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131.
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Ahn JH Shin YD Nath GY Park SY Rahman MS Samal S Lee JS 《Journal of the American Chemical Society》2005,127(12):4132-4133
The living anionic polymerization of isocyanates carried out using conventional initiators is associated with side reactions due to rapid initiation rates as well as back-biting by the growing chain, resulting in a lack of control on the molecular weight (MW) and molecular weight distribution (MWD) of the polymers. Successful control over the reaction was possible by using additives that could prevent back-biting. We find an initiator in sodium benzanilide (Na-BA), which has a slow initiation rate combined with additive function, so that use of an external additive is eliminated. The initiator has resulted in polymers with high yields and an unprecedented control over the MW and MWD. It is possible to introduce a number of functionalities at the termini of the polymer by using Na-BA derivatives as well as suitable terminating agents, leading to macromonomer, reactive and chiral polymers, and chiral macromonomer in approximately 100% yields. In the process, the finding has expanded the scope of polyisocyanates in diverse applications. 相似文献
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Prem Nath Gupta Abani K. Bhattacharya 《Fresenius' Journal of Analytical Chemistry》1972,262(5):363-364
Ohne Zusammenfassung
Teil IV: diese Z. 256, 7 (1971) 相似文献
Automation in and with analytical chemistryV. Classification of working ranges in analytical chemistry with regard to computers
Teil IV: diese Z. 256, 7 (1971) 相似文献
138.
Temporal evolution of local and global hardness during an ion-atom collision process has been studied within a quantum fluid
density functional framework. A dynamical variant of the maximum hardness principle has been found to be operative. Entropy
maximises in the encounter regime. Time dependence of density and its laplacian provides important insights into the collision
processvis-a-vis the hardness maximisation. 相似文献
139.
Sarmistha Das Samirgopal Bhattacharya Rupendra Nath Banerjee Debabrata Banerjea 《Transition Metal Chemistry》1982,7(5):249-252
Summary The title complex aquates in acid media, first to [Co(mal)-(H2O)2(en)]+ (1) (Step 1) and subsequently to [Co(H2O)4(en)]3+
(2) (Step 2). Complex species (1) has been separated and characterised in solution. While Step 1 involves only a second-order acid catalysed path, Step 2 involves both a first-order acid independent path and a second-order acid catalysed path. The rate constants and activation parameters evaluated for these reaction paths have been compared with those for similar carboxylato-cobalt(III) complexes. This, together with an observed isokinetic relation, indicates that the rate-determining step involves opening of the unprotonated (in the spontaneous acid independent path) or the protonated (for the acid catalysed path) chelate ring of the malonate ligand and insignificant solvation of the central metal ion. 相似文献
140.
Nilamoni Nath N. Suryaprakash 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2010,207(2):190-196
The increasing scientific and industrial interest towards metabonomics takes advantage from the high qualitative and quantitative information level of nuclear magnetic resonance (NMR) spectroscopy. However, several chemical and physical factors can affect the absolute and the relative position of an NMR signal and it is not always possible or desirable to eliminate these effects a priori. To remove misalignment of NMR signals a posteriori, several algorithms have been proposed in the literature. The icoshift program presented here is an open source and highly efficient program designed for solving signal alignment problems in metabonomic NMR data analysis. The icoshift algorithm is based on correlation shifting of spectral intervals and employs an FFT engine that aligns all spectra simultaneously. The algorithm is demonstrated to be faster than similar methods found in the literature making full-resolution alignment of large datasets feasible and thus avoiding down-sampling steps such as binning. The algorithm uses missing values as a filling alternative in order to avoid spectral artifacts at the segment boundaries. The algorithm is made open source and the Matlab code including documentation can be downloaded from www.models.life.ku.dk. 相似文献