Skip Navigation Bar
NLM Technical Bulletin

NLM Technical Bulletin 1997 Jan-Feb; 294



In This Issue:

Grateful Med for Windows®

dot Searching for Chemicals

Gold Standard Search

Technical Notes


Appendixes:

HHAI Order Form

AHA Order Form


Current Issue

Home

Back Issues

Index

Searching for Chemicals in MEDLARS® Databases

The publication Medical Subject Headings -Supplementary Chemical Records has been discontinued. This tool contained the listings for chemicals which are not MeSH headings and have been mentioned in a significant way in journals indexed in MEDLINE. These chemical names may be found online in the Name of Substance (NM) field. The NM field is searchable. However, the NM exists only in the dictionary files, MEDLINE, the MEDLINE Backfiles, and the MEDLINE-derived portions of the following composite files: AIDSLINE, CANCERLIT, HealthSTAR and in the MEDLINE-derived portion and DART subfile in TOXLINE.

MeSH, ChemID, and CHEMLINE

Chemicals are listed in three dictionary files online: MeSH, ChemID, and CHEMLINE. The MeSH file is updated several times each week, throughout the year. It is the most current of all the online files listing chemicals. ChemID and CHEMLINE are updated several times a year and therefore may not have an entry for a chemical that does have a record in MeSH (which means that there are citations present in MEDLINE and/or the MEDLINE Backfiles).

See Figure 1 for an example of locating the same chemical in the MeSH, ChemID and CHEMLINE files. Note that File MeSH does not indicate which MEDLINE files contain postings for any chemical. Files ChemID and CHEMLINE both contain a Locator (LO) field which indicates the files in which a particular chemical appears. Keep in mind that these Locator listings may be several months out-of-date, depending on when you are conducting your search. Also note that searching MeSH and ChemID are roughly comparable in price; for example, it costs about $0.11 to find and download the information for fluoromethane. It costs $1.79 to retrieve this same information in CHEMLINE (a file containing Chemical Abstracts Service (CAS®) royalty data).

Which Chemical Dictionary File Should You Use?

You might want to consider restricting your search for a chemical to MeSH if you were only interested in citations appearing in MEDLINE or the MEDLINE Backfiles and you wanted the most current information available. You would use ChemID in place of or in addition to MeSH, when you were interested in citations from the full range of MEDLARS files (including TOXNET files) and you want the convenience of seeing the Locator files (realizing that they are not completely current). You would use CHEMLINE last, in addition to or in place of MeSH and ChemID, if you couldn't find a chemical in the first two files. There are chemicals which are only listed in CHEMLINE; generally, the citations for these chemicals appear only in TOXLIT and the TOXLIT backfile which are also CAS royalty files.

Searching the non-Dictionary Databases for non-MeSH Chemicals

Once you have found your chemical in MeSH, ChemID or CHEMLINE, in most MEDLARS files it is easiest to retrieve citations about that chemical by searching on the Registry Number. The Registry Number may be entered in all MEDLARS files (including TOXNET files) qualified by (rn) or without qualification. In MEDLINE, MEDLINE Backfiles, and MEDLINE-derived files, you may choose to substitute the Name of Substance qualified by (nm) for the Registry Number. In TOXNET files, searching on the registry number is easiest and yields consistent results because all records contain an RN field. In the composite file TOXLINE, not all records contain a Registry Number, so it is best to search on the Registry Number ORed together with the chemical name as a Text Word.

To display the Name of Substance field (in those files where it exists), you need to print the Registry Number (RN) field. If you give the command PRINT NM, you will see the following response online: 'NM' IS NOT A VALID PRINT PARAMETER. COMMAND IGNORED. This situation is analogous to the one for displaying subheadings. You can search on the subheading field, but you cannot give the command PRT SH; subheadings display only as part of the MeSH heading field. Similarly NMs display only as part of the Registry Number field.

