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以Fe39.35Ni30Co18Al10.5Nb2B0.15形状记忆合金为研究对象,运用X射线衍射仪、扫描电镜、压力试验机、金相显微镜和能谱仪研究了时效时间对合金组织结构和性能的影响。结果表明,随着时效时间的增加,γ'相和B2相相继析出,γ'相的析出强化了奥氏体母相,B2相的析出降低了合金的塑性。从伪弹性曲线可以看出,在873 K温度下时效时,随着时效时间的增加,合金的抗压强度、可恢复应变和维氏硬度均随着时效时间的增加呈现先增大后减小的趋势,而合金的最大应变则随时效时间的增加先快速后缓慢增大。时效时间为60 h时,合金的抗压强度、可恢复应变及硬度均达到最大值,分别为1239.05 MPa、10.76%、496 HV10,合金的残余应变相对最小。 相似文献
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Hongchuan Yang Ruo Yuan Yaqin Chai Ying Zhuo Huilan Su 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(4):577-582
BACKGROUND: A new electrochemical immunosensor for human chorionic gonadotropin (HCG) assay was developed based on Pt hollow nanospheres and silver/titanium dioxide nanocomposites. Silver nanoparticles were initially doped into TiO2 and chitosan (Cs) colloids to form silver/titanium dioxide nanocomposites (Ag? TiO2? Cs), which had good redox electrochemical activity and excellent film‐forming ability. Then, the free amino groups of chitosan were used to attach Pt hollow nanospheres for immobilization of human chorionic gonadotropin antibody (anti‐HCG) to construct an immunosensor. RESULTS: Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) confirmed consecutive growth of the multilayer films, and transmission electron microscopy (TEM) was used to describe the microstructure of nanoparticles. Optimal response of the immunosensor was obtained at pH 6.5 and 25 °C with an incubation time of 40 min. The immunosensor exhibited a linear range from 0.5 to 250 mIU mL?1 HCG with a detection limit of 0.26 mIU mL?1 at three times background noise. The selectivity, stability and repeatability of the immunosensor were satisfactory. CONCLUSION: The strategy showed low‐cost, high sensitivity, broad linear range and fast analytical time. It is expected that the immobilized technique and the detection methodology could be further developed for other proteins. Copyright © 2010 Society of Chemical Industry 相似文献
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分别用钠硼氘、钠硼氚还原人参皂甙Rh1的活性形式20(S)-protopanaxadiol(aPPD)的氧化前体aPPD=O,制备氘、氚标记的aPPD。标记物经板层析(TLC)、质谱(MS)、核磁共振(NMR)分析鉴定,结果与标准品的测量数据一致;氚标记的aPPD放化纯度为98%,放射性比活度为7.64×1011Bq/g。将3H-aPPD作用于人肺腺癌A549细胞,检测不同时间细胞浆及细胞核中氚的活度,结果提示aPPD在A549细胞浆、核内均于24 h达到最高浓度,表明aPPD作为一个与甾体类激素结构相类似的药物,可以进入细胞甚至细胞核发挥药理作用 相似文献
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The state and future outlook of research to determine the Earths orbital parameters, i.e., Universal Time and the coordinates of the pole, carried out by the State Time and Frequency Service and in calculations of the Earths orbital parameters are described.Translated from Izmeritelnaya Tekhnika, No. 1, pp. 24–27, January, 2005. 相似文献
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利用MADYMO软件建立了国内某微型车正面碰撞数学模型,并在对模型进行试验验证的基础上结合试验设计、响应面方法和鲁棒性概率优化设计对乘员侧约束系统进行优化,优化的参数主要有安全带刚度、安全带上挂点位置、限力器撕裂力和撕裂增加长度等。采用该方法引入鲁棒性概率优化设计后能减少和控制目标函数响应的波动,降低在设计点上的敏感性,提高产品的质量。结果表明,所采用的方法既实现了对设计目标的优化,又提高了设计变量的可靠性和目标函数的鲁棒性,对工程应用具有较大指导意义。 相似文献
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含铵化肥厂废水污灌有可能引起地下水污染。包气带土壤的吸附作用是阻滞其铵进入含水层的重要过程。选取某包气带不同深度4个典型土样,利用室内批模拟实验,以实验室配制硫酸铵溶液作对比,研究土壤对化肥厂废水中铵的吸附动力学及等温吸附特征。结果显示:土壤颗粒极易吸附铵,废水有机物等物质能延长吸附平衡时间,并影响土壤对铵的吸附能力——在低浓度铵溶液中表现为增加作用,在高浓度铵溶液中的表现为受土壤有机质含量影响;不同质地土壤对铵具有不同的吸附行为,总体上黏性土的吸附能力大于砂土;与Freundlich和Langmuir等温式相比,BET等温式能够与实验吸附数据更好拟合,验证了BET公式用于铵等温吸附特征研究的可行性,表明铵在土壤胶体颗粒中的吸附方式为多分子层吸附。 相似文献
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生长发育期铅接触可使血脑屏障通透性增加,脑毛细血管内皮细胞紧密连接蛋白occludin表达降低可能是血脑屏障通透性改变的主要分子机制之一;铅接触的同时适量补充铁元素,可保护由慢性铅接触所造成的血脑屏障紧密连接的损伤.Effects of iron suppleme 相似文献
10.
Ashok Sudarsanam Sharad Malik Masahiro Fujita 《Design Automation for Embedded Systems》1999,4(2-3):187-206
We address the problem of code generation for embedded DSP systems. Such systems devote a limited quantity of silicon to program
memory, so the embedded software must be sufficiently dense. Additionally, this software must be written so as to meet various
high-performance constraints. Unfortunately, current compiler technology is unable to generate dense, high-performance code
for DSPs, due to the fact that it does not provide adequate support for the specialized architectural features of DSPs via
machine-dependent code optimizations. Thus, designers often program the embedded software in assembly, a very time-consuming
task. In order to increase productivity, compilers must be developed that are capable of generating high-quality code for
DSPs. The compilation process must also be made retargetable, so that a variety of DSPs may be efficiently evaluated for potential
use in an embedded system. We present a retargetable compilation methodology that enables high-quality code to be generated
for a wide range of DSPs. Previous work in retargetable DSP compilation has focused on complete automation, and this desire
for automation has limited the number of machine-dependent optimizations that can be supported. In our efforts, we have given
code quality higher priority over complete automation. We demonstrate how by using a library of machine-dependent optimization
routines accessible via a programming interface, it is possible to support a wide range of machine-dependent optimizations,
albeit at some cost to automation. Experimental results demonstrate the effectiveness of our methodology, which has been used
to build good-quality compilers for three fixed-point DSPs.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献