As noted in this blog yesterday, as the date approached for students in Hong Kong to boycott classes in an attempt to force the central government to reconsider its recent decision on political reform, Sina Weibo began censoring "Hong Kong Boycott Classes" (香港 罢课).
These screenshots show that on September 22, 2014, the first day of the boycott, Sina Weibo began censoring searches for "Boycott Classes" (罢课).
These screenshots were taken on September 23, and show that Tencent was censoring searches for "Hong Kong Boycott Classes" but not "Boycott Classes," and Baidu had banned users from setting up a "PostBar" (Tieba 贴吧) forum on the topic of "Boycott Classes."
These screenshots show that on September 22, 2014, the first day of the boycott, Sina Weibo began censoring searches for "Boycott Classes" (罢课).