See Figure 2 for an example of retrieving on the registry number for fluoromethane in MEDLINE and displaying the Registry Number field containing the Name of Substance. See Figure 3 for an example of retrieving information on fluoromethane in TOXLINE.

--prepared by Toby Port
MEDLARS Management Section

Figure 1 - Searching for a chemical Name in MeSH, ChemID, and CHEMLINE


     SS 1 /C?

     USER:

     file mesh



     PROG:

     YOU ARE NOW CONNECTED TO THE MESH VOCABULARY (1997) FILE.



     SS 1 /C?

     USER:

     fluoromethane (nm)



     PROG:

     SS (1) PSTG (1)



     SS 2 /C?

     USER:

     prt dl



     PROG:



     1

     NM - fluoromethane

     RN - 593-53-3

     RR - 59122-96-2 (ion(1+))

     RR - 20666-44-8 (13C-labeled cpd)

     RR - 3832-44-8 (18F-labeled cpd)

     RR - 20666-45-9 (14C-labeled cpd)

     SY - methyl fluoride

     HM - *HYDROCARBONS, FLUORINATED

     DA - 810626

     MR - 830801

     RO - O:RLS

     RO - C:NLM

     RO - M:ACS

     SO - Arch Phys Med Rehabil 1981;62(3):100

     TH - Merck Index, 9th ed, #4060

     FR - 24                             

		       *  Indicates the frequency of  

			  postings in MEDLINE and the

			  Backfiles, but not the 

			  specific file locations.

     NO - RN given refers to parent cpd            

     RY - C                                      

     UI - C029999 



     SS 2 /C?

     USER:

     show cost



     PROG:

     THE ESTIMATED TOTAL ONLINE COST FOR THIS 0 MINUTE MESH VOCABULARY 

     SESSION IS $ 0.11.



     SS 1 /C?

     USER:

     file chemid



     PROG:

     YOU ARE NOW CONNECTED TO THE CHEMID (NON-ROYALTY) FILE.



     SS 1 /C?

     USER:

     fluoromethane (nm)



     PROG:

     SS (1) PSTG (1)



     SS 2 /C?

     USER:

     prt dl

     PROG:



     1

     RN  - 593-53-3

     MF  - C-H3-F  [EINECS:TSCAINV]

     N1  - Fluoromethane  [EINECS]

     N1  - Methane, fluoro- (8CI)(9CI)  [TSCAINV]

     NM  - Fluoromethane  [MESH]

     NM  - [LIST] Methyl fluoride [UN2454]  [Flammable gas]  [DOT]

     NM  - [LIST] UN2454  [DOT]

     SY  - EINECS 209-796-6  [EINECS]

     SY  - Fluoromethane  [NLM]

     SY  - Fluorure de methyle [French]  [NLM]

     SY  - Fluoruro de metilo [Spanish]  [NLM]

     LLO - DOT

     LO  - CANCERLIT ; EINECS ; HSTAR ;   

		       *  Shows the files where 

			  citations on fluoromethane

			  can be found.



	   MEDLINE ; MED80 ;MED85 ; MED90 ;            

	   MESH ; TOXLINE ; TOXLINE65 ;                   

	   TOXLIT ; TOXLIT65 ; TSCAINV ; 

	   SUPERLIST         

     EM  - 9701    



     SS 2 /C?

     USER:

     show cost



     PROG:

     THE ESTIMATED TOTAL ONLINE COST FOR THIS 0 MINUTE CHEMID 

     SESSION IS $ 0.11.



     SS 1 /C?

     USER:

     file chemline



     PROG:

     YOU ARE NOW CONNECTED TO THE CHEMLINE (ROYALTY) FILE.



     SS 1 /C?

     USER:

     fluoromethane (nm)



     PROG:

     SS (1) PSTG (1)



     SS 2 /C?

