Chemical Abstracts Service, Columbus, OH. Contact CAS Customer Service, 800/753-4227 or 614/447-3700, for details. Cost for subscribers to print Chemical Abstracts: $15,000 for one simultaneous user; $6000 for each additional simultaneous user. Cost for nonsubscribers to print CA: $20,400 for one simultaneous user; $8400 for each additional simultaneous user.

The minimum computer requirements to use SciFinder Scholar are:

PC: 486-66 MHz, DOS 5.0 or higher, 12 MB RAM, Internet connection, Windows 95 or NT 4.0 or higher.

Macintosh: Mac PowerPC, System 7.0 or higher with Mac TCP, 12 MB RAM, 32 bit addressing, color monitor.

SciFinder Scholar offers very easy-to-use computer searching of the complete CAplus, CASREACT, and Registry databases from Chemical Abstracts Service. This means students, faculty, and other researchers have ready access to all journal articles, book chapters, patents, conference proceedings, technical reports, and dissertations covered in Chemical Abstracts (CA). Because it searches CAplus, rather than the CA file (available with the STN Academic Plan), access is extended to articles that are currently being indexed and to nontechnical material such as book reviews and biographical information. The full Registry and CASREACT files are drawn on seamlessly for searches that involve substances and reactions.

SciFinder Scholar is designed so infrequent searchers can explore the chemical literature, thereby eliminating the need to learn the intricacies of searching CA on STN International computer system. It serves that purpose very well. Institutions pay an annual subscription fee, so students and faculty do not need to be concerned about the cost of individual searches. As a result, searches are more likely to be done as part of teaching and research, and students will learn to search CA as part of their work as professional scientists. SciFinder Scholar serves as an excellent resource for teaching students about the coverage, content, indexing policies, and different types of publications covered by the CAplus and CASREACT files, as well as the value and content of the Registry file. In fact, searchers can do more productive searches if they understand the content and indexing policies of CA. Similarly, all searchers should review the tips for searching SciFinder Scholar, which are planned for the Chemical Abstracts Service Web site (http://www.cas.org/SCIFINDER/). This is especially important for understanding how to state research topic questions effectively and understanding the limitations of chemical name searches. Molecular formula searching is easy because the Hill order is not necessary, but searchers need to understand the indexing policies, such as those related to multicomponent substances.

Excellent structure-drawing capabilities increase searching ease. The Help screens answered all of my questions. At this time, structure searching can complete searches for exact matches or family matches (i.e., exact searches and families of structures-different isomers, isotopes, etc.). Substructure searching capabilities were offered to commercial SciFinder subscribers in September 1997; addition of this capability to SciFinder Scholar in the future will be an extremely valuable feature.

While SciFinder Scholar is not meant to replace a thorough search of CA or the Registry file (both available using the Academic Plan) via STN, it will serve both undergraduates and all levels of researchers well for most of their searches. The number of STN searches needed will decrease significantly. When crucial research or publication decisions are made, an STN search of CA is essential. The point-and-click graphical interface is easy to use, although it lacks some Web-type capabilities. There is a Previous button, which works like a Back button. The Go function is not present, although a click on History will tell you what you have done even though it will not take you to a specific place in the search.

Overall, it is easy to navigate throughout the search. The first screen offers a choice of four search options: chemical substance or reaction, research

topic, author name, and CA abstract number or patent number. With the last option, the full record of a CA abstract or a patent number is displayed. Author Name Searches. A template is provided for typing the last name and middle and first initials or names. Alternative forms of authors' last names is a valuable feature, so one automatically searches on similar namesspelling (i.e., Corey and Correy), phonetics (i.e., Caplan and Kaplan), etc.

Author searches sometimes lead to extremely large answer sets. Several choices exist for being more specific. The Refine References option permits selection of another author, type of publication (i.e., patent, review article), or publication years and may help focus the search. The Refine References option can be used multiple times during the same search. If use of the refine features does not produce satisfactory results, the best search tactic would be to search by Research Topic and select "Refine References" by author name. Similarly, to find references by an author on a subject, use the Research Topic option along with the refine feature by author name.

Research Topic Searches. As shown by the search examples on the screen, it is best to type the search topic as a phrase or sentencefor example, chiral epoxidation using metal catalysts. The search system has some built-in "smarts" and divides the question into searchable segments. (Note: if only keywords are strung together, the computer has difficulty deciding how to divide the question into logical segments). In the above search, there are 2 primary concepts: chiral epoxidation and metal catalysts. These concepts are searched several ways:

1. Closely associated. This means that the search terms are all in one sentence. The search is not as precise as an STN search. For example, "chiral" and "epoxidation" from the phrase "chiral epoxidation" will be in the same sentence but not necessarily adjacent. However, good answers will be included in the answer set. The search system automatically finds plurals, abbreviations (epoxidn), and variant versions of a word (epoxides), so there is no need to think of all variations of a term.

2. Both concepts present anywhere in the reference. This is equivalent to a Boolean AND, although the two words in each concept may not be adjacent. This group usually includes additional useful references.

3. Concept #1 only, and

4. Concept #2 only. These last 2 search results are rarely useful, unless the question includes very specific concepts or there are relatively few answers.

