suppose you want /articles.php?cat=$1&art=$2 to become magazine/1/2

then you need these two rules:

#articles.php?cat=$1&art=$2
RewriteRule ^magazine/([^/]*)/([^/]*)$ /articles.php?cat=$1&art=$2&marker [L]

RewriteCond %{REQUEST_URI} /articles\.php [NC]
RewriteCond %{QUERY_STRING} ^cat=(.*)&art=(.*)
RewriteCond %{QUERY_STRING} !marker

RewriteRule (.*) http://mydomain/%1/%2? [R=301,L]