丝绸之路是古代中西方文化交流的通道，其中玻璃是早期贸易往来的宝贵物证。早期的玻璃在西亚和埃及地区常被制作成珠形饰品传入我国，我国古代玻璃吸收其技术后在本土就地取材制作，因此与外来的玻璃制品外观相...

(全国竞赛2021年B题) 无人机集群在遂行编队飞行时，为避免外界干扰，应尽可能保持电磁静默，少向外发射电磁波信号。为保持编队队形，拟采用纯方位无源定位的方法调整无人机的位置，即由编队中某几架...

(全国竞赛2022年A题) 随着经济和社会的发展，人类面临能源需求和环境污染的双重挑战，发展可再生能源产业已成为世界各国的共识。波浪能作为一种重要的海洋可再生能源，分布广泛，储量丰富，具有可观...

In September 2019, a colony of Vespa mandarinia (also known as the Asian giant hornet) was discov...

The 2019-2020 fire season in Australia saw devastating wildfires in every state, with the worst i...

The carbon cycle describes the process of the exchange of carbon throughout the geochemical cycle...

Since the 1950s, the manufacturing of plastics has grown exponentially because of its variety of ...

Researchers have identified several island nations, such as The Maldives, Tuvalu, Kiribati, and T...

As societies become more interconnected, the set of challenges they face have become increasingly...

In the online marketplace it created, Amazon provides customers with an opportunity to rate and r...

Wherever there are recreational sandy ocean beaches in the world, there seem to be children (and ...

Global ocean temperatures affect the quality of habitats for certain ocean-dwelling species. When...