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排序方式: 共有262条查询结果,搜索用时 578 毫秒
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扁球面网壳的混沌运动研究 总被引:3,自引:0,他引:3
在圆形三向网架非线性动力学基本方程的基础上,用拟壳法给出了圆底扁球面三向网壳的非线性动力学基本方程.在固定边界条件下,引入了异于等厚度壳的无量纲量,对基本方程和边界条件进行无量纲化,通过Galerkin作用得到了一个含二次、三次的非线性动力学方程.为求Melnikov函数,对一类非线性动力系统的自由振动方程进行了求解,得到了此类问题的准确解.在无激励情况下,讨论了稳定性问题.在外激励情况下,通过求Melnikov函数,给出了可能发生混沌运动的条件.通过数字仿真绘出了平面相图,证实了混沌运动的存在. 相似文献
23.
定态火焰在可燃预混气中产生的压力波 总被引:1,自引:0,他引:1
火焰在可燃预混气中传播时,在火焰面前方产生一道压力波。忽略点火及火焰的初期加速,仅考虑火焰达到稳定传播速度的情况。用Openheim自相似解分析流场,得到相应的控制方程及定解条体;用自适应步长的四阶Runge-Kutta法对方程积分,讨论了流场压力波结构及弱激波近似声波解;认为火焰为间断面,能量释放在火焰面后瞬时完成。利用火焰面两侧的能量关系,得到了火焰位置、燃速及对应C-J条件的火焰位置、C-J燃速。 相似文献
24.
We report a self‐propelled Janus silica micromotor as a motion‐based analytical method for achieving fast target separation of polyelectrolyte microcapsules, enriching different charged organics with low molecular weights in water. The self‐propelled Janus silica micromotor catalytically decomposes a hydrogen peroxide fuel and moves along the direction of the catalyst face at a speed of 126.3 μm s?1. Biotin‐functionalized Janus micromotors can specifically capture and rapidly transport streptavidin‐modified polyelectrolyte multilayer capsules, which could effectively enrich and separate different charged organics in water. The interior of the polyelectrolyte multilayer microcapsules were filled with a strong charged polyelectrolyte, and thus a Donnan equilibrium is favorable between the inner solution within the capsules and the bulk solution to entrap oppositely charged organics in water. The integration of these self‐propelled Janus silica micromotors and polyelectrolyte multilayer capsules into a lab‐on‐chip device that enables the separation and analysis of charged organics could be attractive for a diverse range of applications. 相似文献
25.
Organic fluorescent dyes are widely used in single molecule localization microscopy, where their performances are determined by the photophysical properties. Herein, we utilized a sensitive method to modulate the fluorescence of organic dyes by external potentials using a combination of electrochemical cell and super‐resolution fluorescent microscopy. Cy5 (cyanine dye) was chosen as a model molecule considering its wide application and commercial availability. We applied different potentials on the Au electrode to change the Coulombic charge microenvironment of Cy5. When the electrode potential was adjusted negatively, Cy5 displayed a better photostability. This method is proved effective in adjusting the fluorescence of organic dyes. 相似文献
26.
Ting‐Zheng Xie Kai Guo Zaihong Guo Wen‐Yang Gao Lukasz Wojtas Guo‐Hong Ning Mingjun Huang Xiaocun Lu Jing‐Yi Li Sheng‐Yun Liao Yu‐Sheng Chen Charles N. Moorefield Mary Jane Saunders Stephen Z. D. Cheng Chrys Wesdemiotis George R. Newkome 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(32):9259-9259
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Nanoparticle carriers based on copolymers of poly(ε-caprolactone) and hyperbranched polymers for drug delivery 总被引:1,自引:0,他引:1
Novel amphiphilic copolymers based on poly(ε-caprolactone) (PCL) and hyperbranched poly (amine-ester) (HPAE) with various compositions were synthesized. The amphiphilic copolymers can self-assemble into nanoscopic micelles and their hydrophobic cores can encapsulate doxorubicin (DOX) in aqueous solutions. The DOX-loaded HPAE-co-PCL nanoparticles diameter increased from 121 to 184 nm with the increasing PCL segment in the copolymer composition. An in vitro study at 37°C demonstrated that DOX-release from nanoparticles at pH 5.0 was much faster than that at pH 7.4. The cytotoxicity for HeLa cells study demonstrated that DOX-loaded HPAE-co-PCL nanoparticles exhibited the anti-tumor effect was enhanced significantly, suggesting that the DOX-loaded HPAE-co-PCL nanoparticles have great potential as a tumor drug carrier. 相似文献
29.
We report herein the mechanochromic luminescent property of a dendritic polypeptide with a fluorescent aromatic moiety at the focal point. The different luminescent property of 1 under mechanical stimulus is attributed to the switch of self-assembled structures. Moreover, the photoluminescence property of 1 also depends on the thermal history. 相似文献
30.
Shan Y Hao X Shang X Cai M Jiang J Tang Z Wang H 《Chemical communications (Cambridge, England)》2011,47(12):3377-3379
We applied force spectroscopy based on atomic force microscope (AFM) to demonstrate the possibility of measuring the interaction force between single quantum-dots (QDs) and living cells at single particle level under native conditions. In the force-distance cycle, we recorded the events of cellular uptake of single QDs and single QD detachment from the cell. 相似文献