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31.
The article describes the synthesis and extraction properties of a new chiral calix[4]arene Schiff base ligand 5, which has been synthesized from 5,17-diformyl-25,27-bis-(4-nitrobenzyloxy)-26,28-dihidroxycalix[4]arene (4) by treatment with (S)-(-)-1-phenylethylamine. In this synthesis, it was thought to explore the role of chiral, as well as Schiff base sites in the recognition of targeted species ions (such as dichromate anions) as well as neutral/chiral molecules. At low pH, the ligand 5 is more effective for transferring the dichromate anions from an aqueous into a dichloromethane layer; may be due to the protonation of nitrogen atoms. The extraction properties of ligand 5 towards the some selected α -amino acid methylesters are also reported. However, the ligand 5 did not display any selectivity towards the selected α-amino acid methylesters. 相似文献
32.
water proton T1 in blood from healthy volunteers and patients with acute leukaemia, lymphoma; iron deficiency anaemia, post hepatitic cirrhosis and tuberculosis, was measured by a FT-NMR spectrometer. Relaxation measurements were performed at 60MHz frequency and a temperature of (20 ± 0.5)C. The T1 measured for each disease correlates strongly with hemoglobin content. The spin-lattice relaxation time in each abnormal group was signaficantly (p < 0.001) elevated over normal group. There is little overlap between the healthy and abnormal groups. On the contrast, T1 ranges obtained for malignant groups and non-malignant diseases do overlap. 相似文献
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Journal of Thermal Analysis and Calorimetry - Aminosilane-modified MCM-41 and SBA-15 mesoporous silicas were synthesized using sodium silicate extracted from gold mine tailings slurry in this... 相似文献
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Selenium has been identified as an essential dietary trace e1ementQ)which is a component of glutathione peroxidase (GSH-Px)(2)and a cytochrome C-like protein(3), The enzyme,the four subunits of which each contain one atom of selenium in the form of selenocysteine, the selenium containing active centre being amenable to chemical modification, catalyses the reduction of H,O,and organic hydroperoxides to water.In this way GSH-Px plays an important role in the protection of the cell from oxidative stresses such as the superoxide anion,organic hydroperoxides and H2O2 相似文献
38.
Cemil İbiş Zeliha Gökmen Nihal Yilmaz Bozkurt 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2907-2914
Mono(thio)substituted dienes 1a-1b gave compounds 3a-c and 5d-g with piperazine and piperidine derivatives in dichloromethane. Compounds 8 , 9 , and 10 were obtained from the reactions of perchlorobutadiene ( 6 ) with 1,4-butanedithiol ( 7 ) in ethanol in the presence of sodium hydroxide. Compounds 12a-b , 13a-b were obtained from the reactions of perchlorobutadiene ( 6 ) with allylmercaptan (CH 2 =CH--CH 2 --SH) and mercaptoethanol (HO--CH 2 --CH 2 --SH). 相似文献
39.
A new calixcrown‐6 oligomer 5 was synthesized by reacting a 1,3‐distal di‐amino derivative of cone p‐tert‐butylcalix[4]crown‐6 with malonyl dichloride. Extraction studies with precursor monomers 2 and 3 and oligomer 5 showed differences in their metal cation extraction behavior and selectivity. Precursors monomers 2 and 3 were selective for Hg2+; whereas, oligomer 5 showed high affinity towards both alkali (Li+, Na+, K+, and Cs+) and heavy metal cations (Cu2+, Cd2+, Hg2+ and Pb2+). 相似文献
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Sevtap Yildiz Faruk Yilmaz Haluk Özbek Önder Pekcan Koi˙chi˙ Ito 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1573-1588
Random copolymers of poly(ethylene oxide) macromonomer with p‐vinylbenzyl end‐functional group (PEOVB) and liquid crystalline monomer, namely 6‐(4‐cyanobiphenyl‐4′‐oxy)hexyl acrylate (COA), were prepared by conventional free radical polymerization. A living anionic polymerization technique was employed for the synthesis of PEO macromonomers bearing p‐vinylbenzyl moiety at one end. The photon transmission method was also applied to study the phase transitions of COA monomer and its random copolymer with PEO. It was found that, for both samples, the nematic‐smectic A transition is continuous, but the critical fluctuation regions do not allow to obtain 3D XY values. Instead, we have obtained the values close to mean field regime. Scaling of thermal hystersis for random copolymer sample near the nematic‐isotropic transition was studied as well. Thermal hysteresis loops were produced under linearly varying temperature. It was shown that the areas of the hysteresis loops scale with the temperature scanning rate with an exponent being equal to 0.614 which is in good agreement with the field‐theoretical value. 相似文献