QUOTE(Intermission @ Sep 25 2012, 04:00 PM)
Thanks for the thorough reply, I was wondering if I've just asked a very silly question.....

and perhaps I did.
For me, the purpose of doing further reading is build up insight in my desired field, engineering which is deeply rooted in chemistry, physics and mathematics. I originally thought that reading such journals may help, but after some further researching I guess I really did ask a silly question after all. So, scientific journals are just not meant for people not in the academic field, right? I guess that I will be much better off reading
these instead. Do you agree? As for the "good" and "important", I actually meant influential, i.e impact factor. Sorry for the confusion.
It's not a silly question, my dear. Everyone has to start off somewhere, and your quest for knowledge at your age is commendable. Keep it up, we need more intellectually inclined people like yourself. Knowledge is power.
Reading such journals DOES help, but not at your level. Journals can be read by anyone who is able to read them (by read, I mean utilize them) and it's just a waste if you subscribe and can't make use of it. There is no stopping you from downloading them by the truckloads under a free account courtesy of your uni, though *coughs*looksguiltilyaround*coughs*.
Yes, the site you provided looks sound. They're meant for undergrads, but just have a looksee if you are able to understand it. I must emphasize that without a sound understanding of the basics of what you want to read about, it would be immensely tedious and pointless. So brush up on your basic knowledge of terms and jargons in the 3 sciences before investing in something you need to pay cash for.
By influential, they probably mean it contains peer-reviewed journals? If so, then it means that in a way, yes, it is more 'credible', because peer-reviewed journal articles undergo more rigorous scrutiny of their research, and this is important for those who are doing research as it needs to be cited, and peer-reviewed articles have more solid research methodologies. Not so much a concern for you now at this stage.
But always remember: Research is not the gospel truth. They are not facts, they merely shed light on areas that enlightenment.