排序方式: 共有64条查询结果,搜索用时 15 毫秒
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Kelei Zhuo Hongxun Liu Honghao Zhang Yaohui Liu Jianji Wang 《The Journal of chemical thermodynamics》2008,40(5):889-896
Activity coefficients of CaCl2 in disaccharide {(maltose, lactose) + water} mixtures at 298.15 K were determined by cell potentials. The molalities of CaCl2 ranged from about 0.01 mol · kg?1 to 0.20 mol · kg?1, the mass fractions of maltose from 0.05 to 0.25, and those of lactose from 0.025 to 0.125. The cell potentials were analyzed by using the Debye–Hückel extended equation and the Pitzer equation. The activity coefficients obtained from the two theoretical models are in good agreement with each other. Gibbs free energy interaction parameters (gES) and salting constants (kS) were also obtained. These were discussed in terms of the stereo-chemistry of saccharide molecules and the structural interaction model. 相似文献
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This study investigated underwater explosive compaction-sintering for coating a high-density tungsten–copper composite on a copper surface. First, 50% W–50% Cu tungsten–copper composite powder was prepared by mechanical alloying. The composite powder was pre-compacted and sintered by hydrogen. Underwater explosive compaction was carried out. Finally, a high-density tungsten–copper coating was obtained by diffusion sintering of the specimen after explosive compaction. A simulation of the underwater explosive compaction process showed that the peak value of the pressure in the coating was between 3.0 and 4.8?GPa. The hardness values of the tungsten–copper layer and the copper substrate were in the range of 87–133 and 49?HV, respectively. The bonding strength between the coating and the substrate was approximately 100–105?MPa. 相似文献
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为了研究爆炸焊接结合界面机理及材料强度对爆炸焊接的影响,采用相同的爆炸焊接参数对不同强度的基板进行了爆炸焊接。通过光学显微镜、扫描电子显微镜以及数值模拟技术对焊接试样的形貌、缺陷以及焊接机理进行了分析。结果表明:当材料强度较低时,碰撞点动压与基板材料强度的比值较高,界面出现较大的塑性应变并生热,此时界面熔化区较大,在焊接过程中可以将界面等效为不可压缩流体;当材料强度较高而碰撞点动压与基板强度的比值较低时,试样界面形貌受材料强度的影响较大。随着材料强度的上升,周期性的波状界面逐渐趋于平直。界面熔化现象减弱但温升速率较高,并受碰撞点附近高压出现热失稳现象形成剪切带及裂缝。此时材料强度的影响不可忽略,界面不能等效为不可压缩流体。 相似文献
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为了改善爆炸焊接质量,解决高噪低效的问题,选取Cu为复板、Q235钢为基板,采用LS-DYNA软件和光滑粒子流体动力学方法分别设计了均匀布药和梯形布药方案,研究了硝铵炸药对爆炸焊接界面波的影响。均匀布药结果显示:沿着爆轰方向碰撞压力逐渐增大;炸药量越多,碰撞压力越大,界面波波形越大。梯形布药方案中,通过改变炸药起爆端和末端的高度,设计了4种方案,结果显示:梯形布药可以消除爆炸焊接界面波不均匀现象,使界面波形尺寸基本保持一致,而且节省了炸药用量;当起爆端和末端的高度分别为67.2 mm和42.0 mm时,波形效果最好。通过研究界面波的形成过程可知,SPH法模拟的界面波形成过程与复板流侵彻机理的一致性较好,证明了复板流侵彻机理解释界面波形成过程的有效性。 相似文献
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气相色谱-质谱法测定氯氮平及其去甲基代谢物 总被引:9,自引:0,他引:9
建立了测定人血清中氯氮平及其去甲基代谢物的柱前衍生化气相色谱-质谱选择离子监测的分析方法。以三氟乙酸酐作酰化剂,对衍生化条件和样品预处理方法实施了优化。氯氮平和去甲氯氮平的线性范围为1~128μg/L,最低检测浓度:氯氮平为0.1μg/L,去甲氯氮平为0.2μg/L,两者的回收率均大于83%,相对标准偏差都小于10%。将所建立的方法应用于服用细胞色素氧化酶P4501A2抑制剂前后低剂量氯氮平的药代动力学自身对照试验中,结果显示氯氮平的代谢水平明显受P4501A2活性的影响。 相似文献
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采用尺寸为4 mm×410 mm×410 mm的5083铝合金和尺寸为15 mm×400 mm×400 mm、表面开有燕尾槽的Q345钢板作为爆炸焊接的覆板与基板,根据理论公式得到铝合金-钢爆炸焊接下限后,选取其附近的参数进行爆炸焊接,再通过力学性能检测和微观形貌观察研究5083/Q345复合板界面的结合性能。实验结果表明:铝合金与钢在冶金结合和燕尾槽的挤压啮合共同作用下实现爆炸复合;铝合金与燕尾槽上底面、倾斜面和下底面的界面均呈平直状。铝合金与燕尾槽上底面、下底面以直接结合和不连续熔化块相结合的方式复合,而铝合金与燕尾槽倾斜面以连续熔化层的方式复合;复合板的剪切强度大于172 MPa,满足Al/Fe复合板结合强度的要求。 相似文献