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61.
C型电枢通过尾翼弹性变形为电磁发射提供枢轨壁面初始接触力,初始接触状态对电磁轨道发射全过程的滑动界面状态起决定作用,影响系统效率和轨道寿命。通过建立接触模型进行模拟计算和设计多组对比试验,研究了C型电枢作用下初始接触状态。考虑材料的安全变形控制范围,在电枢头部尺寸的微小变动和尾翼的不同设计尺寸下,分析了接触压强、接触区域(面积)、接触力的变化规律。提出了控制接触状态的关键参量——压入比,接触区域随压入比的增大从电枢尾部向头部移动,最大接触面积约占总接触表面的50%。讨论了良好电接触要求下最佳接触状态及其工程实现方法。 相似文献
62.
Peixun Li Yilin Wang Buxing Han Haike Yan Ruilin Liu 《Journal of solution chemistry》1996,25(12):1281-1289
The solubilities of ethane int-butanol (TBA) and water mixtures have been determined at 10, 15, and 20°C and pressures up to 3.1 MPa. Thermodynamic properties have also been calculated based on the measured solubility data and the hydrophobic interaction for the methane-methane pair interaction in the mixed solvent is discussed. 相似文献
63.
旋量法在机器人动力学分析中的应用 总被引:1,自引:1,他引:0
本文用旋量方法研究机器人的动力学模型,将速度和角速度,力和力矩的内在联系有机地融合为一体,使Newton-Euler方法更加简明有效率.文中相对于机器人各臂质心建立参考系,使惯性张量和质心加速度计算简化,进一步减少计算量,达到快速实时计算. 相似文献
64.
Ruilin Bai Qiaosong Lin Xinyu Li Fangxin Ling Huijuan Wang Sha Tan Lingxiang Hu Mingze Ma Prof. Xiaojun Wu Yu Shao Xianhong Rui Prof. Enyuan Hu Dr. Yu Yao Prof. Yan Yu 《Angewandte Chemie (International ed. in English)》2023,62(26):e202218165
Room temperature sodium-sulfur (RT Na-S) batteries are highly competitive as potential energy storage devices. Nevertheless, their actually achieved reversible capacities are far below the theoretical value due to incomplete transformation of polysulfides. Herein, atomically dispersed Fe-N/S active center by regulating the second-shell coordinating environment of Fe single atom is proposed. The Fe−N4S2 coordination structure with enhanced local electronic concentration around the Fermi level is revealed via synchrotron radiation X-ray absorption spectroscopy (XAS) and theoretical calculations, which can not only significantly promote the transformation kinetics of polysulfides, but induce uniform Na deposition for dendrite-free Na anode. As a result, the obtained S cathode delivers a high initial reversible capacity of 1590 mAh g−1, nearly the theoretical value. This work opens up a new avenue to facilitate the complete transformation of polysulfides for RT Na-S batteries. 相似文献
65.
An ionic liquid-based microwave-assisted extraction (ILMAE) approach has been successfully applied to the effective extraction of the phenolic alkaloids present in samples of the medicinal plant Nelumbo nucifera Gaertn. The ionic liquids investigated comprised a range of four anions, four 1-alkyl-3-methylimidazolium derivatives differing in hydrophobic chain length. The results indicate that varying the anion has apparent effects on the overall extraction efficiency. In addition, the influence of some microwave parameters, such as irradiation power, extraction time and solid-liquid ratio, are also investigated. Under the optimized conditions, the proposed approach has been evaluated in comparison with the conventional heat-reflux extraction (HRE) and regular MAE. The reduction of the extraction times (from 2h to 90s) and remarkable higher efficiency (20-50% improved) supports the suitability of the proposed approach. In addition, the proposed method is validated by the recovery, correlation coefficient (R(2)), and reproducibility (RSD, n=5), which are in the range of 98-105%, 0.9994-0.9998, and 1.2-5.4%, respectively. 相似文献
66.
