Scientific portals and specialized search engines

In researching for a report, an assignment, your exjobb, master thesis, a scientific paper, etc it is essential to check the available literature or state-of-the-art. For that reason you need specialized tools instead of the regular, off-the-shelf, search engines. The reason is that search engines will drown you with noise. That is, pages upon pages where the query terms appear but are not authoritative information sources.

For that reason I will provide some scientific portals and search engineers that index scientific content in mathematics and computer science.

ACM
Academic search
American Mathematical Society
American Statistical Association
arXiv
Citeseer
Computer Science DB
CrossRef Search
Digital Dissertations
DBLP
Delphion
Derwent
Dialog
Elsevier
Ebsco Host
HighWire
IEEE Xplore
Ingenta
INSPEC (IET Research Journals)
InterScience
JSTOR
Kluwer
Los Alamos ePrint/Preprint server
Mathematics Preprint
Public Library of Science (PLoS)
Science Citation Index
SciFinder
SpringerLinkSynergy (Blackwell)
Scirus
Springer
Taylor and Francis Journals Online
Thomson Innovation (T-Innovation)
Usenix
ZentralblattMATH

Moreover I would like to suggest the following amazing extension for Firefox. Its name is Zotero and it will make your life much easier.
Zotero
(Image copied from the official Zotero site)