.com/index.php?show=list&search=whatever

if someone request somthing that have show=list
I like to have a limit like max 1 request every sec.

bin trying something like this but I can get it to work. with out it takes all like show=item

http{
map $arg_show $list_limit {
default $binary_remote_addr;
}
limit_req_zone $arg_index zone=one:10m rate=1r/s;

server {
limit_req zone=one burst=5;
}

}