PUBMED简介（PUBMED abstract）Source: /sjs/pubmedjj.htmA brief introduction to PubMed retrieval systemPubMed retrieval system /PubMed /The PubMed system was developed by the National Center for Biotechnology Information (NCBI), an online retrieval system for retrieving MEDLINE and PreMED-LINE databases. MEDLINE is the most important bibliographic abstracts database ofU.S.National Library of Medicine, which covers medicine, nursing, dentistry, veterinary medicine, health care and basic medicine. More than 4000 kinds of biomedical journals have been collected in more than 70 countries and regions in the world, with over 1000 entries of bibliography abstracts in 1966.PreMEDLINE is a temporary database of medical literature. It receives new data every day, providing users with basic bibliographic entries and abstracts, which are moved to MEDLINE once a week after indexing and processing.PubMed also accepts the document entry data provided by the publisher via electronic communication, which is illustrated with [MEDLINE, record, in, process], and is marked with the [Record as supplied by publisher]. The daily entries are constantly sent to the PreMEDLINE database, but some entries due beyond MEDLARS database scope, will never be replaced by PreMEDLINE or MEDLINE entry, for example in the comprehensive scientific journal (Science or Nature) on the table the geography etc..Main features of PubMed systemPubMed searchThe use of the Details keyThe use of the --URL key for storage retrieval policyFeature column (Feature Bar) introducedSearch results display, save, print--------------------------------------------------------------------------------Main features of PubMed system1. vocabulary automatic conversion function (Automatic, Term, Mapping)In the search questions box of the PubMed home, type a search word, and the system will use the following 4 tables or indexes sequentially to retrieve the retrieved words and then retrieve them.(1) MeSH conversion table (MeSH, Translation, Table), including MeSH words, see words, sub topics, etc.. If the system has found the word matching the search word, it will automatically translate it into the corresponding MeSH word and TextWord word (Title noun and abstract word). For example, type"Vitamin H", and the system converts it to "Biotin [MeSH Tems] OR Vitamin h [Textword]" after retrieval.(2) of the conversion table (Journal Tanslation Table), including full name, abbreviation of MEDLINE and ISSN. The conversion table can type of name into the "MEDLINE Name]" after the retrieval of the abbreviation [Journal. For example, in the search questions box, type "New England Journal of medicine", and PubMed converts it to "N, Engl, J, Med, [Journal, Name]".(3) phrase list (Phrase, list). The unified medical language system in the table and form phrases from MeSH containing synonyms or different English vocabulary writing (UMLS: Unified Medical Language System) and supplementary concept (material) name [Supplementary Concept (Substance) Name]. If the PubMed system is not found and the retrieval word matching the words in the MeSH and of the conversion table, will find a short list.(4) author index (Author, Index). If the word entered does not find the matching word in the above table, or the typed word is a phrase followed by an 1~2 letter, the PubMed is the author index. If you still can't find matching words,PubMed will break the word and repeat the automatic vocabulary conversion process until the word matches the word entered. If there are still no matching words, individual words are joined together (in AND) to retrieve in all fields.For example, "single cell", the system automatically divides it into two words: "single" and "cell" retrieval, and itsretrieval expression is "single AND cell"". To check the conversion of the search term, click the "Details" key.2. word retrieval functionPubMed allows the use of * numbers as a wildcard for word retrieval. If you type 'bacter *', the system will find the words in the previous section, such as bacteria, bacterium, bacteriophage, and bacter, and retrieve them separately. If the word is less than 150, PubMed will be one by one word retrieval, if more than 150 (such as Staph*), PubMed will display the following warning: "Wildcard search for'term*'used only the first Lengthen the root word 150 variations. to search for all endings". Truncation function is limited to words and is invalid for phrases. Such as: "infection*" includes "infections", but does not include "infection control" and so on.When using the truncation function, the PubMed system automatically turns off the lexical conversion function.3. mandatory search functionAs mentioned above, the PubMed homepage and search box type questions a phrase and click "Go", with the high speed automatic conversion function to find the corresponding word matching and retrieval system; however, when the type of words, no words, PubMed will enter the words off after the automatic repeat vocabulary conversion process, if still no match, the system will be decomposed into words and phrases, AND together in all fields in search. Obviously, the results of this retrieval arenot consistent with the user's requirements. Therefore, PubMed allows double quotation marks ("" "" ") to enforce systematic phrase retrieval. For example, in the PubMed page retrieval type "Single cell" question