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891.
892.
Martin Anderson Antony G. Brinnand 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2)
Abstract A wide range of 2-substituted-5,6-dihydro-4H-1,3-thiazines (I) and tetrahydro-2H-1,3-thiazines (II) have been found to undergo a facile ring transformation reaction with aliphatic diamines to form the corresponding dinitrogen heterocycles (III) and (IV). 相似文献
893.
Stephen Brand John Milton Martin F. Jones Christopher M. Rayner 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):367-368
A new method for the synthesis of cyclic and acyclic optically active S,O-acetals is reported, along with subsequent stereocontrolled transformations, culminating in a synthesis of the important antiviral nucleoside Lamivudine. 相似文献
894.
Klaus Merz Stefan Martin Vassili Pintchouk Hans Pritzkow Matthias Driess 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract The reactions of primary silylphosphanes and -arsanes 1 with BuLi yield the three-dimensional M2ER-aggregates 2 (E = P, As). We observed that the double lithiation of 1 in the presence of Li2O results in the formation of the aggregates 3 and 4. 相似文献
895.
896.
A study has been made of the radiation-induced grafting of styrene to cellulose in the presence of cobalt 40 gamma irradiation at low total doses and dose rates. For copolymerization, What mans 41 filter paper was immersed in solutions of styrene in methanol at various monomer concentrations. The dose rates were varied from 140 to 3100 rads/hr while the total dose varied from lo3 to 2 × 105 rads. In the presence of oxygen the grafting results showed considerable scatter, but a statistical analysis revealed that at all concentrations a linear relationship existed between total dose and graft %. Three factors contributing to the variance about the regression line were examined. Residual oxygen in the solution, while not important at high dose rates, was shown markedly to contribute to the variance in the range examined. A linear dose-rate effect involving a decrease in graft with increasing dose rate was demonstrated. A LET effect also contributed to the over-all variance. Preliminary results indicate the presence of a maximum which may be a Trommsdorff effect. 相似文献
897.
The synthesis and spectroscopic studies of a convex bis-porphyrin based molecular tweezer are reported. The complexation of small bidentate ligands by metallated derivatives of the bis-porphyrin host were monitored through UV–visible and 1H NMR spectroscopy and yielded large association constants. 相似文献
898.
Tomáš Bříza Martin Havlík Bohumil Dolenský Zdeněk Kejík Pavel Martásek 《Supramolecular chemistry》2013,25(3):237-242
Highly functionalized fluorinated porphyrins were synthesized by a convergent strategy. Nucleophilic substitution using fluorinated branched unit and 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin afforded highly functionalized fluorinated porphyrin 8 containing 24 fluorinated chains in the peripheral region. 相似文献
899.
Martin T. Palou Ľubomír Bágeľ Vladimír Živica Marta Kuliffayová Tomáš Ifka 《Journal of Thermal Analysis and Calorimetry》2013,113(1):385-394
Various hydrothermal curing regimes were used to investigate the hydration and physical characteristics of two kinds of inorganic binder composites: high alumina cement–silica fume–Portland cement and high alumina cement–silica fume–sodium polyphosphate. Simultaneous thermal analysis (DTA and TG) was used to identify temperature ranges of thermal decomposition of cured samples and to characterize the nature of hydrate products. Two kinds of products are formed. The first ones consist of C3AH6, AH3, calcium carbonate (C–C) as a product of carbonation, and C3AH1.5 resulted from the partial decomposition of C3AH6 under higher hydrothermal pressure. The second ones are the products formed by acid–base reaction between monocalcium aluminate and sodium polyphosphate to form NaCaPO4·xH2O and Al2O3·xH2O that could convert to chemically bonded ceramic binders like hydroxyapatite (Ca5(PO4)3OH) and gibbsite (Al(OH)3). These two hydroceramic products formed under these conditions act also as binder and could be useful as cement binders for the protection of petroleum, gas, or geothermal wells. Mercury intrusion porosimeter was used for the estimation of the pore structure parameters of the composites. It turned up that longer curing time coupled with higher hydrothermal pressure has improved the pore structure of the first composite, while that of the second has remained unchanged. 相似文献