In the stupid quest to know everything about a subject, i just wonder if there exist databases out there that include all the existing journals to search for an specific topic. I currently use Science Direct, but that is restricted only to Elsevier journals. For example, it does not include papers in Nature, Science, or Physical Reviews, which I have to search in each individual website. What utilities are available to search across the most journals? I have hear about Web of Science, but haven't tried it. Which databases or journal search utilities do you use and recommend?