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As the information acquisition of mobile terminals such as mobile phones becomes more and more convenient, new media has gradually become the major way for people to obtain information. The WeChat public account is one of the main channels for people to receive information in their daily lives. This article introduces some practices of using the WeChat public account "Chemical Science Park" to carry out popular science work, as well as the difficulties encountered in the process and reflections. 相似文献
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According to the risk management process of financial markets,a financial risk dynamic system is constructed in this paper.Through analyzing the basic dynamic properties,we obtain the conditions for stability and bifurcation of the system based on Hopf bifurcation theory of nonlinear dynamic systems.In order to make the system’s chaos disappear,we select the feedback gain matrix to design a class of chaotic controller.Numerical simulations are performed to reveal the change process of financial market risk.It is shown that,when the parameter of risk transmission rate changes,the system gradually comes into chaos from the asymptotically stable state through bifurcation.The controller can then control the chaos effectively. 相似文献
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We investigate the photoinduced anisotropy of a photochromic material of pyrrylfulgide/PMMA films. It is proven that when the film is illuminated with a linear polarization light, an optical axis that has the same polarization as the excitation light could be induced in the film. A matrix of light spots with different polarizations is recorded 相似文献
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可擦写俘精酸酐/PMMA薄膜的全息记录特性研究 总被引:10,自引:10,他引:0
对一种新型可擦写有机光致变色材料-吡咯俘精酸酐的光全息记录特性进行了实验研究.用涂布法制成厚度约10 μm 的吡咯俘精酸酐/PMMA聚合物薄膜.样品无色态吸收峰在373 nm处,经紫外光照射发色后,变为呈色态,其吸收峰移动到626 nm处,呈色态在氦氖激光照射下可以重返为无色态.无色态和呈色态在室温下都是稳定的.以呈色态吡咯俘精酸酐/PMMA薄膜作为记录材料,以氦氖激光作为记录光,分别建立了双光束干涉衍射记录装置和四波耦合实验系统.实验测得该薄膜的空间分辨率至少可以达到1680 lines/mm,一级衍射效率大于2%,全息记录中的最佳曝光量约为1 J/cm2.实验测量了衍射效率与曝光量的特性曲线,分析了衍射光强度和光斑模式随曝光时间的变化关系. 相似文献
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本文纠正了论文“de Sitter空间中具有平行中曲率的完备类空子流形”证明中的一些失误,证明了de Sitter空间中具有平行中曲率的n维完备类空子流形的—个刚性定理. 相似文献
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The implementation of image contrast reversal by using a photochromic material of Bacteriorhodopsin (BR) films is demonstrated with two methods based on the optical properties of BR. One is based on the absorption difference between the B and M states. Images recorded by green light can be contrast reversed readout by violet light. The other is based on the photoinduced anisotropy of BR when it is excited by linear polarization light. By placing the BR film between two crossed polarizers (i.e. a polarizer and an analyser), the difference of polarization states of the recorded area and the unrecorded area can be detected, and thus different contrast images can be obtained by rotating the polarization axis of the analyser. 相似文献
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