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排序方式: 共有68条查询结果,搜索用时 46 毫秒
1.
Fanny Danton Dr. Mohamed Othman Dr. Ata Martin Lawson Dr. Ján Moncol Dr. Alina Ghinet Prof. Benoît Rigo Prof. Adam Daïch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(24):6113-6118
An efficient domino transformation using a phenyliodine(III) diacetate (PIDA)/I2 combination towards Morin 1,4-thiazine compounds has been developed starting from N,S-acetals. The latter leads to “one-step” regioselective methylene insertion without the need for traditional sulfoxide intermediates in good yields. The reaction involves easily accessible N,S-acetals obtained from cost-effective basic ketones and cysteamine as starting materials. This process ultimately leads to 1,4-thiazines related to natural product and fused derivatives necessary for further QSAR study. 相似文献
2.
桑色素及其配合物与DNA作用的研究 总被引:11,自引:0,他引:11
桑色素 (Morin)是黄酮类化合物 ,具有一定的抗肿瘤活性 [1] .前文 [2 ] 以桑色素为配体合成了 6种过渡金属的配合物 ,并研究了这些配合物与配体对超氧阴离子自由基的清除作用和抗肿瘤活性 .研究表明 ,配合物对超氧阴离子自由基的清除作用明显高于配体 ,桑色素合铜 ( )和桑色素合锌 ( )配合物对 Hep- 2 ,BHK- 2 1和 HL - 6 0癌细胞瘤株的抑制作用强于配体 .配合物具有比单一有效成分更显著的药效 [3 ,4 ] .本文采用荧光方法和电化学方法研究了桑色素和抗肿瘤活性较强的桑色素合铜 ( )、桑色素合锌 ( )与 DNA在生理条件下的相互作用 ,试图… 相似文献
3.
Xiaojun Zou Yuemei Cui Xiangbing Zhu Zheng Hu Xijun Chang 《Journal of Sol-Gel Science and Technology》2009,50(1):35-43
Morin was successful as a chemical modifier to improve the reactivity of the nanometer SiO2 surface in terms of selective binding and extraction of heavy metal ions. This new functionalized nanometer SiO2 (nanometer SiO2-morin) was used as an effective sorbent for the solid-phase extraction (SPE) of Cd(II), Cu(II), Ni(II), Pb(II), Zn(II) in
solutions prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions
for effective adsorption of trace levels of metal ions were optimized with respect to different experimental parameters using
static and dynamic procedures in detail. The pH 4.0 was chosen as the optimum pH value for the separation of metal ions on
the newly sorbent. Complete elution of the adsorbed metal ions from the nanometer SiO2-morin was carried out using 2.0 mL of 0.5 mol L−1 of HCl. Common coexisting ions did not interfere with the separation and determination at pH 4.0. The maximum static adsorption
capacity of the sorbent at optimum conditions was found to be 22.36, 36.8, 40.37, 33.21 and 25.99 mg metal/g SiO2-morin for Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II), respectively. The time for 95% sorption for Cu(II) and Ni(II) and 70%
sorption for Cd(II), Pb(II) and Zn(II) was less than 2 min. The relative standard deviation (RSD) of the method under optimum
conditions was lower than 5.0% (n = 11). The procedure was validated by analyzing the certified reference river sediment material (GBW 08301, China), the results
obtained were in good agreement with standard values. The nanometer SiO2-morin was successfully employed in the separation and preconcentration of trace Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II)
from the biological and natural water samples yielding 75-folds concentration factor. 相似文献
4.
