Scientific Links

Search Engines

www.google.com Great all purpose search engine
www.webofscience.com Find a paper by author, title, subject, or keyword. 
www.Scirus.com Scientific content search enging (searchs all of Elsevier's journals too!)
researchindex.org Project at NEC Research Institute to use autonomous citation indexing. Can search content in postscript and PDF files.
www.search4science.com Meta-search engine for scientists; includes colleague search and science news headlines.

Major Journal Servers

(some of these sites may be accesable only from PSU)

ojps.aip.org - on-line journal publishing service of the American Institute of Physics (includes all AIP journals)
pubs.acs.org - on-line journals from the American Chemical Society
www.sciencedirect.com/web-editions - on-line journals from Elsevier
www.jstor.com - various journals (Science included minus the past 5 years) all the way back to 1850s!!
www.idealibrary.com - IDEAL Publishers:  Academic Press, Churchill Livingstone, W.B. Saunders, Mosby, Baillière Tindall
www3.interscience.wiley.com - on-line journals published by by Wiley

www.lias.psu.edu - PSU library
www.lias.psu.edu/alallpsu.html - Fast Track to all PSU resources
 
archives.math.utk.edu - Math Archives, tutorials and reviews on any kind of math you can think of.  Great resource.
http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html - Hyperphysics - a fast rundown on the basic concepts for EVERYTHING? Enough detail to answer your questions - this is REALLY handy.
http://hyperphysics.phy-astr.gsu.edu/hbase/tables/ttab.html - Hyperphysics Tables - need to know a constant or equations related to that constant, check this out!

My most used journals

Science
Nature
Virtual Journal of Nanotechnology
Physical Review B
Physical Review Letters
Applied Physics Letters
Review of Scientific Instruments
Journal of Physical Chemistry B
Langmuir
Nano Letters
Advanced Materials
Surface Science -> Go trough science direct.