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?”)
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这些都需要你有一定的技术判断力。
Unions argue that "one day less" can be good for energy, productivity and society, and that normalising four‑day patterns can keep people in work who might otherwise drop out altogether.。业内人士推荐新收录的资料作为进阶阅读
語言學習對長遠的大腦健康與幸福感有明顯益處，這點早已廣為人知，因此我對此從無遺憾。但我念了四年語言學位、花了無數時間在動詞變化、死背單字——這樣的學習方式是否已經過時了？
（一）有关旅客死亡的请求权，发生在运输期间的，自旅客应当离船之日起计算；因运输期间内的伤害而导致旅客离船后死亡的，自旅客死亡之日起计算，但是此期限自旅客离船之日起不得超过三年；。新收录的资料对此有专业解读