STN's proximity operators can help you generate a comprehensive set of records relevant to your topic of interest, while eliminating extraneous answers. Placed between terms in your query, proximity operators are effective tools to limit, widen, or otherwise define your search. You can use proximity operators not only to require that two terms appear near each other but also to require that two fragments appear within the same term.
Overview of proximity operators and their standard usage
In addition to the Boolean search operators AND, OR, and NOT, STN offers proximity operators with which you can indicate, with even greater precision, how closely terms and concepts must appear within a record.
Although proximity operators can have additional, specialized applications in some databases, the inverted triangle below illustrates the overall relationship between the operators and their definitions in most databases. As you move toward the tip of the triangle, the operators require tighter linkage between the concepts or terms in your query.
For this discussion, a term is defined as "space-to-space" and a fragment can be any 4-letter portion of a term. However, in two cases described later in this article, "fragment" has a more specialized definition.
The (T) proximity operator
Linking two fragments in a search query with (T) requires that they appear within a single term in the retrieved record(s). This intra-term association differentiates (T) from all other proximity operators, which specify inter-term associations.
Since two fragments cannot simultaneously occur at the beginning of a single term, you must use left truncation to indicate the fragment(s) that may be found embedded in or at the end of a term. Therefore, the (T) operator can typically only be used when conducting text searches in fields that permit simultanous left and right truncation (SLART).
Answers retrieved with (T)
The following search example returns records with both of the fragments anti and allerg in a single term in the Basic Index.
=> FIL WPINDEX
=> S ?ANTI? (T) ?ALLERG?
1171169 ?ANTI?
35080 ?ALLERG?
L6 16477 ?ANTI? (T) ?ALLERG?
This search yields an answer set in which records contain terms such as antiallergic...
=> D KWIC 1-10
L6 ANSWER 2 OF 16477 WPINDEX COPYRIGHT 2007 THE THOMSON CORP on STN
ACTV ACTIVITY - Antiasthmatic; Antiallergic; Antiinflammatory...
...as well as terms in which anti and allerg are not adjacent but are still within a single term, such as antiimunoallergic.
L6 ANSWER 14651 OF 16477 WPINDEX COPYRIGHT 2007 THE THOMSON CORP on STN
ACTV ACTIVITY - Antiinflammatory; antiimmunoallergic; keratinocyte antiproliferation agent; dermatological; antirheumatic...
It is possible that the fragments specified in the search query overlap in the retrieved record.
=> FILE CAPLUS
=> S ?PYRO? (T) ?OXYL?
354799 ?PYRO?
1065632 ?OXYL?
L1 1996 ?PYRO? (T) ?OXYL?
=> D L1 2 AB
L1 ANSWER 2 OF 1996 CAPLUS COPYRIGHT 2007 ACS on STN
AB ...connected with the anti-F1 antibody of Yersinia pestis to pyroxylin membrane and assembled...
Or, they may appear in the reverse order.
=> D L1 14 AB
L1 ANSWER 14 OF 1996 CAPLUS COPYRIGHT 2007 ACS on STN
AB ...conversion of Pheid a to a precursor of pyropheophorbide (PyroPheid), C-132-carboxylPyroPheid a, by demethylation,...
Using (T) to find chemical substances
In CHEMSAFE and DETHERM, the (T) operator performs a specialized function. It can be used to define a search for chemical substances in the Element Count (/ELC) or Element Symbol (/ELS) field. You can use (T) to limit search results to records in which two elements are part of the same molecular formula. Further, you can specify the number of those elements in the molecular formula.
In the following search, the query requires that 2 silver atoms and 3 oxygen atoms are present in a single molecular formula.
=> FIL DETHERM
=> S 2/AG (T) 3/O
177 2/AG
36135 3/O
L2 9 2/AG (T) 3/O
=> D HIT
L2 ANSWER 1 OF 9 DETHERM COPYRIGHT 2007 DECHEMA/FIZC on STN
Substance (1) of (1):
Chemical Name (CN): Silver bromide metaphosphate (AgBr0.55(PO3)0.45)
Molecular Formula (MF): Ag2 Br O3 P
CAS Reg. Number (RN): 172850-19-0
Using (T) in patent databases
The (T) operator also has a specialized use in the following patent databases: PCI, FRANCEPAT, KOREAPAT, INPADOCDB, and the Derwent World Patents Index (DWPISM) databases. In addition to finding fragments or elements in a single "term" in a record, (T) can require that the fragments belong to a single patent classification or structure identifier. For example, each IPC Main Group (/MGR) or Subgroup (/SGR) can be linked to the corresponding subclass entries.
=> FIL WPINDEX
=> S B31B/ICM (T) 19-41/MGR
852 B31B/ICM
5489292 19-41/MGR
L2 213 B31B/ICM (T) 19-41/MGR
=> D HIT
L2 ANSWER 1 OF 213 WPINDEX COPYRIGHT 2007 THE THOMSON CORP on STN
IC ICM B31B019-00
ICS B31B019-62; B31B027-00
Too many terms
Using the (T) operator with common word fragments occasionally retrieves so many answers that system limits are exceeded.
=> FIL CAPLUS
=> S ?OXYL? (T) ?AMIN?
TERM '?AMIN?' EXCEEDED TRUNCATION LIMITS - SEARCH ENDED You have entered a truncated stem which occurs in too many terms. Make the stem longer and try again. For example, if your original term was 'degr?' to search for variations and the abbreviation for 'degradation', you could replace it with the expression '(degrdn OR degrad?)'. If your search term was numeric, e.g., 'C>5', reduce the size of the range.
In such instances, you may consider imposing additional restrictions on your search, or lengthening at least one of the fragments. In this example, adding the letter O to the end of AMIN keeps the search results within system limits.
=> S ?OXYL? (T) ?AMINO?
1068940 ?OXYL?
1864028 ?AMINO?
L1 16923 ?OXYL? (T) ?AMINO?
Conclusion
The (T) operator has the unique ability to require that multiple fragments appear in a single term in the retrieved records. In most databases, a fragment is any 4-letter portion of a term. In a limited number of databases, the definition of "fragment" can be extended to include elements within a molecular formula or even components of patent data.
The (T) operator is one of many STN tools that can help you increase the precision of your search queries.
Additional resources
For more information on using (T), log on to a particular database and enter HELP (T) at an arrow prompt (=>). If no help message displays, (T) can be used in fields with SLART. If you are in a database in which (T) can be used to find chemical substances or patent data, the help message gives a brief description and search example.
To learn more about search term proximity operators, visit STN User Documentation and STN Databases with SLART pages.
Updated: 7/24/2008 2:51:49 PM
