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901.
902.
903.
一套预测冰面上汽车牵引力的模型 总被引:4,自引:3,他引:4
根据传热学中的热平衡原理及冰的摩擦经理论,建立了冰面汽车牵引力的预测模型。研究表明:所建立的理论模型比已有的模型更接近实际,从摩擦学角度系统分析了汽车工作条件和环境因素以及表面粗糙度等对牵引力的影响,提出了今后研究中有待解决的几个问题。 相似文献
904.
Studies on the structure and catalytic performance of Cu-Zn-Al catalyst prepared by liquid-phase preparation technology under different heat treatment atmosphere
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Cu-Zn-Al slurry catalysts were prepared using a complete liquid-phase preparation technology under different heat treatment atmospheres. The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscope, and N2 adsorption-desorption. Their application in the single-step synthesis of dimethyl ether from syngas was also investigated. The results indicate that the type of heat treatment atmosphere has an influence on the Cu species and the Cu0/Cu+ ratio on the catalyst surface. Moreover, the final Cu/Zn ratio on the catalyst surface is mainly dependent on the composition and reaction environment of the catalyst and little on the type of heat treatment atmosphere. The prepared catalysts can suppress sintering of active sites at high temperatures, and the type of heat treatment atmosphere mainly affects the capability of the catalyst for methanol synthesis. The catalysts perform best using N2 as the heat treatment atmosphere. 相似文献
905.
Weiting Yu Junzhang Lin Xiudong Liu Hongguo Xie Wei Zhao Xiaojun Ma 《Journal of membrane science》2010
The semi-permeable membrane of alginate–chitosan (AC) microcapsules has been proven important to control the microcapsule stability and selective substance diffusion rate. Therefore, a novel and operable methodology based on gel permeation chromatography (GPC) was established for quantitative characterization of the membrane formation process, so as to provide guidance on performance improvement of AC microcapsules in biomedical applications. Not only the molecular weight (Mw) and its distribution of chitosan can be obtained by GPC, but also the area integral of molecular weight peaks can be linearly correlated to chitosan concentration in certain range. The dynamic membrane formation process was then obtained by quantitatively analyzing reaction amount of chitosan with time, which showed that for chitosan molecules with wide Mw distribution, only parts of molecules bind with alginate to form microcapsule membrane. Moreover, the contribution of chitosan molecules participating in the membrane formation process was also different. These new findings, therefore, are helpful for adjusting and controlling the membrane formation process and properties of microcapsule membrane. 相似文献
906.
Qing-Song Ye Xi-Zhu Chen Ming-Jin Xie Wei-Ping Liu Jia-Lin Chen Zai-Fu Pan 《Transition Metal Chemistry》2010,35(5):585-590
Dirhodium tetraoctanoate (1), without any exogenous axial ligands, has been obtained in crystalline form by slow evaporation from ethanol. The molecules
are linked by axially ligating each other to form infinite chains, which is similar to the only other two structurally characterized
rhodium(II) carboxylates, Rh2(O2CCF3)4 and Rh2(O2CC3H7)4, which also lack exogenous axial ligands. The infinite chains of 1 are cleaved by strong donor solvents such as pyridine to produce the corresponding pyridine adduct (2). Both the complexes were characterized by elemental analysis, MS, IR and NMR spectra. 相似文献
907.
采用AAO模板及后处理方法合成了圆盘状a-Co(OH)2并研究了其电化学电容性能.在该合成方法中,先采用阳极氧化铝模板结合交流电沉积的方法获得钴纳米线,而后将其在碱液中通过溶解氧氧化生成终端产物.用红外光谱(FT-IR),X射线衍射(XRD)和场发射扫描电子显微镜(FE-SEM)表征了产物的结构和形貌;用循环伏安、恒电流充放电测试方法对其电化学性能进行了测试.此外,对圆盘状Co(OH)2的形成机理进行了初步探讨.结果表明,用此方法合成的Co(OH)2具有圆盘状形貌,属a相态,且表现出较好的电容特性. 相似文献
908.
首先合成配合前驱体对氨基苯甲酸(PABA)-二乙烯三胺五乙酸(DTPA)-3-氨丙基三甲氧基硅烷(APTMS)及双稀土配合物Eu3+/Tb3+-PABA-DTPA-APTMS,然后采用反相微乳液法成功制备出表面带氨基的核壳型稀土配合物Eu3+/Tb3+-PABA-DTPA-APTMS掺杂的Ag@SiO2荧光纳米粒子.利用透射电子显微镜、荧光光谱、紫外-可见光谱等手段进行表征,并进行了光稳定性及氨基测定等实验,结果表明,该纳米粒子中Eu3+与Tb3+在最大发射峰处的荧光强度较Eu3+/Tb3+-PABA-DTPA-APTMS掺杂的没有银核的SiO2荧光纳米粒子分别提高了3.0和3.4倍,所制备的纳米粒子呈规则球状,具有良好的分散性和光稳定性,纳米粒子表面带有氨基,可不需要进行表面修饰而直接与生物分子反应.该纳米粒子有望作为一种新型的稀土荧光探针应用于高灵敏检测的时间分辨荧光免疫分析、生物传感器、生物芯片等. 相似文献
909.
Xu F Zhang H Ilavsky J Stanciu L Ho D Justice MJ Petrache HI Xie J 《Langmuir : the ACS journal of surfaces and colloids》2010,26(24):19199-19208
The dispersion of Nafion ionomer particles and Pt/C catalyst aggregates in liquid media was studied using both ultra-small-angle X-ray scattering (USAXS) and cryogenic TEM. A systematic approach was taken to study first the dispersion of each component (i.e., ionomer particles and Pt/C aggregates), then the combination of the components, and last the catalyst ink. Multiple-level curve fitting was used to extract the particle size, size distribution, and geometry of the Pt/C aggregates and the Nafion particles in liquid media from the scattering data. The results suggest that the particle size, size distribution, and geometry are not uniform throughout the systems but rather vary significantly. It was found that the interaction of each component (i.e., the Nafion ionomer particles and the Pt/C aggregates) occurs in the dispersion. Cryogenic TEM was used to observe the size and geometry of the particles in liquid directly and to validate the scattering results. The TEM results showed excellent agreement. 相似文献
910.
Zhuo Wang Feng‐Ying Bai Yong‐Heng Xing Prof. Dr. Yan Xie Mao‐Fa Ge Shu‐Yun Niu 《无机化学与普通化学杂志》2010,636(8):1570-1575
Two new lanthanide complexes [Sm2(ad)2.5(BSA)(H2O)2]n ( 1 ) and [Nd2(ad)2.5(BSA)(H2O)2]n ( 2 ) (H2ad = adipic acid, HBSA = benzenesulfonic acid) were synthesized hydrothermally from the reaction of the lanthanide ions (Ln3+) with flexible aliphatic dicarboxylate and the rigid benzene sulfonic acid and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. They crystallize monoclinic in space group P21/ c. Structural analyses revealed that the two complexes have intricate 3D net structures constructed by the bridging adipic ligand and benzenesulfonic acid. The thermogravimetric analysis of 1 and 2 , as well as photoluminescent properties of 1 are discussed in detail. 相似文献