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排序方式: 共有101条查询结果,搜索用时 31 毫秒
1.
Bruno Gabel Denis Thiéry Vaclav Suchy Frédéric Marion-Poll Peter Hradsky Pavel Farkas 《Journal of chemical ecology》1992,18(5):693-701
The European grapevine moth (EGVM),Lobesia botrana, is a major pest of grapes in Europe. Females are attracted to a nonhost plant: tansy (Tanacetum vulgare L.), which is a common weed in Slovakian vineyards. A steam distillate extract of tansy flowers was analyzed by means of a GC-EAG technique to screen constituents detected by the olfactory receptors of EGVM females. From more than 200 GC peaks, nine peaks corresponding to monoterpenoids released an EAG response in more than 70% of the females (N=15):p-cymene,d-limonene,-thujene,-thujone,-thujone, thujyl alcohol, terpinene-4-ol, (Z)-verbenol, and piperitone. The steam distillate of tansy as well as a synthetic blend of identified compounds released consistent attraction in a field cage. The use of nonhost plants and host plant odors in integrated pest management is discussed. 相似文献
2.
We describe a two-level method for computing a function whose zero-level set is the surface reconstructed from given points
scattered over the surface and associated with surface normal vectors. The function is defined as a linear combination of
compactly supported radial basis functions (CSRBFs). The method preserves the simplicity and efficiency of implicit surface
interpolation with CSRBFs and the reconstructed implicit surface owns the attributes, which are previously only associated
with globally supported or globally regularized radial basis functions, such as exhibiting less extra zero-level sets, suitable
for inside and outside tests. First, in the coarse scale approximation, we choose basis function centers on a grid that covers
the enlarged bounding box of the given point set and compute their signed distances to the underlying surface using local
quadratic approximations of the nearest surface points. Then a fitting to the residual errors on the surface points and additional
off-surface points is performed with fine scale basis functions. The final function is the sum of the two intermediate functions
and is a good approximation of the signed distance field to the surface in the bounding box. Examples of surface reconstruction
and set operations between shapes are provided. 相似文献
3.
Sania Saheli Ali Reza Rezvani Azim Malekzadeh Michal Dusek Vaclav Eigner 《International Journal of Hydrogen Energy》2018,43(2):685-694
The silica- and alumina-supported Co–Zn catalysts were synthesized by thermal decomposition of new inorganic precursors [Co4.32Zn1.68(HCO2)18(C2H8N)6]/SiO2 or Al2O3. A novel coordination polymer formulated as [Co4.32Zn1.68(HCO2)18(C2H8N)6] (1) was prepared using the solvothermal technique and characterized by elemental analysis, FT-infrared spectroscopy. Thermal stability of the complex 1 was investigated by thermogravimetric analysis and differential scanning calorimetry, and its structure was determined by single-crystal X-ray diffraction. Characterization of catalysts was carried out using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET specific surface area. The catalysts were evaluated for Fischer–Tropsch synthesis (FTS) in the temperature range 200–300 °C. The results revealed that the synthesized catalysts have higher selectivity to the desired products at 260 °C. The performance of the catalysts was compared to those of catalysts constructed via impregnation method and the fabricated catalysts show higher activity and selectivity than the reference catalysts. 相似文献
4.
Alena Reznickova Zdenka Kolska Jakub Siegel Vaclav Svorcik 《Journal of Materials Science》2012,47(17):6297-6304
Grafting of gold nanoparticles and nanorods on the surface of polymers, modified by plasma discharge, is studied with the aim to create structures with potential applications in electronics or tissue engineering. Surfaces of polyethyleneterephthalate and polytetrafluoroethylene were modified by plasma discharge and subsequently, grafted with 2-mercaptoethanol, 4,4′-biphenyldithiol, and cysteamine. The thiols are expected to be fixed via one of –OH, –SH or –NH2 groups to reactive places on the polymer surface created by the plasma treatment. “Free” –SH groups are allowed to interact (graft) with gold nanoparticles and nanorods. Gold nano-objects were characterized before grafting by transmission electron microscopy and UV–Vis spectroscopy. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and electrokinetic analysis (zeta potential determination) were used for the characterization of polymer surface at different modification phases. It was proved by FTIR and XPS measurements that the thiols were chemically bonded on the surface of the plasma-treated polymers, and they mediate subsequent grafting of the gold nano-objects. On the surfaces, modified polymers were indicated some objects by AFM, size of which was dramatically larger in comparison with that of original nanoparticles and nanorods. This result and the other results of UV–Vis spectroscopy indicate an aggregation of deposited gold nano-objects. 相似文献
5.
Paul F. Fewster Vaclav Holy Norman L. Andrew 《Materials Science in Semiconductor Processing》2001,4(6):321
Some of the most important material systems, GaInN alloys and quantum dot structures create interesting and complex challenges for structural analysis. This paper concentrates on the interpretation of the microstructure of both these materials, the former to assess the defect separation and the latter to obtain the shape and composition of the quantum dots. The methods used are based on mapping the X-ray intensity in reciprocal space and simulating proposed models to achieve good agreement with the experimental results. An indication of the reliability of these methods is presented.The simulation of the 0002 reciprocal space map of a 0 0 0 1 orientated InGaN/GaN sample yielded a range of dimensions of the perfect regions between defects of 60 and 220 μm. This comes from careful fitting of the tails of the scattering parallel to the surface plane. The average composition within an InGaAs quantum dot has been determined to a reliability of ±3% and the dimensions of these buried dots evaluated from simulating the reciprocal space maps using the in-plane scattering geometry. 相似文献
6.
