$(document).ready(function() {
    $("#thumbnails").children("img").each(function() {
        $(this).mouseover(function() {
            $(this).css("cursor", "pointer");
            var url = $(this).attr("src").split("/");
            var imgName = url.pop().replace("small", "large");
            var src = url.join("/").concat("/" + imgName);
            $("#examplelarge").attr("src", src);
        });
    });
});