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排序方式: 共有1337条查询结果,搜索用时 15 毫秒
1.
介绍了油库油料计量中,在油品高度、油品温度和油品密度测量中存在的问题及应遵循的操作规范和注意事项。 相似文献
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本文根据溶液缩聚基本原理及反应过程的基本事实,用随机过程方法,得到缩聚产物分子量分布函数,并对分子量及其分布的控制作了讨论。 相似文献
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Summary A water insoluble azo-containing polyelectrolyte (PEAPB6P-AC) was successfully fabricated into multilayer films based on the layer-by-layer adsorption technique by using N, N-dimethylformamide (DMF) as the assembling media. The multilayer growth and structure were studied with UV-vis spectroscopy, and the multilayer surface were imaged with Atomic Force Microscopy and compared with that fabricated in water. The results show that assembling PEAPB6P-AC in DMF can effectively eliminate the hydrophobic aggregation of the azo units and consequently results in a much smoother multilayer surface than that fabricated in water. This improvement to the layer-by-layer adsorption technique, which can avoid some major difficulties faced when assembling hydrophobic polyelectrolytes in aqueous solutions, seems to be a versatile way to fabricate high quality multilayer films when using the hydrophobic even water-insoluble polyelectrolytes as assembling units. 相似文献
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脱油沥青作为谢尔气化工艺的气化原料生产化肥在国内尚属首次,由于沥青原料中的灰分和重金属比渣油原料大得多,若仍采用石脑油萃取碳黑技术,灰分和重金属随碳黑返回气化装置,将造成设备的堵塞、磨损,无法保证设备安稳长期运行.通过对碳黑水分离技术进行多方面的研究,寻找到适宜的工艺路线与解决方案. 相似文献
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Component contacting degree in a composite material is an important reference for evaluation the performance characteristics. In this article, two composite material systems involving polylactic acid (PLA) with acrylonitrile butadiene styrene (ABS) and PLA with thermoplastic polyurethane (TPU) were prepared by blending and laminating through fused deposition modeling (FDM) 3D printing technology. The mechanical and thermal properties of the as-prepared composite materials were examined. The results indicated that PLA and TPU played a dominant role in tensile strength and breaking elongation, respectively, in individual composite material. ABS and TPU changed the glass transition peek, crystallinity, and modulus of PLA. The results also suggested that although the processing design of the blending method was more suitable for the contact between two components, but the mechanical properties of laminated composites were closer to theoretical predictions. The structural design and processing technology provide a comparative method and reference basis for studying the performance characteristics of composite materials. 相似文献
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Jing Lv Longhai Guo Chunjie Xie Weitong Xu Jun Ye Xiaoyu Li Teng Qiu Xinlin Tuo 《应用聚合物科学杂志》2021,138(44):51316
Being a new kind of nanomaterials, aromatic polyamide nanofibers (ANF) have been much highlighted in recent studies. We here demonstrate an isopropyl alcohol (IPA) accelerated chemical cleavage on poly (p-phenylene terephthalamide) chopped fibers, which provides an efficient preparation method of ANF. The comprehensive study on the processes accelerated by different alcohols revealed that the preparation time of ANF in the mixed medium of dimethyl sulfoxide (DMSO)-alcohol (20:1 in volume) was shorten to 45 min and 75 min for methanol (ethanol) and isopropanol, respectively. However, the nanofibers prepared in DMSO-IPA exhibited the minimum in axial and radial dimensions, providing the finest and most uniform diameter of 16 nm. The corresponding ANF films through vacuum assisted filtration also showed the highest tensile strength of 150 MPa, in comparison with those of the ANF films prepared using other alcohols, which were about 110 MPa. Furthermore, ANF/silicon hybrid films were prepared by the ionic ring-opening reaction followed by the alkoxysilane condensation and nanoparticle fabrication. By changing the organo functional groups in the alkoxysilane, the surface of the films were adjustable in a wide contact angle range from 56° (hydrophilic) to 150° (superhydrophobic), suggesting the amendable interfacial properties potential applicable to composite fabrication with most of the resin matrix. 相似文献
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高膜厚PU防腐系统可解决防腐工程上的死角,包括异形、补口、三通、弯头、法兰、阀门等几何形状复杂金属外表面的防腐,以及老龄在役管线的防腐结构的修复。这种防腐系统的使用寿命可达30a。对国内油气管道防腐涂层常用的国产环氧粉末防腐结构和高膜厚PU防腐结构各项技术性能指标进行了对比,又以环氧粉末和高膜厚PU防腐系统用于管道防腐和储罐防腐进行了详细的对比,论证了使用高膜厚PU防腐系统技术的可行性和经济性。 相似文献
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首先介绍网络应用系统发展的现状,提出采用应用Flex作为表示层实现,应用Hibernate作为持久层实现,并结合Spring技术作为业务层搭建富英特网应用(RIA)系统模型。采用粒子群优化PSO算法组卷,从而设计出了一套多层次、高性能、智能化的网络考试系统。 相似文献