The reason the search produces 667 results with the subject limiters of "koran" and "social aspects" is because of Boolean Logic. Boolean Logic allows you to separate or join concepts when searching a computer database. In the search above, the terms "koran" and social aspects" are treated as "koran" OR "social aspects." Combine this with the term "Islam" and you have results that deal with Islam and the koran solely as well as those that deal with Islam and social aspects solely. The articles in this search do not necessarily have be about all three terms to be returned.
Boolean operators are both limiters and extenders to searches and and are defined through the use of the terms AND, OR and NOT. Imagine you are ordering ice cream and are given the options of vanilla, chocolate and strawberry. If you order "vanilla OR chocolate OR strawberry" you will get them all individually. If you order "vanilla NOT chocolate NOT strawberry" you will get only vanilla. If you order "vanilla AND chocolate NOT strawberry" you will get a vanilla and chocolate swirl. If you order "vanilla AND chocolate AND strawberry" you will get all three in the Neapolitan flavor.
OR is used to be more comprehensive in searching. In order to cover a lot of bases in terms, you can use multiple terms to describe the same thing. If you are not sure what is the best term for child is to use multiple terms to cover your bases: "child OR children OR juvenile OR kid OR youth." So the database will then return articles that mention all of those terms. However, if you use the Boolean AND it will only bring back articles that deal with ALL of those terms combined.
So let's see how the search behaves with those Boolean operators. You can use any combination and any number of terms, but for the sake of simplicity, let's remove the "Islam" from our search and focus on "social aspects" and "koran." Using the advanced search feature, you can submit multiple terms and select the boolean phrase from a drop down menu. Since "social aspects" and "koran" are subject terms or portions of subject terms, we will search the subject terms only by selecting "SU Subject Terms" in the "in" drop down menu. This allows you to search any field including title, publication, author, all text (keyword), etc.
In this instance the OR extends the search to mean anything that is on the subject of social aspects even if it has nothing to do with Islam or the Koran and all those results that have to due with the Koran but not with social aspects. While there will be some overlap, 44000 results will have nothing to do with your topic of social aspects of the koran.
In this instance AND limits the search to just those articles that deal with the social aspects of the Koran. These 6 articles will be very closely related to your topic and you will probably be able to use all 6 of them in your research.
In this instance NOT limits the search concerning these two terms and only will return results that deal with social aspects EXCLUDING all mentions of the Koran. None of these 45036 results will help you in your topic.