Technical Notes - e1

NLM Classification, 5th Edition Additions and Changes List 4 - e2

PubMed: Searching Using Subsets - e3

OLDMEDLINE Database Moves Back in Time - e4

Hands On: PubMed Update - e5

MEDLINEplus - e6

Subsets allow searchers to limit their search to a particular portion of the PubMed database. This article discusses two existing categories of subsets and the associated subset tags to be used in searching. The two subset categories currently available are: processing status subsets and a subject subset for AIDS. Processing status tags are used to indicate the status of those citations that are not indexed with MeSH headings and that have not been through quality control procedures. Subsets based on journal title lists will also be available in the future and are highlighted at the end of this article.

Citation Status Subsets
The PubMed database contains MEDLINE records and PREMEDLINE records (http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=helppubmed.section.pubmedhelp.PubMed_Quick_Start) and records that are electronically supplied by publishers [This link was removed because it is no longer valid.] directly into PubMed. Only the MEDLINE records have been indexed with MeSH headings and been through quality control procedures to ensure the accuracy of the data. The PREMEDLINE citations are on their way to indexing and quality control.

The records that are electronically supplied by the publisher have had the least scrutiny and the data are made available as supplied and without revision. The majority of these publisher-supplied electronic records quickly convert to PREMEDLINE and eventually MEDLINE records. The remainder of the publisher-supplied citations are the out-of-scope articles from selectively indexed journals and permanently retain the [Record as supplied by publisher] tag.

As a result, your search retrieval may include PUBLISHER-supplied citations, indicated by the tag, [Record as supplied by publisher], PREMEDLINE citations indicated by the tag, [MEDLINE record in process], or MEDLINE citations (no tag). These three subsets that denote citation processing status are mutually exclusive. These tags display in different locations depending on the PubMed display format you are viewing; however, the processing tags are easily seen in all displays.

Subsets for Subjects
Another kind of subset, that is subject-oriented, is also available. As citations are added to PubMed they are run through a special AIDS search filter which utilizes the strategy used to create NLM's AIDSLINE database on ELHILL. The AIDS subset in PubMed may include MEDLINE, PREMEDLINE, and PUBLISHER-supplied citations. The PubMed AIDS subset does not contain all the data found in AIDSLINE. The AIDS-related journal citations not available in PubMed are still available when you search AIDSLINE using Internet Grateful MED (IGM). If you first run your search in PubMed, use IGM'S MEDLINE overlap feature in the Apply Limits area of the search screen and select: Exclude MEDLINE references. This will avoid duplicate retrieval of the MEDLINE references in IGM.

In the future PubMed will provide an easier way to limit by subset, with the ability to select these subsets from the Advanced Search screen. For now, type in the subset name qualified with [sb].

Search Examples
You can now limit your retrieval to one or more of the processing status subsets using a Subset search field qualifier [sb] as shown in Figure 1.

Figure 1 - Limiting Retrieval to the Processing Status Subsets

You can limit your retrieval to the AIDS subset by using "aids" with the subset search field qualifier [sb] as shown in Figure 2.

Figure 2 -Searching Using the AIDS Subset

Coming Soon: Journal Title List Based Subsets
NLM looks forward to adding three more subsets later this year based on journal title lists:

--prepared by Annette Nahin

MEDLARS Management Section

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