题干

显微镜在观察细胞结构过程中起到不要或缺的重要作用,下列哪些实验的实验结论得出,显微镜起到了重要作用(  )

①施莱登提出细胞是构成植物体的基本单位

②科学家揭示分泌蛋白的合成和运输过程

③罗伯特森提出细胞膜结构模型

④萨克斯证明光合作用产物之一是淀粉

⑤鲁宾和卡门证明光合作用释放的氧气来自于水

⑥卡尔文探明CO2转化成有机物的途径.

A:①②③

B:②③④

C:③④⑤

D:④⑤⑥

上一题 下一题 0.0难度 选择题 更新时间:2019-09-09 01:01:32

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A

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    A team of engineers at Harvard University has been inspired by Nature to create the first robotic fly. The mechanical fly has become a platform for a series of new high-tech systems. Designed to do what a fly does naturally, the tiny machine is the size of a fat housefly. Its mini wings allow it to stay in the air and perform controlled flight tasks.

    “It's extremely important for us to think about this as a whole system and not just a bunch of individual components (零件),” said Robert Wood, the Harvard engineering professor who has been working on the robotic fly project for over a decade. “The added difficulty with such a project is that actually none of those components are off the shelf and so we have to make them all on our own,” he said.

    They engineered a series of systems to start and drive the robotic fly. “The seemingly simple system which just moves the wings has a number of individual components, each of which individually has to perform well, and then has to be matched well to everything it's connected to,” said Wood. The flight device was built into a set of power, computation, sensing and control systems. Wood says the success of the project proves that the flying robot with these tiny components can be built and manufactured.

    Wood says the design offers a new way to study flight mechanics and control at insect- scale. Yet, the power, sensing and computation technologies on board could have much broader applications (应用). “You can start thinking about using them to answer open scientific questions, you know, to study biology in ways that would be difficult with the animals, but using these robots instead,” he said. “So there are a lot of technologies and open interesting scientific questions that are really what drives us on a day to day basis.”