How to do it depends on what you want to retrieve and what retrieval system you use, otherwise no one will know how to do it ~
The specific introduction can go to Baidu Encyclopedia, where the description of retrieval style is much more detailed than what I said. To write a retrieval style with numbers, there are many things to learn. You can check the introduction and help of related books and the retrieval system you want to use ~
The address of the encyclopedia is: baike.baidu/view/1978045.
Question 2: The basic search of search type is 1. Type one or more search terms (which can be any word), such as protein ambiguous isomerase, or enter an abbreviated name, such as pdi. 2. When multiple words are input, they can be automatically recognized as phrases; But if there are too many words, it will be recognized by logical AND. For example, it can be recognized as a word, or it may be recognized as "protein and ambiguity", especially when symbols such as numbers appear, it is difficult to recognize as a phrase; 3. Unrecognized retrieved phrases need to be emphasized by quotation marks. For example, if you enter "Insight II", it will be retrieved by the document author. The input format of the author's name is: last name+first name, for example, if you enter: Free *** an DJ, where "last name" is the full name and "first name" is the acronym ("first name" can be omitted); 4. Enter the name of the magazine, which can be the full name of the magazine name, MedLine abbreviation format or ISSN magazine number (see journal browsing). 5. When searching, you can add "*" to the suffix to search for all words with the same prefix. If you type: biolog*, you can find the words biological or biological. 6. You can also query multiple words in the form of phrases. For those phrases that can't be identified, you need to put quotation marks to emphasize them. For example, if you type "Insight II", you will be recognized as the phrase "Insight II" to query. If you enter "Insight II", you may be recognized as "Insight II" and "Insight II", so as to search in a logical and "Insight II" way. 7. You can search for conjunctions between words through AND, OR or NOT logic. 8. After entering the search term, don't forget to select the search period (30 days, range 10 year) and the number of pages of the displayed literature. 9. In the mouse click interface, press Enter or "Search" button to enter the document summary page.
Question 3: What is the function of quotation marks on search expressions in Baidu? The function of quotation marks is to keep the integrity of search terms. For example, if you search for Peking University, use quotation marks to say that Peking University defines Peking University. In this way, there will be no separation between Peking University and the university in the search results.
Cut as follows
Question 4: What is the construction of retrieval type and retrieval field retrieval type?
A search formula is a query string that a search engine can understand and operate. It consists of keywords, logical operators, search instructions (search syntax) and so on. Keywords are the main body of retrieval, and logical operators and search instructions restrict keywords from different angles according to specific query requirements.
1, keywords
Keywords are keywords that describe the search content. Keywords in network search are a broad concept and belong to uncontrolled free words. All meaningful expressions and writing forms, such as words, words, phrases, phrases and letters, numbers, symbols, formulas, etc., can be used as search keywords.
Network search is actually a matching search in the index database of search engines. Search engines don't use controllable language to index their own databases, but mechanically output web pages that match the form of keywords. With the continuous growth of database scale, more and more results that meet the matching conditions of forms will be output. Although some search engines use intelligent word segmentation technology and have a certain degree of concept retrieval function, a lot of useless information will inevitably appear. Under the technical conditions of formal matching, keyword optimization is the main method to eliminate useless information to the maximum extent. Keywords play a "key" role in network search. The accuracy of keyword selection is directly related to the success or failure of search, and the sign of successful search is that the first page of the result list can meet the query requirements.
Formally, the number of keywords is inversely proportional to the result output. The more keywords are used, the less the result output is. For example, when searching in GOOGLE with "search engine optimization", "there are about 603,000 query results conforming to search engine optimization", "search engine optimization website promotion", "there are about 215,000 query results conforming to search engine optimization website promotion" and "search" For example, searching with "library reference service" and "library reader service" is more meaningful than searching with "library service", and the results are more specific and applicable. From the logical relationship between words, "and" and (and&; Not) Use multi-word restriction and irrelevant exclusion methods to narrow the search scope and improve the accuracy, such as "Andy Lau and height, weight and place of origin" and "Dragon and Eight-part essay C TV series". "or" (or) using multi-word expansion method to expand the search scope, such as "Andy Lau or Andy Lau" search, you can get a higher recall rate.
To select keywords accurately, it is necessary to explore the query content from the aspects of expression, writing habits and writing rules, and strive for the consistency between keywords and content descriptors. Because of the form matching principle of search engines, the results of using the same concept by different words are completely different. For example, the word "capital" will not appear in the search for "Beijing", and the Beijing Library can't find the relevant content of "national map". The search results of "WTO" and "World Trade Organization" are very different. Therefore, we must pay attention to the understanding and application of idioms, technical terms, full names, abbreviations, synonyms, synonyms and prefixes and suffixes of pinyin characters, so as to improve the probability of formal matching of keywords as much as possible and minimize false detection and missed detection.
Keywords can be divided into thematic keywords and characteristic keywords. Topic keywords refer to the necessary words to express the main search content, and it is impossible to accurately search the specific content without using topic keywords. Characteristic keywords refer to quantifiers, adjectives, nouns and other words that appear at the same time and are close to the topic keywords in the content description, and further explain and limit the topic keywords. Feature keywords can effectively narrow the search scope and make the results rank higher. In search practice, we often encounter such a situation: despite the accurate selection and proper use of subject keywords, the query content is still not on the first page or the first three pages of the results. At this time, if the use of characteristic keywords is increased, the search results will be significantly improved. For example, when searching for chess pieces, Baidu has 42,600 results, and there is no clear answer in the first few pages. However, if you add the characteristic keyword "Ge" and search for "Chess", the result will be reduced to 1270, and the first item on the first page of the result will be "Chess * * *". & gt
Question 5: Are retrieval formulas and retrieval conditions the same thing? Search formula: refers to the search string understood and operated by the search engine, which consists of keywords, logical operators and search instructions (search grammar). Keywords are the main body of retrieval, and logical operators and search instructions restrict keywords from different angles according to specific query requirements.
Search criteria: enter the keyword to be searched in the text box behind the keyword, and then click the "Start Search" button. The system will automatically find out the information that meets the search criteria from the collected information, and sort it from high to low by default. If you just entered a keyword and want to cancel it, you can click the "Re-fill" button on the page, so that all the information you just entered will be cleared.
I hope I can solve your problem.
Question 6: The logical expression of search expression refers to the expression of the relationship between search terms by Boolean logical operators, also known as Boolean logical expressions. Boolean logic is the simplest and most basic matching method in computer retrieval at present, and it is also a logical expression widely used in the field of computer retrieval. Boolean operators include logical AND, logical OR, logical NOT, etc. It means that the second concept should be excluded from the first one among the two search terms it connects, and the search formula can be written as: a not B. In some Chinese databases, "-"is used to indicate logical "no". For example, if you want to find the information of "graduate education", but the requirement does not include in-service graduate students, you can write the search type as "(graduate education)-in-service graduate students" or "in-service graduate education". Logical "no" refers to a group of combinations that do not contain a certain conceptual relationship, which is used to narrow the search scope. However, it should be used with caution in actual retrieval. In the above logical operators, the operation priority order is not AND, AND, or, but the operation order between them can be changed by brackets. It should also be noted that for the same logical expression, different operation sequences have different operation results.