BTW did you know that Firefox supports keywords for bookmarks OOTB?
You can set up a keyword e.g. "shb" for (code from above)
javascript:window.location='http://sci-hub.se/'+window.location
and you can run it writing "shb" in the address bar.
No need for bookmarklets.Or how do y'all use boorkmarklets? E.g. on chrome? Is your boorkmark bar always visible?