How To Search for a Phrase in PubMed

Searching for phrases in PubMed can be an exercise in frustration. To understand why, we need to look at how PubMed interprets your search, a process that is now described in detail in a new training module from the National Library of Medicine.

When you enter a phrase into PubMed without using quotation marks, the database does several things:

  1. Looks for the phrase as a subject heading, or MeSH, term. Subject headings have been preselected by the database and are assigned to each citation on a topic.
  2. Breaks apart the phrase and looks for each word separately.
  3. Looks for the phrase, if recognized.
A graphic describing how PubMed Searches for a phrase.

How PubMed searches for a phrase. From the National Library of Medicine.

Sometimes, this process brings back the results you need. But it can also lead to search results that do not match your topic.

What happens when you search using quotation marks?

  • Instead of looking for matching subject headings, PubMed checks for the phrase in its phrase index, a list drawn from the literature included in the database.
  • Not every phrase is included in the phrase index. If your phrase is not found, PubMed may ignore your quotation marks and follow the search steps above, bringing in irrelevant results.
  • You can see how many results include your phrase from the advanced search page. Start typing your term, then click “Show index” to the right of the search box.
A screenshot showing how to check if a phrase is included in PubMed's phrase index.

Use the “Check index” button on the advanced search page to see if your phrase is included in PubMed’s Phrase index. From the National Library of Medicine.

Fortunately, there is a workaround if your phrase is not found. You can recommend the addition of phrases to PubMed. You can try searching for the phrase in different databases,  most of which are much more user-friendly when phrase searching. You can also try searching for the phrase in PubMed using adjacency.

For example, “Adult Non-Verbal Pain Scale” is not a phrase PubMed recognizes. Have PubMed look for the phrase with all words next to each other, in any order, by telling it to look in the title and abstract fields (tiab) with the words adjacent to each other (:~0):

The PubMed advanced search page showing the difference in results using quotation marks and proximity searching for a phrase.

Using proximity searching ([tiab:~0]) when a phrase is not included in PubMed’s phrase index can lead to more focused results compared to using quotation marks alone.

For more search help, or to request a literature search, contact the Library.

Google Dataset Search, a dataset-discovery tool 

With data sharing increasingly being encouraged in academic research and datasets increasingly being added to data repositories and being published on the Web, it makes sense that a Web browser company like Google would dedicate resources towards the goal of developing a Web discovery tool that is optimized for finding datasets.

How does it work?

Google Dataset Search, a dataset-discovery tool, basically uses Google’s web crawl technology to search for datasets that have been made available on the Web, identifying them based on their metadata (standardized descriptions of the datasets added to them by their owners/publishers).“ Google’s Dataset Search extracts dataset metadata—expressed using schema.org and similar vocabularies—from Web pages in order to make datasets discoverable.”

For an in-depth overview of how Google Dataset Search has been developed – please see:

Sostek, Katrina, Daniel M. Russell, Nitesh Goyal, Tarfah Alrashed, Stella Dugall, and Natasha Noy. “Discovering datasets on the web scale: Challenges and recommendations for Google Dataset Search.” Harvard Data Science Review Special Issue 4 (2024).

How can you search it?

To get started with using Google Dataset Search, go to: Dataset Search at https://datasetsearch.research.google.com/

If you are looking for something specific, you can refine your search results by limiting your search to a particular website domain (for example, site:nih.gov) or adding additional terms to your search. You can also filter your results by when the dataset was last updated, by format, by usage rights, topic/discipline, and whether the dataset is freely-available. Furthermore, you can save your search results, link-out to the external source website where you can download the datasets, and you can easily cite the dataset by copying the citation information that is generated when you click on the citation button (i.e. the quotation mark button).

To learn more – see:

Dataset Search Quick Start Guide –
https://newsinitiative.withgoogle.com/resources/trainings/dataset-search-quickstart-guide/

User Support Center – https://datasetsearch.research.google.com/help

Dataset Developer Page –
https://developers.google.com/search/docs/appearance/structured-data/dataset

How is it being used?

It appears that biomedical researchers have already started using Google Dataset Search in their scholarly projects. Some examples focusing on finding image datasets include:

  1. Abbad Andaloussi M, Maser R, Hertel F, Lamoline F, Husch AD. Exploring adult glioma through MRI: A review of publicly available datasets to guide efficient image analysis. Neurooncol Adv. 2025;7(1):vdae197. Epub 20250128. doi: 10.1093/noajnl/vdae197. PubMed PMID: 39877749; PMCID: PMC11773385.

