LinkOut is a service that allows you to link directly from PubMed and other NCBI databases to a wide range of information and services beyond the NCBI systems. LinkOut aims to facilitate access to relevant online resources in order to extend, clarify, and supplement information found in NCBI databases.

Third parties can link directly from PubMed and other Entrez database records to relevant Web-accessible resources beyond the Entrez system. Includes full-text publications, biological databases, consumer health information and research tools.

The List of Serials Indexed for Online Users (LSIOU) provides bibliographic information for all journals whose articles were ever indexed over time with the MeSH® vocabulary and cited in MEDLINE®, the backbone of the NLM PubMed® database. It includes titles that ceased publication, changed titles, or are no longer indexed. More detailed bibliographic data and information about indexing coverage for serials cited in MEDLINE/PubMed can be found in LocatorPlus Catalog®, the NLM online catalog, and the NLM Catalog, an Entrez database.

LitCovid is a curated literature hub for tracking up-to-date scientific information about the 2019 novel Coronavirus. The articles are updated daily and are further categorized by different research topics (e.g. Long Covid) and geographic locations for improved access.

Provides up-to-date, accurate, and easily accessed information on the diagnosis, cause, frequency, patterns, and management of liver injury attributable to prescription and nonprescription medications, herbals and dietary supplements.

A MARC-based catalog, the LocatorPlus Catalog provides access to NLM bibliographic data for journals, books, audiovisuals, computer software, electronic resources and other materials.

MAGPIE is an interactive tool to help users (e.g., professional coders, researchers, clinicians) find SNOMED CT and ICD-10-PCS codes for medical procedures and interventions. MAGPIE is an NLM research tool (it has not been tested in a production environment), and is developed primarily for the 2018 version of ICD-10-PCS. MAGPIE combines lexical and map-assisted searching strategies to look for SNOMED CT, ICD-9-CM, and ICD-10-PCS codes sequentially.

An online edition of XML-encoded speeches, articles, and Congressional Appropriations testimonies by former NLM director Martin M. Cummings, based on the collection of his papers in HMD’s Modern Manuscripts collection.

MedGen is NCBI's portal to information about conditions and phenotypes related to Medical Genetics. Terms from the NIH Genetic Testing Registry (GTR), UMLS, HPO, Orphanet, ClinVar and other sources are aggregated into concepts, each of which is assigned a unique identifier and a preferred name and symbol. The core content of the record may include names, identifiers used by other databases, mode of inheritance, clinical features, and map location of the loci affecting the disorder. The concept identifier (CUI) is used to aggregate information about that concept, similar to the way NCBI Gene serves as a gateway to gene-related information.

MedGen provides links to such resources as: Genetic tests registered in the NIH Genetic Testing Registry (GTR), GeneReviews, ClinVar, OMIM, Related genes, Disorders with similar clinical features, Medical and research literature, Practice guidelines, Consumer resources, Ontologies such as HPO and ORDO.

Links to the GTR, GeneReviews, and Practice Guidelines are based on curation by NCBI staff. Other data feeds are automated, but reviewed by NCBI staff and informed by feedback from the community.

Medical Subject Headings (MeSH) is a hierarchically-organized terminology for indexing and cataloging of biomedical information. It is used for the indexing of PubMed and other NLM databases. Please see the Terms and Conditions for more information regarding the use and re-use of MeSH. NLM produces Medical Subject Headings XML, ASCII, MARC 21 and RDF formats.

Updates to the data files are made according to the following schedule:

MeSH XML
MeSH Descriptor files updated annually
MeSH Qualifier files updated annually
MeSH Supplemental Concept Records (SCR) updated daily (Monday - Friday)

MeSH ASCII
MeSH Descriptor files updated annually
MeSH Qualifier files updated annually
MeSH Supplemental Concept Records (SCR) updated daily (Monday - Friday)

MeSH MARC21
All files posted monthly

MeSH RDF
All files posted daily (Monday - Friday)

A system for producing indexing recommendations to assist in the indexing process at NLM. Currently provides indexing recommendations to more than 100 journals based on the NLM Medical Subject Headings (MeSH) vocabulary.

MTI is the main product of the Indexing Initiative project and has been providing indexing recommendations based on the Medical Subject Headings (MeSH®) vocabulary since 2002. In 2011, NLM expanded MTI's role by designating it as the first-line indexer (MTIFL) for a few journals; today the MTIFL workflow includes over 350 journals and continues to increase. The close collaboration of the NLM Index Section, Lister Hill National Center for Biomedical Communications, and Office of Computer & Communications Systems continues to expand and refine the ability of MTI to provide assistance to the indexers.