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PubMed Ten TipsIf you are a biomedical researcher, clinician, teacher, or student you probably have used or will use MEDLINE for most of your literature searching. The Health Sciences Library provides access to MEDLINE via the PubMed search system from the National Library of Medicine. PubMed is an expanded version of MEDLINE, with not only the core medical database but also articles from OldMEDLINE (pre-1966), PreMEDLINE (most recent two weeks, and updated nightly), and publisher-contributed individual articles. All told, PubMed contains more than 17 million citations and can be searched for free from anywhere in the world. The system is very powerful but not always fully intuitive. We recognize that you may have specific search strategies that you want to learn how to do in PubMed. While you are always welcome to attend a class or get a one-on-one consultation (see our schedule and registration form), you may want to use the following ten tips for self-study or as a reference:
1: The Basics - Simple Searching and Viewing ResultsIt is very important that you enter PubMed (MEDLINE) via the databases page. Doing so ensures you have access to added features of PubMed MEDLINE that are only available to UNC-CH affiliates, including full-text access to some of our electronic journals. The new PubMed screen provides a series of links organized below the search bar to help pages, PubMed services (several of which are discussed in this guide), and related resources for searching biomedical information. Across the top of the screen you will see the grey search bar newly eqipped with a drop-down menu to make the search transition between different NCBI/NLM databases (such as PubMed and MEDLINE) easy. Beside the drop-down menu are the links to the Advanced Search and many of the more useful search features of PubMed. To begin searching, simply type your keyword(s) into the search box. Don't worry about MeSH (Medical Subject Heading) terms, unless you already know them; PubMed will attempt to match (or "map") your keyword(s) to appropriate MeSH terms. If you type in more than one keyword or phrase, connect them with the Boolean connectors AND, OR, or NOT. Make sure your connectors are in ALL CAPS! Click Go to run the search.  Your initial results will be displayed below the gray search bar. You may notice that your results from a simple search in PubMed are often more "on target" than a similar search in OVID. The database defaults to showing a "Summary" view (citation only) of articles in reverse chronological order. The Display options indicate the amount and format of information for each article. The Display options can now be found via the blue link above your search results at the far left corner of your window. Highlight Abstract from the pull-down menu to see the citation, abstract, and related records information. PubMed will automatically switch to the newly selected display type.  Other options include:
In addition, you can change the number of articles shown on a screen and/or the order in which they are shown (by date, author, or journal) by selecting an option from the appropriate pull-down menus. 2: Setting LimitsYou may limit the results of a search in several ways. Click the Advanced Search link above the search bar and scroll down to access PubMed's Limits features.  Choose appropriate Limits by selecting the appropriate check-boxes provided in the scrolling menus. For example, if you are interested in early-onset cancers in women, you could choose Adult 19-44 from the Ages menu, Human from the Humans or Animals menu, and Female from the Gender menu. Likewise you can select from a variety of article types (e.g., clinical trial, review, editorial, etc.), languages, subsets (subject-based journal collections), dates, and fields in which your keyword(s) should appear.  Once you have selected your Limits, make sure your keywords have been properly marked, and click Go. PubMed automatically applies your Limits to everything else you search in this session unless you take the Limits off. To turn off or modify your Limits, return to the Limits section of the Advanced Search function and click the Clear All button provided below the Limits menus. To simply refine your Limits, you can edit them individually by checking or unchecking the appropriate limit boxes or by clicking the Clear button located next to the subject heading of each Limits topic menu. NOTE: Setting Limits in a search will remove "In Process" citations from your search, because these articles have not yet been indexed. To capture "In Process" citations, take off your Limits and run your search as before, but add AND in_process[sb] to the end of your search. 3: Combining Searches Using HistoryYou can combine different searches in PubMed by viewing your History. You can also find your search History by clicking the Advanced Search link above the search bar. Any searches you have run in PubMed this session will be displayed. The number on the left is the search number. The hyperlinked number on the right takes you to the results of the search.  To combine searches, type # number of one search in the search box, followed by AND, OR, or NOT (depending on how you want the terms to relate to each other), then # second search number. You can add new terms if needed. Click Go to run the new search, or Preview to see how many articles are found with the search (this will keep you in the History screen rather than showing you articles. You can then view your search results by clicking the linked search result number). 