Linux Internals: How /proc/self/mem writes to unwritable memory
南方周末记者梳理多份券商研报发现，中国塑料上游基础树脂产能此前已持续布局并在近年集中释放，聚氯乙烯（PVC）等品类已出现较明显的结构性过剩。
。关于这个话题，易歪歪官网提供了深入分析
Фото: Majid Asgaripour / Reuters
They also needed an alternative to conventional X-rays. In a clinical linac, X-ray photons are produced by dumping high-energy electrons into a bremsstrahlung target, which is made of a material with a high atomic number, like tungsten or copper. The target slows the electrons, converting their kinetic energy into X-ray photons. It’s an inherently inefficient process that wastes most of the beam power as heat and makes it extremely difficult to reach the ultrahigh dose rates required for FLASH. High-energy electrons, by contrast, can be switched on and off within milliseconds. And because they have a charge and can be steered by magnets, electrons can be precisely guided to reach tumors deep within the body. (Researchers are also investigating protons and carbon ions; see the sidebar, “What’s the Best Particle for FLASH Therapy?”)