Isolation and purification of two antioxidant isomers of resveratrol dimer from the wine grape by counter‐current chromatography 下载免费PDF全文
Ruilin Hu Xuefeng Yin Guoshan Jiang Yuanjiang Pan 《Journal of separation science》2016,39(12):2374-2379
Resveratrol dimers belong to a group of compounds called stilbenes, which along with proanthocyanidins, anthocyanins, catechins, and flavonols are natural phenolic compounds found in grapes and red wine. Stilbenes have a variety of structural isomers, all of which exhibit various biological properties. Counter‐current chromatography with a two‐phase solvent system composed of n‐hexane/ethyl acetate/methanol/water (2:5:4:5, v/v/v/v) was applied to isolate and purify stilbene from the stems of wine grape. Two isomers of resveratrol dimers trans‐ε‐viniferin and trans‐δ‐viniferin were obtained from the crude sample in a one‐step separation, with purities of 93.2 and 97.5%, respectively, as determined by high‐performance liquid chromatography. The structures of these two compounds were identified by 1H and 13C NMR spectroscopy. In addition, their antioxidant activities were assessed by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) assay. The antioxidant activities of trans‐δ‐viniferin were higher than that of trans‐ε‐viniferin in this model. This work demonstrated that counter‐current chromatography is a powerful and effective method for the isolation and purification of polyphenols from wine grape. Additionally, the DPPH radical assay showed that the isolated component trans‐δ‐viniferin exhibited stronger antioxidant activities than trans‐ε‐viniferin and a little bit weaker than vitamin E at the same concentration. 相似文献
67.
Strong electromagnetic fields produced in the non-central heavy-ion collisions can induce vector meson photoproduction. In this paper, we study the photoproduction J/ψ and φ mesons in the relativistic heavy-ion collision from ultra-peripheral nuclear collisions to peripheral hadronic heavy ion collisions. And then include both initial hadronic production and thermal production in quark-gluon plasma (QGP). We find, for the charm anti-charm bound state J/ψ, the photoproduced J/ψs are mainly in the very low momentum region and clearly exceed the hadronic production. However, considering the thermal production of strange quark anti-quark pairs in QGP produced in relativistic heavy-ion collisions, the photoproduced φ is usually smaller than the thermal production and only evident at very peripheral collisions as even their photoproduction is much larger than J/ψ. 相似文献
68.
Xurong Qin Xiaoyu Li Quan Huang Hu Liu Di Wu Qiang Guo Jingbo Lan Ruilin Wang Jingsong You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(24):7273-7276
RhIII‐catalyzed oxidative C H/C H cross‐coupling between (hetero)aromatic carboxylic acids and various heteroarenes has been accomplished to construct highly functionalized ortho‐carboxy‐substituted bi(hetero)aryls. The use of a carboxy group as the directing group obviates tedious steps for installation and removal of extra directing groups, and enables a facile one‐step synthesis of ortho‐carboxy bi(hetero)aryls. The method provides opportunities for rapid assembly of a library of important fluorene and coumarin‐type poly‐heterocycles through intramolecular electrophilic substitution or oxidative lactonization. As illustrative examples, the strategy developed herein greatly streamlines accesses to a variety of appealing polyheterocycles such as DTPO (5H‐dithieno[3,2‐b:2′,3′‐d]pyran‐5‐one), CPDTO (cyclopentadithiophen‐4‐one), and indenothiophenes. 相似文献
69.
70.
亲水作用色谱-串联质谱法测定稻米中的草甘膦和氨甲基磷酸残留量 总被引:1,自引:0,他引:1
采用亲水作用色谱-串联质谱建立了同时测定稻米中草甘膦及其主要代谢物氨甲基磷酸残留量的检测方法。样品经水提取,C18固相萃取柱和超滤膜净化,以1 mmol/L乙酸铵溶液(用氨水调pH=11.0)-乙腈为流动相,亲水作用色谱柱分离,采用电喷雾离子源、负离子扫描模式和多反应监测模式质谱检测,基质匹配标准溶液外标法定量。草甘膦和氨甲基磷酸分别在0.001~0.250 mg/L和0.0025~0.250 mg/L质量浓度范围内线性关系良好,检出限(信噪比为3)分别为0.010 mg/kg和0.020 mg/kg。通过对空白大米样品进行0.100、0.500和2.500 mg/kg 3个加标水平的回收试验,草甘膦和氨甲基磷酸的平均回收率和相对标准偏差分别为96.3%~107.3%和1.3%~9.1%(n=3)。该方法无需衍生,净化步骤简便快速,定量准确,可满足稻米中草甘膦和氨甲基磷酸残留检测要求。 相似文献