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多环芳二酐型聚酯亚胺膜的透气性能李悦生,丁孟贤,徐纪平(浙江大学高分子科学与工程研究所,杭州,310027)(中国科学院长春应用化学研究所)关键词聚醚酰亚胺,聚酯酰亚胺,膜,透气性通常的聚酰亚胺加工性能较差,在芳环二酐的苯环间引入醚键等柔性基团后,其... 相似文献
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微量元素与疾病诊断治疗的研究现状及展望 总被引:8,自引:0,他引:8
对国内外微量元素与疾病的关系及其诊断治疗的研究现状及研究动向进行了综述,包括:微量元素与地方病、癌肿、心血管病、糖尿病、眼病、神经系统病等。参考文献72篇。 相似文献
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Wenbi Guan 《International journal of environmental analytical chemistry》2013,93(6):679-691
A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg?1, the maximum residue level of European Union for quizalofop-p-ethyl). 相似文献
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Prof. Inmaculada García‐Moreno Lu Wang Prof. Angel Costela Dr. Jorge Bañuelos Prof. Iñigo López Arbeloa Prof. Yi Xiao 《Chemphyschem》2012,13(17):3923-3931
Herein, we present the synthetic route and the photophysical, electrochemical as well as laser properties of novel red‐emitting boron‐dipyrromethenes (BODIPYs) bearing arylethyne moieties. Such functionality is added along the main axis of the chromophore leading to single‐ and double‐substituted derivatives. The relationship between the dye structure and the lasing properties is studied in detail with the help of the photophysical and electrochemical properties as well as quantum mechanical simulations. The asymmetric substitution of the parent dye induces inhomogeneities in the charge distribution, which leads to an overall loss of the fluorescence capacity, mainly in polar media. Such non‐radiative deactivation processes can be softened by decreasing the electron‐donor ability of the substituent or even avoided by symmetrical substitution. Thus, grafting of the arylethyne moieties at the longitudinal axis of the indacene core results in an effective strategy to develop red‐edge BODIPYs with highly efficient and photostable laser emission. 相似文献
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Ti-V基储氢合金在室温、常压下即可表现出良好的储氢特性,且质量储氢容量明显高于传统AB5型储氢合金,从而在氢气的精制和回收、运输和储存及热泵等方面有较早的应用。 此外,在混合气体分离、核反应堆中处理氢的同位素、镍氢电池及燃料电池负极材料等方面也得到了广泛的研究与关注。 基于目前Ti-V基储氢合金的研究现状,概述了该类合金的优势、限制性因素(包括成因)及改性手段。 此外,为了进一步理解Ti-V基合金储氢机理、构建合金组分与储氢特性之间的对应关系,本工作重点围绕Ti-V基储氢合金及其氢化物的结构、组分优化设计展开综述,并对其未来研究方向做出展望。 相似文献
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The monomeric ν(N—H) vibrations of various trisubstituted ureas of the R2UPh type and -thioureas of the R2TUPh type have been studied. The trans—out isomerism in the former and the trans—out—cis isomerism in the latter are discussed from the point of view of steric effect. The monomeric ν(N—H) vibrations of RPhUPh and RPhTUPh are also examined. The single band appearing in the spectrum of both ureas is characteristic of the cis form; this suggests the existence of phenyl—phenyl interaction (the stacking interaction proposed by Galabov et al. [10]). Behavior of ν(N—H) vibrations at several concentrations is shown to be clearly different in the three forms (trans, out and cis). The presence of the cis form is confirmed by solvent effect experiments. 相似文献
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Charles Manzi-Nshuti 《Polymer Degradation and Stability》2007,92(10):1803-1812
In this work, ferrocene- and ferrocenium-containing salts were employed to modify montmorillonite. X-ray measurements show an increase in the interlayer spacing upon clay modification, which means that the larger and more organophilic cations were inserted into the gallery space of montmorillonite. Attempts to prepare nanocomposites of polystyrene and ethylene vinyl acetate copolymers lead to immiscible systems; the morphology of these systems was elucidated with TEM, XRD and cone calorimetry. The thermal stability of the composites is greater than that of the virgin polymer. 相似文献
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Peter Kis Eva Horvthov Elika Glov Andrea ev
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ov Veronika Antalov Elena Karniov Potock Vladimír Mastihuba Mria Mastihubov 《Molecules (Basel, Switzerland)》2021,26(24)