     USER:

     prt dl



     PROG:



     1

     RN  -  593-53-3

     MF  -  C-H3-F

     N1  -  Methane, fluoro- (8CI)(9CI)

     NM  -  Fluoromethane  [MESH]

     SY  -  Fluoromethane  [NLM]

     SY  -  Fluorure de methyle [French]  [NLM]

     SY  -  Fluoruro de metilo [Spanish]  [NLM]

     SY  -  Methyl fluoride  [CAS:MESH]

     LO  -  CANCERLIT       

		       *  Shows the files where 

			  citations on fluoromethane

			  can be found.

     LO  -  EINECS          

     LO  -  HSTAR           

     LO  -  MEDLINE

     LO  -  MED80

     LO  -  MED85

     LO  -  MED90

     LO  -  MESH

     LO  -  TOXLINE

     LO  -  TOXLINE65

     LO  -  TOXLIT

     LO  -  TOXLIT65

     LO  -  TSCAINV

     EM  -  9502

	 

     SS 2 /C?

     USER:

     show cost



     PROG:

     THE ESTIMATED TOTAL ONLINE COST FOR THIS 0 MINUTE 

     CHEMLINE SESSION IS $1.79.


Figure 2 - Retrieving on RN and Displaying the Name of Substance in MEDLINE


     YOU ARE NOW CONNECTED TO THE MEDLINE (1994 - 97) FILE.



     SS 1 /C?

     USER:

     593-53-3                 

		       *  The Registry Number for 

			  fluoromethane.

     

     PROG:

     SS (1) PSTG (1)



     SS 2 /C?

     USER:

     prt include nm           

		       *  PRINT commands may not be 

			  used with NM.

     

     PROG:

     'NM' IS NOT A VALID PRINT PARAMETER.  COMMAND IGNORED.

     

     SS 2 /C?

     USER:

     prt include rn            

		       * The NM will display in the RN 

			  field in MEDLINE, MEDLINE Backfiles, 

			  MEDLINE-derived files, and the DART 

			  subfile in TOXLINE.

     

     PROG:

     

     1

     UI  -  94368117

     AU  -  Hyman MR

     AU  -  Page CL

     AU  -  Arp DJ

     TI  -  Oxidation of methyl fluoride and dimethyl ether 

	    by ammoniamonooxygenase in Nitrosomonas europaea.

     RN  -  EC 1. (Oxidoreductases)

     RN  -  EC 1.7.3.- (ammonia monooxygenase)

     RN  -  0 (Hydrocarbons, Fluorinated)

     RN  -  0 (Methyl Ethers)

     RN  -  115-10-6 (dimethyl ether)

     RN  -  50-00-0 (Formaldehyde)

     RN  -  593-53-3 (fluoromethane)    

		       *  The NM is displayed here.

     RN  -  67-56-1 (Alcohol, Methyl)

     SO  -  Appl Environ Microbiol 1994 Aug;60(8):3033-5


Figure 3 - Retrieving on RN and Displaying the RN field in TOXLINE

     

     file toxline

     

     PROG:

     YOU ARE NOW CONNECTED TO THE TOXLINE (1981 FORWARD, 

     NON-ROYALTY) FILE.

     

     SS 1 /C?

     USER:

     593-53-3          * RN for fluoromethane.           

     

     PROG:

     SS (1) PSTG (16)

     

     SS 2 /C?

     USER:

     1 or fluoromethane (tw)       

     

     PROG:

     SS (2) PSTG (18)

     

     SS 3 /C?

     USER:

     1 and fluoromethane (nm)

     

     PROG:

     SS (3) PSTG (1)  

		       *  Only one of the eighteen citations 

			  retrieved contains fluoromethane 

			  in the Name of Substance (NM) field.

				      

     SS 4 /C?              

     USER:

     prt include rn

     

     PROG:

     1

     AU  -  Green T

     TI  -  The metabolic activation of dichloromethane and 

	    chlorofluoromethane in a bacterial mutation assay 

	    using Salmonella typhimurium.

     SI  -  TOXBIB/84/013878        

		       * TOXBIB is the MEDLINE-derived 

			 subfile in TOXLINE.



