Keywords combined with synonyms are pretty reliable. However, if you find a strange mix of results, not enough results or results that are not relevant to your search question, you may have better luck with a subject search.
As you can see in this example, articles are assigned subject headings, descriptors or tags in the database.
This means that either the author or an editor at the database has looked at the article and given it a subject or descriptor that is the same as all the other articles in the same subject. So even if the keywords aren't in the title, searching by the subject will return all the articles in the same subject.