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Databases for Chemists and Chemical Engineers

Chemical Abstracts

SciFinder Scholar | CAS Online | Standard Abbreviations | Index Guide | Guide to CASREACT | Structure Searching with STN Express

CAS Online

Basic STN Commands | Cheat Sheet | Current Awareness | Quiz

Cheat Sheet: STN Version

Academic Program Hours

The CA, REG, CAOLD, and STNGUIDE files are available:

Monday - Friday 5pm - 5am
Saturday Midnight - 3pm
Sunday 3pm - 5am (Monday)

The LCA, LREGISTRY, LCASREACT, LMARPAT, AND STNGUIDE files are available 24 hours a day.

Selected Commands

All STN files, including Chemical Abstracts Service Online, are searched using the same command language. The commands used most frequently are listed below. You can use the full or abbreviated form of a command at any STN system prompt (=>).

Command Abbreviation Function Example
FILE FIL Enter a STN database =>file ca
=>fil reg
=>fil caold
SEARCH S Search terms in database =>search organometallics
=>s organometallics
EXPAND E View search term and its
neighbor in an index
=>expand pearson w/au
=>e tetrahedron/jt
EXPAND LEFT E LEFT View search term plus words
where term has a prefix
=>e left assay
DISPLAY D Display search results
on screen
(L#/format/record #'s)
=>enter (L1), L#, or ?: L1
=>format (bib): ti
=>enter answer number or range (1): 1-3

=>D L1 ti 1-3

=>d history full
=>d cost full
HELP ? View online help =>help display
LOGOFF LOG Disconnect from STN =>log y
Truncation and Character Masking Symbols

Truncation is the process of using a wildcard charater to locate variant spellings and words having the same word stem. The truncation symbol can be used several ways:

Truncation Symbol Function Example
? Open truncation: represents any number of
characters to the left or to the right of the term
=>s analy?
=>s ?assay?
# Restricted: represents one or zero characters
at the end of a term
=>s polymer#
! Variable character: represents exactly one
character and can be used either in the middle
or at the end of a term
=>s wave!
=>s alk!ne
Combining Search Terms Using Boolean Logic

Boolean operators are used with the SEARCH command to establish a relationship between two or more search terms.

Boolean Operator Function Example
AND Retrieves records where both terms exist =>s gas and chromatography
OR Retrieves records where either term exists =>s gas or liquid
NOT Retrieves records where term is excluded =>s gas not solid
Using >1
If OR is used with AND or NOT in the same
search statement, surround terms being
ORed together with parentheses
=>s (gas or liquid) and chromatog?
Combining Search Terms Using Proximity Operators

Proximity operators are used to specify the relative nearness or adjacency of search terms within the same record.

Proximity Operator Function Example
(W) or (nW) Terms must occur next to each other (or within
n number of words) and in the order specified
=>s gas(w)chromatog?
(A) or (nA) Terms must occur next to each other (or within
n number of words) but may be in any order
=>s gas(2a)chromatog?
(S) Terms must occur within the same sentence.
Useful when search terms within an abstract
=>s gas(s)chromatog?/abs
(L) Terms must be present in the same field (e.g.
title, keyword, or index entry)
=>s gas(l)chromatog?
The CA File

The CA file contains all bibliographic references to literature cited in printed CA since 1967 and complete CA abstracts since 1969. Type FILE CA to enter the CA file. The Learning CA File (LCA) contains a fixed 5% of the full file and may be used to practice online searching.

Subject Searching Example
* Basic Index (default; = title, abstract text, keywords
& index terms)
=>s (solar or sun) and collector?
* Title words only =>s crystallograph?/ti
Author Searching
(Always view author index by using EXPAND command because author names are put into the CA file more than one way. Some records have first name spelled out while others contain only initials for first name.) =>e counsell r e/au
E1  5 counsell patrick j/au
E2  7 counsell patrick james/au
E3 13 counsell r e/au
E4 20 counsell raymond e/au

=>s e3-e4
Chemical Substance Searching
* Individual substances, use CAS Registry
Number (use REG File to find CAS RN's)
=>s 42228-92-2
  • Limit to articles on prepn of compound
  • Limit to articles on derivative of cmpd
  • Limit to articles on prepn of derivative of cmpd
  • =>s 42228-92-2p
  • =>s 42228-92-2d
  • =>s 42228-92-2dp
* Classes of compounds, use text terms =>s ketones
Tailoring Your Search
Review papers =>s crystallograph? and review
=>s L1 and review
Language =>s crystallograph? and eng/la
Publication year- may use 4
digits, 2 digits, or truncation
=>s crystallograph? and 1989/py
=>s crystallograph? and 89/py
=>s crystallograph? and 198?/py
=>s crystallograph? and 8?/py
Range of File- can limit one
search statement or entire
search session
=>s L1 range=(1989,)
=>s L1 range=(1985,1989)
=>s L1 ran=(,1980)

=>set ran=(1985,)
=>set ran=(all)
CA File: Selected Display Formats
Type of Formats Information Obtained
TI Title only
SAM Sample = Title and indexing data
IBIB Indented bibliographic data (all field names spelled out)
BIB Bibliographic data (one line per field)
CBIB Compressed bibliographic data (wordwrapped)
ABS Abstract
ALL BIB, ABS, and INDexing
CBIB ABS Can use more than one display format at a time

The REGISTRY File contains chemical substance information for compounds published in the literature from 1957 to the present. It is possible to search the REGISTRY File several ways: CAS Registry Number, complete chemical name, name fragments, formula, chemical elements, and structure. Type FILE REG to enter the REGISTRY file. The Learning REGISTRY File (LREG) contains a fixed 5% of the full file and may be used to practice online searching. Search term costs are high, so verify that term exists by using EXPAND command before searching it.

Chemical Abstracts Registry Number =>s 1234-55-9
Complete Chemical Name Searching (/CN) =>e sulfadiazine/cn
Name Fragment Searching
(use longest possible name fragment)
=>s amino(L)phosphono
Molecular Formula (/MF)
Arrange elements in Hill System Order:
Carbons first, Hydrogens next, and then all
remaining elements in alphabetical order.
All elements in alpha order if no Carbon
is present.
=>e c8h10n4o2/mf
Chemical Element Searching =>s 1-3/n (L) 6/c (L) cu>0
REGISTRY File: Selected Display Formats
Type of Formats Information Obtained
IDE Identification information (default display)
IDE CBIB ABS Identification information plus display of ten most recent citations along with abstracts in compressed bibliographic citation format
RN CBIB CAS Registry Number & 10 most recent citations
Using search results from REGISTRY File as search terms in CA File

After locating CAS Registry Numbers (using techniques specified above), you can use the L# as a search term in the CA File. For example:

Part 1: Search REGISTRY File =>fil reg
=>s sulfadiazine/cn
Part 2: Use Reg File L# in CA File.
(limits answers to articles on prepn of cmpd)
=>fil ca
=>s L1
=>s L1/p
The CAOLD File

The CAOLD file covers 1957-1966 and is searchable only by CAS Registry Number. Records contain the Printed CA volume and abstract numbers, the document type for patents, and CAS Registry Numbers. You need to search Printed CA to find out where an item was published. You do not need to specify the format when viewing records, just enter DISPLAY command, L#, and number of records you want to display (e.g. D L2 1-25).

Last modified: June 24, 2005

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