     SO  -  Mutat Res; VOL 118, ISS 4, 1983, P277-88

     RN  -  0 (Hydrocarbons, Chlorinated)

     RN  -  0 (Hydrocarbons, Fluorinated)

     RN  -  0 (Hydrocarbons, Halogenated)

     RN  -  0 (Mutagens)

     RN  -  593-53-3 (fluoromethane)        

		       *  The NM is displayed in 

			  the RN field.



     RN  -  593-70-4 (chlorofluoromethane)

     RN  -  75-09-2 (Methylene Chloride)



     SS 4 /C?

     USER:

     2 and not 3

     

     PROG:

     SS (4) PSTG (17)       

     

     SS 5 /C?

     USER:

     prt 1 include rn          

		       *   In TOXLINE, only MEDLINE-derived records 

			   and DART subfile records have a Name of 

			   Substance (NM) field.

     

     PROG:

     1

     CN  -  UNIV COLLEGE DUBLIN

     TI  -  KINETICS AND MECHANISMS FOR THE REACTIONS OF 

	    HALOGENATED ORGANIC COMPOUNDS IN THE TROPOSPHERE - 

	    STEP-HALOCSIDE/AFEAS WORKSHOP, WITH COVER LETTER 

	    DATED 032494

     SI  -  TSCATS/442284   

		       *  This record comes from the TSCATS 

			  subfile of TOXLINE.

     SO  -  EPA/OTS; Doc #86940000219

     RN  -  56-23-5; 71-55-6; 74-84-0; 74-98-6; 75-10-5; 

	    75-28-5; 75-37-6; 75-43-4; 75-44-5; 75-45-6; 

	    75-46-7; 75-68-3; 75-73-0; 75-87-6; 75-89-8; 

	    76-02-8; 76-05-1; 100-42-5; 110-83-8; 306-83-2; 

	    334-99-6; 353-36-6; 353-49-1;353-50-4; 354-32-5; 

	    354-33-6; 354-34-7; 359-35-3; 377-36-6; 421-14-7; 

	    422-56-0; 425-82-1; 431-89-0; 507-55-1; 556-82-1; 

	    593-53-3;    

		       *   RN for fluoromethane without NM.  

			   TSCATS  records do not have NMs.

		     

	    593-70-4; 679-86-7; 690-22-2; 763-32-6; 811-97-2; 

	    927-84-4; 1493-02-3; 1674-10-8; 1691-17-4; 

	    1717-00-6; 1885-48-9; 2551-62-4; 2837-89-0; 

	    3822-68-2; 6117-91-5; 6185-26-8; 7631-99-4; 

	    7722-84-1; 7727-37-9; 7732-18-5; 7782-44-7; 

	    7782-50-5; 10028-15-6; 10102-43-9; 10102-44-0; 

	    16413-86-8; 21811-29-0; 69884-58-8; 70490-95-8; 

	    73761-32-7; 108083-11-0; 118986-32-6; 119437-62-6; 

	    119437-63-7; 134469-96-8; 134469-97-9; 

	    134469-98-0; 134469-99-1; 138495-42-8; 

	    139702-33-3; 143645-30-1; 144109-03-5; 

	    145252-03-5; 147703-38-6; 147703-39-7 

		    

     SS 5 /C?

     USER:

     prt si            

		       *  This displays the Secondary Source 

			  ID (SI) fields, indicating the 

			  subfile sources for the other 

			  records retrieved in a search on 

			  the RN associated with fluromethane.

				 

     PROG:

     

     1

     SI  -  TSCATS/442284   

	 .       

	 .       

	 .

     16        

     SI  -  BIOSIS/89/05815

     

     17

     SI  -  HEEP/83/04303

Next article

Table of contents

Home

Index



U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894
National Institutes of Health, Department of Health & Human Services
Copyright, Privacy, Accessibility, Viewers and Players
Freedom of Information Act (FOIA)
Last updated: 11 April 2012