Effective searching in web-based databases depends on how well your search is formulated. Usually at least two types of searches can be performed: subject and keyword. Most online searches tend to default to the keyword variety. Database users have to read onscreen directions to see how, or if, subject and keyword searches are differentiated.
When you type in a keyword search in a database, you are instructing the search mechanism to analyze every eligible document in its inventory, and return to you only the ones that include all the relevant terms you typed in.
Since the computer will only retrieve articles containing all of the significant terms that you type in, good researchers must choose their terms well. Which "key" words will the authors of documents be likely to use when writing on a certain topic? What terms, if any, have database designers decided to formalize into an official list of searchable key words? It pays to take a few minutes before beginning your search to organize it. Read onscreen directions to help optimize your research strategies. Using too many terms, or too few, will too often retrieve nothing useful.
Analyze your search strategy frequently. As necessary, narrow the search by deleting extraneous terms, or broaden it by adding appropriate ones, to get the best results. Using synonyms or related terms in one or a series of keyword inquiries will help to make searches more effective.
To perform a subject search, database searchers usually have to use another interface of the database other than the keyword approach. This subject connection to database contents would allow searches by concept rather than by individual words.
Keyword Searching and Boolean Operators
If you were writing a paper asserting, for example, that "marijuana use in California should not be legal", you might achieve good results with a keyword search. Keyword searching allows you to "customize" your searches by combining more terms than a less-flexible subject search could do. Use only the key words (important words; words that have substance and meaning) in the thesis (such as marijuana, California, and legal in the example above) and type them in. Discard meaningless words such as in, should, not, and be, since they are unimportant for retrieving information in the search. Such insignificant terms are called stopwords.
Keyword searches that combine two or more terms imply a connection between the terms. These connections are expressed in what is called Boolean terms or operators. The three Boolean operators for keyword searching are AND, OR, and NOT (or AND NOT).
Using AND and NOT will narrow search results; OR will expand the results. The sample thesis above assumes an AND connection between terms: when you type in the search words, you’re asking for all the documents with the words marijuana AND California AND legal in them. Many databases and some search engines default into an AND search.
The sample search above could be broadened by using the OR option. If you used, for instance, the words "legal OR lawful", you would add another variable, a word meaning almost the same thing as the word "legal". Since this is a word search, the computer would now pick up articles that might have the word "lawful" in place of "legal".
Similarly, the NOT option changes the parameters of a search, cutting down on the number of articles retrieved. The search "marijuana AND legal AND California NOT San Francisco" would omit articles that mentioned San Francisco when discussing, for example, legal use of marijuana in California.
Try to keep your search to only 3 to 4 relevant terms at a time, with their proper Boolean connections. If you need to use more terms, try breaking your unwieldy single search into two or more smaller searches.
Review the section above and prior sections, if applicable. Then:
Click Here for Quiz 4: Online Searching Basics
Online Searching: Library Databases
Ebscohost MasterFile Premier and General Science Full-text 1984-Present
The fundamentals of Boolean searching, the basics of using the OPAC, and an introduction to using print indexes and the Periodicals Holdings List
have been explored in previous pages. And several of the searching principles learned in prior readings can be applied to searching Ebscohost MasterFile Premier.
When you are at SMC you have on-campus access to Ebscohost
without having to log in with your SMC username and password. However, for off-campus access to Ebscohost
, and to other Library online resources, you will need to use the username and password provided by your SMC student account
Ebscohost is one of SMC Library’s electronic periodical indexes, used in order to find appropriate articles from magazines, newspapers, or journals. Ebscohost is a web-based database to which the SMC Library subscribes. This online general index comes to us via the World Wide Web, but it is a proprietary database published by the Ebsco company. Since Ebscohost is a general index, it contains articles on many subject areas instead of just one. In addition, it offers keyword, customizable searching and the full text of many of its articles, which come from magazines, journals, newspapers, and other sources.
Ebscohost indexes over 2,700 periodicals. This database supplies articles on many subjects across the disciplines, including many science articles. Sources used include magazines, journals, and newspapers. Full text of many articles is provided. Current articles as well as those that go back as far as the 1980s are included. Ebscohost searches are not case-sensitive and can be done in twomajor ways: by subject, or by several variations on a keyword search.
In Ebscohost you may limit your searches by factors additional to your keywords or subject, such as to a specific periodical used in the database, to specific dates, or only to "hits" that contain the entire article, and not just a citation or abstract.
Not only can you choose the periodical or date limiters, but in addition, searches can be confined to scholarly journals by selecting the Peer Reviewed limiter on the "Guided Search" or "Expert Search" page. When this is done, all articles retrieved will come from scholarly sources. A "peer-reviewed article" is one that, before being accepted for publication, has been reviewed or examined and judged to be worthy of publication by a panel of experts in the relevant field.
The default in Ebscohost is to a very fundamental keyword search, called a "Basic Search". Keyword searches are more efficient when using Boolean strategies.