Tyrosol (T) and hydroxytyrosol (HOT) and their glycosides are promising candidates for applications in functional food products or in complementary therapy. A series of phenylethanoid glycofuranosides (PEGFs) were synthesized to compare some of their biochemical and biological activities with T and HOT. The optimization of glycosylation promoted by environmentally benign basic zinc carbonate was performed to prepare HOT α-L-arabino-, β-D-apio-, and β-D-ribofuranosides. T and HOT β-D-fructofuranosides, prepared by enzymatic transfructosylation of T and HOT, were also included in the comparative study. The antioxidant capacity and DNA-protective potential of T, HOT, and PEGFs on plasmid DNA were determined using cell-free assays. The DNA-damaging potential of the studied compounds for human hepatoma HepG2 cells and their DNA-protective potential on HepG2 cells against hydrogen peroxide were evaluated using the comet assay. Experiments revealed a spectrum of different activities of the studied compounds. HOT and HOT β-D-fructofuranoside appear to be the best-performing scavengers and protectants of plasmid DNA and HepG2 cells. T and T β-D-fructofuranoside display almost zero or low scavenging/antioxidant activity and protective effects on plasmid DNA or HepG2 cells. The results imply that especially HOT β-D-fructofuranoside and β-D-apiofuranoside could be considered as prospective molecules for the subsequent design of supplements with potential in food and health protection. 相似文献
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Ling Yun Wang 《European Polymer Journal》2006,42(2):322-327
Neutral nickel(II) and palladium(II) complexes bearing β-ketoiminato ligand have been synthesized. The two complexes have been investigated as catalyst for the polymerization. Using methylaluminoxane (MAO) as a cocatalyst, both complexes produce vinyl-addition polynorbornenes, but palladium(II) complex displays much higher activity up to 8.0 × 107 g/(molPd h). Furthermore, both Ni(II) and Pd(II)/MAO system can efficiently copolymerize norbornene and 5-norbornene-2-yl acetate (NB-OCOMe) in moderate yields and in relatively high molecular weights. The analyses of the product by FTIR, 1H NMR and 13C NMR spectra give the verification of vinyl addition copolymer. The copolymers show narrow molecular weight distribution and good solubility in common organic solvents. 相似文献
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Brunsveld L Kuhlmann J Alexandrov K Wittinghofer A Goody RS Waldmann H 《Angewandte Chemie (International ed. in English)》2006,45(40):6622-6646
Chemical biology can be defined as the study of biological phenomena from a chemical approach. Based on the analysis of relevant biological phenomena and their structural foundation, unsolved problems are identified and tackled through a combination of chemistry and biology. Thus, new synthetic methods and strategies are developed and employed for the construction of compounds that are used to investigate biological procedures. Solid-phase synthesis has emerged as the preferred method for the synthesis of lipidated peptides, which can be chemoselectively ligated to proteins of the Ras superfamily. The generated peptides and proteins have solved biological questions in the field of the Ras-superfamily GTPases that are not amendable to chemical or biological techniques alone. 相似文献
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Preparation and photochromic properties of dye-doped aluminosilicate and ORMOCER gels and coatings 总被引:1,自引:0,他引:1
L. Hou B. Hoffmann M. Mennig H. Schmidt 《Journal of Sol-Gel Science and Technology》1994,2(1-3):635-639
