The 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 The National Center for Biotechnology Information (NCBI) is part of the 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. The NCBI is lo ...

(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 The National Institutes of Health (NIH) is the primary agency of the United States government responsible for biomedical and public health research. It was founded in 1887 and is part of the United States Department of Health and Human Service ...

(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 In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

and

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

sequences and chromosome 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 linked 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: biomedical literature citations and abstracts, including Medline—articles from (mainly

medical Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

) 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 The GenBank sequence database is an open access, annotated collection of all publicly available nucleotide sequences and their protein translations. It is produced and maintained by the National Center for Biotechnology Information (NCBI; a par ...

) *''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 has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

'': 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 Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and Risk factor (epidemiology), determinants of health and disease conditions in a defined population, and application of this knowledge to prevent dise ...

) *''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 (chemistry), salt of a fatty acid (sometimes other carboxylic acids) used for cleaning and lubricating products as well as other applications. In a domestic setting, soaps, specifically "toilet soaps", are surfactants usually u ...

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
Internet properties established in 1993 1991 establishments in the United States Online databases Entrez Biological databases Government-owned websites of the United States Scholarly search services