The "Subject Search" is initiated by clicking on the appropriate icon near the top right of the screen. Instead of searching for words as in a keyword search, it groups all articles on the same topic under an authorized subject heading, and searches for the subject heading and the articles grouped thereunder.
The "Guided Search" and the "Expert Search" are variations of the keyword search, but each allows for different types of customizing and limiting of search parameters. For example, a keyword construction such as "California AND marijuana AND legal" might be modified, in a Guided Search as well as in a Basic Search, to include limiters like "full text only", etc. But a Guided Search also allows for specifying the fields, or areas, in which you want each selected keyword to appear. You might want the keyword "marijuana" to appear in the subject field, the word "legal" to appear in the title field, and "California" to appear in the abstract field. Or you may elect to have each keyword appear in any of the fields.
Read the search tips provided by the database to gain a good idea of when to use each search variation; experiment with different variations to see which ones net the best results for your research needs.
The citation below represents an entry from Ebscohost. Its components are explained in the list following the citation. Note that the article below is the same article that was cited earlier from the print source General Science Index. This illustrates the fact that different indexes sometimes carry the same information, whether the sources are electronic or in print. Compare the differences and similarities of both indexes, noting the styles, information covered, sources used, scope, and intended audiences. Use this information, and the other information in this and previous chapters, to answer the questions following this section:
Analysis of a Record from the Ebscohost Database:
Title of the Article: "U. S. considers medical role for marijuana"
Subject Heading(s) for the Article: MARIJUANA--Therapeutic Use--Law & Legislation--United States; MEDICINAL Plants--Government Policy--United States; etc.
Source (i.e. Title of the Periodical containing the article): BMJ: British Medical Journal
Date of the Article: 04/07/01 (April 7, 2001)
Volume Number of the Periodical: 322
Issue Number of the Periodical: 7290
Page Number of the Article: 817
Length of the Article (i.e. how many pages long): 1/2 page
Type of Illustrations (or other additional information in the article): 1c (1 chart)
Author(s) of the Article: Deborah JOSEFSON
Summary of the Article: The abstract, beginning with the words "Debates whether...."
Finding Scholarly Research Articles in Ebscohost
Ebscohost database maintains many full-text documents and abstracts of scholarly journal articles in its database. Follow these basic instructions on finding peer-reviewed articles from scholarly journals in Ebscohost:
Go to Databases on the Library Home Page
Click the Health &Science option
Find and click the Ebscohost MasterFile Premier link
At the "Basic Search" default, enter your search term(s) into the text box, using Boolean expression if applicable
For scholarly/peer-reviewed articles from journals, use the "Guided Search" or the "Expert Search" option
Find the "Limit Your Results" section below the search box and select the Peer Reviewed option
Click Search. Only peer-reviewed (scholarly) journal articles will be retrieved
Remember that Ebscohost, like many online databases, may undergo appearance, content, and search-option changes from one day to another, and always read the onscreen instructions
For more in-depth help, click "Online Help" at the upper right of an Ebscohost search screen.
Ebscohost is just one of the online databases available at SMC Library that would be of interest to life sciences students. Others include CINAHL (Cumulative Index to Nursing and Allied Health Literature). It is an index to health sciences journals and provides citations for the indexed articles, but not the entire text of the articles. See a complete list of SMC’s Library Databases.
General Science Full-Text is another useful online periodicals index/database. Again, while you are at SMC you have on-campus access to General Science Full-Text without having to log in with your username and password. Just as with Ebscohost, however, you need to use the username and password provided by your SMC student account, for off-campus access to General Science Full-Text.
General Science Full-Text is a database that includes articles and citations from science-related magazines and journals, starting from 1984. By far the greater portion of its entries are abstracts or citations of journal articles, with its available full-text articles appearing from 1995 onward. This online periodicals index does not as yet index nearly as many periodicals as Ebscohost, but its concentration on one subject area, the sciences, makes it a valuable resource nonetheless.
In SMC’s Library Databases, find and click General Science Full-Text 1984-present.
At upper right, click "SearchPlus".
At the search screen, type your subject /keyword in "Enter terms, select options" box.
Choose where the keyword should appear, e. g. words anywhere, subject etc.
Click the AND option to add a second term to your search, if applicable.
Analyzing a Record from General Science Full-Text
The record below represents an entry from General Science Full-Text. Its components are explained in the list following the record. Note that it carries substantially the same type of information found in Ebscohost records, with a different layout and different details. This reinforces the fact that different indexes usually display the same core information, with individualizing details, additions, or omissions.
