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张子刚 《华中科技大学学报(自然科学版)》1988,(2)
本文提出了以用户优化为下级决策,以设施选址优化为上级决策的网络选址两级决策模型,给出了树状网络下模型求解的基本定理及相应的算法,并从一个重要的反例出发,讨论了Braess佯谬与模型的联系。 相似文献
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Mg ions can enhance the proliferation and redifferentiation of chondrocytes and the osteogenic differentiation of osteoblasts at specific concentrations, respectively. However, degradation of Mg alloys at varying degradation rates could lead to complex changes in the surrounding tissue environment, such as changes in the dynamic concentration of Mg ions and subsequent p H value. Considering the above mentioned factors, the comprehensive effects of Mg alloys on chondrocytes and osteoblasts behaviors have not yet been optimized. In this study, we evaluated the effects of Mg–1Ca microspheres on cell behavior with an aim to optimize conditions favorable for both cell types. Cells were cultured with Mg–1Ca microspheres prepared using the following concentrations: 250 μg/ml, 500 μg/ml and 1000 μg/ml. At specific time points,cytotoxicity, expression of specific genes and extracellular matrix deposition by cells(Alizarin Red Staining of osteoblasts and Alcian blue staining for chondrocytes) were evaluated. The experimental results revealed that Mg–1Ca microspheres prepared at a concentration of 250 μg/ml were optimum for both cell types, where chondrocytes were found to be in hypertrophy state while osteoblasts in close proximity to the microspheres showed osteogenetic differentiation. Interestingly, a slight change in osteoblasts behavior was observed nearer to and at a relative distance away from Mg–1Ca microspheres, an important observation for administering the application of microspheres as potential scaffolds. 相似文献
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周自刚 《西南师范大学学报(自然科学版)》1999,24(3):290-296
利用少体物理的方法,研究了磁场中二维量子点五电子系统基态能量与角动量间的变化关系,以及磁场强度和约束势的大小对五电子系统基态的影响,数值计算表明,量子力学对称性是出现幻数角动量的重要因素 相似文献
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Analysis of the International Geomagnetic Reference Field (IGRF) 1900-2000 shows that the Earth's main magnetic field has changed dramatically during the 20th century: its dipole moment has decreased by 6.5% since 1900, the strengths of its quadrupole and octupole have increased by 95% and 74%, respectively, four major planetary-scale magnetic anomalies on the Earth's surface have enhanced by 21%-56%, and the magnetic center has shifted 200 km towards the Pacific Ocean. These time-variation features are similar to the behavior before a geomagnetic polarity reversal. 相似文献
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通过沉积结构及构造研究.本文对平泉地区长城系进行了详细岩相分类.并对其沉积环境及演化进行了综合分析。 相似文献
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编制了用于稀土元素ICP-AES法分析中校正光谱干扰的计算机程序.有七套程序供七种带宽条件的光谱仪选用. 相似文献
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本文采用三维有限元法分析了周期来压不同工作面长度对底板影响的应力分布规律,计算结果与井下压力作用符合。最后根据分析结论提出了防治底板承压水的建议。 相似文献