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以表面活性剂聚乙烯吡咯烷酮(PVP)为软模板,采用水合肼作还原剂还原钴盐制备出钴纳米棒,通过XRD、XPS、TEM等分析手段对其结构和形貌进行了表征。结果表明:这种方法制备出来的钴纳米棒长度约为3-4μm,直径约为70~100nm,具有hcp晶相和fcc晶相,其含量比例约为1:1。 相似文献
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用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)为形貌控制剂,通过室温液相反应成功制备出BaCO3纳米棒.纳米棒的直径为60~250nm、长度达几微米.用X射线粉末衍射和透射显微镜技术对所制备纳米晶的成分、形状和尺寸进行了表征分析.研究结果表明,表面活性剂对BaCO~纳米棒的形成起着关键的作用.对BaCO~纳米棒的形成机理作了深入的讨论,提出了BaCO3纳米棒的表面活性剂软模板诱导自组装生长机理. 相似文献
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表面活性剂对二氧化钛纳米流体分散性的影响 总被引:1,自引:1,他引:0
通过二步法将纳米二氧化钛分散到去离子水中,制备TiO2-水纳米流体。通过加入3种不同的表面活性剂作为分散剂,即阴离子表面活性剂十二烷基苯磺酸钠(SDBS)、非离子表面活性剂聚乙烯吡咯烷酮(PVP)和阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)制备出3种不同的纳米流体。用纳米粒度分析仪测定纳米流体中的纳米粒子的粒径和粒径分布,用Zeta电位分析仪测量纳米流体的电位,分析了不同浓度、不同种类的表面活性剂对水基TiO2纳米流体分散性的影响。 相似文献
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综述了表面活性剂在合成金纳米晶溶胶中应用的最新进展,主要就十二烷基硫酸钠(SDS)、聚乙烯吡咯烷酮(PVP)、硫醇类物质及十六烷基三甲基溴化铵(CTAB)等表面活性剂作了较详细地讨论. 相似文献
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聚乙烯吡咯烷酮(PVP)是一种重要的工业化大分子表面活性剂,由于其大分子结构的特殊性及生物适应性,使得PVP在制备金属纳米粒子过程中得到了广泛应用。近年来,有大量关于以PVP为大分子表面修饰剂制备不同形貌金属纳米粒子的文献报道。文中综述了以PVP为表面修饰剂,分别以乙二醇、乙醇、N,N-二甲基甲酰胺及水为溶剂,通过溶剂和PVP自身的还原作用,在不同反应条件下制备不同形貌金、银纳米粒子的研究现状,提出了不同溶剂体系中不同形貌金属纳米粒子的形成机理研究是未来该领域要解决的主要问题。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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《中国标准化(英文版)》2014,(4)
正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from 相似文献
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《中国标准化(英文版)》2014,(5)
正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively. 相似文献
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《中国标准化(英文版)》2014,(4)
正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to 相似文献