I believe that your question equates "how to study" with "categories of study."
Biology does not necessarily study in a different way, we just call it "biology" because of what is studied.
As for the way we study, many subjects of study use the scientific method, such as biology, physics, chemistry, etc. However, other subjects do not have experiments that are observable, measurable, and repeatable. For example, history would not be studied in the same way that biology or physics is studied.
1) Is there a possibility that there are some subjects that humanity has not found yet?
2) I mean a new way of research, study and looking at things?
These are two different questions with two different answers:
1) Yes, there is certainly the possibility that we discover some totally new subject that we have never studied. Perhaps there is something hidden deep within the atom or in space that, once discovered, will open up a brand new field of study (just like your example about nuclear research).
2) Yes, maybe. People are quite fond of the scientific method. It produces results that seem quite accurate, and those results have been used to make accurate predictions and technological advances. Is there a "new way of research", besides those ways already used? It is possible, but it probably wouldn't be "found" in the same way that protons and electrons were "found."