There are differences among secondary abstracting and indexing (A&I) services both with respect to the depth and breadth of coverage of chemistry and with respect to the swiftness with which the average reference to a new primary work makes its way into the A&I databases. A very significant change in scientific publishing is now underway. Innovations such as the ACS's "As soon as publishable" process make possible the appearance of Web editions of some original research articles several weeks before the corresponding print versions. This affects the time needed by the A&I services to cover the newest primary literature.
PRIMARY LITERATURE refers to the first place a scientist will reveal to the general population in a publicly accessible document the results of scientific investigations. In many cases, the document that describes these results has undergone rigorous review by one or more peers who help insure the integrity of scientific knowledge. Increasingly, however, we are seeing appear on the Web PREPRINTS, unreviewed literature that is posted by the original author. More traditional primary publications include scientific journal articles, published conference proceedings, technical reports, dissertations or theses, and patents. All of these are collectively called DOCUMENTS.
Different types of information and different levels of detail are found in each of the DOCUMENT TYPES of primary literature. Since that is the case, it is sometimes important to distinguish the document type when a search is being conducted. Therefore, the type of primary document may be coded in a database or printed abstracting or indexing journal that covers more than one type of document in order to aid in retrieval.
Let's look at a few journal titles that one might expect to find in any respectable chemistry library. See the American Chemical Society's Committee on Professional Training Journal List for Undergraduate Programs (Fall 1992 version). Included are news journals such as Science and Nature, primary research journals such as Inorganic Chemistry, and primary journals designed to rapidly communicate new research results such as Chemical Communications and Tetrahedron Letters. Also on the list are some secondary sources, such as Chemical Reviews
The terms "primary," "secondary," and "tertiary" literature are interpreted differently by different authors. We will call SECONDARY LITERATURE textbooks, treatises, monographs and "multigraphs" (books with multiple authors), encyclopedias and dictionaries, handbooks and data compilations, review articles and review serials, bibliographies, and indexing and abstracting services.
All of these secondary works have in common the goal of repackaging and better organizing the new information reported by researchers in the primary literature. Since there is additional work involved in creating the secondary works (that is, they gather their information and facts from the primary works), they are always less current than the primary literature.
Depending on the type of effort expended in their compilation, the secondary works require varying periods of time to repackage or explicate new knowledge. Thus, there is a definite flow of scientific information from the inception of a research idea through the various types of secondary sources. One can typically expect to find the repackaged new knowledge or pointers to/summaries of new primary works in:
It is important to understand that the lag time is only partially linked to the frequency of updating of the secondary publication or database. An illustration of the time lag for journal articles entered in the Chemical Abstracts Service database, which is updated weekly, can be seen in the following abstracts:
Thus, the fact that an abstracting or indexing journal is updated every week or even daily does not necessarily mean that the primary literature covered in that update is the new primary literature that appeared that week. Quite the contrary, there is almost always some lag time between the appearance of the new primary literature and its coverage in the secondary sources. However, with some abstracting or indexing sources, notably ingenta (formerly, UnCover), the time lag is quite small, on the order of a few days.
A development that is reducing the time lag between the publication of new primary literature and its inclusion in A&I services is the electronic publishing of new journal articles long before the appearance of the print versions. The "As Soon As Publishable" (ASAP) policy of the American Chemical Society and similar early publication policies of other primary publishers (e.g., Springer Verlag) have tended to drastically reduce the lag time. Under ASAP, the articles published in ACS journals appear in the electronic versions of the primary journals some two to six weeks prior to the corresponding print title. The references to the articles are also fed into the Chemical Abstracts database (which is a part of the ACS) much earlier than those for the primary journals of other publishers.
Other categories of secondary works are directories, buyers' guides, biographical works, etc. These cannot be related easily to the primary literature in a temporal sense.
There are databases that correspond to the different primary and secondary printed sources. They can be categorized as:
Non-bibliographic databases are sometimes called FACTUAL or SOURCE databases, as opposed to bibliographic databases that traditionally give only pointers to primary publications that have facts in them.
The Internet, especially applications based on the World-Wide Web, is accelerating the creation of true full-text databases and blurring the distinction between abstracting/indexing databases and primary journals. Many scientific full-text databases on the Web now include graphics, such as the Web versions of the American Chemical Society journals. Both HTML versions and pdf versions of the articles are found in some databases. The HTML versions may have enhanced features such as links in the references of the bibliography of an article to ABSTRACTS (summaries) of the cited articles in an A&I database, with further links to the full-text Web version of the cited older articles. For example, it is now possible to link directly from the various options for searching the Chemical Abstracts database to over 1,000 primary journals through the ChemPort option. A project (CrossRef) is underway to provide direct links from the citations in an article directly to the cited article without having to visit an A&I service as an intermediate step.
Most primary chemistry journals are now available on the Web. See the list of WWW versions of primary journals accessible through the IUB Chemistry Library.
The options for database searching include:
VENDORS of online search services (for example, STN International) lease or acquire databases from the database PRODUCERS (such as Chemical Abstracts Service or the Institute for Scientific Information) and make them available on remote computers. For a given vendor, which may have dozens or hundreds of databases on its computers, the databases are all searched by a common command language or graphical user interface. In the vast majority of these cases, there is a fee for searching the databases.
Another option is to search free databases on the Internet. Usually, the quality of the databases that are freely accessible on the Internet is not as high as that of the commercial databases. In addition, there are many differences in the search interfaces that the user encounters among free Internet databases. Nevertheless, they should not be ignored for certain types of searches.
Local organizations now routinely load databases on their own computers. This includes the placement of CD-ROM products on local-area networks (LANs). Doing so often requires the searcher to utilize a number of different search systems, since each product typically comes with its own unique search interface. Several new models of providing databases searching are now being explored with the advent of client/server computer systems.
We will consider works that are designed to teach you how to use primary and secondary works to be TERTIARY works. Many of these are GUIDES of one sort or another. Guides are covered more thoroughly in a later session.
Link to
supplemental readings
Link to Internet
resources on this topic
Copyright
Gary Wiggins
24 August 1997