The Entrez (pronounced ''ɒnˈtreɪ'') Global Query Cross-Database Search System is a

federated search Federated search retrieves information from a variety of sources via a search application built on top of one or more search engines. A user makes a single query request which is distributed to the search engines, databases or other query engines ...

engine, or web portal that allows users to search many discrete

health sciences The following outline is provided as an overview of and topical guide to health sciences: Health sciences are those sciences which focus on health, or health care, as core parts of their subject matter. Health sciences relate to multiple a ...

databases at the

National Center for Biotechnology Information The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. Th ...

(NCBI) website. The NCBI is a part of the

National Library of Medicine The United States National Library of Medicine (NLM), operated by the United States federal government, is the world's largest medical library. Located in Bethesda, Maryland, the NLM is an institute within the National Institutes of Health. Its ...

(NLM), which is itself a department of the

National Institutes of Health The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the lat ...

(NIH), which in turn is a part of the

United States Department of Health and Human Services The United States Department of Health and Human Services (HHS) is a cabinet-level executive branch department of the U.S. federal government created to protect the health of all Americans and providing essential human services. Its motto is ...

. 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 In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

and

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

sequences and

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins ar ...

maps. Some textbooks are also available online through the Entrez system.

Features

The 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 alike.

Databases

Entrez searches the following databases: *

PubMed PubMed is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. The United States National Library of Medicine (NLM) at the National Institutes of Health maintai ...

: biomedical literature citations and abstracts, including

Medline MEDLINE (Medical Literature Analysis and Retrieval System Online, or MEDLARS Online) is a bibliographic database of life sciences and biomedical information. It includes bibliographic information for articles from academic journals covering med ...

- 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 ( GenPept) *''Genome'': whole genome sequences and mapping *''Structure'': three-dimensional macromolecular structures *''Taxonomy'': organisms in GenBank Taxonomy *'' dbSNP'': single nucleotide polymorphism *''

Gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

'': gene-centered information *''HomoloGene'': eukaryotic homology groups * PubChem Compound: unique small molecule chemical structures *PubChem Substance: deposited chemical substance records *

Genome Project Genome projects are scientific endeavours that ultimately aim to determine the complete genome sequence of an organism (be it an animal, a plant, a fungus, a bacterium, an archaean, a protist or a virus) and to annotate protein-coding genes ...

: genome project information * UniGene: gene-oriented clusters of transcript sequences *'' CDD'': conserved protein domain database *''PopSet'': population study data sets (

epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evi ...

) *''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).

Access

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 Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are us ...

interface which was terminated in July 2015.

History

In 1991, 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, the Entrez Gene database was developed.

References

{{Reflist

External links

Entrez search engine form

Entrez Help
Online databases National Institutes of Health Biological databases Government-owned websites of the United States Scholarly search services