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101.
A new approach to the evaluation of two-electron repulsion integrals over contracted Gaussian basis functions is developed. The new scheme encompasses 20 distinct, but interrelated, paths from simple shell-quartet parameters to the target integrals, and, for any given integral class, the path requiring the fewest floating-point operations (FLOPS ) is that used. Both theoretical (FLOP counting) and practical (CPU timing) measures indicate that the method represents a substantial improvement over the HGP algorithm. 相似文献
102.
Yu Gui Gu Xiaolin Zhang Richard F. Clark Stevan W. Djuric Zhenkun Ma 《Tetrahedron letters》2004,45(15):3051-3053
An intramolecular 1,3-dipolar cycloaddition of azomethine ylide, generated in situ via the reaction of C12-glycinate derivative of macrolide with formaldehyde, provided a novel tricyclic macrolide. The high stereoselectivity of this [2+3] reaction was achieved by introducing a suitable directing group at C-6 position of macrolide. 相似文献
103.
Richard Neu 《Fresenius' Journal of Analytical Chemistry》1954,143(1):30-38
Ohne ZusammenfassungII. Mitteilung: R. Neu 7. 相似文献
104.
105.
The synthesis, characterisation and polymerisation studies of a homologous series of α,ω-bis(pyrrolyl)alkanes are described. These α,ω-bis(pyrrolyl)alkanes were produced using Friedel-Crafts acylation followed by reduction of the carbonyl group using Red-Al®. Chemical polymerisation of the resultant dimers using FeCl3 produced poly(α,ω-bis(pyrrolyl)alkane) films, which were characterised by SEM, FTIR and tested for conductivity. 相似文献
106.
Nidetzky Bernd Griessler Richard Weinhausel Andreas Haltrich Dietmar Kulbe Klaus D. 《Applied biochemistry and biotechnology》1997,(1):159-172
Some important process properties of α-l,4-D-ghican phosphorylases isolated from the bacteriumCorynebacterium callunae and potato tubers (Solatium tuberosum) were compared. Apart from minor differences in their stability and specificity (represented by the maximum degree of maltodextrin
conversion) and a 10-fold higher affinity of the plant phosphorylase for maltodextrin (K
M of 1.3 g/L at 300 mM of orthophosphate), the performances of both enzymes in a continuous ultrafiltration membrane reactor
were almost identical. Product synthesis was carried out over a time course of 300–400 h in the presence or absence of auxiliary
pullulanase (increasing the accessibility of the glucan substrate for phosphorolytic attack up to 15–20%). The effect of varied
dilution rate and reaction temperature on the resulting productivities was quantitated, and a maximum operational temperature
of 40°C was identified. 相似文献
107.
Viorica Lopez-Avila Richard Young Werner F. Beckert 《Journal of separation science》1997,20(9):487-492
This paper describes the extraction of 49 organophosphorus pesti-cides (OPPs) from water samples using solid-phase microextraction (SPME). Three fibers, including a 15-μm XAD-coated fiber, a 85-μm polyacrylate-coated fiber, and a 30-μm polydimethylsilox-ane-coated fiber (PDMS), were evaluated here. The effects of stirring and the addition of NaCl to the sample were examined for the polyacrylate-coated fiber. The precision of the technique was examined for all three fibers and the extraction kinetics were investigated using the XAD- and polyacrylate-coated fibers. With some exceptions, the XAD- and polyacrylate-coated fibers performed better than the PDMS-coated fiber. The superiority of the XAD-nd polyacrylate-coated fiber. The superiority of the XAD- and polyacrylate-coated fibers over the PDMS-coated fibers can be attribuibuted to the aromatic functionalities of the XAD and the polar functionalities in the polyacrylate. The relatively high percent RSDs indicate that the SPME technique needs to be further refined before it can be used for anything other than screening. A more effective form of agitation than mechanical stirring may be neccessary to reduce variability and achieve a faster equilibrium between the sample and the SPME fiber. 相似文献
108.
109.
110.
Richard Neu 《Fresenius' Journal of Analytical Chemistry》1956,151(5):328-332
Ohne ZusammenfassungVIII. Mitt. Über Tetraphenyl-diboroxyd.VII. Mitt. Vgl. Naturwissenschaften 43, 82 (1956).Verf. dankt Frl. Elisabeth Buhl für zuverlässige und eifrige Mitarbeit. 相似文献