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71.
RRN Sailaja 《Polymer International》2005,54(12):1589-1598
Lignin was graft copolymerized with methyl methacrylate using manganic pyrophosphate as initiator. This modified lignin was then blended (up to 50 wt%) with low density polyethylene (LDPE) using a small quantity of poly[ethylene‐co‐(glycidyl methacrylate)] (PEGMA) compatibilizer. The mechanical properties of the blend were substantially improved by using modified lignin in contrast to untreated lignin. Differential scanning calorimetry studies showed loss of crystallinity of the LDPE phase owing to the interaction between the blend components. Thermogravimetric analysis showed higher thermal stability of modified lignin in the domain of blend processing. This suggested that there is scope for useful utilization of lignin, which could also lead to the development of eco‐friendly products. Copyright © 2005 Society of Chemical Industry 相似文献
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氨氮监测采用预蒸馏处理后,比色测定结果明显偏低。在样品预蒸馏处理过程中,硼酸作为吸收液,使显色时溶液pH值偏低,导致显色不充分是其主要影响因素。通过采取增加显色剂加入量的方法,解决了显色pH值偏低的问题,得到满意的测定结果。 相似文献
74.
应用遗传神经网络研究低渗透储层成岩储集相—以胜利渤南油田三区沙河街组为例 总被引:3,自引:2,他引:1
以渤南油田三区沙河街组为例,应用遗传人工神经网络模式识别方法,开展了低渗透储层成岩储集相的研究。该工作是在储集层沉积相、成岩作用研究的基础上,选用流动层带指标、孔隙度、渗透率、粒度中值、泥质含量、孔喉半径均值和变异系数等7项参数,采用神经网络模式识别方法,通过建立遗传神经网络的学习及预测模型,对渤南油田三区沙河街组进行了成岩储集相识别,识别出4类成岩储集相:不稳定组分强溶解次生孔隙成岩储集相、碳酸盐胶结物溶解次生孔隙成岩储集相、强压实强胶结残余粒间孔成岩储集相和极强压实强胶结致密成岩储集相。Ⅰ类储集相的储集性能最好,Ⅳ类最差,为非储层或差储层。 相似文献
75.
介绍了钻孔灌注桩成孔质量的影响因素 ,详细叙述了钢筋笼的制作和吊放处理步骤 ,阐述了断桩发生的原因 ,提出了具体的防治措施 ,经实践效果良好 相似文献
76.
When Teachers' and Parents' Values Differ: Teachers' Ratings of Academic Competence in Children From Low-Income Families. 总被引:1,自引:0,他引:1
The authors examined predictors of teachers' ratings of academic competence of 105 kindergarten children from low-income families. Teachers rated target children's expected competence in literacy and math and completed questions about their perceptions of congruence-dissonance between themselves and the child's parents regarding education-related values. Independent examiners assessed children's literacy and math skills. Teachers' instructional styles were observed and rated along dimensions of curriculum-centered and student-centered practices. Controlling for children's skills and socioeconomic status, teachers rated children as less competent when they perceived value differences with parents. These patterns were stronger for teachers who exhibited curriculum-centered, rather than student-centered, practices. The findings suggest a mechanism by which some children from low-income families enter a path of diminished expectations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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O. Gravrand E. De Borniol S. Bisotto L. Mollard G. Destefanis 《Journal of Electronic Materials》2007,36(8):981-987
This paper aims at studying the feasibility of very long infrared wavelength (VLWIR) (12–18 μm) focal plane arrays using n-on-p planar ion-implanted technology. To explore and analyze the feasibility of such VLWIR detectors, a set of four Cd
x
Hg1−x
Te LPE layers with an 18 μ cutoff at 50 K has been processed at Defir (LETI/LIR–Sofradir joint laboratory), using both our “standard” n-on-p process and our improved low dark current process. Several 320 × 256 arrays, 30-μm pitch, have been hybridized on standard Sofradir readout circuits and tested. Small dimension test arrays characterization
is also presented. Measured photonic currents with a 20°C black body suggest an internal quantum efficiency above 50%. Typical
I(V) curves and thermal evolution of the saturation current are discussed, showing that standard photodiodes remain diffusion
limited at low biases for temperatures down to 30 K. Moreover, the dark current gain brought by the improved process is clearly
visible for temperatures higher than 40 K. Noise measurements are also discussed showing that a very large majority of detectors
appeared background limited under usual illumination and biases. In our opinion, such results demonstrate the feasibility
of high-performance complex focal plane arrays in the VLWIR range at medium term. 相似文献