Tools/materials: Lenovo ThinkVision, Microsoft Windows 7 Ultimate Edition, 360 Secure Browser 13. 1.

1. First, open 360 security browser, search "HowNet", and click to enter China HowNet official website.

2. Click "Login" on HowNet homepage, enter the correct HowNet account and password, and then click "Login". Those who do not have an account need to register and log in.

3. Enter the papers you want to find in the search box, for example, enter the keyword "breathing gas" here, click "Search in the results", and select the target literature in the search results page.

4. After entering the home page of this document, there are download options (mobile phone reading, CAJ download, PDF download) at the bottom of the page, and select "PDF download".

5. After that, you will enter the specific PDF download interface. Because the download of HowNet documents is not free, you need to pay. Click "Download Now" to download the file in PDF format.