Scientific search engines and information resources:

PubMed : Search engines for abstracts and articles (Medline)
PubMedCentral  : archive of Free Full Text Articles
Elibrary  : search for scientific publications, Russian Science Citation Index (RSCI), Hirsch index, impact factors of scientific journals and their presence in the list of HAC
HighWirePress : scientific journals providing free full-text access to their articles.
OpenAccessJournals  : list of open-access journals
Library of Congress : periodicals and news of the library of the congress
MedBioWorld : magazines (sorted by 80 specialty categories)
MedScape  : clinical Medicine
PharmWeb  : medical conferences
BioMed Central : electronic publications, citation index, 130 journals are free
Free Medical Journals : free medical journals
OxfordUniversityPress : review for contents of journals OUP (without access to the full text)
WHO (ВОЗ) : International classification, there are full texts (Russian)
MedMir : clinical journals, reviews in Russian
FreeBooks for Doctors : full-text books on Medicine
MedHist : history of Medicine
Scholar Google  : publishing search platform, citation index (in search results)
ScienceDirect : scientific search engine that provides full-text searches in magazines of major scientific publishers (Elsevier, Highwire, IEEE, Nature, Taylor & Francis, etc.). Search for articles and documents in open scientific databases (Directory of Open-accessJournals, Library of Congress Online Catalog).
Hardin.MD : Meta catalog, list of disease resources + illustrations
Scientific & Academic Publishing : Over 120 Open Magazines, Book Contents, and Information about conferences
Higher Attestation Commission (HAC)
Brill : free medical magazines
Springeropen : full-text magazines
Springer Protocols : a database of protocols of laboratory researches and experiments in the field of Biochemistry, Biotechnology, Cytology, Radiology, Molecular Biology, Pharmacology, Toxicology, Microbiology, Immunology, Neurology, Genetics, Bioinformatics
EDP Sciences : full-text journals, information about conferences
Faculty of 1000 , http://f1000.com/posters : scientific assessment database of journals and articles in the field of Medicine and Biology
Palgrave Macmillan : full-text magazines
Wiley Online Library : full-text magazines