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磁性多壁碳纳米管吸附水中双氯芬酸的热力学与动力学 总被引:4,自引:0,他引:4
研究了磁化多壁碳纳米管(MWCNTs)对于水中非甾体抗炎药双氯芬酸的吸附过程.结果表明,双氯芬酸的吸附量随磁性MWCNTs投加量的增加而增大,而且吸附剂量增加到一定阶段后,双氯芬酸的吸附量达到平衡.在磁性MWCNTs的量为0.7g·L-1时,水溶液中双氯芬酸被磁性MWCNTs吸附的量达到最大,为33.37mg·g-1,对应的双氯芬酸去除率为98.1%.双氯芬酸的去除率随溶液pH的增加先增大后下降,随温度的升高而下降.用准一级、准二级模型进行了动力学分析.回归结果表明,准二级模型更准确地反映了吸附动力学.通过实验确定了Langmuir和Freundlich等温线的线性相关系数与标准偏差,结果揭示出Langmuir等温线与实验数据有很好的拟合度.对热力学参数的计算表明,ΔG00,意味着磁性MWCNTs对双氯芬酸的吸附是自发的;ΔH00,指明吸附是一个放热的物理吸附过程,温度低对吸附有利;ΔS00,代表该吸附是熵增过程. 相似文献
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A novel adaptive watermarking algorithm in discrete wavelet transform (DWT) based on quantization index modulation (QIM) technique is presented. The host image is decomposed into wavelet subbands, and then the approximation subband is divided into non-overlapping small embedding blocks. The secret watermark bit is embedded into singular value vector of each embedding block by applying QIM. To improve the invisibility and robustness of watermarking system, the quantization step for each embedding block is set by combining statistical model with particle swarm optimization (PSO) algorithm. The experimental results show that the proposed algorithm not only preserves the high perceptual quality, but also effectively stands against joint photographic experts group (JPEG) compression, low-pass filtering, noise addition, scaling, and cropping attacks, etc. The comparison analysis demonstrates that our scheme has better performance than the previously reported watermarking algorithms. 相似文献
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Palladium carbene shows high efficiency without any promoter on oxidative carbonylation of amines to ureas and a new type of palladium carbene complex containing both an aniline and an NHC ligands was found to be the active species for the reaction. 相似文献
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Three new copper(Ⅰ) complexes, namely [Cu(DPEphos)(Biq)]CF_3SO_3(1) and [Cu(PPh_3)_2(Biq)]CF_3SO_3(2) and [Cu(PPh_3)_2(Biq)]ClO_4(3)(DPEphos = bis[2-(diphenylphosp hino)phenyl]ether, PPh_3 = triphenylphosphine and Biq = 2,2?-biquinoline), are synthesized and characterized by IR, ~1H NMR, ~(31) P NMR, fluorescence spectra and terahertz time-domain spectroscopy(THz-TDS). Complex 1 crystallizes in triclinic, space group P1 with a = 12.6997(5), b = 13.2813(5), c = 15.3593(6) ?, α = 80.211(3)°, β = 88.752(3)°, γ = 70.113(3)°, V = 2398.85(15) ?~3, C_(55)H_(41.2)CuF_3N_2O_(4.6)P_2S, Mr = 1018.27, Z = 2, Dc = 1.410 g/cm3, F(000) = 1048, μ = 0.628 mm-1, the final R = 0.0450 and w R = 0.1105 for 9419 observed reflections(I 2σ(I)). Complex 2 crystallizes in monoclinic, space group C2/c with a = 19.9961(7), b = 15.9774(5), c = 17.7908(6) ?, β = 119.758(4)°, V = 4982.8(3) ?~3, C_(56.47)H_(47.88)CuF_3N_2O_(4.47)P_2S, Mr = 1040.54, Z = 4, Dc = 1.387 g/cm~3, F(000) = 2154, μ = 0.606 mm-1, the final R = 0.0430 and w R = 0.1218 for 4897 observed reflections(I 2σ(I)). Complex 3 crystallizes in monoclinic, space group C2/c with a = 19.7534(8), b = 15.0797(5), c = 17.8097(7) ?, β = 116.400(5)°, V = 4751.8(3) ?~3, C_(56)H_(45)ClCuN_3O_4P_2, Mr = 984.88, Z = 4, Dc = 1.377 g/cm~3, F(000) = 2040, μ = 0.635 mm-1, the final R = 0.0731 and w R = 0.2180 for 4670 observed reflections(I 2σ(I)). In the emission spectra, shifts of emission peak are derived from ligand-centered(π-π*) transition. 相似文献
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在甲苯溶剂中,以价廉易得的Pd2(dba)3作为催化剂,以三乙胺作为碱,在无膦体系中成功实现了碘代芳烃和端位炔烃的Sonogashira羰化偶联反应,最高收率达95%,且该催化体系具有较好的底物适应性.该研究发展了α,β-不饱和炔酮类化合物的高效合成方法. 相似文献
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离子液体作为一种绿色溶剂,因其具有独特的性质和功能可以稳定产生的纳米钯颗粒.用离子液体制备了纳米钯催化剂,并成功地应用于碘代芳烃的双羰化反应,从而合成了一系列的α-酮酰胺,最高收率可达83%,丰富了α-酮酰胺的合成方法.该催化体系应用于碘代芳烃双羰化反应具有广泛的底物适应性. 相似文献
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本文给出加权 Plancherel公式与Hermite对称空间上的齐性线从上Plancherel公式的关系,由此导出一般有界对称域上的加权Plancherel公式. 相似文献
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基于Contourlet变换域的自适应量化索引调制数字图像水印算法 总被引:1,自引:0,他引:1
提出了一种新的基于Contourlet变换域的自适应量化索引调制数字图像水印算法.原始二值水印经过扩展置乱、降维和伪随机序列加密,嵌入到宿主图像经Contourlet变换后的低通子带系数中.根据低通子带能量分布特性,对分块低通子带的最大奇异值采用自适应量化索引调制,实现水印嵌入.实验结果表明,该水印算法不仅对嵌入的水印具有良好地视觉保真度,而且对JPEG压缩、低通滤波、加性噪声、重采样、剪切等多种攻击具有很强的稳健性.同时采用量化嵌入策略,水印提取时不需要宿主图像,即可实现水印网像盲提取. 相似文献