Factual database types

A strict separation of these three types of databases is difficult hence most databases contain a mixture of data types. Therefore the classification given here is based on the predominating data type. For example, the major emphasis of a patent database is on hterature, whereas it also comprises numeric and structural data. Another type is the integrated database, which provides a supplement of additional information, especially bibhographic data. Thus, different database types are merged, a textual database and one or more factual databases. 

The fact-based databases are divided into numerical (factual) databases, metadatabases, research databases, and catalogues of chemical substances. These types will be explained in the following sections,... 

The deeper levels of this data hierarchy can hardly be listed here for obvious reasons, but one example is shown expanded in Figure 4, for the upper-level entry Transport Phenomena . It will be seen that the deeper-lying parameter fields include three different types of viscosity measurement, and the respective temperatures, as well as self-diffusion and thermal conductivity. These parameters are individually searchable in this factual database, and may be freely combined with other data elements (e.g., pK values) and substructure attributes. 

The user is often more interested in the contents than in the technical organization of databases. The wide variety of data allows the classification of databases in chemistry into literature, factual (alphanumeric), and structural types (Figure 5-10) [12, 13). 

Compounds are stored in reaction databases as connection tables (CT) in the same manner as in structure databases (see Section 5.11). Additionally, each compound is assigned information on the reaction center and the role of each compound in the specific reaction scheme (educt, product, etc.) (see Chapter 3). In addition to reaction data, the reaction database also includes bibliographic and factual information (solvent, yield, etc.). All these different data types render the integrated databases quite complex. The retrieval software must be able to recall all these different types of information. 

This chapter has only scratched the surface of the multitude of databases and data reviews that are now available. For instance, more than 100 materials databases of many kinds are listed by Wawrousek et al. (1989), in an article published by one of the major repositories of such databases. More and more of them are accessible via the internet. The most comprehensive recent overview of Electronic access to factual materials information the state of the art is by Westbrook et al. (1995), This highly informative essay includes a taxonomy of materials information , focusing on the many different property considerations and property types which an investigator can be concerned with. Special attention is paid to mechanical properties. The authors focus also on the quality and relutbility of data, quality of source, reproducibility, evaluation status, etc., all come into this, and alarmingly. 

The TOXNET databases contain various types of information. One group of these databases, sometimes referred to as the factual databanks , contain... 

ECDIN is a factual databank, created at the Ispra Establishment of the Joint Research Centre (JRC) of the Commission of the European Communities as a part of the Commission s Environmental Research Programme. The databank enables people engaged in environmental management and research to obtain reliable information on chemical compounds. The databank brings together a wide variety of data on chemicals which actually or potentially occur in the environment as a result of human activities. The broad spectrum of parameters and properties contained in ECDIN provides the user with general information on chemical substances and supports the evaluation of the risks connected to the use of these substances. The ECDIN database establishes links between various types of data is therefore a powerful tool for correlation analyses. 

These chemical reaction databases contain not only reaction-type data, but also in most cases, bibliographic or factual information as well. 

All the information from the printed Handbook has been thoroughly checked for errors and redundancies and published in the Main Series and the first four Supplementary Series (Table 1). In addition to this information a large collection of unreviewed excerpts is available on cards, covering the time span from 1960 to 1979 these contain only the substance identification, an indicator of the type of factual information, and a reference to the literature. All the cards have been added to the database. The publication of the 5th Supplementary Series has started and the corresponding information is also being added to the database, thus replacing the former short file data. Since 1980 the excerpts from the primary literature have been directly input to the database and have thus become available in machine-readable form in a very short time. The... 

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