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991.
The 1:1 reactive intermediate generated by the addition of alkyl isocyanides to dibenzoylacetylene or dialkyl acetylenedicarboxylates was trapped by fairly strong NH acids such as isatin, phthalimide, 4-nitroimidazole, or 2-benzoylimidazole to yield highly functionalized ketenimines. 相似文献
992.
By combining a ceric ammonium nitrate (CAN)–catalyzed aerobic oxidation of α-hydroxy ketones with a subsequent three-component condensation reaction using aldehydes and ammonium acetate, highly substituted imidazole derivatives can be assembled. This reaction is an important approach for the synthesis of highly substituted imidazole derivatives and was carried out in good to excellent yields in ethanol as an environmentally benign solvent. 相似文献
993.
Furan-2(5H)-one derivatives have been synthesized by a simple, efficient, one-pot, three-component condensation of anilines, dimethylacetylenedicarboxylate, and aromatic aldehydes in the presence of a catalytic amount of tin(II) chloride in excellent yields. 相似文献
994.
In this study, silica-supported titanium tetrachloride was prepared and used as a novel catalyst for rapid and efficient synthesis of 2,4,5-trisubstituted imidazoles by a three-component, one-pot condensation of 1,2-diketones and aryl aldehydes in excellent yield under solvent-free conditions using conventional heating or microwave irradiation.
995.
Based on microreactors, the representative Baylis‐Hillman reaction of cyclopent‐2‐enone coupled with 4‐nitrobenzaldehyde in the presence of imidazole could be accelerated by manipulating the temperature and electric field. Furthermore, the electric field was used in promoting Baylis‐Hillman reaction for the first time with the rate acceleration approximately 5.2‐fold higher than that carried out in conventional vessels as well as 4.0‐fold under control of temperature. Meanwhile, the products of Baylis‐Hillman reaction at every time point could be collected and then determined by capillary micellar electrokinetic chromatography. 相似文献
996.
To test whether the fiber Bragg grating (FBG) sensor can endure the steady-state inertial loads caused by the acceleration and the sensing properties during the loads, a FBG strain and temperature sensor with aluminium alloy substrate package was designed, and the acceleration performance on the sensor was tested. The sizes of FBG strain and temperature sensor were designed and its package process was described. The strain and temperature sensing mechanisms of FBG sensor were analyzed, and the spectrum detection and demodulation system based on volume phase grating and linear array photodetector was developed. Finally, the acceleration test equipment was established, and the acceleration performance test of the selected FBG strain and temperature sensor was carried out in accordance with the requirements and methods of GJB150.15A acceleration test. The experimental results show that in the 2 min performance test before and after the acceleration test, the wavelength offset is below to ±50 pm, and the change of light intensity is below to 0.3 V. In acceleration test, the maximum fluctuation of wavelength offset is ±7 pm, and the light intensity is in the range of 1.3 V~4.003 V. It is proved that the designed FBG sensor has the ability to endure the acceleration loads and has the good sensing performance during the acceleration loads. Copyright ©2022 Journal of Applied Optics. All rights reserved. 相似文献
997.
分别研究了微机串行通讯口和定时器原理,借助C语言编程,实现了微机对外界时间信息的数据采集.在此基础上,开展了数字毫秒计制作、重力加速度及弹性模量检测的研究. 相似文献
998.
999.
基于高斯分布的哨声波谱密度分布、偶极子背景磁场模型以及建立在卫星观测数据基础上的半经验电子密度纬度分布模型,对于等离子体层顶以外区域(4≤L≤7),计算了准线性当地及弹跳平均电子共振扩散系数,并估算了与磁层哨声波回旋共振导致的辐射带电子损失及加速时间尺度.结果表明,波粒共振相互作用区域取决于电子能量、波谱分布、电子赤道抛射角以及当地电子密度及背景磁场.哨声波共振频率除了与以上5个参量有关外,还与地磁纬度有关.赤道哨声波主要影响较低能量辐射带电子的加速,中高纬度哨声波主要作用于较高能量辐射带电
关键词:
共振波粒相互作用
地球辐射带
哨声波
回旋共振加速及散射沉降 相似文献
1000.
超短超强激光与固体靶相互作用中发射质子的截止能量估算 总被引:2,自引:1,他引:1
根据超短超强激光与固体靶相互作用中质子靶前表面加速和靶后表面加速两种机制,对在SILEX-I激光器上进行的质子加速实验中获得的质子最大截止能量进行了估算,认为实验中质子产生的主要机制是靶后表面加速。同时结果表明:对该装置的实验条件,靶前表面加速机制可以产生质子的最大能量约为2 MeV;靶后表面加速机制可以产生的质子的最大能量约11 MeV。另外用Multi2005程序计算了激光器信噪比对靶后表面加速机制的影响。计算表明:SILEX-I激光器信噪比达到108∶1时,预脉冲对用5 μm靶时鞘层加速电场的影响可以忽略。 相似文献