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排序方式: 共有209条查询结果,搜索用时 15 毫秒
1.
针对芳香硝基化合物的催化选择性加氢反应,开发可替代贵金属催化剂的低成本、高效非贵金属催化剂,对于芳香胺类化合物的绿色生产具有重要意义。利用简易、可规模化的制备方法,以镍—2,5-吡啶二羧酸金属有机框架为前驱体,热解制备了氮掺杂石墨碳包覆镍纳米催化材料(Ni@CN)。采用X射线衍射、扫描电镜、透射电镜、元素分析、N2吸脱附等检测手段对Ni@CN的物化性质进行了表征,并对其催化性能进行了评价。结果表明,Ni@CN可在温和条件下(85℃,1.0 MPa H2)高效加氢含取代官能团的芳香硝基化合物生成对应的芳香胺类化合物。对比试验表明,镍纳米颗粒是Ni@CN的加氢活性中心,而石墨碳壳的存在有利于优先吸附硝基官能团。此外,进一步考察了Ni@CN的循环使用性能以及抗硫化物中毒的特性。  相似文献   
2.
纳米药物非临床药代动力学的研究策略及关注要点   总被引:1,自引:0,他引:1  
随着纳米技术的迅速发展,纳米药物的研发已成为目前药物创新的发展方向之一。纳米药物具有基于纳米结构的尺度效应,其药代动力学特征与普通药物相比存在明显差异,其药代动力学研究与普通药物相比也有其特殊性。本文着重探讨纳米药物的非临床药代动力学的研究策略及关注要点,包括受试物、体内/外试验、生物样本分析、数据评价分析等,期望为研发者提供参考。  相似文献   
3.
Low temperature delamination of plastic encapsulated microcircuits   总被引:1,自引:0,他引:1  
Plastic encapsulated microcircuits (PEMs) are increasingly being used in applications requiring operation at temperatures lower than the manufacturer’s recommended minimum temperature, which is 0°C for commercial grade components and −40°C for industrial and automotive grade components. To characterize the susceptibility of PEMs to delamination at these extreme low temperatures, packages with different geometries, encapsulated in both biphenyl and novolac molding compounds, were subjected to up to 500 thermal cycles with minimum temperatures in the range −40 to −65°C in both the moisture saturated and baked conditions. Scanning acoustic microscopy revealed there was a negligible increase in delamination at the die-to-encapsulant interface after thermal cycling for the 84 lead PQFPs encapsulated in novolac and for both 84 lead PQFPs and 14 lead PDIPs encapsulated in biphenyl molding compound. Only the 14 lead novolac PDIPs exhibited increased delamination. Moisture exposure had a significant effect on the creation of additional delamination.  相似文献   
4.
新型包膜尿素的制备及其特性的研究   总被引:2,自引:0,他引:2  
唐辉  王亚明 《化肥工业》2003,30(3):20-23
以桐油为主要成膜物质制备新型包膜尿素。研究结果表明,包膜后尿素颗粒的粒径分布更加均匀,有外密封层时可在包膜尿素表面形成连续致密的包膜,包膜尿素因之获得逐步释放特性。使用溶解率和无土柱淋溶率可以评价包膜尿素的养份释放特性。  相似文献   
5.
Hierarchical nanostructure, high electrical conductivity, extraordinary specific surface area, and unique porous architecture are essential properties in energy storage and conversion studies. A new type of hierarchical 3D cobalt encapsulated Fe3O4 nanosphere is successfully developed on N‐graphene sheet (Co?Fe3O4 NS@NG) hybrid with unique nanostructure by simple, scalable, and efficient solvothermal technique. When applied as an electrode material for supercapacitors, hierarchical Co?Fe3O4 NS@NG hybrid shows an ultrahigh specific capacitance (775 F g?1 at a current density of 1 A g?1) with exceptional rate capability (475 F g?1 at current density of 50 A g?1), and admirable cycling performance (97.1% capacitance retention after 10 000 cycles). Furthermore, the fabricated Co?Fe3O4 NS@NG//CoMnO3@NG asymmetric supercapacitor (ASC) device exhibits a high energy density of 89.1 Wh kg?1 at power density of 0.901 kW kg?1, and outstanding cycling performance (89.3% capacitance retention after 10 000 cycles). Such eminent electrochemical properties of the Co?Fe3O4 NS@NG are due to the high electrical conductivity, ultrahigh surface area, and unique porous architecture. This research first proposes hierarchical Co?Fe3O4 NS@NG hybrid as an ultrafast charge?discharge anode material for the ASC device, that holds great potential for the development of high‐performance energy storage devices.  相似文献   
6.
