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Qingbao Song Xiaoxia An Fengfeng Che Tianhua Shen 《Journal of heterocyclic chemistry》2015,52(5):1496-1502
Di‐DACH‐pyridylamide ligands, symmetrical bridged bis‐Schiff base, and spiro pyrrolizines as catalysts in the synthesis of dihydropyrimidinethiones (DHPMs) using the Biginelli reaction is first reported. This new protocol has the advantages of environmental friendliness, short reaction time, excellent yields, and simple post‐treatment procedure. A series of DHPMs were obtained in high yields (up to 98%) in only 6 h. Moreover, based on the optimized condition, a novel Biginelli‐like reaction was first developed. 相似文献
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High bit rates optical communication systems pose the challenge of their tolerance to linear and non-linear fiber impairments. Coherent optical receivers using digital signal processing techniques can mitigate the fiber impairments in the optical transmission system, including the chromatic dispersion equalization with digital filters. In this paper, an adaptive finite impulse response filter employing normalized least mean square algorithm is developed for compensating the chromatic dispersion in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying coherent communication system, which is established in the VPI simulation platform. The principle of the adaptive normalized least mean square algorithm for signal equalization is analyzed theoretically, and at the meanwhile, the taps number and the tap weights in the adaptive finite impulse response filter for compensating a certain fiber chromatic dispersion are also investigated by numerical simulation. The chromatic dispersion compensation performance of the adaptive filter is analyzed by evaluating the behavior of the bit-error-rate versus the optical signal-to-noise ratio, and the compensation results are also compared with other present digital filters. 相似文献
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Changyong Sun Guangzong Fang Xiaoguang Guo Yuanli Hu Shuqi Ma Tianhua Yang Jie Han Hao Ma Dali Tan Xinhe Bao 《天然气化学杂志》2015,(3):257-263
Long-term stability test of Mo/HZSM-5-N catalysts(HZSM-5-N stands for nano-sized HZSM-5) in methane dehydroaromatization(MDA)reaction has been performed with periodic CH4-H2 switch at 1033-1073 K for more than 1000 h.During this test,methane conversion ranges from 13% to 16%,and mean yield to aromatics(i.e.benzene and naphthalene) exceeds 10%.N2-physisorption,XRD,NMR and TPO measurements were performed for the used Mo/HZSM-5 catalysts and coke deposition,and the results revealed that the periodic hydrogenation can effectively suppress coke deposition by removing the inert aromatic-type coke,thus ensuring Mo/HZSM-5 partly maintained its activity even in the presence of large amount of coke deposition.The effect of zeolite particle size on the catalytic activity was also explored,and the results showed that the nano-sized zeolite with low diffusion resistance performed better.It is recognized that the size effect was enhanced by reaction time,and it became more remarkable in a long-term MDA reaction even at a low space velocity. 相似文献
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Si Chen Jiabin Zhang Ning Gan Futao Hu Tianhua Li Yuting Cao Daodong Pan 《Mikrochimica acta》2015,182(3-4):815-822
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AbstractThe present study explored the antidepressant-like activity of α-mangostin (α-MG) and the possible mechanism in this process in the tail suspension test (TST) in mice. The results revealed that α-MG (5?mg/kg, i.p.) exhibited markedly antidepressant-like activity, which could be reversed by pretreatment with haloperidol (a non-selective D2 receptor antagonist), bicuculline (a competitive GABA antagonist), p-chlorophenylalanine (an inhibitor of 5-HT synthesis). Meanwhile, α-MG also effectively increased the brain DA, 5-HT and GABA levels in mice exposed to TST, indicating that the antidepressant-like effect of α-MG might be mediated by the GABAergic, serotonergic and dopaminergic systems. 相似文献
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教学悬念,指的是教师将教材内容引发出一种魅力,使学生产生关切的心情。有的老师认为悬念是一种文学技巧,与化学教学关系不大。其实不然。悬念的应用是一种教学艺术,能有效地开发学生的智力。 相似文献
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Hankun Zhou Ning Gan Tianhua Li Yuting Cao Saolin Zeng Lei Zheng Zhiyong Guo 《Analytica chimica acta》2012
A novel and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor was fabricated on a glassy carbon electrode (GCE) for ultra trace levels of α-fetoprotein (AFP) based on sandwich immunoreaction strategy by enrichment using magnetic capture probes and quantum dots coated with Au shell (CdS-Au) as the signal tag. The capture probe was prepared by immobilizing the primary antibody of AFP (Ab1) on the core/shell Fe3O4-Au nanoparticles, which was first employed to capture AFP antigens to form Fe3O4-Au/Ab1/AFP complex from the serum after incubation. The product can be separated from the background solution through the magnetic separation. Then the CdS-Au labeled secondary antibody (Ab2) as signal tag (CdS-Au/Ab2) was conjugated successfully with Fe3O4-Au/Ab1/AFP complex to form a sandwich-type immunocomplex (Fe3O4-Au/Ab1/AFP/Ab2/CdS-Au), which can be further separated by an external magnetic field and produce ECL signals at a fixed voltage. The signal was proportional to a certain concentration range of AFP for quantification. Thus, an easy-to-use immunosensor with magnetic probes and a quantum dots signal tag was obtained. The immunosensor performed at a level of high sensitivity and a broad concentration range for AFP between 0.0005 and 5.0 ng mL−1 with a detection limit of 0.2 pg mL−1. The use of magnetic probes was combined with pre-concentration and separation for trace levels of tumor markers in the serum. Due to the amplification of the signal tag, the immunosensor is highly sensitive, which can offer great promise for rapid, simple, selective and cost-effective detection of effective biomonitoring for clinical application. 相似文献
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本文介绍了APPLE-Ⅱ微型计算机构成的数据采集和处理系统,及其在MM3稳态磁镜实验装置上进行的数据采集、数据处理,由此而获得的等离子体有关温度、密度和电位等参数。 相似文献
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IIntroductlonIntegrMle systems;both classical ajnd quantum me山anies,are aMclnatingsubject·Decades ofresearch In this areahave led to mathematical developme血s that are quite beau-tiful.However,not ail systems posed in physics are Integrable,M Instajnce,the Korteweg-deVies-Burgers(KdV-Burgers),Kur。ot。SI、hinsky(KS)and ifth-order dispersi、Kortevegde Vries(ifth-order KdV)eqUatio。 Therefore the direct methods to sol。nonlinear systemsppear to be more important.In this paper… 相似文献
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