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101.
HU Yen-Yi RU Wan-Huey WEI Chao-Jen LIN Sheu-Jen LAY Yen-Yuan YEH Shun-Tsai YANGTeng-Kuei 《高等学校化学学报》2000,21(Z1):429
Recently, we found the N-(hydroxyalkyl) aza-rings 1 can produce 2-oxazolidine 2 through electrolysis. With the chiral side chain, the 2-oxazolidine 2 can generate a new chiral center at the 0-aminocarbon when treated with Grignard reagents. Repeat the process of electro-oxidation and substitution by Grignard reagents, we can prepare the two most popular alkaloids bases, pyrroliding and piperidine, with substitutions in an enantioselective fashion. This presentation will discuss the efficiency of electro-oxidation of aza-ring compounds in terms of the oxidation conditions, such as the applied potential, quantity of electricity, solvent effect,and temperature effect. Meanwhile, several demonstrative syntheses of chiral alkaloids, such as Monomorine,(-)-pyrroliding 197B, and(-)-Solenopsin A, will also be presented. 相似文献
102.
The photon–photon entanglement dynamics in a bimodal nanocavity, filled with a centrosymmetric nonlinear medium, is studied. In the present study, we have included the first and third order susceptibilities, giving rise to linear and the Kerr-type couplings. With no restrictions placed on the relative strength of these effects, we prove that the corresponding Hamiltonian is block-diagonal, each with ever-growing dimensions. We then show that, depending upon the initial total photon number, one needs to diagonalize a specific low-dimensional block, leading to the time evolution operator. Consequently, the time-evolution of the von Neumann entropy, as a measure of entanglement, is determined. From an analysis of the von Neumann entropy, we show that the entanglement exhibits oscillations, with plateaus, whose characteristics (period, duration, … ) strongly depend upon the strength of third order susceptibility. Moreover, it is shown that the entanglement is enhanced as the linear coupling is increased. The effect of detuning between photon's frequencies is also discussed. 相似文献
103.
The effect of variable viscosity on the peristaltic motion of MHD third‐order fluid in a channel is studied using slip condition. The series solution for stream function, longitudinal velocity and pressure gradient are first derived and then discussed in detail. The pressure rise and frictional forces are monitored through numerical integration. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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基于RLS自适应算法的音频数字水印检测技术 总被引:1,自引:0,他引:1
实现了一种基于音频信号掩蔽曲线的水印嵌入方法,提出了一种基于RLS(递归最小二乘方)自适应滤波算法的水印检测算法,该算法在检测水印时无需原音频文件,实验结果表明,在不影响听觉效果的前提下,这种水印嵌入和检测方法对MPEG压缩,常规滤波,加噪等处理均具有很好的抗攻击性即鲁棒性。 相似文献
107.
基于Turbo码的图像数字水印技术 总被引:5,自引:0,他引:5
在详细分析数字水印系统等效信道的基础上,提出了一种基于Turbo码的图像数字水印算法.该算法利用Turbo码的纠错性能和人眼视觉特性,以实现静止图像中数字水印的嵌入和提取;在水印嵌入之前,对水印序列进行Turbo码编码,然后利用人眼视觉特性进行水印嵌入,并采用了Turbo迭代译码算法进行水印提取,最后进行了数值仿真和算法比较.实验结果表明,该算法降低了水印在传输过程中的误码率,提高了水印的抗攻击能力,同时较好地解决了水印的鲁棒性和不可见性之间的矛盾. 相似文献
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Sajjad Abbasi Ali Sarafraz-Yazdi Amirhassan Amiri Ferial Ghaemi 《Journal of the Iranian Chemical Society》2018,15(1):153-161
We describe a magnetic nanocomposite that consists of Fe3O4/carbon nanosphere/polypyrrole (Fe3O4/CNS/PPy). The synthesized nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The nanocomposite was successfully applied to extract of the polycyclic aromatic hydrocarbons (PAHs) from water samples. Compared to Fe3O4/PPy, the Fe3O4/CNS/PPy nanocomposite exhibits improved properties in terms of extraction. The amount of adsorbent, salt effect, extraction time, desorption time, type, and the volume of desorption solvent were optimized. Following the desorption of the extracted analytes, the PAHs (i.e., naphthalene, 2-methylnaphthalene, 2-bromonaphthalene, fluorene, and anthracene) were quantified by gas chromatography–flame ionization detector. The PAHs can be determined in 0.05–100.00 ng mL?1 concentration range, with limits of detection (at an S/N ratio of 3) ranging from 0.01 to 0.05 ng mL?1. The repeatability of the method was investigated with relative standard deviations of lower than 9.9% (n = 5). Also, the recoveries from spiked real water samples were in the range of 88.9–99.0%. The results indicate that the novel material can be successfully applied for the extraction and analysis of PAHs from water samples. 相似文献
110.
研究了基于生成式对抗网络(GAN)和跨域自适应迁移学习的样本生成和自动标注方法。该方法利用自适应迁移学习网络,基于已有的少量可见光图像样本集,挖掘目标在红外和可见光图像中特征内在相关性,构建自适应的转换迁移学习网络模型,生成标注好的目标图像。提出的方法解决了红外图像样本数量少且标注费时的问题,为后续多频段协同目标检测和识别获得了足够的样本数据。实验结果表明:自动标注算法对实际采集的装甲目标图像和生成的装甲目标图像各1 000张进行自动标注测试,对实际装甲目标图像的标注准确率达到95%以上,对生成的装甲目标标注准确率达到83%以上;利用真实图像和生成图像的混合数据集训练的分类器的性能和使用纯真实图像时基本一致。 相似文献