纳米改性氢氧化铝与包覆红磷协效阻燃PBT的研究   总被引:2,自引:0,他引:2  
以纳米改性氢氧化铝(CG-ATH)与包覆红磷(RP)为无卤阻燃剂,研究其对聚对苯二甲酸丁二醇酯(PBT)的阻燃性能和力学性能的影响。首先探讨了包覆红磷的添加量对PBT阻燃性能和力学性能的影响,然后固定包覆红磷用量,考察纳米CG-ATH的添加量对PBT/RP复合体系的阻燃性能和力学性能的影响。实验结果表明,纳米CG-ATH和包覆红磷能协效阻燃PBT复合体系,在包覆红磷添加量为10phr,纳米CG-ATH为20 phr时,PBT复合材料的氧指数从21%提高到30%,达到V-0级;复合材料的拉伸强度为57.0 M Pa,冲击强度为3.03 kJ/m2,断裂伸长率为5.79%,表明该PBT复合体系具有优良的阻燃性能和力学性能。  相似文献   
7.
嵌入式操作系统封装层的设计与实现   总被引:12,自引:2,他引:12  
文中对嵌入式操作系统封装的必要性作了较详细地论述,并以商用嵌入式操作系统VxWorks对通信类产品的封装为例对封装层的设计与实现进行了探讨。  相似文献   
8.
9.
Black chrome‐graphite encapsulated FeCo nanoparticles (BC‐GEFeCo NPs) composite coatings were electrodeposited on substrates such as stainless steel, Cu, and Ni‐coated Cu. The major content of the deposited film is contributed by Cr, Fe‐Cr, Fe2AlCr, and FeCr0.29Ni0.16C0.06 as deduced from X‐ray diffraction. The root‐mean‐square roughness value of black chrome on Ni‐coated Cu employing PbSb anode is measured by atomic force microscopy (nanoindentation) studies as 57.176 nm, which is in satisfactory agreement with the literature value of 53.83 nm. With the addition of GEFeCo Nps, the root‐mean‐square roughness value for BC‐GEFeCo composite coatings on Ni‐coated Cu increases approximately 6.1 times that of black chrome surface. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
10.
High‐temperature‐induced and humidity‐induced degradation behaviors were investigated through the failure analysis of encapsulated Cu(In,Ga)Se2 (CIGS) modules and non‐encapsulated CIGS cells. After being exposed to high temperature (85 °C) for 1000 h, the efficiency loss of CIGS modules and the resistivities of the aluminum‐doped zinc oxide (AZO) layer, CIGS layer, and Mo layer were slightly increased. After damp heat (DH) testing (85 °C/85% RH), the efficiency of some modules decreased significantly accompanied by discoloration, and in these areas, the resistivity of the AZO layers increased markedly. The causes of degradation of CIGS cells after high temperature and DH tests were suggested through X‐ray photoelectron spectroscopy analysis. The high‐temperature‐induced degradation behaviors were revealed to be increases in series resistance of the CIGS cells, due to the adsorption of oxygen on the AZO, CIGS, and Mo layers. The degradation behavior after DH (85 °C/85% RH) exposure was caused by the adsorption of oxygen, as well as the generation of Zn(OH)2 due to water molecules. In particular, the humidity‐induced degradation behavior in discolored CIGS modules was ascribed to the generation of Zn(OH)2 and carboxylic acids in the AZO layer, due to a chemical reaction between the AZO, ethylene‐vinyl acetate copolymer, and water. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
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