  2. Rozhyna A, Somfai GM, Atzori M, DeBuc DC, Saad A, Zoellin J, Müller H. Exploring Publicly Accessible Optical Coherence Tomography Datasets: A Comprehensive Overview. Diagnostics (Basel). 2024;14(15). Epub 20240801. doi: 10.3390/diagnostics14151668. PubMed PMID: 39125544; PMCID: PMC11312046.

  3. Wen D, Khan SM, Ji Xu A, Ibrahim H, Smith L, Caballero J, Zepeda L, de Blas Perez C, Denniston AK, Liu X, Matin RN. Characteristics of publicly available skin cancer image datasets: a systematic review. Lancet Digit Health. 2022;4(1):e64-e74. Epub 20211109. doi: 10.1016/s2589-7500(21)00252-1. PubMed PMID: 34772649.

  4. Khan SM, Liu X, Nath S, Korot E, Faes L, Wagner SK, Keane PA, Sebire NJ, Burton MJ, Denniston AK. A global review of publicly available datasets for ophthalmological imaging: barriers to access, usability, and generalisability. Lancet Digit Health. 2021;3(1):e51-e66. Epub 20201001. doi: 10.1016/s2589-7500(20)30240-5. PubMed PMID: 33735069.

Questions? Ask Us at the MSK Library!

Speed Up Your Searching with LibKey Nomad

LibKey Nomad is a browser extension (available for Firefox, Chrome, Edge, Safari, and more!) that provides seamless one-click access to full-text MSK library resources from a wide variety of databases and journals!

Simply install the extension in your preferred browser; during installation you will be asked to select your organization – search and select Memorial Sloan Kettering Library.

How LibKey Nomad Works

Once you’ve downloaded and installed the LibKey Nomad browser extension, a new icon will appear at the bottom of the page when searching on various databases, websites, and journal platforms.

Note: Depending on the browser and/or the settings you have set, you may need to tell LibKey Nomad to allow access to a website, which you can usually set to always allow access to a specific site (eg. PubMed’s website). The browser extension should be visible in the top of your browser and will look like the green LibKey icon above.

Once the page loads, the browser extension will identify the citation(s) and, based on our library’s collection, will guide to access the full-text of each citation on the page.

If PDF full-text is available, a single-click Download PDF button will appear below the citation. If additional authentication is required you will be prompted to sign in via the MSK single sign-on. In most cases the PDF will be coming directly from the publisher or a supporting platform, however in some cases it may find the full-text through PubMed Central (PMC) or a institutional repository.

LibKey Nomad access buttons

  • Download PDF: In a single click the user should be able to either view the PDF in their browser or be prompted to download the PDF to their computer.
  • Article Link: Similar to the PDF full-text, this option appears when either the full-text is only available as HTML, or if a PDF is available but an additional click is required once arriving at the publisher’s website
  • Manuscript PDF: This option appears if the article has been located in a repository as an Accepted Manuscript; while this manuscript has been peer-reviewed and accepted for publication, it is likely not formatted for publication yet and may simply be a Word document converted to PDF
  • Manuscript Link: Like the Manuscript PDF button, this will appear if the manuscript is available, but not in PDF format (HTML, Word document, etc.)
  • Access Options: Lastly, if full-text cannot be located immediately, this button will bring you to the MSK Library catalog where you can submit a request through our document delivery service[
  • View Complete Issue [BrowZine]: Integration with BrowZine in certain databases will provide a link to the entire journal issue in BrowZine for a selected citation

Where can I use LibKey Nomad?

Third Iron is continually adding new platforms and publishers to their list of places with LibKey Nomad integration. Currently the extension is supported in a number of databases and websites, as well as a wide range of major journal and eBook publishers.

Library databases with LibKey Nomad Integration:

publishers/Platforms with libkey nomad integration

Note: These publisher sites and platforms represent the discovery starting points but do not represent the coverage of content which extends to *all* eBooks and journals within a libraries collection!  

What’s the difference between libkey nomad and Browzine?

Both LibKey Nomad and BrowZine are produced by Third Iron and they work in conjunction to provide access electronic access to journal articles. LibKey Nomad is a browser extension to identify full-text articles on the web, while BrowZine is a platform to browse and read articles. In certain databases a citation may be able to provide both a link to download the PDF as well as a link to view the entire journal issue that the citation is found in.

For more information about LibKey Nomad

LibKey Nomad tutorial video:

ThirdIron: LibKey Nomad browser extension delivers one-click article access (1:58 min)