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991.
Vipul Dav John Z. Wang Wolfgang G. Glasser David A. Dillard 《Journal of Polymer Science.Polymer Physics》1994,32(6):1105-1114
Cellulose acetate butyrate (CAB) fibers were prepared by spinning from liquid crystalline (LC) solutions containing lithium chloride (LiCl). Ionic interactions were observed between carbonyl oxygen and lithium cation by 13C nuclear magnetic resonance (NMR) spectroscopy. Isotropization of the anisotropic phase by LiCl was found to cause a dramatic rise in the viscosity of LC solutions. The mechanosorptive creep behavior described earlier decreased in the presence of residual LiCl salt, possibly due to the formation of electrostatic interactions between Li+ and CAB backbone. © 1994 John Wiley & Sons, Inc. 相似文献
992.
Reactions of the title compound with the malonic acid derivatives diethyl ethoxymethylenemalonate (EMME), ethyl ethoxymethylenecyanoacetate (EMCA) and ethoxymethylenemalononitrile (EMMN) are reported. Condensations occur at the amino group or C-4, depending on conditions and the former intermediate was successfully cyclized to the pyrimido[1,2-b]isoquinoline system. Reactions with 2,4-pentanedione and p-bromophenacyl bromide gave only the angular systems, pyrido[2,3-c]isoquinoline and pyrrolo[2,3-c]isoquin-oline, respectively. 相似文献
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995.
We present an elementary proof of a result due to Ewald and Wessels: in a pointed, polyhedral cone of dimension n ≥ 3 with integer-valued generators, any linearly independent generator representation for a minimal Hilbert basis element has coefficient sum less than n — 1. Our proof makes explicit use of the geometry of the polyhedron given by the convex hull of the Hilbert basis elements. 相似文献
996.
Daniel C. Leslie Afshin Sohrabi Pranvera Ikonomi Marian L. McKee James P. Landers 《Electrophoresis》2010,31(10):1615-1622
Proximity ligation is a powerful technique to measure minute concentrations of target protein with high specificity, and it has been demonstrated to be effective on a wide variety of protein targets. The proximity ligation assay (PLA) technique is shown to be compromised by the amplification of a nonspecific fluorescent product that is not indicative of protein presence, which was previously unidentified in a published procedure. This result illuminates the complexity of designing the optimal PLA and the possibility of using a size‐based separation to increase the reliability of PLAs in general. Nucleic acid controls were developed to optimize the assay, which led to a novel end‐point detection method that exploits microchip electrophoresis to size the products. This method provides a greater ability to distinguish a between the target protein's signal and noise in a PLA. The utility of the PLA is demonstrated by the detection of human pathogenic Escherichia coli O157:H7 bacteria, a pathogen at the root of many recent life‐threatening food poisoning outbreaks. The results of the PLA show a detection limit of 100 E. coli O157:H7 cells with minimal cross‐reactivity with gram positive control Staphylococcus aureus bacteria. The advantages of miniaturizing this process are the 100‐fold reduction in volume, greatly reducing reagent requirements, and doubling of the thermocycling speed via noncontact infrared heating. This work, consequently, adds to the understanding of background fluorescence in PLAs, provides a method for evaluating nonspecific amplification, and shows that a qualitative PCR response indicative of the presence protein can be achieved with PLA. 相似文献
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999.
R. Chapman J.R. Leslie M. Maynard P. Skensved D. Ward J.F. Sharpey-Schafer 《Nuclear Physics A》1983,397(2):296-312
162 MeV 40Ca ions have been used to Coulomb excite the ground-state band of 159Tb up to spin . Lifetimes for levels up to spin have been determined with DSA and recoil distance methods. Multipole mixing ratios for several cascade transitions were extracted from an analysis of γ-ray angular correlation data. Reduced transition probabilities thus deduced in a model-independent way were found to be in agreement with the rotational model with Q0 = 7.41 ± 0.06 e · b and gK?gR = 1.377 ± 0.010. 相似文献
1000.
Leslie S. Ettre 《Journal of separation science》1995,18(5):277-278
Indications that already in the Ancient World, methods based on chromatographic principles were utilized, are discussed. As pointed out, they had little to do with chromatography. 相似文献