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Where to look for scientific information

For the health area, there are specific sources recommended for the search of information which are set out below:

  • PubMed

PubMed is a search engine, freely accessible, of the MEDLINE database for the search of research articles in the biomedical area. This is a service offered by the National Library of Medicine of the United States (NLM) as part of the Entrez plan (Global Query CrossDatabase Search System) of the National Center for Biotechnology Information (NCBI) of the NLM and the National Institutes of Health (NIH). It is estimated that the data bank of MEDLINE covers around 4.800 journals published in the United States and in more than 70 countries around the world; the web address is: http://www.ncbi.nlm.nih.gov/ pubmed/

Before you begin this section it is convenient to warn that there is no correct way to search in PubMed. This will depend on the expertise, creativity and good taste of each researcher, things that are acquired through practice and a greater knowledge on the subject of the search. However, below are some general guidelines that can help those who are just getting in the management of this system.

a) Taking chances.

A search through PubMed is based primarily on the use of key terms or descriptors that are typed in the command line, which you can refine and combine in accordance with your own interests. In the example below, one of the most basic modes of searching through this system is introduced.

Example:

Let’s suppose that the interested person wants a little introduction to the field of stem cell transplants in the treatment of diabetes. The first thing you should do is locate the key words: Transplantation, stem cells, and diabetes. These terms shall be typed in the main page of PubMed as shown in the figure.

Then, click on the search box and the system will show by default a list of the 20 most recent publications in the area. Furthermore, the upper left corner will indicate the total number of records found, that in this case was 907. In the upper right area it is displayed the filtered result in three groups: the total number (907), the number of reviews (347), and the total number of publications for which there is possibility of full access to the text (272). PubMed also provides with some help to the search as records in which the search terms appear as part of the title (and therefore the PubMed interprets that they may be of greater relevance for the search). It should not be forgotten that in this mode, PubMed locates the typed terms in any part of the record (title, authors, key words, abstract, journal, etc.), as shown in the following figure.

b) Optimizing a search.

It is necessary to understand the logic of PubMed for the search. PubMed offers various filters through a system of advanced search (PubMed advanced search) in which you can enter various filters to refine the search by making use of different labels. In addition, there is the possibility to use the specialized terms through the Medical Subject Headings (MeSH), or through the search engine of magazines and authors.

It should be borne in mind that in a search without tags, PubMed will search for the term in any field. Consequently, the possibility of records extends but it is also more likely to find records that are not of interest in the search that is being made. All the information on these assistances, in addition to being available in the tutorials for users, is something that is acquired with practice.

c) Election of the appropriate terms.

To perform a search through most of the fields of PubMed (including the title, abstract or MeSH terms of an article) terms must be typed in English.

It is equally important to be careful with the use of accents and letters that are not used in the Anglo-Saxon vocabulary. This is especially important in the search for authors with surnames in which it is possible to find this type of letters. As much as possible, it is recommended to avoid the use of accents and replace “ñ” by “n” when required.

When you want to search for an exact phrase, it must be enclosed in quotation marks, otherwise the system will assume you are looking for each term separately. This is, if you are looking for lung cancer, it is recommended to type “lung cancer” and not lung cancer.

d) The MeSH terms.

The PubMed search system automatically identifies the MeSH terms or related synonyms that match the terms of a search. However, it is very useful to know the use of these terms in first instance. The MeSH thesaurus contains about 22.000 of these terms. They are hierarchically organized: from the most general to the most specific ones. Through PubMed, it is possible to access the MeSH Database, in which all MeSH terms are organized and you can make a systematized search from them as shown in the following figure.

It is worth mentioning that the search made using the parameters of the MeSH is just one more tool. Its use is not necessarily a guarantee of a more thorough or accurate search. Therefore, the recommendation remains to be the use of more than one search strategy and the own experience. Even, the system of MeSH is not totally foolproof and can lead to limitations and important weaknesses. For example, as it has been already discussed in the PubMed, not all citations have MeSH terms assigned and that can lead to errors or gaps when you start a search.

e) Limit by publication periods.

You can restrict your search to projects published in a given period of time. This can be done through the advanced search option or directly on the general search engine using the tag [dp] then the year of publication that you want (for example, 1977[dp]) or period of years in which you want to perform that search (for example, 1977:1987[dp]).

Example:

In the case below it has done a search for projects made in embryos in the year 1938. In the search box you will see that there is the search term embryo followed by the year 1938 and the tag [dp]. PubMed showed 9 records for this search, as seen in the following figure.

f) Related articles.

In the result of a search, after each reference, there is the link “related citations”. By using it, you can access articles selected by PubMed which by its structure or citation system may be closely associated to the article you are looking for or the records that the system offers based on some of the search parameters. The selection can be based on the existence of common words in titles, abstracts and MeSH terms of the projects in question.

Related articles can be organized into a new page in decreasing order of association with the initially found.

g) Search limits.

