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NLM Technical Bulletin

NLM Technical Bulletin. 1999 May-June; 308

In This Issue:

Technical Notes - e1

dotConverting SDI searches to PubMed - e2

HealthSTAR Unique Journal Citations Migrate to PubMed - e3

Internet Grateful Med Update - e4

MLA 1999 - e5

BIOETHICSLINE Regenerated and New Bioethics Thesaurus Published - e6

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Converting SDI searches to PubMed

There are several issues you need to consider when initially converting SDI searches to the PubMed environment.

Don't Compare Postings from an ELHILL SDI search to a PubMed search

  1. You cannot convert an ELHILL SDILINE search to a PubMed search by entering it in PubMed syntax and limiting to the last 30 days and expect to receive the same number of postings in PubMed as you received in ELHILL. The last 30 days does not equate to the exact date range of the current SDILINE file.
  2. You cannot match a PubMed Entrez Date [EDAT] date range to the monthly SDILINE Date of Entry (DA) date range and expect to receive the same number of postings in PubMed as you received in ELHILL's SDILINE. The Entrez Date value represents the date a citation (whether publisher-supplied or PREMEDLINE) was added to the PubMed database; the Date of Entry (DA) field in SDILINE represents the date a citation was indexed for MEDLINE. An important point to remember is that the Entrez Date will remain unchanged and is not updated to reflect the date a publisher-supplied record is elevated to PREMEDLINE or when a PREMEDLINE record is elevated to MEDLINE.

It is therefore not recommended that you take either of the above mentioned steps in formulating your SDI searches in PubMed.

What Next?
Generally, what you need to do at this time is to run your PubMed search strategy on a particular date. Evaluate your retrieval for what's new since the last time the search was run on ELHILL. This may take some time but the citations print out in "last in, first out" order so you should be able to find everything new by scanning the retrieval by eye. Mark on a calendar when you ran the search. When you rerun your search strategy use an Entrez Date range from the previous date to the present. [Editor's Note: See Saving a Search Strategy in PubMed's online Help ( for instructions on how to save a strategy so you can run it at a later date. See Search Fields Descriptions and Tags in PubMed's online Help ( to learn how to enter a date range for Entrez dates.]

MeSH vs Text Words
If your search is entirely MeSH-based, this approach also is not foolproof because the Entrez Date value does not change when MeSH headings are added to the PubMed record. If a record remains in PREMEDLINE longer than your Entrez Date range, you may fail to retrieve a citation because it won't have MeSH headings on it. Therefore, it is recommended that you include Text Words in your strategy either by qualifying with [tw] or more simply by letting PubMed do it for you automatically by not qualifying any subject terms.

See the examples below for the preferred format and for the format that is not recommended for entering a subject search term, when running a search that is meant to include citations recently added to the database and not yet indexed with MeSH.

Preferred:informed consent
Not recommended: informed consent [mh]

The Future
At some time in the future, PubMed will offer an SDI-like capability using the proposed "Cubby" service, which is briefly mentioned in the New/Noteworthy area of PubMed. Click on New/Noteworthy ( from the gray sidebar of PubMed's opening screen. Tentative plans call for making the MEDLINE Date of Entry (DA) field searchable for current awareness searching, which will be especially useful for MeSH-based strategies. When the "Cubby" service is implemented, the DA will change when a PREMEDLINE record is elevated to MEDLINE. Stay tuned.

--prepared by Janet Zipser
MEDLARS Management Section

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Last updated: 20 August 2012