box, and use double quotes, and then click "Go", the system will be as an integral phrase retrieval in all fields in the database.Using double quotation marks automatically turns off the lexical conversion function.4. link function(1) linking relevant documents. Each document in the PubMed system has a related literature link. In the display state of the retrieval results, there is a "Related Articles" hyperlink on the right of each record. Click on the chain, the system shows the relevant documents from high to low according to the relevance of the document. Using the search history (History) button can further restrict the relevant literature. Click on "History", enter the relevant search numbers into the query box, and then type additional conditional words, and finally click "Go"". If you type "#7 AND english[la]" in the query question box, the search can be further limited to the English literature.(2) link NCBI (National, Center, for, Biotechnology, Information) database. PubMed built hyperlinks on its home page with 5 NCBI databases. These databases include: Protein[amino acid sequence database (protein), Nucleotide (DNA sequence) database, Popset (population, phylogenetic or mutation sequence) database, Structure (molecular structure model) andGenome database (genome sequence database).(3) linking external resources. PubMed provides links from search results to full journal text, biological data, sequence centers, and more. This function is achieved by linking to the above resource site. In the status of the search results, click "LinkOut" to enter the relevant web site.(4) link related books. Click on "Books" to refer to the abstract page of the related books.Some of the phrases on the book Abstract page are hyperlinks, and click the phrase hyperlink to connect to the page list of the relevant books and find the phrases on the table.In addition, the PubMed system allows the user to view the cited journal name table, click on the PubMed Journal Brower on the home page, and PubMed provides the user with the abbreviated name and ISSN number of the journal.PubMed searchPubMed system search range: MEDLINE database and PreMEDLINE database.1. words (subject) retrievalOn the PubMed homepage question box type English words or phrases (uppercase or lowercase can enter or click the "Go", PubMed is using the vocabulary automatically search, and search results are directly displayed on the home page below. Forexample, type "vitamin C common cold", then enter or click Go, and PubMed begins to retrieve and displays the search results.If the search results do not meet the requirements, can increase or delete the box in question words, or in the Details state (see Details key usage) to modify search, can also use the "Limits" (see Limits.) select restricted condition after retrieval. In addition, users can use wildcards, * * or double quotation marks to make word search or mandatory search as needed.2. authors searchIn the question box type author surname name and initials, format: author name space name acronyms, such as Smith JA, then press enter or click on Go, the system will automatically go to the field of retrieval, and display the search results.If you enter the author's last name, the system will first find the author's last name in the MeSH conversion table. After you've checked, the system retrieves the topic fields and title and digest fields, otherwise the system will retrieve them in all fields.If you use double quotes around the author's name and use the author field identifier - [au] to qualify, such as "Smith JA" [au], then the system retrieves only author fields.3. of the searchIn the question of the box type or MEDLINE form, referred toas ISSN, for example: molecular biology of the cell Mol Biol, or cell, or 1059-1524, then press enter or click on Go in the field of retrieval, the system will display the search results, and. If the words in the vocabulary of MeSH and the same, for example: Gene Therapy, Science or Cell, PubMed will use the word as the word retrieval MeSH. In this case, need of field identification -- [ta] is defined as "gene therapy[TA"".Single word title also need to be qualified, with [TA]: Scanning[TA]. Otherwise, the system will retrieve in all fields. The use of the MEDLINE can be retrieved or referred to all relevant records in the database. Retrieval using the ISSN number does not guarantee an earlier record in the checked database.If there should be input of parentheses, brackets omitted. For example: J, Hand, Surg[, Am] J Hand Surg Am should be typed.4. Boolean logic searchThe PubMed system allows Boolean logic retrieval, but type Boolean logic operators (AND, OR, or NOT) in the question box. Such as: vitamin, C, OR, zinc.Boolean logic searches sequentially from left to right, but parentheses can be used to change their order of operations. For example, common, cold, AND (vitamin, C, OR, zinc), the first search in parentheses is the first operation.Boolean logical retrieval allows you to add field identifiers after the retrieval word to qualify the retrieval field (fieldidentifiers are enclosed in square brackets and placed behind the search words). The format of its retrieval expression is: search word [field identifier], Boolean operator, search word [field ID]. Such as: [dna[, MH], AND, Crick, [au] AND 1993 [DP];又如：ansthma /治疗[MH]回顾[葡]和孩子，学前[MH]各种字段标识见表1。
