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TOXNET HELP TEXT - CTD


Contents


SEARCH SCREEN



SEARCH RESULTS



SELECTED RECORD SCREEN



HOW THE SYSTEM SEARCHES FOR AND DISPLAYS RECORDS



CTD CONTENT AND FIELD MNEMONICS


RECOMMENDED BROWSERS



SEARCH SCREEN


CTD Search for Benzene


Entering a Search Query


In the long empty query box, enter one or more terms (e.g., benzene) which describe your search needs topic. These may be any combination of words, chemical names, and numbers, including Chemical Abstracts Services (CAS) Registry Numbers (RN). Common "stop words" such as "a," "an," "for," "the," and "it," although you may enter them, will not be searched.


Examples of search terms:


-          acetone

-          vinyl chloride

-          67-64-1

-          75-01-4

-          brain

-          dna adducts

-          skin tumors in mice

-          biomarkers

-          aflatoxin b1


The term(s) entered will be searched for in all CTD fields.


The search will be initiated when you click the "Search" button. To erase your search term(s) and start over with a blank query box again, click on the "Clear" button.


Synonym Searching


If your query consists of chemicals, TOXNET will, by default (i.e., the radio button "Yes" is marked selected), expand your search by adding synonyms and CAS Registry Numbers. Thus, if you enter "perchloroethylene," the system will add the CAS RN 127-18-4 and synonyms such as "tetrachloroethylene" and "tetrachloroethene." You have the option to turn off this feature by marking selecting the button "No." This will result in a search only for the exact word(s) you entered. In the example above, the system would then look only for the word "perchloroethylene."


For typical queries, it is suggested that you leave the synonym searching feature on (leave "Yes" button markedselected) in order to maximize retrieval. On the other hand, if you were searching specifically for a brand name product, say "tylenol," and were interested only in records that mentioned the chemical with that name, you might want to turn off synonym searching (mark "No" button selected).


Browse the Index


Browse for hexachlorobenzene Results of Browse for hexachlorobenzene


Clicking on the Browse the Index button willThis feature displays a segment of the CTD index, beginning with the term you enter (e.g., hexachlorobenzene), and lets you scan the index alphabetically (or numerically) above or below the original display by clicking on the "UP"Up or "DOWN"Down button. For each index term, the system displays Tthe number of CTD records containing each of thethat terms is displayed. By checking the "Check to Select" box(es) nextcorresponding to the index term(s) of interest and clicking on the "Check to Select" button, you can search on these selected term(s). You may browse the index to all words, CAS Registry Numbers, or chemical names.


Databases (The Left Column of the Screen)


Clicking on any of the cells in this column will take you directly to the search screen for the database listedselected. "Multi-databases" offers simultaneous searching of HSDB, CCRIS, IRIS, and GENE-TOX. The information icon ( "i") next to each database provides a brief description of it, with links to a more detailed Fact Sheet and a sample record.


Other NLM Resources, Support Pages (The Right Column of the Screen)


You may also visit additional NLM Web-Based Resources:


DIRLINE - Directory andof health and scientific organizations.


Tox Web Links - Links to additonaladditional toxicology wWeb sites.


MEDLINEplus Tox/Env Health - Consumer health information on toxicology and environmental

Hhealth topics.


PubMed - Access to the MEDLINE database of biomedical literature.


NLM Gateway - Searches across multiple NLM databases.


Locatorplus - NLM�s online catalog of books, audiovisuals, and journals.


Or Support Pages:


Help - Page specific dDetailed documentation, such as what you are now reading now, about searching TOXNET.


Fact Sheet - ForProvides an expanded description of CTD.


Sample Record - A look at a sample CTD record.



SEARCH RESULTS


About Your Search Results


CTD search results for benzene


Your initial retrieval is displayed as a list of chemical names, highlighted in blue and underlined, and their CAS Registry Numbers. If your search was for a chemical (e.g., benzene) and there is a match for it in the database, the record for this chemical, referred to as the primary chemical record, will display first, followed by a list of other chemical records which also contain some mention of the chemical you entered. This latter list of chemicals is displayed according to a Relevancy Ranking algorithm. Clicking directly on any of the items will provide a display of the Selected Record Screen, containing all the data, for that item.


If your query consists of words that are not chemical terms, this same Relevancy Ranking algorithm determines the order of display of all your search results.


By checking one or more of the numbered boxes to the left of eachthe list of records, you can perform later operations, such as downloading, on these selections at a later time.


You can alter your search, if you choose, directly in the query box which reappears on this page with your search terms. Alternately, you can use the Modify Search button, described below.


The sidebar vertical series of buttons on the left side of the Search Results page offers a variety of options:


Save Checked Items - This is used to create a subset of your search results. First check the records you want to save, . Tthen click on "Save Checked Items." The system confirms the number of items you saved and lets you display just these references by clicking on a new button - Display Saved Items - which is added to the series of buttons "."


Sort - Sort all or some of the records alphabetically (in ascending or descending order) by chemicalsubstance name.


Details - Summarizes the strategy used by TOXNET to perform your search. This will include your query terms plus any synonyms or CAS rRegistry nNumbers added by the system.


History - Reviews your search session by itemizing your search statements, numbering them sequentially, and listing the number of records retrieved. Clicking on "History" allows you to view earlier search result sets or combine these sets provided they are within the same database.


