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介绍了不同学科领域里与椭圆有关的3 种物理规律:光线反射规律、开普勒第二定律、细杆平衡规律, 并对其进行相互推导, 得出结论: 这3 个物理规律是等价的, 它们的本质都是椭圆所特有的几何特征, 它们只是这一本质在不同领域的不同表现. 相似文献
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Pan Ou Ruilong Zhang Zhengjie Liu Xiaohe Tian Guangmei Han Bianhua Liu Zhangjun Hu Zhongping Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2283-2287
Enzyme activity in live cells is dynamically regulated by small‐molecule transmitters for maintaining normal physiological functions. A few probes have been devised to measure intracellular enzyme activities by fluorescent imaging, but the study of the regulation of enzyme activity via gasotransmitters in situ remains a long‐standing challenge. Herein, we report a three‐channel imaging correlation by a single dual‐reactive fluorescent probe to measure the dependence of phosphatase activity on the H2S level in cells. The two sites of the probe reactive to H2S and phosphatase individually produce blue and green fluorescent responses, respectively, and resonance energy transfer can be triggered by their coexistence. Fluorescent analysis based on the three‐channel imaging correlation shows that cells have an ideal level of H2S to promote phosphatase activity up to its maximum. Significantly, a slight deviation from this H2S level leads to a sharp decrease of phosphatase activity. The discovery further strengthens our understanding of the importance of H2S in cellular signaling and in various human diseases. 相似文献
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Liulin Wang Wei Du Zhangjun Hu Kajsa Uvdal Lin Li Wei Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14164-14181
Fluorophores and probes are invaluable for the visualization of the location and dynamics of gene expression, protein expression, and molecular interactions in complex living systems. Rhodamine dyes are often used as scaffolds in biological labeling and turn‐on fluorescence imaging. To date, their absorption and emission spectra have been expanded to cover the entire near‐infrared region (650–950 nm), which provides a more suitable optical window for monitoring biomolecular production, trafficking, and localization in real time. This review summarizes the development of rhodamine fluorophores since their discovery and provides strategies for modulating their absorption and emission spectra to generate specific bathochromic‐shifts. We also explain how larger Stokes shifts and dual‐emissions can be obtained from hybrid rhodamine dyes. These hybrid fluorophores can be classified into various categories based on structural features including the alkylation of amidogens, the substitution of the O atom of xanthene, and hybridization with other fluorophores. 相似文献
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汞离子是毒性最大的重金属之一,对环境和人体都会造成严重的不良影响,开发能够快速检测环境中汞离子的分析方法引起了越来越多的关注。纳米材料由于其优良的光学性能和良好的稳定性,被广泛用于环境中汞离子的检测。本文主要综述了近年来一些代表性的基于纳米材料的汞离子荧光、比色传感器。根据纳米材料的不同,将这些传感器分为基于金、银、碳和硅基材料,以及量子点、有机纳米颗粒和其他纳米基材料的荧光、比色传感器,并分别从设计原理、识别性能和实际应用等方面对这些传感器进行了描述和讨论。最后对该领域的研究和发展提出了展望。 相似文献
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Erbo Cheng Shoushuang Huang Dayong Chen Ruting Huang Qing Wang Zhangjun Hu Yong Jiang Zhen Li Bing Zhao Zhiwen Chen 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(7):969-978
Metal oxides have a large storage capacity when employed as anode materials for lithium‐ion batteries (LIBs). However, they often suffer from poor capacity retention due to their low electrical conductivity and huge volume variation during the charge–discharge process. To overcome these limitations, fabrication of metal oxides/carbon hybrids with hollow structures can be expected to further improve their electrochemical properties. Herein, ZnO‐Co3O4 nanocomposites embedded in N‐doped carbon (ZnO‐Co3O4@N‐C) nanocages with hollow dodecahedral shapes have been prepared successfully by the simple carbonizing and oxidizing of metal–organic frameworks (MOFs). Benefiting