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71.
A novel transition-metal-catalyzed rearrangement of silylated cyclopropenes to the corresponding allenes is described. The presence of both the trimethylsilyl group on the cyclopropene and the platinum catalyst are crucial for this rearrangement. 相似文献
72.
Readily available, stable, and inexpensive N-tosylhydrazones react with arynes under mild reaction conditions to afford 3-substituted indazoles in moderate to good yields. The reaction appears to involve a dipolar cycloaddition of in situ generated diazo compounds and arynes. 相似文献
73.
[reaction: see text] A copper-mediated deracemization of the vaulted biaryl ligands VANOL and VAPOL can be readily achieved in the presence of (-)-spartiene. The optimal procedure involves the in situ generation of copper(II) and leads to the reproducible formation of (S)-VANOL and (S)-VAPOL in greater than 99% ee from the racemates. This method is superior to existing procedures for BINOL (92% ee). 相似文献
74.
Although complex Lü systems have been considered in many studies, application of the self-time-delay synchronization (STDS) of complex Lü systems in secure speech communications does not appear to have been covered in much of the literature. Therefore, it is meaningful to study the STDS of complex Lü systems and its application in secure speech communication. First, a complex Lü system with double time-delay is introduced and its chaotic characteristics are analyzed. Second, a synchronization controller is designed to achieve STDS. Third, the improved STDS controller is used to design a speech communication scheme based on a complex Lü system. Finally, the effectiveness of the controller and communication scheme are verified by simulation. 相似文献
75.
Li Dai Yuning Wang Ruirun Chen Shunxiang Yang Xianbo Han Chunrui Liu Yu Shao 《Crystal Research and Technology》2020,55(6):1900176
A series of Sc:Yb:Tm:LiNbO3 crystals with variable Sc3+ (0, 1, 2, and 3 mol%) concentration are grown by the Czochralski method. The effective distribution coefficients of Sc3+, Yb3+, and Tm3+ ions in the Sc:Yb:Tm:LiNbO3 crystals are determined by inductively coupled plasma atomic emission spectrometer. Sc3+ ions distribute uniformly in crystals when Sc3+ concentration reaches up to 3 mol%. The influence of Sc3+ concentration on the dopant occupancy and defect structure of Sc:Yb:Tm:LiNbO3 crystals is investigated by IR transmission spectra. Threshold concentration of Sc3+ ions in Sc:Yb:Tm:LiNbO3 crystals is nearly 3 mol%. By analyzing UV–vis–NIR absorption spectra, absorption property of Sc:Yb:Tm:LiNbO3 crystals is improved by doping Sc3+ ions. Additionally, the Sc:Yb:Tm:LiNbO3 crystals can be pumped by commercially available high power AlGaAs LDs. 相似文献