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141.
本文通过溶液聚合法合成了一种结构型聚酰胺酸,经过热亚胺化处理后得到了主链型聚酰亚胺,探讨了合成光敏聚酰亚胺的关键技术,并以重均分子量为参考,分析了各种条件对反应的影响规律,得到了较佳的工艺条件。 相似文献
142.
Friction experiments were conducted on C/C composites at low and high temperatures during braking with the use of a pin-on-disc tribometer. The surface grooves formed were investigated by an optical camera and a laser profilometer, while scratches were characterized by optical microscopy. Damages were correlated with tribological performances (friction and wear). It is shown that friction at low temperature leads to high friction coefficient and wear rate, and to surfaces strongly grooved and abraded. For friction experiments performed at high temperature, they lead to lower friction coefficient and wear, and the resulting surfaces are rather smooth and slightly grooved. 相似文献
143.
Santiago P. Aubourg 《European Food Research and Technology》1998,206(1):33-37
Lipid damage during prolonged storage of canned fish was studied. Albacore tuna was processed under two sterilization conditions
(115°C, 74 min; 120°C, 40 min) and then stored for up to 6 years. Analyses (lipid oxidation and hydrolysis, browning and formation
of fluorescent compounds) of the lipids extracted from the white muscle of the fish and the packing oils were carried out.
Muscle lipids were partially extracted by the packing oil, so that an increase in the storage time produced higher levels
of free fatty acids, browning and fluorescence development in the packing oils. As regards the types of muscle, little difference
between them throughout the canned storage was detected.
Received: 17 February 1997 / Revised version: 12 May 1997 相似文献
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分析地铁和地铁车厢火灾特点及其引发的严重后果;探讨地铁车厢中火灾探测器的选择;分析比较点型感烟探测器和吸气式感烟火灾探测器在地铁车厢中应用的优劣势;得出吸气式感烟火灾探测器更能满足地铁车厢中早期火灾探测需求的结论。 相似文献
146.
The effects of the physical damages induced by heavy ion irradiation on the performance of partially-depleted SOI devices are experimentally investigated. After heavy ion exposure, different degradation phenomena are observed due to the random strike of heavy ions. A decrease of the saturation current and transconductance, and an enhanced gate-induced drain leakage current are observed, which are mainly attributed to the displacement damages that may be located in the channel, the depletion region of the drain/body junction or the gate-to-drain overlap region. Further, PDSOI devices with and without body contact are compared, which reveals the differences in the threshold voltage shift, the drain-induced barrier lowing effect, the transconductance and the kink effect. The results may provide a guideline for radiation hardened design. 相似文献
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149.
This study focuses on developing a mixed frame finite element formulation of reinforced concrete and FRP composite columns in order to give more accuracy not only to predict the global behavior of the structural system but also to predict the local damage in the cross-section. A hypo-elastic constitutive law of concrete is presented under the basis of a three-dimensional stress state in order to model the compressive behavior of confined concrete wrapped with FRP jackets. To predict the nonlinear load path-dependent confinement model of FRP-confined concrete, the strength enhancement of concrete was determined by the failure surface of concrete in a tri-axial stress state, and its corresponding peak strain was computed by the strain-enhancement factor proposed in this study. The behavior of FRP jacket was modeled using the two-dimensional classical lamination theory. The flexural behavior of concrete and composite members was defined using a nonlinear fiber cross-sectional approach. The results obtained by developed mixed finite element formulation were verified with the experiments of concrete composite columns and also were compared with a displacement-based finite element formulation. It is shown that the proposed formulation gives e more accurate results in the global behavior of the column system as well as in the local damage in the column sections. 相似文献
150.
设计合成了一种碱溶性光敏有机硅聚氨酯丙烯酸酯(Alkali-soluble polysiloxane urethane acrylate,APSUA),以期用于阻焊油墨.详细研究了体系组成对APSUA体系的耐水性、体积收缩、硬度、拉伸性能及耐热性能的影响.研究发现:含羟基活性单体会使体系吸水率上升;随着体系交联度增加,... 相似文献