杨振宁遗体告别仪式在京举行各界人士排长队送别

By: Sexy

On: October 24, 2025

Tagged: Academy, Art, Award, Culture, Education, Energy, Engineering, Event, Expose, Government, Health, History, Life, Magazine, Man, Memori, Minister, Nature, Paradise, School, Science, Service, Space, Spell, Style, Technology

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订阅频道，获取更多精彩：https://bit.ly/2GzuCVG
10月18日，诺贝尔物理学奖获得者、中国科学院院士、清华大学高等研究院名誉院长杨振宁在北京逝世。10月24日，杨振宁先生遗体告别仪式在北京八宝山殡仪馆大礼堂举行。当天上午9时许，前来送别的人们已在殡仪馆外排起长队，大家神情肃穆，一同来和杨先生做最后的告别。

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Spider

Web crawler, sometimes called a spider or spiderbot and often shortened to crawler, is an Internet bot that systematically browses the World Wide Web and that is typically operated by search engines for the purpose of Web indexing (web spidering).

Web search engines and some other websites use Web crawling or spidering software to update their web content or indices of other sites' web content. Web crawlers copy pages for processing by a search engine, which indexes the downloaded pages so that users can search more efficiently.

Crawlers consume resources on visited systems and often visit sites unprompted. Issues of schedule, load, and "politeness" come into play when large collections of pages are accessed. Mechanisms exist for public sites not wishing to be crawled to make this known to the crawling agent. For example, including a robots.txt file can request bots to index only parts of a website, or nothing at all.

The number of Internet pages is extremely large; even the largest crawlers fall short of making a complete index. For this reason, search engines struggled to give relevant search results in the early years of the World Wide Web, before 2000. Today, relevant results are given almost instantly.

Crawlers can validate hyperlinks and HTML code. They can also be used for web scraping and data-driven programming.