【作者】 Carol DeAngelo
【出版日期】 July, 1999
A surprisingly powerful source of chemical information is now available on the Web of which many people are unaware. Mention the National Library of Medicine (NLM) to those who have used it, and MEDLINE usually comes to mind. For those who haven't explored the NLM Web site, a treasure trove of biomedical, chemical, and toxicological knowledge and data await. For three years now, NLM, located in Bethesda, MD, has been adding to its store of freely available databases on the Internet. Improvements and updates to these databases continue at a steady pace. This move was publicized at the time, but there has been little fanfare since; with MEDLINE now available free as PubMed, it's a good time to take a look at the riches hiding at the NLM site (1).
For those not acquainted with PubMed, it was the first of the free services from the NLM. This database offers access to more than 9 million articles - from 1966 to the present - from medical and research journals at the National Library of Medicine. The articles are indexed, using MeSH (Medical Subject Headings) subheadings, and many contain abstracts as well. The database is updated weekly. PubMed also offers access to PREMEDLINE, a service that is updated daily. Articles that have not yet been given their MeSH subheadings are uploaded into PREMEDLINE with citation information and abstracts.
PubMed is easily searched and is a very forgiving database. Not familiar with the Boolean "and", "or", and "and not"? You don't need to worry about them with PubMed. Just type in your terms with spaces between the words. For example, the search "pulmonary and egashira" pulled up nine citations that included "Egashira" as an author and "pulmonary" somewhere in the citation or abstract. If you want to search in a specific journal, PubMed offers a new feature: Journal Browser. Just type in the name or abbreviation of the journal. Journal Browser returns with the full name, ISSN, and MEDLINE abbreviation. You can then copy and paste the ISSN into your search screen or just click on the hotlink for the journal to find out how many articles from that journal are contained within MEDLINE. One flaw, however: You need to know how MEDLINE recognizes the journal to find it. JAMA was recognized when typed into the journal query box, but Journal of the American Medical Association was not.
If you are concerned about the correct subject terms to search, PubMed offers MeSH Browser. Just type your term, for example, "cancer", in the search box, and you will retrieve an explanation about the medical term "neoplasm" and the tree that comes under this term. Each term is hotlinked to branches beneath it, to allow the user to get the exact MeSH term needed.
Advanced Search adds a drop-down menu to allow the user to search only in a particular field, such as title or author. However, additional limits are due soon, along with a "cubby" feature, in which the user can sign up for storage of individual information such as search strategies and personal preferences. You can read about upcoming features in the New/Noteworthy section that updates all new and proposed changes to the database sites.
The user can access various databases from Internet Grateful Med (IGM) (2). IGM searches MEDLINE using the same search engine utilized by PubMed. What's the difference? The search interface in IGM offers many more options, including
limiting the search subject, title or author fields;
using "and" or "or" between the terms; and
setting the limitations for language, study groups, age groups, publication types, gender, journals, and date or date range.
To further assist the end user, IGM provides all the choices listed above with drop-down menus, so you don't have to guess what the study group or publication type is called in that particular database. If you don't like your search results, the search page includes an Analyze Search option that will give you suggestions to improve your search. Do you only want to search in journals that focus on toxicology? Choose the Specify Journals button, which takes you to a screen where you can select up to 15 journals, by clicking on radio buttons, to significantly narrow your search. After your search, you can see the query strategy you selected by choosing the Details of Search button on the search results page.
Both ChemID and TOXLINE are databases of particular interest to chemists. ChemID can be searched by chemical name, name fragment, CAS number, or molecular formula. All these choices are available in a pull-down menu. The search can be narrowed further by adding a word or descriptor in the classification or notes section of the retrieved information. Two other pull-down menus allow the searcher to query a particular listing agency (such as the U.S. Environmental Protection Agency [EPA] pesticide list) or a database in which the chemical is mentioned (for example, HSDB - see below). The retrieved record includes the molecular formula, CAS number, synonyms, and classification lists in which the chemical is located and databases in which records with this substance can be found.
