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371.
In this Account, the intramolecular hydrogen bonding (HB) properties of various proton acceptor groups (BX(n): C=N, NO(2), C=O, P=O, F, CF(3)) with OH and NH(2) (AH) in benzene derivatives are assessed on the basis of gas electron diffraction, spectroscopic, and quantum chemical results. The most important properties are the HB energy, the characteristic geometrical changes in the interacting groups (lengthening of the A-H and B-X, shortening of the C-A and C-B bonds) and in the benzene ring, and the vibrational properties of the AH groups. These properties are characteristic of the particular HB interaction (in particular of the AH and BX(n) pair in single and multiple hydrogen-bonded systems); however, they cannot be related directly to the computed HB energies. 相似文献
372.
Attila Lerch
Dmitry Chetverikov
《Engineering Applications of Artificial Intelligence》1991,4(6):433-438LeaVis (for Leather Vision) is a machine-vision system that provides visual input for a CAD system used in the leather industry. It has recently been developed in the Computer Vision and Robotics Laboratory of the Computer and Automation Institute. Its task is to process and segment images of hides that are manually marked by lines and other symbols. A key feature of the vision system is its ability to correct line drawings by connecting broken lines and bridging gaps in line junctions. The correction is guided by a set of knowledge-based rules that allow the program to handle the contours in a consistent way. The paper gives an overview of LeaVis and discusses the mechanism of line correction in more detail. 相似文献
373.
374.
Serdar?AbaciEmail author Yasemin?Aslan Attila?Yildiz 《Journal of Materials Science》2005,40(5):1163-1168
Electrochemical copolymerization of aniline and thiophene was investigated on -PbO2 electrode in acetonitrile. Optimum experimental conditions were determined forcopolymerization. Copolymer films synthesized on -PbO2 electrode were analyzed bycyclic voltammetry, dry conductivity measurements, FT-IR spectroscopy, elemental analysisand thermal methods. 相似文献
375.
Emel Yildiz Hande Gülü Hüseyin Yildirim Abdülkadir Kuyulu Attila Güngr 《大分子材料与工程》1995,230(1):105-115
In this study, the dependence of the mechanical properties of a UV curable acrylated urethane on reactive diluent types and their amounts was investigated. The acrylated urethane prepolymer was synthesized from isophorone diisocyanate (IPDI), an aliphatic diisocyanate, and polypropylene glycol monomethacrylate (PPGMMA) by stepwise addition reaction. UV sensitive mixtures containing N-vinylpyrrolidinone (NVP), thiodiethylene glycol diacrylate (TDGDA) and isobornyl acrylate (IBoA) as reactive diluents were irradiated by UV light. An increase in reactive diluent content, either TDGDA or IBoA, caused an increase in tensile strength and a decrease in elongation values. In contrast, above a certain concentration a decrease in tensil strength was observed when NVP was used as reactive diluent. The water absorption capacities of the UV curable acrylated urethane films were observed to depend on type and amount of reactive diluent that was used. Thermooxidative properties of the films were also improved by incorporation of reactive diluents into formulations. 相似文献
376.
Overweight vehicles require permits to cross the highway bridges, which are designed for “design load vehicles” (prescribed in the national standards). A new, fast, and robust method is presented for the verification of bridges, which requires minimal input only: the axle loads, axle spacing, the bridge span(s), and the superstructure type. The bridge can be a single or a multispan girder, an arch bridge, a frame structure, or a box girder. The overweight vehicle may operate within regular traffic or it may cross the bridge at a given lane position while other traffic is prohibited on the bridge. The method is illustrated by numerical examples for deck-girder bridges and for a box girder. 相似文献
377.
378.
Small-angle scattering was measured from activated carbon monoliths prepared from three different wood species (European beech, Pedunculate oak and Norwegian spruce). Substantial differences were found in the scattering images of axial and tangential slices, attributed to their characteristic phytogenic structures. The decrease in anisotropy in the nanostructured carbon matrix due to the activation process is also different among the three investigated types of wood. For quantitative characterization of the anisotropy and its decrease, the degree of alignment was calculated from the azimuthal scattering curves. A simple numeric model was constructed on the basis of direct information obtained by atomic force microscopy. Scattering patterns calculated from the model were compared with the experimental ones to explain the possible structural changes in the carbon skeleton. 相似文献
379.
The study aims to present a detailed theoretical investigation of noncovalent intermolecular interactions between different π–π stacking nitrogen substituted phenothiazine derivatives by applying second-order Møller-Plesset perturbation (MP2), density functional (DFT) and semiempirical theories. The conformational stability of these molecular systems is mainly given by the dispersion-type electron correlation effects. The density functional tight-binding (DFTB) method applied for dimer structures are compared with the results obtained by the higher level theoretical methods. Additionally, the optimal configuration of the investigated supramolecular systems and their self-assembling properties are discussed. 相似文献
380.
Frigeri C Serényi M Khánh NQ Csik A Riesz F Erdélyi Z Nasi L Beke DL Boyen HG 《Nanoscale research letters》2011,6(1):189
Hydrogenated multilayers (MLs) of a-Si/a-Ge have been analysed to establish the reasons of H release during annealing that
has been seen to bring about structural modifications even up to well-detectable surface degradation. Analyses carried out
on single layers of a-Si and a-Ge show that H is released from its bond to the host lattice atom and that it escapes from
the layer much more efficiently in a-Ge than in a-Si because of the smaller binding energy of the H-Ge bond and probably of
a greater weakness of the Ge lattice. This should support the previous hypothesis that the structural degradation of a-Si/a-Ge
MLs primary starts with the formation of H bubbles in the Ge layers. 相似文献