One of the most powerful tools that PubMed has is the option of limited search. This option is accessible via the option “limits” in the search area. The limits allow you to establish a series of criteria that allow the custom setting of the search. These are:

  • Publication date or temporary parameter for the search.
  • Type of document (letters, meta-analysis, articles, reviews, or other).
  • Language. It indicates the original language in which the document has been published.

(It should not be forgotten that even though the document has been published in another language, your search in PubMed will always be in English).

  • Species. It allows to distinguish between studies that have been performed in humans than those which have been made in animal models.
  • Gender. It allows to distinguish if the study was done with females or males.
  • Sub-groups. It allows you to organize the search based on a group of magazines (journals in the area of nursing, psychiatry, clinic, or other).
  • Ages. It allows you to organize the documents according to the study group (adults, children, adolescents, or other).
  • Document options. It allows access only to articles of free access or restricted access.
  • Record Type. In the event that you search for articles, patents, formulas, genetic sequences or other.

  • ISI Web of Knowledge (ISI-WOK)

The ISI Web of Knowledge (ISI-WOK) is another on-line academic database developed by the Thomson Scientific’s Institute for Scientific Information. Unlike PubMed, access to WOK is prior subscription. However, one of the main virtues of ISI-WOK, that differs from the PubMed, is the managing of multiple independent databases: the Web of Science, which includes the Science Citation Index (SCI), the Social Sciences Citation Index (SSCI), and the Arts and Humanities Citation Index (A&HCI); the Current Contents Connect; the Derwent Innovations Index; the MEDLINE and the Journal Citation Reports. In this way, ISIWOK covers more than 10.000 magazines of science, technology, social sciences, arts and humanities. The web page is: http://wokinfo.com/

  • Excerpta Medica / EMBASE

Excerpta Medica is a database published in the Netherlands since 1948, it is together with the Index Medicus one of the most important databases in the field of health sciences. However, it differs from the previous one in a highly selective and analytical nature in such a way that it only includes publications of the highest level. It covers around 4.500 magazines and books.

EMBASE is a specialized search platform of the Excerpta Medica Database, developed by Elsevier that contains more than 11 million documents from 1948 until the present day. It covers publications from 70 countries. The database is accessible through the Internet but requires a subscription. The website is: http://www.embase.com/

  • Dialnet

Dialnet is a portal for the dissemination of scientific production in Spanish language. It began in the year 2001 specializing in human and social sciences. Its database, freely accessible, was created by the University of La Rioja (Spain) and constitutes a virtual newspaper library containing the indexes of humanistic and scientific journals from Spain and Latin America, including books (monographs), doctoral theses, homages and other types of documents. Many of the documents are available on-line. Although it is not a database specialized in the biomedical area, it does collect a large part of bibliographic material in the areas of bioethics, ethics of health and scientific and medical ethics. The website is http://dialnet.unirioja.es/

  • LILACS / SciELO

The LILACS or Latin American and from the Caribbean Literature in Health Sciences (in Portuguese Literature Latino-Americana e do Caribe em Ciências da Saúde) is a bibliographic on-line database for the area of medicine and health sciences, developed by BIREME (Latin American and Caribbean Center on Health Sciences Information), with headquarters in Sao Paulo, Brazil. It collects publications that have not been introduced in MEDLINE and which are part of the scientific publications in the Latin American region.

Subsequently, the platform SciELO (Scientific Electronic Library On-line or Scientific Electronic Library On-line) was formed. It is an electronic library project, initially developed by FAPESP or Sao Paulo Research Foundation (in Portuguese Fundação of Amparo à Pesquisa do Estado de São Paulo) and by the BIREME and, over the years, other international institutions have been adding to this project. SciELO enables the electronic publication of complete editions of scientific journals, also facilitates the access through different mechanisms, including lists by titles and by subject, indexes of authors and subjects and a search engine.

The principal countries involved in the project are: Argentina, Brazil, Chile, Colombia, Cuba, Spain and Venezuela; and to a lesser extent, Costa Rica, Mexico, Peru, Portugal and Uruguay. The website is: http://www.scielo.cl/

  • Other bibliographic sources in health

    • MEDLINE (international literature in health sciences).
    • ADOLEC (adolescent health).
    • COCHRANE (data sources of information on health care).
    • ERIC (search of information in the area of education).
    • HISA (history of public health in Latin America and the Caribbean).
    • MEDCARIB (Caribbean literature in health sciences).
    • BIOETICA (Database of the regional bioethics program of PAHO/WHO).
    • PAHO (Catalog of the PAHO headquarters library).
    • PROQUEST (clinical and biomedical collection).
    • WHOLIS (information system of the WHO library).

Bibliographic references

Books

[1]     Vivanco, L. (2009). Metodología de la investigación científica aplicada a las ciencias biomédicas. España: Funiber.

Internet:

[2]     Virtual Health Library (Biblioteca Virtual en Salud). Web link: http://bases.bvs.br/public/scripts/php/page_show_main.php?lang=es&form=simple