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采用毛细管电泳法分离检测结核杆菌耐热抗原样品中的活性成分。熔融石英毛细管55cm(40cm处检测窗口)×50μm i.d.;缓冲液:0.15mol·L-1硼酸盐(含5g·L-1PEG-4000,pH=10.92);分离电压:+12 kV;进样压力:0.5 psi(3.45 kPa),进样时间3.0s;分离温度:25℃;UV-Vis检测器检测波长:200nm。本方法能分离溶菌酶标准蛋白和牛血清白蛋白标准品,根据分子量大小能有效分离结核杆菌耐热抗原样品活性成分,线性回归方程相关系数r2在0.99673以上,定量限在19.47μg·mL-1左右。样品加标回收率在96.09%左右,相对标准偏差小于8.13%,本方法与快速蛋白液相色谱法结果一致。该方法简便、灵敏、快速、可靠、重现性好,能用于结核杆菌耐热抗原样品中活性成分测定。 相似文献
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随着磁共振成像(MRI)技术的发展,图像引导放射治疗在放射肿瘤学中的作用和重要性正在迅速增加,本研究分析了外加均匀磁场对碳离子束的剂量平均LET以及纳剂量学量的影响。通过基于GEANT4内核的GATE蒙特卡罗(Monte Carlo, MC)模拟平台,模拟计算了不同磁场环境下,不同能量碳离子束剂量平均LET和纳剂量学量的分布。结果发现,平行磁场对碳离子束的剂量平均LET和纳剂量学量均无显著影响,垂直磁场对碳离子束的剂量平均LET及纳剂量学量的影响主要集中在布拉格峰区域,其影响主要是碳离子束在磁场中受到洛伦兹力作用而发生横向偏转,进而使得碳离子束布拉格峰位置发生横向侧移导致的。这些结果为进一步研究磁场对碳离子束治疗性能的影响打下了坚实的基础。 相似文献
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FLUX CREEP, FLUX PINNING AND CRITICAL CURRENT DENSITY OF Y-, Gd-, AND Tl-BASED SUPERCONDUCTIVE THIN FILMS 下载免费PDF全文
Magnetic hysteresis loops have been measured for YBa2Cu3O6+x, GdBa2Cu3O6+x and Tl2Ba2Ca2Cu3O10-y films at different temperatures with a vibrating sample magnetometer. Based on Bean model, magnetic critical current density Jcm has been derived approximately. The field and temperature dependence of Jcm for all samples can be written as: Jcm= Jc0(T)×f(B,T), Where f(B,T) = 1 - Aln(B/B0(T)), which is similar to the transport critical density strongly affected by flux creep: Jct = Jc0(B,t)(1 - (kBT/U0)ln(BΩd/Ec)). The extraordinary similarity suggests that Jcm is determined not only by flux pinning but also by flux creep. In the first formula, f(B,T) may be correlated with the effect of flux creep on Jcm, and Jc0(T) is determined by flux pinning. Jc0(T) is independent of magnetic field and is proportional to (Tc - T). Similar results have also been found for other samples. It may be the common characteristic of high-Tc superconductors. Magnetic relaxation of YBa2Cu3O6+x and GdBa2Cu3O6+x films has been measured at LN2 temperature. Using the equation of Hagen et al., effective activation energy U0 has been deduced, which is about 0.3eV, one order bigger than the value obtained by A = kBT/U0. U0 is almost independent of the field in the field range selected. 相似文献
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纳米复合材料中的微观界面结构和界面作用对材料的宏观介电性能, 如介电常数、介电损耗、击穿强度等有十分重要的影响. 本文发展了一种基于扫描静电显微探针技术的测量方法, 可以直接表征二氧化钛/环氧树脂纳米复合材料的微观界面结构及相应的动态介电响应行为. 实验中利用扫描探针的纳米尺度分辨能力, 探测到不同温度下环氧树脂纳米复合材料的局域动态介电响应变化过程, 从而获得纳米颗粒与高分子界面相互作用及极化相关的温度特性. 进一步通过对二氧化钛纳米颗粒进行表面修饰, 得到了两种不同特性的二氧化钛/环氧树脂界面, 验证了不同界面作用引起的复合材料界面区域与非界面区域高分子链介电损耗图像的反差. 相似文献
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We propose a femtosecond laser polarization modulation scheme to control the up-conversion(UC) luminescence in Er~(3+)-doped NaYF_4 nanocrystals dispersed in the silicate glass. We show that the UC luminescence can be suppressed when the laser polarization is changed from linear through elliptical to circular, and the higher repetition rate will yield the lower control efficiency. We theoretically analyze the physical control mechanism of the UC luminescence polarization modulation by considering on- and near-resonant two-photon absorption, energy transfer up-conversion, and excited state absorption, and show that the polarization control mainly comes from the contribution of near-resonant two-photon absorption. Furthermore, we propose a method to improve the polarization control efficiency of UC luminescence in rare-earth ions by applying a two-color femtosecond laser field. 相似文献
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Topology optimization of continuum structures with design-dependent loads has long been a challenge. In this paper, the topology optimization of 3D structures subjected to design-dependent loads is investigated. A boundary search scheme is proposed for 3D problems, by means of which the load surface can be identified effectively and efficiently, and the difficulties arising in other approaches can be overcome. The load surfaces are made up of the boundaries of finite elements and the loads can be directly applied to corresponding element nodes, which leads to great convenience in the application of this method. Finally, the effectiveness and efficiency of the proposed method is validated by several numerical examples. 相似文献
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High resolution mode-selective excitation in the mixture of C6H6 (992 cm^-1) and C6D6 (945 cm^-1) is experimentally achieved by adaptive femtosecond pulse shaping based on the genetic algorithm (GA), and second harmonic generation frequency-resolved optical gating (SHG-FROG) is adopted to characterize the original and optimal laser pulses, and its mechanism is experimentally validated by tailoring the frequency components of the pump pulses at the Fourier plane. It is indicated that two-pulse coherent mode-selective excitation of the Raman scattering mainly depends on the effective frequency components of the pump pulse related to specific molecular vibrational mode. The experimental results have attractive potential applications in the complicated molecular system. 相似文献