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Nuclei from the normal mouse liver were partially digested with micrococcal nuclease, followed by DNA extraction, agarose gel clectrophoresis and dot blot hybridization with ~(32)P-labeled cDNA probes of CPS_1 and ACT complex, It was clearly shown that the CPS_1 genes were distributed on the monomer, dimer. and trimer of nucleosomes, while the genes coding for ACT complex were distributed on the condensed oligonucleosomes. An opposite manner of distribution of CPS_1 and ACT complex genes was, however, noted in the case of ascites hepatoma cells, in which the specific activity of ACT was 13 times higher than that in the normal liver, while that of CPS_1 was remarkably reduced. Similar patterns of change in mRNA level of CPS_1 and ACT complex were observed in the normal mouse liver and ascites hepatoma cells, indicating a close relationship between chromatin structure and gene expression of these enzymes. 相似文献
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增塑剂对1,1,1-三[1′-(2′-氧杂-4′-氧代-5′-氮杂-5′-甲基)十二烷基]丙烷PVC膜钠离子电极性能的影响 总被引:2,自引:0,他引:2
以1,1,1-三[1′-(2′-氧杂-4′-氧代-5′-氮杂-5′-甲基)十二烷基]丙烷(即ETH 227,Fluka No.71732)为中性载体的钠离子选择电极由于具有较强的抗钾离子干扰的能力,因而颇受注意。Guggi等首先用邻硝基苯辛醚和癸二酸二丁酯增塑,以合成的ETH227制成了K_((Na)~+,K~+)~(pot),<<10~(-2)的PVC膜钠离子电极.Jenny等以癸二酸二异辛酯为增塑剂, 相似文献
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研究了一种新型的负载Er3 的二氧化硅介孔分子筛纳米材料,分析了其在有无功能化试剂全氟甲基磺酰(bis(perfluoromethylsulfonyl)amine)修饰作用下的吸收和荧光光谱特性,获得了高强度的荧光发射.应用Judd-OfelI理论计算了强度参数(Ω2=1.88×10-20,Ω4=5.45×10-20 cm2,Ω6=3.11×1O-20cm2)、跃迁振子强度、自发跃迁概率、能级辐射寿命等重要的光谱参数,讨论了吸收和发射跃迁截面(Ωem=10.9×10-21 cm2),研究了在介孔分子筛纳米材料中的Er3 在不同的抽运功率条件下的荧光强度变化情况.比较了Er3 在不同基质材料中的带宽特性.研究表明二氧化硅介孔分子筛有利于实现高效率的激光输出或具有较宽带宽的高增益光放大,能够成为掺铒激光器或光放大器的新型基质材料. 相似文献
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自行研制了一台基于双边缘技术的多普勒激光雷达,用于测量对流层大气风场。该雷达采用具有高光谱分辨率的双Fabry-Perot干涉仪来检测气溶胶后向散射的多普勒频移量。给出了多普勒测风激光雷达的结构和参数。利用干涉仪参数讨论了雷达系统的测量精度。实验测定了双干涉仪的频谱曲线。通过计算和分析,由测量的干涉仪频谱曲线的的标准偏差引起的系统测量误差为0.5 m/s。系统的测量误差随着测量的高度和所测速度的增加在增大,在高度10 km测量50 m/s的风速时系统的测量误差小于2 m/s。 相似文献
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Generation of UV laser light by stimulated Raman scattering in D2, D2/Ar and D2/He using a pulsed Nd:YAG laser at 355nm 下载免费PDF全文
A pulsed Nd:YAG laser at 355nm is used to pump Raman cell filled with D_2, D_2/Ar and D_2/He. With adequately adjusted parameters, the maximum photon conversion efficiency of the first-order Stokes light (S_1, 396.796nm) reaches 33.33% in D_2/Ar and the stability of S_1 in pure D_2 is fairly high, the energy drift being less than 10% when the pump energy drifts in the range of 5%. The conversion efficiency and stability, which are functions of the composition and pressure of the Raman medium and the energy of pump laser, are investigated. The result has been used to optimize the laser transmitter system for a differential absorption lidar system to measure NO_2 concentration profiles. 相似文献
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光学粒子计数器测量结果的订正 总被引:20,自引:1,他引:19
本文根据球形粒子的米(Mie)散射原理计算了光学粒子计数器的散射相函数和仪器响应曲线。根据被测粒子的折射率对测量结果做出订正。在研究大气气溶胶粒子尺寸谱变化规律时,这种订正是很重要的。文中举例说明了实际订正方法。 相似文献