PubMed is the free public interface to MEDLINE. It provides access to bibliographic information in MEDLINE as well as additional life science journals.
Searching articles on PubMed requires some skill and more over it does not support some of search strings like popular search engines (Google and Yahoo).
Eventhough we can search through Google Scholar it gives many false positive results. But, Google provides us to customise our own search engine through google co-op. Through this we can create our own search engine on our interested topic.
I have created a search engine for bioinformatics through Google Co-op, this search engine searches only bioinformatics related journals and it has less false positive results. But this BioMed search engine is still in beta version and it requires further improvement.
You can access the BioMed - Search engine for bioinformatics by clicking here.