Entrez Global Query Cross-Database Search System is a federated
search engine, or web portal that allows users to search many discrete
health sciences databases at the National Center for Biotechnology
Information (NCBI) website. The NCBI is a part of the National
Library of Medicine (NLM), which is itself a department of the
National Institutes of Health
National Institutes of Health (NIH), which in turn is a part of the
United States Department of Health and Human Services. The name
"Entrez" (a greeting meaning "Come in!" in French) was chosen to
reflect the spirit of welcoming the public to search the content
available from the NLM.
Entrez Global Query is an integrated search and retrieval system that
provides access to all databases simultaneously with a single query
string and user interface.
Entrez can efficiently retrieve related
sequences, structures, and references. The
Entrez system can provide
views of gene and protein sequences and chromosome maps. Some
textbooks are also available online through the
6 External links
Entrez front page provides, by default, access to the global
query. All databases indexed by
Entrez can be searched via a single
query string, supporting boolean operators and search term tags to
limit parts of the search statement to particular fields. This returns
a unified results page, that shows the number of hits for the search
in each of the databases, which are also links to actual search
results for that particular database.
Entrez also provides a similar interface for searching each particular
database and for refining search results. The Limits feature allows
the user to narrow a search a web forms interface. The History feature
gives a numbered list of recently performed queries. Results of
previous queries can be referred to by number and combined via boolean
operators. Search results can be saved temporarily in a Clipboard.
Users with a MyNCBI account can save queries indefinitely and also
choose to have updates with new search results e-mailed for saved
queries of most databases. It is widely used in the field of
biotechnology as a reference tool for students and professionals
Entrez searches the following databases:
PubMed: biomedical literature citations and abstracts, including
Medline - articles from (mainly medical) journals, often including
abstracts. Links to
PubMed Central and other full-text resources are
provided for articles from the 1990s.
PubMed Central: free, full-text journal articles
Site Search: NCBI web and FTP web sites
Books: online books
Online Mendelian Inheritance in Man (OMIM)
Nucleotide: sequence database (GenBank)
Protein: sequence database
Genome: whole genome sequences and mapping
Structure: three-dimensional macromolecular structures
Taxonomy: organisms in
SNP: single nucleotide polymorphism
Gene: gene-centered information
HomoloGene: eukaryotic homology groups
PubChem Compound: unique small molecule chemical structures
PubChem Substance: deposited chemical substance records
Genome Project: genome project information
UniGene: gene-oriented clusters of transcript sequences
CDD: conserved protein domain database
PopSet: population study data sets (epidemiology)
GEO Profiles: expression and molecular abundance profiles
GEO DataSets: experimental sets of GEO data
Sequence read archive: high-throughput sequencing data
Cancer Chromosomes: cytogenetic databases
PubChem BioAssay: bioactivity screens of chemical substances
Probe: sequence-specific reagents
NLM Catalog: NLM bibliographic data for over 1.2 million journals,
books, audiovisuals, computer software, electronic resources, and
other materials resident in LocatorPlus (updated every weekday).
In addition to using the search engine forms to query the data in
Entrez, NCBI provides the
Entrez Programming Utilities (eUtils) for
more direct access to query results. The eUtils are accessed by
posting specially formed URLs to the NCBI server, and parsing the XML
response. There was also an eUtils SOAP interface which was terminated
on July 2015.
Entrez was introduced in CD form. In 1993, a client-server
version of the software provided connectivity with the internet. In
1994, NCBI established a website, and
Entrez was a part of this
initial release. In 2001,
Entrez bookshelf was released and in 2003,
Gene database was developed.
^ NCBI Resource Coordinators (2012). "Database resources of the
National Center for Biotechnology Information". Nucleic Acids
Research. 41 (Database issue): D8–D20. doi:10.1093/nar/gks1189.
PMC 3531099 . PMID 23193264.
^ "Home -
Gene - NCBI".
^ "The E-utility Web Service (SOAP)".
^ Smith, Kent. "A Brief History of NCBI's Formation and Growth". The
NCBI Handbook [Internet]. 2nd edition. Retrieved 3 May 2014.
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