金币
UID282357
帖子
主题
积分5720
注册时间2016-12-19
最后登录1970-1-1
听众
性别保密
|
发表于 2025-10-11 12:14:14
|
显示全部楼层
既然都没有你想要的结果,那纠结这的目的意义是啥了?
按照我的理解,第二个才是正确的,这个是官方关于布尔运算的解释:
Boolean operators, search function results and wildcard searches
Modified on: Wed, 26 Feb, 2025 at 6:57 PM
When no search operators like "AND" or quotes are used, all results that include any of the terms are returned, along with those that contain all terms the greatest number of times in important fields displayed at the top.
The following operators can be used for greater specificity over search results:
"Phrase match"
A search with multiple terms entered within quotation marks ("") will return only results that contain those words in that exact order.
Example: "plastic bottles" OR "water pollution"
The OR operator (OR or |)
The OR operator (case-sensitive) allows results to be returned even when they contain only one of the words entered.
Example: wheat OR maize
will give results which include either one of the terms "wheat" or "maize"
The NOT operator (NOT or -)
The NOT operator (case-sensitive) excludes results that contain the term following the NOT.
Example: wheat NOT maize
will give results which include the term "wheat" but exclude the term "maize"
The AND operator (AND or +)
The AND operator (case-sensitive) provides the same results as the default on our site.
Example: evolutionary patterns of families the search that will actually be carried out will be (evolutionary AND patterns AND of AND families)
Precedence
Enables the ( and ) operators to control operator precedence, without parenthesis order is from left right.
Examples: plastic bottles OR water pollution
will be interpreted as:
plastic AND bottles OR water AND pollution effectively ((plastic AND bottles) OR water) AND pollution
The * Wildcard
An asterisk (*) entered as part of a search is interpreted as a substitute for any number of letters.
Example: hea*
will return results containing any word starting with "hea", such as "head", "heats", "health", "heated", "heating" and so on. The wildcard search works best when there are at least 3 characters before the wildcard operator. |
|