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排序方式: 共有222条查询结果,搜索用时 0 毫秒
1.
In this paper a class of impulsive differential inclusions is investigated. The existence of solution bundle is proved. And we also construct a nonlinear semigroup of operators on cb(E) (closed-bounded subset of E) to describe the set of attainable states. 相似文献
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Wang Jingxiu Zhang Jun Deng Yuanyong Li Jingqun Tian Lirong Yang Xiulan 《中国科学A辑(英文版)》2002,45(1):57-64
Based on the studies on the source regions of a group of coronal mass ejections, we have identified two types of large-scale magnetic structures, and suggested that they are intrinsic components of solar magnetism, their destabilization, expansion, and eruption into the interplanetary space are the basic physical processes which lead to the coronal mass ejections. These two types of large-scale structures are giant magnetic loops connecting the two active belts on the opposite hemispheres of the Sun, and the giant filaments (filament channels) and their related magnetic structures. The latter often appear as two parallel rows of sunspots and plage fields, which align side by side in the full disk daily and synoptic magnetograms. The magnetic neutral lines of these large-scale structures are usually longer than 50 heliographic degrees. We name this type of structure “super A configuration”. Sometimes, they are shown as very long filaments and related large-scale magnetic fields. As these magnetic structures are of very large scale, they extend to a great altitude into the corona, they are not easily recognized in magnetic field observations which are usually aimed at solar flare studies. To identify these large-scale structures becomes a key to understanding and predicting coronal mass ejections. 相似文献
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在具有电致发光(EL)的有机整合染料8-羟基喹啉铝(Alq3)中接以染料罗丹明6G(R6G),用真空热蒸发的方法制备器件,获得了峰值波长575nm的黄色直流薄膜电致发光,从而通过掺杂改变了发光颜色.并在Alq3发光层不同区域插入一掺杂薄层(Alq3:R6G),利用其发光波长与未掺杂部分(Alq3)的不同,以此作为“探测层”,通过对器件光谱及电学特性的测量与分析,探讨了有关发光区域,发光机理,界面对发光影响等基本问题. 相似文献
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Superbasic Alkyl‐Substituted Bisphosphazene Proton Sponges: Synthesis,Structural Features,Thermodynamic and Kinetic Basicity,Nucleophilicity and Coordination Chemistry 下载免费PDF全文
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Xiulan Hu Xin Zhang Xiaodong Shen Hongtao Li Osamu Takai Nagahiro Saito 《Plasma Chemistry and Plasma Processing》2014,34(5):1129-1139
Fiber-shaped cupric oxide (CuO) nanoparticles and flower-shaped ZnO nanoparticles were facilely synthesized by plasma-induced technique directly from copper and zinc electrode pair in water, respectively. The phase composition, morphologies and optical property of nanoparticles have been investigated by energy dispersive X-ray analysis, X-ray powder diffraction, transmission electron microscopy and UV–vis. The in situ analysis by an optical emission spectroscopy clarified the formation mechanism. Plasma was generated from the discharge between a metal electrode pair in water by a pulse direct current power. CuO and ZnO nanoparticles were synthesized via almost the same formation mechanism, which were prepared via the rapid energetic radicals’ bombardment to electrodes’ surface, atom vapour diffusion, plasma expansion, solution medium condensation, and in situ oxygen reaction and further growth. This novel plasma-induced technique will become a potential application in nanomaterials synthesis. 相似文献
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纳米孔测序是有可能实现"$1,000 Genome"目标的技术之一.近年来,研究较多的纳米孔有蛋白质纳米孔和硅基材料的固态纳米孔.蛋白孔寿命比较短,而基于硅基底的固态纳米孔深度显著超过单链DNA相邻碱基的间距,所以,无法实现DNA的单个碱基的分辨.作者用聚焦离子束先制造氮化硅基底,并在该基底上铺设石墨烯,再用聚焦电子束刻蚀石墨烯,获得直径10 nm以下的纳米孔,初步分析了DNA穿越纳米孔时产生的电信号及穿孔噪音,向单层石墨烯纳米孔测序DNA迈出了一步. 相似文献
9.
Chen‐Xi Ye Shuming Chen Feng Han Xiulan Xie Sergei Ivlev K. N. Houk Eric Meggers 《Angewandte Chemie (International ed. in English)》2020,59(32):13552-13556
A transformation of fluxional into configurationally stable axially chiral N‐arylpyrroles was achieved with a highly atroposelective electrophilic aromatic substitution catalyzed by a chiral‐at‐metal rhodium Lewis acid. Specifically, N‐arylpyrroles were alkylated with N‐acryloyl‐1H‐pyrazole electrophiles in up to 93 % yield and with up to >99.5 % ee, and follow‐up conversions reveal the synthetic utility of this new method. DFT calculations elucidate the origins of the observed excellent atroposelectivity. 相似文献
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