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A Novel UWB Antenna with Small Side-Leakage 总被引:2,自引:0,他引:2
Wang Xianghui Jiang Yangsheng Wan Wenbing 《International Journal of Infrared and Millimeter Waves》2004,25(9):1325-1335
A successful design for a UWB (ultra-wideband antennas) antenna based on NRD-guide (nonradiative dielectric waveguide) with small side-leakage is presented. The rule of the theoretical selection of its parameters, if NRD-guide is used as the UWB antennas, is studied firstly, then the temporal propagation characteristics of the NRD-guide and the radiation characteristics for an tapered open-ended NRD-guide are calculated by FDTD (finite-difference time-domain) method. 相似文献
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以NH4Cl作助溶剂,碳还原硫酸钙的方法合成了CaS:Ce。在紫外光激发下,CaS:Ce中存在着Ce^3+的^2D-^2F5/2(500nm)和^2D-^2F7/2(550nm)跃迁发射,但在蓝色光激发下,只有波峰为532nm半宽度为92nm的宽带发射。当Ce^3+的浓度为0.075mol%时,^2D-^2F5/2跃迁发射强度与^2D-^2F7/2跃迁发射强度相等,而532nm发射猝灭。 相似文献
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Ruixian Guo Doudou Zhang Xianghui Zhu Liying Tang Xuemeng Zhang Ligai Bai Haiyan Liu 《Chromatographia》2017,80(1):23-30
A polymer-based monolithic column was prepared for high-performance liquid chromatography (HPLC), using ionic liquids as porogen within the confines of a stainless steel column (50 × 4.6 mm i.d.). In the process, 1-butyl-3-methylimidazolium chloride and dodecyl alcohol were used as bi-porogens, vinyl ester resin as the monomer, ethyleneglycol dimethacrylate as the crosslinker, CCl4 as the initiator, and FeCl2 as the catalytic agent to prepare the polymer-based monolithic column. Scanning electron microscopy, nitrogen adsorption–desorption instrument, and mercury intrusion porosimetry were used to assay the characteristics of the monolith, respectively. The optimized monolith showed uniform structure and good permeability. Then, the column was used as the stationary phase of HPLC to separate standard proteins and human plasma with gradient elution. Besides, the monolith was used to separate aromatic compounds from the mixture. The results showed that the addition of IL could effectively improve the structure of monoliths prepared by atom transfer radical polymerization technique. The results also suggested that this kind of monolith could be used as a simple, cheap and effective stationary phase for HPLC. 相似文献
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Dulin Kong Qinghe Wang Zhongxiang Zhu Xianghui Wang Zaifeng Shi Qiang Lin Mingshu Wu 《Tetrahedron letters》2017,58(27):2644-2647
A one-pot, three-component condensation reaction of 8-quinolinol, 2-thiobarbituric acid and isatins or aldehydes in water to give novel barbituroquinoline derivatives for the first time, is described. The reaction is free of catalysts and toxic solvents, operating under mild conditions and allows for ease of product isolation, making it more environmentally friendly and suitable for large-scale operations. 相似文献
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Xiaoyan Zhou Zhaozhu Zhang Xuehu MenJin Yang Xianghui XuXiaotao Zhu Qunji Xue 《Applied Surface Science》2011,258(1):285-289
A superhydrophobic polyaniline (PANI) film has been fabricated by using a facile one-step spraying method. The PANI was synthesized via in situ doping polymerization in the presence of perfluorooctanoic acid (PFOA) as the dopant. The water contact angle of this superhydrophobic surface reaches to 156°. Both the surface chemical compositions and morphological structures were analyzed. A granular morphology of PANI with a moderate amount of nanofibers was obtained. Moreover, a rapid surface wettability transition between superhydrophobicity and superhydrophilicity can be observed when it is doped with PFOA and de-doped with base. The mechanism for this tunable wettability has been discussed in detail. 相似文献
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将1,4-戊二烯-3-酮结构中的羰基转变为肟醚基团,合成了7个1,4-戊二烯-3-酮肟醚类化合物,其结构经1H NMR、13C NMR、IR和ESI-MS表征。生物活性测试结果表明,在药剂浓度为500mg/L时,化合物4c、4f和4g对烟草花叶病毒(TMV)在治疗作用方面的抑制率为49.6%、53.6%和47.4%,与病毒唑(45.2%)相当;化合物4b、4c、4f和4g对TMV在保护作用方面的抑制率分别为57.2%、58.4%、58.9%和59.0%,稍低于病毒唑(61.8%);化合物4a、4b、4c和4g对TMV在钝化作用方面的抑制率分别为95.5%、92.6%、95.0%和89.5%,优于对照药病毒唑(87.9%)。这些结果表明,1,4-戊二烯-3-酮肟醚类化合物对植物病毒表现有良好抑制作用,在其结构基础上进行适当的优化,有望得到具有良好抗植物病毒活性的先导化合物。 相似文献
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We investigate the compatibility of \(I_0\) with various combinatorial principles at \(\lambda ^+\), which include the existence of \(\lambda ^+\)-Aronszajn trees, square principles at \(\lambda \), the existence of good scales at \(\lambda \), stationary reflections for subsets of \(\lambda ^{+}\), diamond principles at \(\lambda \) and the singular cardinal hypothesis at \(\lambda \). We also discuss whether these principles can hold in \(L(V_{\lambda +1})\). 相似文献