Download - You can download all or some of the records in "brief" or "full" formats and select particular categories of information (custom formats).


Modify Search - Return to the Basic Search Sscreen with your search strategy retained. You can make changes or perform a new search at this point.


Basic Search - Return to the Basic Search Sscreen with the searchquery box cleared. that yYou can now enter a new search.


Browse Index - This feature displays a segment of the CTD index, beginning with the term you enter, and lets you scan the index alphabetically (or numerically) above or below the original display by clicking on the "UP"Up or "DOWN"Down button. For each index term, the system displays Tthe number of CTD records containing each of thethat terms is displayed. By checking the "Check to Select" box(es) nextcorresponding to the index term(s) of interest and clicking on the "Check to Select" button, you can search on these selected term(s). You may browse the index to all words, CAS Registry Numbers, or chemical names.


TOXNET Home - Return to the TOXNET Home Page.


Page Navigation


The top and bottom of each Search Results page always displays the total number of items retrieved and the range of items displayed on the current page, and, depending on the number of search results, the current page number and the total number of pages. You can navigate through multi-page search results either by specifying a page number and pushingclicking on the "Go" button or by using the small blue arrows to go to the following or preceding page(s).


SELECTED RECORD SCREEN


About the Selected Record Screen


CTD benzene record


This screen displays the record for whichever item you selected on the Search Results screen. If you search for a chemical (e.g., benzene) and then click on the "Primary Record" of the Search Results screen, you will see the entire record, along with a Table of Contents frame on the left. If you click on a different chemical record, the sections of the record best matching your query terms will be displayed (see Best Sections), again, with an accompanying Table of Contents frame. From the Table of Contents, you can then select to view portions of the record by expanding and contracting categories and selecting specific categories and/or fields of the record.


If your original search was for a term other than a chemical, any chemical record you click on from the Search Results screen will result in a "Best Sections" display.


The search term(s) you entered, as well as synonyms (if you selected to search for them), will all be highlighted in red wherever they appear in the text of the selected chemical record.


Across the top of the screen is a header series of buttons with more options:


Next Item - Move forward for a display of the next item (if there is one) in your search retrieval or saved items set.


Previous Item - Move backward for a display of the previous item (if there is one) in your search retrieval or saved items set.


Search Results - Return to the Search Results display.


Basic Search - Return to the Basic Search screen with the searchquery box cleared so that you can enter a new search.


Details - Displays a summary of the strategy you specified for your search and synonyms added by the system.


Other Files - Link directly to records in other TOXNET data or bibliographic files (e.g., GENE-TOX, IRIS, TOXLINE) containing information on your selected chemical.


Modify Search - Return to the Basic Search screen with your search strategy retained. You can make changes or perform a new search at this point.


Download - You can download the selected record in "full" format and select particular categories of information (custom formats).


Browse Index - This feature allows you to display a segment of the CTD index, beginning with the term you enter, and lets you scan the index alphabetically (or numerically) above or below the original display by clicking on the "UP"Up or "DOWN"Down button. For each index term, the system displays Tthe number of CTD records containing each of thethat terms is displayed. By checking the "Check to Select" box(es) nextcorresponding to the index term(s) of interest and clicking on the "Check to Select" button, you can search on these selected term(s). You may browse the index to all words, CAS Registry Numbers, or chemical names.


TOXNET Home - Return to the TOXNET Home Page.


HOW THE SYSTEM SEARCHES FOR AND DISPLAYS RECORDS


TOXNET searches for your terms, in singular and plural form, throughout allthe records unless you specify particular fields. The system will automatically look for synonyms and CAS Registry Numbers of chemicals unless you choose to disable this feature.


Multiple Terms


If you search on multiple query terms, and each record retrieved contains all the terms you entered, the system will first display those records in which all the terms appear in the same section of the record. This These records will be followed by records where in which the terms appear anywhere in different sections of the record. If a multiple-term search fails to retrieve any records containing all the terms entered, the system will display the following message: "No records were found which contain all of the search words. The following records contain at least one of the words."


Relevancy Ranking


Relevancy ranking attempts to determine which documents are most pertinent to the search, and to place the most relevant documents first in the list of returned documents. The ranking is based upon the number of individual search terms occurring in a document, the number of times each search term occurs in a document, its rarity within the database, and the nearness of search terms to each other. Documents containing combinations of search words tend to be ranked higher than documents having isolated occurrences of the words.


Best Sections


In searching for a particular chemical, say "benzene," your retrieval may include chemical records in addition of to the initial matching chemical record, called the "primary" record. These other additional records might appear if they otherwise contain the word "benzene." This might occur, for example, if the chemical is a metabolite of benzene, interacts with benzene, or has been tested along with benzene in a toxicity study.


Clicking on any of these non-primary chemicals on the Search Results screen will display the Best Sections, those where the chemical search term appears with greatest frequency. The term searched appears highlighted in red.


Another situation where in which Best Sections would occur is in searching for a subject, say "DNA." In this case, clicking on any of the chemicals in the Search Results screen will display the Best Sections, i.e., the sections of the records where the word "DNA" appears with the greatest frequency.


CTD CONTENT AND FIELD MNEMONICS


CTD Content and field mnemonics


RECOMMENDED BROWSERS


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