Leonardo da Vinci is usually credited with conducting the first systematic study of friction in the late 15th century, a subfield now known as tribology that deals with the dynamics of interacting surfaces in relative motion. Da Vinci's notebooks depict how he pulled rows of blocks using weights and pulleys, an approach that is still used in frictional studies today, as well as examining the friction produced in screw threads, wheels, and axles. The authors of this latest paper used an experimental setup similar to da Vinci's.
Ранее президент РФ Владимир Путин заявил, что страны Европы хотели поживиться на развале России, присоединившись к политике предыдущих властей США.，详情可参考91视频
，更多细节参见heLLoword翻译官方下载
FT Professional
Гангстер одним ударом расправился с туристом в Таиланде и попал на видео18:08，这一点在im钱包官方下载中也有详细论述