4: Viewing Full-Text DocumentsThe Health Sciences Library has coordinated with PubMed to provide direct links from MEDLINE to some of the electronic journals to which we subscribe. These articles will be labeled with a "Find @ UNC" graphic in the Abstract display:  Simply click the graphic to go to a page with information on how to find the article. A new window will open and you will be given the article's availability either via full-text online or through the UNC Library catalog. Articles with full text provided by their publishers will also provide a button next to the "Find @ UNC" logo that will take you to either the article in the electronic journal or, in some cases, the article itself. Depending on the journal you may see an HTML or PDF version of the article made available. The National Library of Medicine has incorporated a database of free, full-text medical journals into PubMed. PubMedCentral contains a number of well-known journals, including the BMJ: British Medical Journal and the Canadian Medical Association Journal, and specialized journals such as Critical Care and Nucleic Acids Research. The journals have varying dates of coverage; some go back to 1997, and some include the most recent issues. However, many start with issues published in 2000 and end with issues published a year to six months ago. 5: Saving, Emailing, and Printing ItemsAs you search PubMed MEDLINE you may find it useful to temporarily store articles of interest on your Clipboard. This feature allows you to keep track of which articles you have already found useful in a previous search in your current session with the database. To add an article to your Clipboard, check the box next to the article, and select Clipboard from the Send To link located to the upper-right corner above your search results. Click Add to Clipboard from the Send To menu to finish. You will get a message stating that your article has been posted to the Clipboard. Now that you have placed items in your Clipboard, a link to your Clipboard will appear at the upper-right of your screen above the "Filter Your Results" function. To view items on your Clipboard, click this new Clipboard link that has just been made available. Articles already posted to the clipboard are marked below their citation information with "Item in Clipboard" in green in both the Summary and Abstract displays.  If you make a habit of putting articles of interest on your clipboard you will find it easier to save, print, and email all of the articles in which you are interested at once:
If you would like to import your results into one of the reference formatting programs such as EndNote you will need to do a few extra steps to make the results fit the format needed by these programs. The Health Sciences Library has created several short guides to help you download citations from PubMed MEDLINE into all three supported reference formatting software programs:
6: MyNCBI: Saving SearchesYou can save a complicated search for repeated use via the MyNCBI system. This will allow you to either manually update the results of your search or to have new citations automatically emailed to you on a regular basis. After you have run a search in PubMed, click the Save Search link located above the search box.  You will be prompted to sign in to My NCBI or create a new account. Once you do so, you will be able to select options for storing and retrieving your search, including whether you would like to have the search be run automatically on a daily, weekly, or monthly basis. The Health Sciences Library has created a special guide for those interested in using the MyNCBI system. Please refer to My NCBI: Saving and Filtering Searches in PubMed for assistance. 7: Using MeSH Subject HeadingsThere are three ways of discovering MeSH terms in PubMed MEDLINE. The first is to expand the MeSH tab located at the bottom of citations with MeSH terms in the Abstract display. The second is to look at the Details of your search. PubMed automatically attempts to map keywords to MeSH terms. You can see what terms PubMed is using in your search by clicking the Abstract link above the main search bar. The third option is to search for terms using PubMed's MeSH Database. You can search for MeSH terms by selecting MeSH from the pull-down menu located in the tab located in the upper-left corner of the search bar. Once in the MeSH Database, enter your keyword into the search box and click Go. Select terms by checking the boxes next to the term name.  Clicking the hyperlinked MeSH term will give you a more complete description of the term, including subheadings, options to limit your search, history of the term, and the placement of the term in the MeSH tree hierarchy. Check the boxes next to subheadings and/or Limits you desire. To search, click Send to Search Box with AND then Search PubMed.  One nice feature of searching with MeSH terms in PubMed is that PubMed automatically explodes these terms. That is, the database assumes you want to see articles coded not only with the term given but also with any term more specific in the tree hierarchy. This means that a MeSH search for "Genes, Tumor Suppressor" in PubMed will include articles indexed under "Genes, BRCA2" that would otherwise have been excluded in a non-exploded search. 8: EBM/Clinical QueriesThe Clinical Queries service offers three modes of searching for articles to support evidence-based medicine. First, you may wish to search for evidence by clinical study category (etiology, diagnosis, therapy, or prognosis) using a broad (sensitive) or narrow (specific) focus. Second, you can find systematic reviews on a topic. Third, you may look for information on the genetics of a disease, including genetic diagnosis, clinical description, management, counseling, molecular genetics, and genetic testing. All three of these modes use preset filters and search terms that have been designed by researchers at the National Library of Medicine. For more details on the Clinical Queries search, please see our Using PubMed to Find Evidence-Based Medicine Articles guide. 9: The Single Citation MatcherOften times you may be looking for a specific article, either because it was recommended to you or because you need to verify the citation for a bibliography. The Single Citation Matcher, now located on PubMed's front page under PubMed Tools, simplifies your search by offering you a form with spaces for the relevant parts of the citation.   This search finds all articles published in Oncogene in 2003 that have the word "BRCA1" in the title. In this case, several articles are found. 10: Getting More HelpIf you would like more training on using PubMed, we have a variety of options. You may wish to read one of our more advanced/specialized guides to PubMed, including:
You may also wish to meet with a librarian to search on a particular topic of interest. We are happy to meet with you at your office or ours, generally during business hours. Please let us know who you are and how we can help you, on our One on One Consultations request form. Finally, the National Library of Medicine has created a number of useful online training tools for PubMed, including their interactive tutorial and a series of animated "quick tours." | |||||