Compare visually the differences and similarities of both indexes as exemplified in both sample records, noting the styles and information offered. Use the information in the analysis below to help you decide on the answers to Quiz 4B, which follows this section:
Full Text: When the entire article is available in General Science Full-text's database, this option appears. Choose to view the article as an HTML document or as a PDF file (using Adobe Acrobat)
Title: "The risks for late adolescence of early adolescent marijuana use"
Personal Author: The person(s) listed as writing, or being responsible for, the content of the article, as opposed to an organization (i. e., "Corporate Author") listed as writing or being responsible for the content of the article:
Brook, Judith S.; Balka, Elinor B.; and Whiteman, Martin
Peer Reviewed Article: Indicates whether an article is from a scholarly research-level source.
Y = Yes; N = No
Abstract: The summary of the article
Publication Year: 1999
Journal Name: Title of the Periodical in which the article appeared
Source: Title of the Periodical, or other supplier, that provided the article
Physical Description: Informational note giving useful additional data about the article:
bibl: the article contains a bibliography
il: the article is illustrated
Language of Document: The original language in which the article is written:
Descriptors: Subject headings/keyword terms or phrases that describe the topics treated by the article:
Youth--Conduct of Life; Marijuana; Drug Abuse
Document Type: Indicates whether the article is a "Feature Article",
Examine the analyzed citation above from General Science Full-Text. Use it as a guide to help you analyze the citation and answer the questions in the following quiz:
Online Searching: Internet Websites
The World Wide Web provides a number of useful life- and health-sciences websites that would repay investigation by students of the biological sciences. The information in websites differs from that in proprietary databases in that the databases pre-screen and pre-select their information before distributing it (usually for a fee) according to sets of pre-existing standards. The documents on the still-evolving Internet, however, are generally not screened according to pre-established academic or other standards; virtually anyone with an Internet-equipped computer can post documents on any and all subjects. A vast quantity of information on the Web is therefore not up to academic professional, scholarly, or authoritative levels.
In academic or scholarly databases, the majority of material included has been somewhat pre-selected for the researcher. The publishers have winnowed out material that they believe do not meet the standards they are striving for, or that do not match the needs of their target audiences. Researchers still have to search for and separate out the materials that fit their needs of the moment. But they can select from a largely pre-screened pool of choices, which means that some of the "work", in a sense, has already been done for them!
The present state of the Web, however, offers no such safety net. Researchers using the Web must do all the work of searching out and evaluating their search results for appropriateness and authenticity, often in what seems like a vacuum. Great care should be taken in relying on information from any research source, and even more care should be taken with information from the Internet. This certainly applies to researchers in the sciences, where accuracy and authoritativeness are so important.
When using the Internet, choose documents from reliable and stable sources. Use the hints from Cornell and UCLA web pages on evaluating web sites to help you decide.
The following information introduces MEDLINE, a much-respected database of the National Library of Medicine. Practice searching for your subject in MEDLINE to gain experience in researching a scholarly website.
The United States National Library of Medicine
The National Library of Medicine (NLM) is "the world’s largest medical library", a U. S. government agency headquartered in Maryland. The NLM has made many of its databases available to the public through the Internet. Two of the main avenues to their information is through PubMed or the NLM Gateway, both of which provide access to MEDLINE.
PubMed and MEDLINE
The web-based NLM Gateway allows simultaneous searching of several of NLM’s databases at once, including MEDLINE, OLDMEDLINE (containing journal references published before 1966), MEDLINEplus (consumer health topics) and others.
The Internet, which can be used to search such websites as MEDLINE for citations and abstracts (no direct full text) of relevant journal articles, is accessible from all SMC Library workstations in the reference area.
Current SMC students and staff do not always have to be physically present on the SMC Library premises to gain access to databases and other electronic resources. The Library’s online offerings are available from all Internet-equipped labs on campus. In addition, current SMC staff and students may access them from home, or from any off-campus Internet-equipped computer to which they have access. You must establish a user account with the College, obtaining a username, password, and e-mail privileges. Sign up here.
MEDLINE is an online database that is often of great help to health and life science researchers. It began years ago as the "Medical Literature, Analysis, and Retrieval System" (or MEDLARS) and has now become MEDLINE (Medical Literature, Analysis, and Retrieval System Online). It is probably the most well-known of the NLM’s databases, and is considered by them to be their "premier bibliographic database. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi
PubMed, an online searching service of the National Library of Medicine, provides access to over 11 million MEDLINE citations back to 1966, and additional life science journals. PubMed includes links to many sites providing full text articles and other related resources.
This resource is one that life sciences students should become familiar with for its vastness, impressiveness, and the fact that it is free to anyone with Internet access. It is part of a retrieval mechanism called Entrez. PubMed is a database of bibliographic information drawn primarily from the life sciences literature, with a focus on biomedicine. PubMed contains links to full-text articles at participating publishers' Web sites as well as links to other third party sites such as libraries.
Click the following to go to the PubMed site to practice searching in MEDLINE via PubMed’s interface. Or you may want to study the PubMed tutorial to become more familiar with its contents and capabilities before beginning trial searches.
Review the section above and prior sections, if applicable. Then:
Click Here for Quiz 4C: Online Searching and Review
Congratulations, you have finished the tutorial!