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961.
962.
2a,4‐Disubstituted 5‐benzoyl‐2‐chloro/2,2‐dichloro‐2a,3,4,5‐tetrahydro‐azeto [1,2‐a] [1,5]benzodiazepin‐1 (2H)‐ones ( 3a–h ) were synthesized by cycloaddition reactions of 2,4‐disubstituted 1‐benzoyl‐2,3‐dihydr o‐1H‐1,5‐benzodiazepines ( 2a–h ) and ketenes, generated from chloroacetyl chloride or dichloroacetyl chloride in the presence of triethylamine, in anhydrous benzene. In some cases, ring contraction of benzodiazepines has also been observed. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:636–640, 2001 相似文献
963.
A general method is described for the synthesis of sterically encumbered porphyrins whose shielding superstructure can take on the enzymatic role of substrate discrimination. This method is based on an improved synthesis of pyrroles substituted with a 2,6‐dibromophenyl group, followed by a Suzuki cross‐coupling to replace the Br with aryl groups. Porphyrins assembled from such pyrrole units have a barrel shape with the metal center completely fenced by four β‐substituted terphenyl shielding wings. The Fe and Mn porphyrins prove to be excellent catalysts for regioselective epoxidation of alkenes. 相似文献
964.
Pravinraj Selvaraj Wen-Fa Cheng Hsiu-Ming Kuo Cheng-Kai Liu Chao-Hsuan Wu Chung Kung Lai Jyun-Cong Lai Sharon Tan Fang Jie Ko-Ting Cheng 《Laser \u0026amp; Photonics Reviews》2024,18(5):2301001
Smart windows are crucial to dynamic control over light transmission to fulfill various demands in energy saving, privacy, and information display; however, most present technologies still perform a single function (often tint or haze adjustment) and require continuous electricity for operation. In this study, novel self-assembled ionic liquid crystals (ILCs) doped with negative cholesteric liquid crystals (CLCs) to offer electrically switchable and stable scattering-mode light modulators are presented. The novel smectic A phase based on the ILCs exhibits high solubility in the adopted nematics, enhancing the LC device's performance in several ways, including improved homogeneity, stable alignment quality, prolonged stability, and simplified fabrication. The LC device can potentially offer a dynamically rapid switching function between stable transparent (imperfect fingerprint textures) states and stable scattering (focal conic textures with small domains) states by using external stimuli and highly maintained multistable states for prolonged periods, even when the external stimuli are removed. The LC device also offers polarization-independent scattering and transparent-mode LC light modulators, low operating voltage, excellent contrast, and broad viewing angles. Its versatility and outstanding field-off stability make it ideal for various applications such as smart lighting, building climate control, energy-saving displays, and augmented reality (AR) glasses. 相似文献
965.
Liuru Fang Yao Guo Xiaojing Bai Yuanbin Xue Changwei Lai Haixiang Song Yuhua Wang 《固体物理学:研究快报》2024,18(3):2300382
Novel optoelectronic and photovoltaic devices are promising, exploiting MoSi2N4-based van der Waals (vdW) heterostructures. Herein, six vertical XSi2N4/Cs2SnI6 (X = Cr, Mo, W) heterostructures are constructed and the atomic structure, stability, and optoelectronic properties via first-principles calculations are investigated. The results of binding energies indicate that XSi2N4/SnI4 is energetically favorable to be established compared to the XSi2N4/CsI. Computed charge density differences show that at the XSi2N4/SnI4 interface, there is no significant charge migration or rearrangement, making it unsuitable for use in charge transport devices. It is worth noticing that the built-in electric field induced by electron transfer from CsI to the XSi2N4 layer prevents light-induced electron and hole recombination, thereby improving carrier lifetime. Furthermore, the CrSi2N4/CsI heterostructure exhibits a wider range of visible light absorption, demonstrating its potential for applications in photoelectronic devices. The electronic and optical properties of XSi2N4/Cs2SnI6 can be tuned through element substitution. The findings could provide useful guidance for designing XSi2N4/Cs2SnI6 photoelectronic and photovoltaic devices. 相似文献
966.
针对金家油田通38块稠油多轮次热采后经济效益变差的现状,开展了采用稠油冷采开发方式的技术探索。稠油冷采技术的核心是研发一种适合目标油藏稠油的低成本高效降黏剂。从油田采出液中筛选到一株能够高产生物表面活性剂菌株Q18,以Q18的发酵代谢产物为基础构建了一种稠油降黏剂RF180。RF180既具有良好的温度和矿化度耐受性,也有较宽的酸碱耐受性,在20~180℃﹑0~120 000 mg/L矿化度和pH 5~11的范围内,具有良好的表面及降黏活性,能够适应金家油田的油藏条件。同时,进一步研究发现浓度大于0.3%的RF180对通38稠油就具有良好的乳化与静置降黏效果,乳化与静置降黏率分别达到99.93%和96.64%。物理模拟驱油实验证明,RF180能够大幅提高通38稠油的驱油效率,在不同注入方式条件下,分别提高12%~26%的目标油藏的采收率。 相似文献
967.
论"智力-技能-认知结构"能力理论 总被引:7,自引:1,他引:6
从心理学、教育学和学科教学论的角度出发,深入分析了目前已有的能力组成结构的优点与不足.在理论研究与学科教学实践研究的基础上,形成了把形式教育说与实质教育说相统一从而建立正确能力理论的思想.依据上述思想,提出了“硬能力”与“软能力”的概念,建立了“智力-技能-认知结构”的能力理论,阐述了该理论的智力观、技能观、知识观和科学方法观.这不仅在一定意义上有助于解决长期以来困惑人们的形式教育说与实质教育说的矛盾,而且也为在教育教学中培养学生的能力奠定了理论和实践基础. 相似文献
968.
Juin-Yih Lai Shun-Fu Lin Fung-Ching Lin Da-Ming Wang 《Journal of Polymer Science.Polymer Physics》1998,36(4):607-615
In this work, the ternary phase diagrams in three nonsolvent/solvent/PMMA systems (n-hexane/n-butyl acetate/PMMA, water/acetone/PMMA, and n-hexane/acetone/PMMA) were constructed by theoretical calculation and experimental measurement. Binodal curves were calculated by using the Flory–Huggins theory for three-component systems and measured by titrating the PMMA solution with nonsolvent until the onset of turbidity. By using concentration-dependent nonsolvent/solvent and solvent/PMMA interaction parameters and constant nonsolvent/PMMA interaction parameters, good agreement has been obtained between the calculation and the measurement. The values of nonsolvent/solvent interaction parameters were taken from the literature sources, and the values of solvent/PMMA and nonsolvent/PMMA interaction parameters were measured by vapor sorption and swelling equilibrium, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 607–615, 1998 相似文献
969.
Raymond Lai 《Mathematical Methods in the Applied Sciences》1998,21(14):1287-1296
The relativistic Vlasov–Maxwell–Fokker–Planck system is used in modelling distribution of charged particles in plasma. It consists of a transport equation coupled with the Maxwell system. The diffusion term in the equation models the collisions among particles, whereas the viscosity term signifies the dynamical frictional forces between the particles and the background reservoir. In the case of one space variable and two momentum variables, we prove the existence of a classical solution when the initial density decays fast enough with respect to the momentum variables. The solution which shares this same decay condition along with its first derivatives in the momentum variables is unique. © 1998 B. G. Teubner Stuttgart—John Wiley & Sons, Ltd. 相似文献
970.