TOXLINE is described as the repository for bibliographical citations about "toxicological, pharmacological, biochemical, and physiological effects of drugs and other chemicals". TOXLINE contains citations from 1981 to the present; its backfile, TOXLINE65, lists 1965-1980 citations. A little confusing, however, are the drop-down year range selections on the search page. The choices do not match the two databases but instead offer the choices of 1965 to the present or 1985 to the present (instead of 1981, as described in the file). There are more than 2.4 million records in these databases, which are updated monthly, and are drawn from 18 subfiles, the identities of which are available in a drop-down menu box. Most of the citations include an abstract. On the search page, the user can search by chemical name or CAS number and include words in the title, author, or subject fields. Additional pull-down menu boxes allow you to limit searches by date, subfile, and whether MEDLINE citations
should be included or excluded.
There's more! TOXNET, (Toxicology Data Network) is a set of databases focusing on toxicology (3).
Until recently, these databases also could only be accessed for a fee. They include
Toxicology Data Files
HSDB: Hazardous Substances Data Bank; more than 4500 potentially hazardous chemicals, human exposure hazards, and safety information
IRIS: Integrated Risk Information System; health risk data on more than 500 chemicals evaluated by the EPA
CCRIS: Chemical Carcinogenesis Research Information System; more than 8000 chemical records on carcinogenicity, mutagenicity, tumor promotion, and tumor inhibition test results (maintained by the National Cancer Institute)
GENE-TOX: Genetic Toxicology; peer-reviewed information on more than 3000 chemicals and their potential or real mutagenicity (created by EPA)
Toxic Releases Files
TRI: Toxic Chemical Release Inventory; 1987-present data from EPA on estimated toxic chemical releases from industry for more than 600 chemicals
Toxicology Literature Files
DART: Development and Reproductive Toxicology; 40,000 1989-present citations on teratology and other aspects of developmental and reproductive toxicology
ETICBACK: Environmental Teratology Information Center Backfile; DART backfile can be searched for similar data for 1950-1989
EMIC: Environmental Mutagen Information Center; 1991-present data on genotoxic activity in chemicals; produced by the Oak Ridge National Laboratory
EMICBACK: Environmental Mutagen Information Center Backfile; similar data for 1950-1990
For a succinct summary of all that TOXNET has to offer, take a look at the TOXNET Fact Sheet page (4).
Other Databases Available
Specialized Information Services (The Chemical Information Page)
offers the collected links for the new ChemIDplus (with 3D structures), HSDB, ChemID, and NCI-3D (structures from the National Cancer Institute) all at one site (5).
Worth a Look! Definitely worth mentioning are two other sites of more general interest. The newly created consumer medical information page, MEDLINE Plus, is certainly worth a look (6). Designed for the lay consumer in need of medical information, the site has medical dictionaries, directories for locating doctors and hospitals, clearinghouses, access to MEDLINE searching, organizations for free publications, and a reading room.
Last (but certainly not least) is one site that shouldn't be missed: the Images from the History of Medicine page (7). This is a wonderful site with more than 60,000 images from the History of Medicine Library. It contains portraits, pictures of buildings and institutions, caricatures, and illustrations. Searching is user-friendly, allowing either keyword searching or browsing through a list of catalogued items.
The extremely accessible NLM databases provide abundant online instruction and explanation. The blue square with an "i" can be found throughout the search pages and leads the user to information about that particular topic. Much effort has gone into the preparation of these pages, and it shows. A well-kept secret, but probably not for long, the NLM databases provide a wide variety of chemical, medical, consumer, and historical information.
Internet Grateful Med
BIOETHICSLINE (BIOETHICS onLINE)
HealthSTAR (Health Services, Technology, Administration, and Research)
Summary by 李晓霞 on 2000-01-10
Last updated by 黄苏华 on 2000-01-12