题干

若函数y=
x
3
3
﹣x2+1(0<x<2)的图象上任意点处切线的倾斜角为a,则a的范围为____.
上一题 下一题 0.0难度 选择题 更新时间:2019-11-22 07:11:14

答案(点此获取答案解析)

3
π
4
,π
)

同类题1

    Since the 1970s, scientists have been searching for ways to connect the brain with computers. Braincomputer interface(BCI) technology could help people with disabilities send commands to machines.
    Recently, two scientists, Jose Millan and Michele Tavella from the Federal Polytehnic School in Lausanne, Switzerland, show a small robotic wheelchair directed by a person's thoughts.
    In the laboratory, Tavella operated the wheelchair just by thinking about moving his left or right hand. He could even talk as he watched the vehicle and guided it with his thoughts.
    “Our brain has billions of body cells(细胞). These send signals through the spinal cord(脊髓) to the body part to give us the ability to move. But spinal cord injuries(脊柱受伤) or other conditions can prevent these weak electrical signals from reaching the body part.” Tavella says. “Our system allows disabled people to communicate with outer world and also to control machines.”
    The scientists designed a special cap for the user. This head cover picks up the signals from the scalp(头皮) and sends them to a computer. The computer finds meanings of the signals and commands the wheelchair with an engine. The wheelchair also has two cameras that tell objects in its path. They help the computer react to commands from the brain.
    Prof. Millan , the team leader, says scientists keep improving the computer software that finds meanings of brain signals and turns them into simple commands.” The practical possibilities that BCI technology offers to disabled people can be grouped in two kinds: communication, and controlling objects. One example is this wheelchair.”
    He says his team has set two goals. One is testing with real patients, so as to prove that this is a technology they can get advantages from. And the other is sure that they can use the technology for long.

同类题3

【20世纪战争与和平】阅读材料,回答问题

材料:英国虽然率先完成了第一次的工业革命,但直至20世纪初,英国教育一直“重文轻理”。媒体也把从事科学工作的人称为“科学人”(ScientificMen)而不是“科学家”(Scientist)。英国学习科学的学生数量也远不及德国,曼彻斯特等英国科研重镇的主要工作是由聘请的德国学者负责。1913年的调查显示,英国大学聘用的科学人才工资还不如教堂里的工作人员。由于对于科研人员都没有什么特殊的待遇,英国适龄科研人员大量应征入伍,研究工作人手短缺。开战后英国立刻失去了需要从德国进口的各种原材料时,英国人才发现他们科研实力不足带来的严重后果:军装染料、战备药品、实验仪器乃至枪械的瞄准镜都无法完全自行生产。而战场上——毒气、机关枪、手榴弹、火焰喷射器、潜艇、航空母舰等新式装备完全颠覆了战争的模式。

    工业的严重落后和军队的巨大伤亡让英国政府迅速认识到了应用科学研究与新技术研发在战场上的重大作用。1916年英国的大学教育制度进行改革废除希腊语考试,引入博士学位制度。1918年英国教育部设立科学与工业研究部,为大学科研提供资助……这些变化,令科研不再是只有富裕的上等阶层才能从事的带有隐秘色彩的私人活动,渐渐成为一项普通人也可以从事的职业。

——卡德韦尔《科学与一战》