排序方式: 共有68条查询结果,搜索用时 15 毫秒
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建立了功能化离子液体/离子液体分散液-液微萃取(FIL/IL-DLLME)测定水中4种苯氧羧酸类除草剂的农药残留分析方法.离子液体[C4MIMBF4]有助于难溶于水的[C6HyMIMTf2N]在水相中形成液滴.离子对[LiWf2N]的引入有利于提高功能离子液体对分析物的提取效率,对影响萃取效率的重要因素进行选择和优化,最佳条件为:100 μL[C6HyMIMTf2N])作为提取剂,100 μL[C4MIMBF4]作为分散剂,在30℃下超声5 min,[LiTf2N]浓度为5%和样品溶液的pH=2.在最佳优化条件下,5~500 μg/L范围内线性良好,相关系数为0.9953 ~0.9996;对自来水、河水、田间水进行浓度为10和20 μg/L添加回收实验,回收率为70.2%~107.5%,相对标准偏差RSD<10%,检出限为0.05 ~0.2 μg/L,得到满意的结果,说明本方法对于实际样本的检测具有可行性. 相似文献
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N-phenylpyridin-2-ylmethanimine, HL reacts with CoBr2 to afford a water-soluble cobalt(II) complex [CoII(HL)2Br2] 1, whose crystal structure has been determined by X-ray diffraction. Electrochemical studies show that this complex can electrocatalyze hydrogen generation from a neutral buffer with a turnover frequency (TOF) of 875.17 mol of hydrogen per mole of catalyst per hour (mol H2/mol catalyst/h) at an overpotential (OP) of 837.6 mV. Compared with the cobalt complex 1, the previously described nickel(II) complex [Ni(HL)2Cl2] (970.45 mol H2/mol catalyst/h at an OP of 837.6 mV) exhibits more efficient activity for hydrogen evolution. 相似文献
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Analysis of the Interaction between Low-Frequency Waves and Ions in the High-Altitude Cusp Region Observed by Satellite Cluster 下载免费PDF全文
段素平刘振兴 曹晋滨史建魁路立 李中元Q. G. Zong H. Reme N. Cornilleau-Wehrlin A. Balogh M. Andre 《中国物理快报》2006,23(5):1351-1354
The energy transfer between ions (protons) and low frequency waves (LFWs) in the frequency range f1 from 0.3 to 10 Hz is observed by Cluster crossing the high-altitude polar cusp. The energy transfer between low frequency waves and ions has two means. One is that the energy is transferred from low frequency waves to ions and ions energy increases, The other is that the energy is transferred from ions to low frequency waves and the ion energy decreases. lon gyratory motion plays an important role in the energy transfer processes. The electromagnetic field of f1 LFWs can accelerate or decelerate protons along the direction of ambient magnetic field and warm or refrigerate protons in the parallel and perpendicular directions of ambient magnetic field, The peak values of proton number densities have the corresponding peak values of electromagnetic energy of low-frequency waves. This implies that the kinetic Alfven waves and solitary kinetic Alfven waves possibly exist in the high-altitude cusp region. 相似文献
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本文研究了中性条件下TiO2纳米粒子与双阴离子态荧光素F2-的结合能力,发现所形成的复合物与文献报道的强酸性条件下TiO2-质子化荧光素H3F+复合物相比,结构与性能均很不同,F2--TiO2复合物吸收光谱红移30 nm以上且发射荧光。用UV-vis吸收光谱测定了复合物的结合常数、用稳态和瞬态荧光光谱测定了复合物的荧光效率和寿命分别为0.14和1.08 ns,与相应自由态F2-的测定值0.92和4.68 ns相比,复合物荧光效率和寿命都有很大的降低,这是由于复合物内部光诱导电子转移所致,因这一电子转移是热力学上非常有利的过程,其自由能变化达1.1 eV。光致电子转移的速率常数为7.1×108s-1,是其它竞争过程的3倍以上,复合物内光诱导电子转移效率达77%。 相似文献
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大脑皮质内部的联系神经束,对于大脑皮质之间的信息传递担任非常重要的角色.传统的语言模型理论提出人类的2个主要语言中枢分别位于大脑皮质的左侧额下回的布罗卡区域(Broca’s area,BA44andBA45)以及颞上回处的维尼基区域(Wernicke’s area,BA22),而联系这2个区域的纤维束,也就是弓状束(arcuate fasciculus).另外,近期研究也发现下顶叶(inferior parietal cortex,BA39and BA40)在语音处理历程具重要性.扩散磁振造影(Diffu-sionMRI)可以提供大脑白质精细的组织结构,配合神经径路追踪(tractography)便能撷取出复杂的神经纤维连结路径.该研究利用扩散磁振影像中的高夹角分辨率扩散磁振造影(high angular resolution diffusion imaging)与神经径路追踪技术,呈现与语言相关的大脑机率神经连结路径(probabilistic language pathway). 相似文献
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以自制的6.0μm单分散大孔交联聚氯甲基苯乙烯-二乙烯基苯(Poly(4-vinylbenzylchloride-co-divi-nylbenzene),PCMS/DVB)微球为基质和引发剂,CuCl和自行合成的三[(2-二甲基氨基)乙基]胺(Tris[2-(dimeth-ylamino)ethyl]amine,Me6TREN)组成混合催化体系,使4-乙烯基吡啶(4-Vinyl pyridine,4-VP)在甲苯中进行原子转移自由基聚合,制得4-乙烯基吡啶聚合物,单体4-乙烯基吡啶的接枝率为8.55%。将该聚合物与正溴丁烷反应制得新型亲水色谱固定相。在亲水作用色谱模式下,流速1 mL/min,乙腈-水为流动相可分离5种芳胺化合物和4种酚类化合物。在离子交换色谱模式下,6 mmol/L Na2CO3-5.5 mmol/L NaHCO3为淋洗液可分别分离5种无机阴离子和4种短链有机酸。结果表明,此固定相对极性化合物和无机阴离子具有良好的分离性能,是一种性能优异的亲水作用色谱固定相。 相似文献
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In this paper, Lie symmetry is investigated for a new integrable
coupled Korteweg--de Vries (KdV) equation system. Using some symmetry
subalgebra of the equation system, we obtain five types of the
significant similarity reductions. Abundant solutions of the coupled
KdV equation system, such as the solitary wave solution, exponential
solution, rational solution and polynomial solution, etc. are
obtained from the reduced equations. Especially, one type of
group-invariant solution of reduced equations can be acquired by
means of the Painlev\'e I transcendent function. 相似文献