Aluminosilicate and ORMOCER gels and coatings containing photochromic dyes, 1, 3-dihydro-1, 3, 3-trimethylspiro-[2H-indole-2, 3-[3H]-naphth-[2, 1-b][1, 4]-oxazine] (SO) and 1, 8a-dihydro-2, 3-dimethoxycarbonyl-spiro [fluorene-9, 1-indolizine] (DHI), were prepared by the sol-gel method and the photochromic activity was monitored in the course of the sol-wetgel-xerogel transformation. The photochromic activity of the aluminosilicate gels decreases rapidly and even vanishes in the wetgel-xerogel stage while that of ORMOCER gels and coatings levels off in the early wetgel-xerogel stage at a reasonably high photochromic intensity with the colour-fading speed similar to that in ethanol and the photostability being considerably improved. The experimental results are discussed in terms of the matrix effect on photochromism of organic dyes. 相似文献
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Kwiatkowski JS Leszczynski J Venkatraman R 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2000,56(14):1-2668
DFT(B3LYP) and MP2 calculations with the 6-311G(2d, 2p)-type basis set have been carried out for the prediction of molecular parameters (bond distances, bond angles, rotational constants, and dipole moments) and vibrational Raman and infrared spectra (harmonic wavenumbers, absolute intensities, Raman scattering activities, and depolarization ratios) of bromochlorofluoromethane (HCBrCIF) and its silicon and germanium analogs (HSiBrClF and HGeBrCIF). The predicted geometry and vibrational Raman and infrared spectra of HCBrClF agree well with the available experimental data for this molecule and their deuterated derivatives. This agreement allows one to believe that the predicted molecular parameters and vibrational spectra of HSiBrClF, HGeBrClF, and their deuterated derivatives will guide their future experimental studies. 相似文献
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通过电化学氧化法制备具有不同孔径氧化铝模板 ,利用交流电镀的方法在模板中沉积金属 ,再用酸溶解模板可以得到相应尺度的金属纳米线或纳米棒的阵列 .本文利用原子力显微镜和表面增强拉曼技术分别表征了金和铜两种金属纳米线阵列 .研究结果表明 ,作为探针分子的硫氰(SCN )在金属纳米线上的碳氮三键的振动频率随纳米线直径的增大而蓝移 .这一现象可能是因为尺寸效应对纳米线的费米能级造成影响 ,使不同直径的金属纳米线电子结构存在微小的差别 . 相似文献
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Synthesis and characterization of thorium and uranium cyanoacetates and their coordination compounds
Tetracyanoacetates of thorium and uranium, M(NCCH2COO)4 (where M = Th or U) and dioxouranium (VI) dicyanoacetate [UO2(NCCH2COO)2H2O] and their coordination complexes with dimethyl sulphoxide (DMSO), dimethyl formamide (DMF), 1,10 phenanthroline (Phen)
and 2,2′-bipyridyl (Bipy) have been synthesised and characterised by elemental analysis, molecular weight determination, molar
conductance measurements, X-ray diffraction and infrared spectroscopic studies (4000–200cm−1). Structural aspects of the compounds and the sites of bonding of the ligands to the central metal atom have been discussed
in the light of shifts in thev(C ≡ N),v(COO),v(UO2) and the metal-ligand stretching vibrations. Thermogravimetric analysis of the compounds have been carried out to study thermal
decomposition modes. 相似文献
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Dr. Crispin R. W. Reinhold Dr. Marc Schmidtmann Dr. Boris Tumanskii Prof. Dr. Thomas Müller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(47):12063-12068
The synthesis of persistent sila- and germacyclopentadienyl (silolyl- and germolyl-) radicals by careful stoichiometric reduction of the corresponding halides with potassium is reported. The radicals were characterized by EPR spectroscopy and trapping reactions. The reduction of tris(trimethylsilyl)silyl-substituted halides was successful while smaller substituents (i. e., t-Butyl, Ph) gave the corresponding dimers. The EPR spectroscopic parameter of the synthesized tetrolyl radicals indicate only small spin delocalization to the butadiene unit due to cross-hyperconjugation. Silolyl- and germolyl anions are unavoidable byproducts and are isolated in the form of their potassium salts and characterized by X-ray crystallography. The comparison of the molecular structures of two closely related potassium silolides provided an example for different coordination of the potassium cation to the silolyl anion (η1 vs. η5 coordination) that triggers the switch between delocalized and localized states. 相似文献