ILEEMS is the acronym for Integral Low-energy Electron Mössbauer Spectroscopy. In this variant of Mössbauer spectroscopy the low-energy electrons, E < ~15 eV, emitted by the probe nuclei in the absorber are counted as a function of source velocity. As a consequence of their low energy, the detected electrons' origin lies within a very thin surface layer with thickness of a few nanometers and consequently, ILEEMS is a useful technique to examine surfaces of Fe-containing substances. In a first part of this paper the authors briefly describe the design of a home-made ILEEMS equipment allowing the temperature of the investigated sample to be varied between 77 K and room temperature. The second part of this contribution deals with a selection of results obtained from ILEEMS spectra for various Fe oxides. In particular, the following items are covered: (1) surface versus bulk Morin transition in small-particle and near-bulk hematite, α-Fe2O3; (2) bulk and thin-film magnetite, Fe3O4; (3) ferrihydrite, 5Fe2O3·9H20, goethite, α-FeOOH, and lepidocrocite, γ-FeOOH, all to some extent in relation to their morphology. Interesting and intriguing findings concerning the surface properties of these oxides were obtained and it is argued that the results encourage more systematic research in this and related fields using the surface-sensitive ILEEMS technique. 相似文献
5.
Hyperfine Interactions - The 57Fe Mössbauer spectra recorded in situ from 5% ruthenium-doped maghemite show parameters typical for maghemite up to 600 K and a hyperfine field distribution... 相似文献
6.
在0.1mol/L(pH=4.7)的HAc NaAc缓冲溶液中,用L 半胱氨酸自组装膜修饰金电极对桑色素的电化学行为进行了初步的研究,考察了修饰时间、富集时间、富集电位、扫描速度、表面活性剂、金属离子等因素对其电化学行为的影响。研究发现,桑色素在0.44V(vs.SCE)左右产生一不可逆的氧化峰。该氧化峰电流与桑色素浓度在5×10-6~2×10-4mol/L范围内呈线性关系(相关系数r=0.9989),检出限为2×10-6mol/L,这比用裸金电极测试降低一个数量级。同时发现,十六烷基三甲基溴化铵(CTAB)对氧化峰电流有一定的增敏作用。该峰且随Pb2+浓度增大而线性增高,因此可用于Pb2+的测定。 相似文献
7.
John Jacob 《Journal of magnetism and magnetic materials》2010,322(6):614-28
In the present work, we have synthesized nanostructured hematite samples using chemical precipitation method. The crystal structure and the grain size of the samples were studied using XRD. The zero field cooled and field cooled magnetization curves of the samples were recorded in the temperature range from 300 to 10 K. The variations of Morin transition temperature and blocking temperature with the grain size of the samples were investigated. The hysterics curves of the samples were recorded and the samples showed a superparamagnetic nature at room temperature whereas, at 10 K the samples showed open hysteresis curves. The sample with smaller grain size showed higher value of coercivity compared to samples with larger grain size. Mössbauer spectra of the samples were recorded and the grain size dependence on Mössbauer parameters was investigated. 相似文献
8.
We used the isotope selectivity of 57Fe Mössbauer spectroscopy to investigate changes in the magnetic properties of polycrystalline hematite exposed to ferrous iron (Fe(II)). We found that sorption of 56Fe(II), followed by interfacial electron exchange, alters the bulk magnetic properties of 57hematite. After reaction with 56Fe(II), we observed partial suppression of the Morin transition of 57hematite to below 13 K. This is significantly lower than the Morin temperature (T M) of ~230 K measured for isotopically enriched polycrystalline 57hematite, as well as the T M of 264?±?2 K reported for normal polycrystalline hematite. 相似文献
9.
10.
铝(Ⅲ)—桑色素—含氧有机溶剂荧光体系的研究 总被引:4,自引:0,他引:4
本文系统研究了醇、酮等7种含氧有机溶剂对铝-桑色素络合物荧光反应的溶剂化效应。研究发现,上述有机溶剂对荧光体系均有增敏作用,以乙醇的效果最佳,使络合物的荧光强度增加6倍多。据此,本文建立了测定微量铝的高灵敏度荧光分析方法,线性范围为0~1.0μg/10ml,检测限为1.6×10~(-9)g/ml。用所建立的方法对化学试剂中的微量杂质铝进行了测定,结果令人满意。并对有机溶剂化效应的机理作了探讨。 相似文献