There are many search engines that you could use for research purposes when looking for information online, however there are some notable issues with them given that there are millions of websites each targeting numerous keywords making it extremely difficult for a search engine to be 100% accurate in returning this results.
Spam is one of the main concerns of search engines and it usually ends up negatively affecting user experience so search engines are continuously improving their algorithm to ensure their results are as accurate and responsive to customer needs as possible. Major search engines can only do as much as they can so customers specifically businesses are constantly on the lookout for particular search engines that they could use to filter results.
There are nowadays a range of desktop search engines that depend for results upon major search engines like Google but then they use their own algorithm to filter results out to ensure they can counter spam effectively. This would ensure that any results that their clients end up getting would be those that would directly address their concerns or answer any questions that they may have. You may want to try out copernic desktop search to get an idea on this search technology.