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101.
超声条件下合成4—戊基(4‘—丙基)双环己基联苯 总被引:2,自引:0,他引:2
在超声辐射下,用相转移催化剂十六烷基三甲基溴化铵作助催化剂,室温下通过氯化钯催化4-(4’-丙基)环己基苯基硼酸与4-(4’-戊基)环己基溴苯偶联反应20min,合成了4-戊基(4’-丙基)双环己基联苯,反应转化率97%,反式产物选择性62%。 相似文献
102.
103.
Generation of Femtosecond Laser Pulse at 1053 nm with Contrast of 10-11 by Optical-Parametric Amplification 下载免费PDF全文
A high contrast 1053nm femtosecond laser pulse with free background is demonstrated based on non-collinear optical-parametric amplification (NOPA). By permuting the signal and idler in two stages of NOPAs, 48.2fs, 62 μJ laser pulse at 1053nm with contrast ratio of 2.3 ×10^-11 is obtained within the time scale of sub-5 ps. The beam quality factors M2 for tangential and sagittal directions are 1.59 and 1.30, respectively. This work not only proves a feasible way to generate a clean femtoseeond laser pulse but can also be employed as an ideal frontend for ultrashort ultrahigh intensity Nd:glass-based laser systems. 相似文献
104.
The near-infrared properties of gold rectangular split nanorings (RSNs) are investigated by simulation using the finite element method. In the results, the distribution and enhancement of electromagnetic (EM) fields are confirmed by the distribution of charge and current density. The spectrum variation with split distance of RSNs in absorption is in accordance with the hybridization theory. The influence of split distance and light wavelength on the enhancement of EM field is also studied for devices that make use of surface plasmon resonance in nearinfrared, such as in optical trapping, biomedicine, and solar energy. Additionally, the spectra in mediums with various refractive indices suggest the potential application of the hybridized plasmonic RSNs as an ultra-sensitive sensor in the near-infrared region. 相似文献
105.
新颖的含乙炔桥键液晶分子设计与合成 总被引:1,自引:0,他引:1
为降低液晶分子的双折射率并获得宽液晶相区, 用环己基替代传统二苯乙炔液晶分子中的一个苯环, 得到一类结构新颖的含乙炔桥键的负介电各向异性液晶分子4a, 4b. 目标化合物采用1-trans-4-(trans-4-正戊基环己基)环己基乙炔与4-碘-2,3-二氟苯基醚进行Sonogashira偶联反应制备, 反应总产率27%~28%. 产物结构经MS, IR, NMR鉴定确认. 采用DSC结合偏光显微镜对液晶相变温度进行了测试, 结果表明新化合物4a, 4b清亮点分别为212, 216 ℃, 向列相温区均达到140 ℃, 与传统二苯乙炔类液晶的相变温区基本相当. 物理性能测试表明, 分子骨架共轭程度的削弱不仅使双折射率大幅降低, 而且介电各向异性绝对值还有所增大, 为分子设计提供了新的思路. 新化合物综合性能得到显著改善, 在大尺寸液晶电视领域具有非常好的应用前景. 相似文献
106.
Clotrimazole (CT)-containing proliposomes were prepared by penetrating an ethanol solution of CT and Egg phosphatidylcholine (PC) into microporous sorbitol particles, followed by vacuum evaporation of the solvent. As a result, CT proliposomes with free-flowing flowability were obtained. On contact with water, the proliposomes were rapidly converted into a liposomal dispersion, in which a certain amount of CT was entrapped by the liposomes. The result in scanning electronic micrograph confirmed the formation of liposomes structures from proliposomes, and the particles revealed round or ellipse. The ratio of drug to total lipid, ratio of PC to cholesterol and ratio of lipid to sorbitol affected the entrapment efficiency (EE%). The EE% of optimized formulation (CT 10 mg, 0.1 g total lipid, PC/CH ratio is 60 : 40 and 1 g sorbitol) in this investigation was 96.2+/-1.5%. The proliposomes system can provide sustaining release in simulated vaginal fluid at 37+/-1 degrees C for 24 h. In-vivo performance of blank proliposomes, a physical mixture of sorbitol and drug, clotrimazole proliposomes and commercial ointment formulation were evaluated using antifungal activity test. At 7 d post-dose, the c.f.u. of C. albicans decreased in proliposomes-treated groups than ointment and the physical mixture (t-Student, p<0.05). The results indicated that CT-containing vaginal proliposomes prolonged drug release and may increase amount of drug retention into the mucosa to result in more antifungal efficacy. In addition, CT-proliposomes did not affect the morphology of vaginal tissues. Therefore, the dosage form might be further developed for safe, convenient, and effective treatment of vaginal candidasis with reduced dosing interval. 相似文献
107.
The emergence of drug resistant bacterium threatens the global public healthcare systems.The urgent need to obtain new antimicrobials has driven antimicrobial peptides(AMPs)research into spotlight.Here we give a brief introduction of the recent progress of AMPs regarding their structures,properties, production and modification,and antimicrobial mechanism.Thereby,this review will give an insight into the trends and challenges facing on this particular kind of antimicrobial materials. 相似文献
108.
109.
Robust Low Voltage Program-Erasable Cobalt-Nanocrystal Memory Capacitors with Multistacked Al2O3/HfO2/Al2O3 Tunnel Barrier 下载免费PDF全文
A n atomic-layer-deposited Al2O3/HfO2/Al2O3 (A/H/A) tunnel barrier is in vestigated for Co nanocrystal memory capacitors. Compared to a single Al2O3 tunnel barrier, the A/H/A barrier can significantly increase the hysteresis window, i.e., an increase by 9 V for ±12 V sweep range. This is attributed to a marked decrease in the energy barriers of charge injections for the A/H/A tunnel barrier. Further, the Co-nanocrystal memory capacitor with the A/H/A tunnel barrier exhibits a memory window as large as 4.1 V for 100 μs program/erase at a low voltage of ±7 V, which is due to fast charge injection rates, i.e., about 2.4× 10^16 cm^-2 s^-1 for electrons and 1.9× 1016 cm^-2 s^-1 for holes. 相似文献
110.
基于交叉相位调制的时间透镜可实现精确的二次相位调制, 但是它在光脉冲压缩领域的应用受到了抽运光脉冲的峰值功率过高的限制. 对该峰值功率的表达式进行了推导, 提出使用带有正色散的传输介质来实现输出段色散, 从而降低了抽运光脉冲的峰值功率.并进一步指出, 可以将基于交叉相位调制的时间透镜应用于4f系统, 来实现光脉冲压缩, 从而更有效地降低了抽运光脉冲的峰值功率. 推导了该系统的抽运光脉冲的峰值功率和分辨率的表达式, 并进行了光脉冲压缩的仿真分析.研究结果表明, 在基于交叉相位调制的4f系统中, 可以利用峰值功率较低的抽运光脉冲产生飞秒量级超短光脉冲; 随着压缩系数的提高, 输出光脉冲的脉冲宽度主要受到4f系统分辨率的限制, 并对4f系统分辨率的提高进行了讨论. 相似文献