BASE in General

  • What is BASE?
    BASE (Bielefeld Academic Search Engine) is one of the world's most voluminous search engines especially for academic web resources. Try searching with BASE right now!
  • What is Different about BASE?
    BASE facilitates effective and targeted searches and retrieves high quality, academically relevant results. Other than search engines like Google or Bing BASE searches the deep web as well. The sources which are included in BASE are intellectually selected and reviewed. That's why data garbage and spam do not occur. Read more details about the project.
  • The People Behind BASE
    BASE represents a project of Bielefeld University Library: The BASE Team.
  • BASE Future Developments
    The strategic project BASE is in a state of constant development.
  • Get in Touch With Us!
    We highly appreciate your comments and feedback. Leave us a message, write a comment in our blog or send a tweet to @BASEsearch.

Indexing / Content Sources

  • Which indexing software is used for BASE?
    Since May 2011 we are using the open source search technology of Solr/Lucene. Until May 2011 the search engine technology of Microsoft FAST (Fast Search And Transfer) was used.
  • Which criteria do new sources have to meet to be added to the BASE index?
    The source has to contain academic content. At least some documents from the source are available as open access (full texts free of charge, without registration). The metadata of the docments are provided via a valid OAI-PMH interface.
  • How can I recommend a new content source?
    You may suggest a new content source anytime if it fits our requirements (see above). We also observe several repository directories like OpenArchives, ROAR and OpenDOAR or repository software directories like DSpace or OJS regularly and harvest and index the content of sources.
  • How do I set up an OAI interface, so that my content source can be indexed by BASE?
    Repository software like DSpace, Eprints oder OJS (for journals) provide an OAI interface by default. Sometimes it has to be activated or configured. Check out our Golden rules for repository managers. They might be helpful to optimize your OAI interface. You can also set up an OAI interface on your own. Look for the implementation guideline at the Open Archives Initiative's website. You can find more general information about OAI at OpenArchives.org and Wikipedia. With our OAI validator OVAL you can easily verify if your repository is compliant with the BASE requirements.
  • My source does not provide an OAI interface. Is it possible to index the documents in BASE nevertheless?
    In case your source does not provide an OAI interface, upload your documents to aggregators like DataCite or Zenodo, to subject repositories like RePEC or add your open access journal to DOAJ. We are indexing these sources regularly. However, the best way to get your documents indexed by BASE is to provide an OAI interface - in this case we can assure fast and smooth indexing of your source and data from your source will be presented completely and in the best possible way.
  • How often do you update the content of indexed sources?
    We are updating all indexed sources twice a month. In larger intervals all content is completely re-harvested and re-indexed.
  • Why are some sources or some documents indexed incompletely?
    If a data source is not indexed completely, this is generally related to trouble with the OAI interface of a data source. The web surface might be OK, but as we index OAI-metadata only, the web surface is not relevant for us. You can report errors via our contact form. If you are a manager of a repository, please check the compliancy of your repository using our OAI validator OVAL.
  • Do you delete data sources from the index?
    All data sources are checked regularly. If a data source is not working properly any more or doesn't offer any open access content, it is deleted from the index - temporarily or permanently.

Searching / Result List

  • How do I search BASE?
    See our search help.
  • Do you offer a full text search in the indexed documents?
    Due to time and performance constraints we are indexing only metadata (title, author names, abstract …) of documents. Thus it's not possible to search the full text of the indexed documents.
  • Can I narrow a search on open access content only?
    After performing a search you can narrow your search on open access documents only. Click on "Access" in the "Refine Search Result" box. The result list will be narrowed on documents, which are clearly marked as open access documents by the data provider in their metadata. Keep in mind that only 40% of all indexed open access documents can be identified as open access because of lack of metadata information.
  • Why can't I access the full text of a document?
    About 60% of the indexed documents in BASE are open access, the rest are mere metadata entries without full text or can only be accessed, if you are authorized for accessing this particular data source. You can search the metadata of all indexed documents. The authorization is always done by the content provider. If you don't have access to a full text although your institution supposedly is authorized, please contact your IT department or the content provider.
  • Why do I always end up with an error message when I try to access a document?
    If you get an error ("page not found"), the web address (URL) of the document might have changed or the document was deleted since we indexed the repository recently. Though content from academic repositories should provide permanent addresses and changes or deletion of documents should be communicated via the OAI interface, in practice it's often not the case. Therefore it might happen that links to documents which appear on our result list do not work. Another reason for an error might be, that the server of the content provider is temporarily or permanently not available. If you encounter an error, please leave us a message. We will contact the content provider or remove the content source from our index, if it's a permanent problem.
  • What are metadata?
    Especially in an academic environment you will often come across documents containing metadata. These are descriptive elements assigned to a document in order to specify it both in technical respect and in terms of content. Metadata are for example author's names, publication dates, abstracts, language or - in case of a journal title - details regarding the title or the issue. If metadata are available, you may perform a targeted search for authors. In the result list you may refine the search result by categories.

BASE Website

  • Why do I always end up on the German-language pages?
    The BASE web pages are presented in the language, which is preselected in your browser settings. These settings can easily be changed (e.g., if you use the Mozilla "Firefox" browser, choose "Preferences" and then "Settings"). Switch to "English" as preferred language and the BASE pages will be presented in English immediately.
  • Is there a print version of the BASE web pages available?
    The BASE web pages are designed to automatically change into a printer optimized version when the printing command is released.
  • Is there an optimized version of the BASE web pages for mobile devices (smartphones etc.) available?
    If you access BASE with a mobile device you will be automatically forwarded to the mobile version of BASE. You can access the mobile version directly at m.base-search.net
  • Do I have to enable Javascript, Java or something similar?
    The BASE web pages are designed to show complete functionality without Javascript. Techniques like Java or Flash are not used at all.
  • Are the pages "optimized" for specific browsers or browser versions?
    There are no restrictions of any kind. The pages are properly designed according to web standards (XHTML, CSS) and comply with the WCAG regulations.