from the advantages of the structural features, i.e. the conductive N‐doped carbon coating, the porous structure of the nanocages and the synergistic effects of different components, the as‐prepared ZnO‐Co3O4@N‐C not only avoids particle aggregation and nanostructure cracking but also facilitates the transport of ions and electrons. As a result, the resultant ZnO‐Co3O4@N‐C shows a discharge capacity of 2373 mAh g?1 at the first cycle and exhibits a retention capacity of 1305 mAh g?1 even after 300 cycles at 0.1 A g?1. In addition, a reversible capacity of 948 mAh g?1 is obtained at a current density of 2 A g?1, which delivers an excellent high‐rate cycle ability. 相似文献
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Xia Yang Li Jiaojiao Wang Hongjie Ye Zhangjun Zhou Xiaozheng Huang Hui Gan Yongping Liang Chu Zhang Jun Zhang Wenkui 《Journal of Solid State Electrochemistry》2019,23(2):519-527
Journal of Solid State Electrochemistry - In this work, a series of rationally designed hybrid membranes composed of poly(vinylidene fluoride) (PVDF) as polymer matrix and silica nanoparticles... 相似文献
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Dr. Zhangjun Hu Maria Ahrén Linnéa Selegård Dr. Caroline Skoglund Dr. Fredrik Söderlind Dr. Maria Engström Dr. Xuanjun Zhang Prof. Kajsa Uvdal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(38):12658-12667
Water‐dispersible and luminescent gadolinium oxide (GO) nanoparticles (NPs) were designed and synthesized for potential dual‐modal biological imaging. They were obtained by capping gadolinium oxide nanoparticles with a fluorescent glycol‐based conjugated carboxylate (H L ). The obtained nanoparticles (GO‐ L ) show long‐term colloidal stability and intense blue fluorescence. In addition, L can sensitize the luminescence of europium(III) through the so‐called antenna effect. Thus, to extend the spectral ranges of emission, europium was introduced into L‐ modified gadolinium oxide nanoparticles. The obtained EuIII‐doped particles (Eu:GO‐ L ) can provide visible red emission, which is more intensive than that without L capping. The average diameter of the monodisperse modified oxide cores is about 4 nm. The average hydrodynamic diameter of the L ‐modified nanoparticles was estimated to be about 13 nm. The nanoparticles show effective longitudinal water proton relaxivity. The relaxivity values obtained for GO‐ L and Eu:GO‐ L were r1=6.4 and 6.3 s?1 mM ?1 with r2/r1 ratios close to unity at 1.4 T. Longitudinal proton relaxivities of these nanoparticles are higher than those of positive contrast agents based on gadolinium complexes such as Gd‐DOTA, which are commonly used for clinical magnetic resonance imaging. Moreover, these particles are suitable for cellular imaging and show good biocompatibility. 相似文献
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Guanqing Yang Zhengjie Liu Ruilong Zhang Xiaohe Tian Juan Chen Guangmei Han Bianhua Liu Xinya Han Yao Fu Zhangjun Hu Zhongping Zhang 《Angewandte Chemie (International ed. in English)》2020,59(37):16154-16160
Understanding the biomolecular interactions in a specific organelle has been a long‐standing challenge because it requires super‐resolution imaging to resolve the spatial locations and dynamic interactions of multiple biomacromolecules. Two key difficulties are the scarcity of suitable probes for super‐resolution nanoscopy and the complications that arise from the use of multiple probes. Herein, we report a quinolinium derivative probe that is selectively enriched in mitochondria and switches on in three different fluorescence modes in response to hydrogen peroxide (H2O2), proteins, and nucleic acids, enabling the visualization of mitochondrial nucleoprotein dynamics. STED nanoscopy reveals that the proteins localize at mitochondrial cristae and largely fuse with nucleic acids to form nucleoproteins, whereas increasing H2O2 level leads to disassociation of nucleic acid–protein complexes. 相似文献