The title is pretty much the question. All three of these mean something like, "standard, norm, etc". I found the following example sentences that helped me get an initial sense of the words:
規範{きはん}:
倫理学{りんりがく}というのは、行動の規範の意味する。
Ethics means the rules of conduct.
それは私たちの道徳的{どうとくてき}規範には受け入れられない。
It is not acceptable to our moral code.
基準{きじゅん}:
あいての基準を受け入れるのは、そのあいての力に服従することだ。
Accepting the other's norms is submitting to the other's power.
標準{ひょうじゅん}:
このシャツは標準サイズだ。
This shirt is standard size.
I get the feeling that 標準 refers to a "tangible" standard -- maybe a property of something -- and 規範 has a meaning that has to do with rules, but is there a more succinct definition of each of these three that is sufficiently different that I don't essentially end up with three different flash cards that say "standard (of the x type)"?