Several ways exist to refine the search. One is to select the Refine References option (i.e., by author name, document type, or publication years). Another is to view the full record of selected articles that look particularly promising from the list of citations. A click on the microscope icon brings up the complete computer record. This offers an opportunity to emphasize the importance of understanding the content and organization of a typical record, including the abstract and different types of indexing. This scanning can trigger other ideas for searching, either to focus the search or extend it with additional terms.

For the chiral epoxidation search above, a review article shows that manganese catalysts are used, so re-searching the topic by substituting manganese for the general term metal will identify other relevant articles. In this way, students learn that they need to use both general words like metal and specific terms like manganese, because the indexers use the most specific terms from the article. An alternative way of extending the search to specify Mn is to do another search, this time adding another phrase: chiral epoxidation using metal catalysts like manganese. Just adding "or manganese catalysts" to the initial search topic would bring back all references to manganese catalysts, not only those related to chiral epoxidation.

Learning to state a research topic search is a skill that all searchers need to develop. While SciFinder Scholar is meant to be used without teaching search commands, there are some ways to ensure more productive searches. (See "Tips" on the CAS Web site). Slightly different ways of stating a research topic could result in some differences in answers.

Chemical Substance or Reaction Searches. The third way to search SciFind Scholar is for substance information. There are four options: drawing the structure, specifying the chemical name, specifying the molecular formula, or searching the RN.

Students will readily learn to draw structures. The drawing software is crisp, very easy to use, and works extremely well. It takes very little time to learn. Templates are available for many common substances, as are shortcuts for common functional groups. If there is uncertainty about how to draw, Help messages are available and it is easy to find relevant sections. Currently, searches are possible only for exact or "family" matches (e.g., different isomers or isotopes). A typical search might be for

After drawing the structure, click on Get Substances and the system searches the 17+ million substances in the Registry File. Twenty-one substances have that structure, with different stereoisomers and isotopes. The search is completed remarkably fast. Searchers can scan the graphic structures quickly with 9 or so structures on a screen. When a likely candidate is identified, a click on the microscope brings up the full Registry File record. Here the RN can be pointed out and defined, as well as other chemical names, etc. A click in the box of a selected structure activates the Get References button. Even though a substance may have many references, a Refine References option facilitates identifying articles that discuss preparation, biological activity, or the substance as a reactant. If other information about a compound is needed, one should use the Research Topic search option with RN as a search term.

After a structure is drawn, a click on the Get Reactions option initiates a search of the CASREACT database. This reaction search, in contrast to Get Substances option, uses substructure searching. Reaction searches allow the searcher to specify one role of one substance in the reaction-as a product, reactant or reagent, or "anywhere in the reaction". There are no options for combining two or more substances in a reaction. The reaction search results show the reaction participants, specify the reagents, may list some terms that describe the reaction, and give the reference. A Get References option enables one to see the citation or full record quickly.

Name searching of chemical substances works extremely well when the name matches an entry in the Registry file. For example, common, noncomplicated chemical names such as methyl sulfoxide are located quickly. A search on the name "oxirane, 2-methyl-3-phenyl" brings up 13 structures. Combining fragments of a name or typing a name that is not an exact match with a name found in the Registry file produces no answers. For example, if the name "oxirane, 2-methyl 3-phenyl" is typed (minus the "-" between methyl and 3) or a comma is used instead of the dash, no answers are found. Just typing several name fragmentsfor example, oxirane methyl phenyl-results in no answers. This limitation, however, can be overcome by searching a structure, which is quick and the structure is easy to draw.

Registry Number searching is quick and easy. Just type the RN as given. Again, the search brings up the structure window and the searcher then proceeds either to request all references or select Refine References by focusing in on preparation, biological study articles, or the substance as a reactant. If other information is desired about the substance, use the Research Topic option. In that way one can search more precisely and specify, for the epoxidation question, the RN as a participant in the chiral epoxidation reaction.

The fourth way of searching for substance information is by molecular formula. The sample searches listed clearly show that the formula can be entered in a variety of formats. It is not necessary to convert the molecular formula into Hill order, which other CA products and many reference books require. C2H3SO brings up 38 structures, as does C2H3OS. A check in the box for methyl sulfoxide structure activates the Get References and subsequent Refine References options. Multicomponent substances, for example, salts, are still found only via the dot-disconnected formula (i.e., CH2O3.Ca for calcium carbonate) long used in CA molecular formula indexes.

The Print function offers the option of selecting from 9 formats (e.g., default Citation/Abstract, Citation, and Full Record with Structures) and provides space to type a title for the printout. Search results can be saved for later use in databases (such as Access, Lotus, Excel, EndNote, Procite, Word, or WordPerfect) and in different formats (such as citation, citation and abstract, full).

SciFinder Scholar continues the restricted hours access similar to STN's Academic Plan. Access is available beginning with 5 pm Sunday­Friday and now extends to Saturday at 6 pm. This lack of daytime access is a definite limitation. However, instructors can request special daytime access for classroom use by calling CAS Customer Service.

SciFinder Scholar relies on client software loaded on individual computers and completes searches on computers at Chemical Abstracts Service in Columbus, Ohio. The client software is provided by CAS and loaded on an institution's own server, with subsequent downloading to individual computers. Although the searches come via the Internet, they are completed quickly, even when they involve the more than 17 million substances in the Registry file. References begin to appear very quickly because references are displayed as soon as they arrive at the individual computer rather than after all records have reached the searcher's computer. So, even answers of 500 have references displayed within seconds.