Yevgeniya Kalachyova Oleksiy Lyutakov Petr Slepicka Roman Elashnikov Vaclav Svorcik 《Nanoscale research letters》2014,9(1):591
In this work, we describe laser modification of poly(methyl methacrylate) films doped with Fast Red ITR, followed by dopant exclusion from the bulk polymer. By this procedure, the polymer can be modified under extremely mild conditions. Creation of surface ordered structure was observed already after application of 15 pulses and 12 mJ cm−2 fluence. Formation of grating begins in the hottest places and tends to form concentric semi-circles around them. The mechanism of surface ordered structure formation is attributed to polymer ablation, which is more pronounced in the place of higher light intensity. The smoothness of the underlying substrate plays a key role in the quality of surface ordered structure. Most regular grating structures were obtained on polymer films deposited on atomically ‘flat’ Si substrates. After laser patterning, the dopant was removed from the polymer by soaking the film in methanol. 相似文献
7.
8.
Vaclav Dolezal 《Circuits, Systems, and Signal Processing》1982,1(2):233-249
Although an operational amplifier is a nonlinear device, the existing methods of analysis of circuits with operational amplifiers view it as a linear element which possibly has an infinite gain. As a result, it is not clear to what extent the results thus obtained hold. In this paper we construct a general model of a (nonlinear) circuit containing operational amplifiers. Viewing such a network as an interconnection of a multiport withn operational amplifiers, we give conditions for solvability (i.e., for the existence of an input-output operator), and establish estimates for the error incurred by replacing such a system by an idealized system whose operational amplifiers have infinite gain. In this way we determine ranges for variables within which the traditional linear analysis gives results that fulfill given accuracy requirements. 相似文献
9.
Josef Pribyl Vaclav Rehout Jindrich Citek Jana Pribylova 《Journal of the science of food and agriculture》2010,90(11):1765-1773
The evaluation of an animal is based on production records, adjusted for environmental effects, which gives a reliable estimation of its breeding value. Highly reliable daughter yield deviations are used as inputs for genetic marker evaluation. Genetic variability is explained by particular loci and background polygenes, both of which are described by the genomic breeding value selection index. Automated genotyping enables the determination of many single‐nucleotide polymorphisms (SNPs) and can increase the reliability of evaluation of young animals (from 0.30 if only the pedigree value is used to 0.60 when the genomic breeding value is applied). However, the introduction of SNPs requires a mixed model with a large number of regressors, in turn requiring new algorithms for the best linear unbiased prediction and BayesB. Here, we discuss a method that uses a genomic relationship matrix to estimate the genomic breeding value of animals directly, without regressors. A one‐step procedure evaluates both genotyped and ungenotyped animals at the same time, and produces one common ranking of all animals in a whole population. An augmented pedigree–genomic relationship matrix and the removal of prerequisites produce more accurate evaluations of all connected animals. Copyright © 2010 Society of Chemical Industry 相似文献
10.
Martin Parizek Nikola Kasalkova Lucie Bacakova Petr Slepicka Vera Lisa Martina Blazkova Vaclav Svorcik 《International journal of molecular sciences》2009,10(10):4352-4374
High-density polyethylene (PE) foils were modified by an Ar+ plasma discharge and subsequent grafting with biomolecules, namely glycine (Gly), polyethylene glycol (PEG), bovine serum albumin (BSA), colloidal carbon particles (C) or BSA and C (BSA + C). As revealed by atomic force microscopy (AFM), goniometry and Rutherford Backscattering Spectroscopy (RBS), the surface chemical structure and surface morphology of PE changed dramatically after plasma treatment. The contact angle decreased for the samples treated by plasma, mainly in relation to the formation of oxygen structures during plasma irradiation. A further decrease in the contact angle was obvious after glycine and PEG grafting. The increase in oxygen concentration after glycine and PEG grafting proved that the two molecules were chemically linked to the plasma-activated surface. Plasma treatment led to ablation of the PE surface layer, thus the surface morphology was changed and the surface roughness was increased. The materials were then seeded with vascular smooth muscle cells (VSMC) derived from rat aorta and incubated in a DMEM medium with fetal bovine serum. Generally, the cells adhered and grew better on modified rather than on unmodified PE samples. Immunofluorescence showed that focal adhesion plaques containing talin, vinculin and paxillin were most apparent in cells on PE grafted with PEG or BSA + C, and the fibres containing α-actin, β-actin or SM1 and SM2 myosins were thicker, more numerous and more brightly stained in the cells on all modified PE samples than on pristine PE. An enzyme-linked immunosorbent assay (ELISA) revealed increased concentrations of focal adhesion proteins talin and vinculin and also a cytoskeletal protein β-actin in cells on PE modified with BSA + C. A contractile protein α-actin was increased in cells on PE grafted with PEG or Gly. These results showed that PE activated with plasma and subsequently grafted with bioactive molecules and colloidal C particles, especially with PEG and BSA + C, promotes the adhesion, proliferation and phenotypic maturation of VSMC. 相似文献