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以2-溴-9-乙基-9H-咔唑为原料,首先与联硼酸频那醇酯经宫浦硼基化反应制得相应的有机硼产物,再与溴代物发生传统的铃木偶联反应合成了3种新型的环金属配体(3a~3c);3a~3c依次与三氯化铱及传统辅助配体乙酰丙酮反应合成了3个新型含苯并唑类(苯并恶唑、苯并噻唑和苯并吡唑)环金属铱配合物(4a~4c),其结构经~1H NMR和MS(ESI或FAB)表征。并对其紫外和荧光光谱进行了研究。结果表明:4a~4c由于主配体的结构微调,可实现发光颜色由黄绿色到橙色的调控。 相似文献
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Using the modified Anderson-Kim theory of flux creep and the Bean model, we derive an analytical ex-pression for magnetic relaxation of high-Tc superconductors, which is applicable in the whole flux creep region. The high driving force limit of the expression gives the usual logarithmic decay law and its low driving force limit takes the exponential form. Theoretical analysis is in agreement with the existing experimental results. 相似文献
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该文综述了基于液相色谱-高分辨质谱联用(LC-HRMS)技术开展的沉积物和颗粒物中有机污染物分析的研究进展,包括LC-HRMS分析策略、分析流程及其在目标物、可疑物和非目标物分析中的实际应用,重点介绍了高通量分析、新兴污染物筛查、不同数据库的特点及应用、未知化合物鉴定置信水平、数据非依赖性采集和优先级策略等内容,初步探讨了该技术目前存在的问题并对其发展和应用进行了展望,以期进一步提高识别和鉴定工作的效率,更好地开展环境样品中有机污染物的筛查和监测研究。文中涉及的高分辨质谱的相关通用性内容,也为该技术在其他领域的应用提供了一定的参考和启发。 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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INVESTIGATION OF THE EFFECT OF SLOW NEUTRON IRRADIATION ON HALOGEN-DOPED HIGH-Tc SUPERCONDUCTORS AND ITS MECHANISM 下载免费PDF全文
Irradiation effect of low-fluence (-108 n/cm2 ) slow neutrons on halogen-doped superconductors is presented in this paper. And the mechanism of the effect is also described from the viewpoint of nuclear physics for both fast and slow neutrons on high-temperature superconductors (HTSC). It is shown ex-perimentally and theoretically that slow neutrons of low fluence has a similar irradiation effect to that of fast neutron beams with an energy En>0.1 MeV and fluence 1016-1018 n/cm2-However,quite differ-ent mechanisms are involved in them: Fast neutrons transfer their energies through elastic scattering in HTSC, whereas slow neutrons give off their energies during the slow neutron capture (n,γ) reaction. 相似文献
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本文比较系统地研究了添加 Ag_2O 对 YBa_2Cu_3O_(7-δ)体材料超导电性的影响.结果表明:在制备过程中添加适量 Ag_2O 可以显著增强 YBa_2Cu_3O_(7-δ)晶粒间的耦合,并改善 YBa_2Cu_3·O_(7-δ)体材料的超导性能.对于在930—1000℃范围内烧成,名义组成为(YBa_2Cu_3O_(7-δ))_(1-x)Ag_x(x=0.2~0.55)的复合超导试样来说,烧成温度对试样的超导性能起关键的作用,而 Ag_2O的添加量(x)和预烧温度的作用相对要小得多,当烧成温度高于970℃时 Ag_2O 的添加效果极为明显.例如1000℃烧成的 x=0.3的试样在77K 下的磁化临界电流密度 J_c 比相同工艺条件制备的未加 Ag_2O 试样提高五倍多. 相似文献
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Increasing the rewriting speed of optical rewritable e-paper by selecting proper liquid crystals 下载免费PDF全文
The effect of interaction between liquid crystal(LC) and photoalignment material on the speed of optical rewriting process is investigated.The theoretical analysis shows that a smaller frank elastic constant K 22 of liquid crystal corresponds to a larger twist angle,which gives rise to a larger rewriting speed.Six different LC cells with the same boundary conditions(one substrate is covered with rubbed polyimide(PI) and the other with photo sensitive rewritable sulfuric dye 1(SD1)) are tested experimentally under the same illumination intensity(450 nm,80 mW/cm 2).The results demonstrate that with a suitable liquid crystal,the LC optical rewriting speed for e-paper application can be obviously improved.For two well known LC materials E7(K22 is larger) and 5CB(K22 is smaller),they require 11 s and 6 s corresponding to change alignment direction for generating image information. 相似文献