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可控/“活性”自由基聚合(CLRP)可以用于制备分子量分布窄、分子链缺陷少的聚合物,如聚乙烯(PE)、聚氯乙烯(PVC)、聚偏氯乙烯(PVDC)和聚偏氟乙烯(PVDF),且易控制上述单体与其他单体共聚得到嵌段聚合物。本文调研了近年来可控/“活性”自由基聚合(如碘转移聚合(ITP)、氮氧稳定自由基聚合(NMP)、可逆加成断裂链转移(RAFT)聚合和金属催化的活性自由基聚合(OMRP)等)制备聚乙烯和聚卤代烯烃等方面的工作,并指出了未来的发展方向。 相似文献
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采用甲基丙烯酸锌加速还原氯化钯(PdCl2) 溶液中的钯离子(Pd 2+)为钯(Pd) 纳米微球, 进而用得到的钯纳米微球直接制备钯/氧化钯(Pd/PdO) 纳米复合微球. 通过扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 粉末X射线衍射分析(XRD)及X射线光电子能谱分析(XPS) 等方法对 Pd/PdO 纳米复合微球进行表征, 结果表明, 制备的纳米复合微球为表面粗糙、 大小均一的纳米微球. 采用紫外-可见吸收光谱(UV-Vis) 等方法考察了 Pd/PdO 纳米复合微球在对硝基苯酚(4-NTP) 还原反应中的催化性能, 发现其具有良好的催化活性和循环稳定性. 相似文献
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Under the Born-von-Karmann periodic boundary condition, we propose a quantization scheme for a non-dissipative distributed parameter circuit (a uniform transmission line). Quantum fluctuations of charge and current in the vacuum state are investigated by adopting the canonical transformation and unitary transformation method. Our results indicate that in distributed parameter circuits, quantum fluctuations, which also have distributed properties, are related to both the circuit parameters and the positions and the mode of signals. 相似文献
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In this paper, it is assumed that an insurer with a jump-diffusion risk process would invest its surplus in a bond market, and the interest structure of the bond market is assumed to follow the Vasicek interest model. This paper focuses on the studying of the ruin problems in the above compounded process. In this compounded risk model, ruin may be caused by a claim or oscillation. We decompose the ruin probability for the compounded risk process into two probabilities: the probability that ruin caused by a claim and the probability that ruin caused by oscillation. Integro-differential equations for these ruin probabilities are derived. When the claim sizes are exponentially distributed, the above-mentioned integro-differential equations can be reduced into a three-order partial differential equation. 相似文献
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基于LED的标准太阳光谱灯拟合算法 总被引:3,自引:1,他引:2
在测量领域中需要使具有高稳定性及良好光谱匹配性的人工模拟太阳光谱标准灯.本文提出一种基于多种不同峰值波长LED光源的方法来准确模拟AM1.5的光谱分布.以最小二乘法和高斯分布数学模型为基础,在理论上实现了非均匀间隔峰值波长的光谱拟合,从而指导LED的种类选择及其所需的驱动电流值,并通过实验论证其可行性.结果表明:在300~1100 nm的范围内,使用较少LED种类的情况下,此方法光谱失配误差小于±2.76%.此算法可精确地分辨标准太阳光谱AM1.5的吸收谷,且应用于AM0的拟合时获得小于±1.67%的光谱失配度.在工程实践中,该算法对快速、准确获得标准太阳光谱灯具有良好的指导意义. 相似文献
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有随机投资回报的随机保费模型的渐近破产概率(英文) 总被引:1,自引:0,他引:1
本文研究了随机投资回报环境下扰动的随机保费模型的破产问题.利用鞅方法和随机分析的理论讨论了盈余过程的一些基本性质,得到了一个可以用来求解破产时刻的Laplace变换的积分微分方程,结果推广了已有的随机投资问报风险模型的结论. 相似文献
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具有超大通道结构的介孔氧化硅柱层状钛酸的合成和催化应用初探 总被引:6,自引:0,他引:6
A mesoporous (d=2.3mm) silica-pillared layered tetratitanate with a super gallery (d001=1.84mm)was prepared by first preswelling layered tetratitanate with n-dodecyl amine, then reacting with 20wt% NH2(CH2)3Si(OC2H5)3 aqueous solution, and finally calcinating the resultant solid product in air at 550℃. All the reaction was carried out hydrothermally in an autoclave at 130℃. The obtained material has a relatively high BET surface area of 204m2·g-1 and a thermal stability beyond 600℃. The catalytic application of the material was also investigated by using the dehydration of isopropanol and the reform of n-hexane as two probing reactions. 相似文献
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