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排序方式: 共有120条查询结果,搜索用时 15 毫秒
1.
European consumers, in general, have negative attitudes towards the use of gene technology in food production. The objective of this study was to examine whether taste and health benefits influence the acceptability of genetically modified (gm) products when they are presented as real product alternatives. Consumers in Denmark, Finland, Norway and Sweden (n=738) assessed two cheeses: one was labelled as genetically modified (preferred in an earlier product test) and the other as conventional (neutral in an earlier product test). A smaller control group received two cheeses with blind codes. Labelling decreased consumers' intentions to buy the originally preferred gm-labelled cheese, but still the intentions were at the same level with the conventionally labelled option. Participants chose two gm cheeses out of five possible when given the option to take cheese home after tasting. Intentions to buy gm cheese could best be explained by respondents' attitudes towards gene technology and perceived taste benefits. General health interest was also a reinforcer of intentions for gm cheese with reduced fat content.  相似文献   
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H.S. JeonG. Kim  D.H. Weinkauf 《Polymer》2003,44(19):5749-5758
The effects of clay dispersion and the interactions between clays and polymer chains on the viscoelastic properties of polymer/clay nanocomposites are investigated using oscillatory shear rheology, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Four different montmorillonite silicates of natural clays, plasma-treated clays, and organically modified clays (OCs) have been used in this study. For the polyisoprene (PI)/clay nanocomposites, the exfoliation of the OC dispersed in the PI matrix is confirmed with XRD and SAXS although TEM images show both exfoliated and non-exfoliated nanoclay sheets. In contrast aggregation or intercalation is obtained for the other PI/clay composites studied here. Additionally, the effective maximum volume packing fraction of OC for the exfoliated nanocomposites is determined from the overlapping of dynamic viscosity at low frequency regime, in which the effective maximum volume packing fraction is larger than the percolation threshold determined from the storage modulus of the nanocomposites.  相似文献   
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Functions that optimize Laplacian‐based energies have become popular in geometry processing, e.g. for shape deformation, smoothing, multiscale kernel construction and interpolation. Minimizers of Dirichlet energies, or solutions of Laplace equations, are harmonic functions that enjoy the maximum principle, ensuring no spurious local extrema in the interior of the solved domain occur. However, these functions are only C0 at the constrained points, which often causes smoothness problems. For this reason, many applications optimize higher‐order Laplacian energies such as biharmonic or triharmonic. Their minimizers exhibit increasing orders of continuity but lose the maximum principle and show oscillations. In this work, we identify characteristic artifacts caused by spurious local extrema, and provide a framework for minimizing quadratic energies on manifolds while constraining the solution to obey the maximum principle in the solved region. Our framework allows the user to specify locations and values of desired local maxima and minima, while preventing any other local extrema. We demonstrate our method on the smoothness energies corresponding to popular polyharmonic functions and show its usefulness for fast handle‐based shape deformation, controllable color diffusion, and topologically‐constrained data smoothing.  相似文献   
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通信行业正在迅速从电路交换网络迁移到基于互联网协议(IP)的分组交换网络.IP融合实现了宽带部署、"三网合一"(语音/视频/数据)业务、3G无线和其它通信业务,它们正在为消费者、服务提供商和设备制造商创造令人激动的新机遇.  相似文献   
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A four-dimensional mapping (three spatial dimensions + time) of myocardial strain-rate would help to describe the mechanical properties of the myocardium, which affect important physiological factors such as the pumping performance of the ventricles. Strain-rate represents the local instantaneous deformation of the myocardium and can be calculated from the spatial gradients of the velocity field. Strain-rate has previously been calculated using one-dimensional (ultrasound) or two-dimensional (2-D) magnetic resonance imaging) techniques. However, this assumes that myocardial motion only occurs in one direction or in one plane, respectively. This paper presents a method for calculation of the time-resolved three-dimensional (3-D) strain-rate tensor using velocity vector information in a 3-D spatial grid during the whole cardiac cycle. The strain-rate tensor provides full information of both magnitude and direction of the instantaneous deformation of the myocardium. A method for visualization of the full 3-D tensor is also suggested. The tensors are visualized using ellipsoids, which display the principal directions of strain-rate and the ratio between strain-rate magnitude in each direction. The presented method reveals the principal strain-rate directions without a priori knowledge of myocardial motion directions.  相似文献   
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Data sets coming from simulations or sampling of real‐world phenomena often contain noise that hinders their processing and analysis. Automatic filtering and denoising can be challenging: when the nature of the noise is unknown, it is difficult to distinguish between noise and actual data features; in addition, the filtering process itself may introduce “artificial” features into the data set that were not originally present. In this paper, we propose a smoothing method for 2D scalar fields that gives the user explicit control over the data features. We define features as critical points of the given scalar function, and the topological structure they induce (i.e., the Morse‐Smale complex). Feature significance is rated according to topological persistence. Our method allows filtering out spurious features that arise due to noise by means of topological simplification, providing the user with a simple interface that defines the significance threshold, coupled with immediate visual feedback of the remaining data features. In contrast to previous work, our smoothing method guarantees a C1‐continuous output scalar field with the exact specified features and topological structures.  相似文献   
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Höche T  Gerlach JW  Petsch T 《Ultramicroscopy》2006,106(11-12):981-985
Prior to transmission electron microscopy (TEM) analyses, insulating specimens need to become coated with a charge-draining layer. Rather than coating the entire TEM foil with a thin film of homogeneous thickness, selective coating is proposed. Using a novel preparation tool, peripheral parts of the sample are coated with a relatively thick (4-8 nm) carbon film while the central, electron-transparent part of the sample is hidden behind a shape-adopted mask and thus not directly exposed to carbon deposition. Beneath the mask, an ultrathin (3-7 A) carbon film is formed that is (i) thick enough to drain charges evolving upon electron irradiation in the electron microscope and (ii) thin enough to avoid typical contamination effects caused by superficial carbon diffusion. Consequently, image quality is becoming enhanced in high-resolution imaging and sensitivity is significantly increased in all nano-beam related techniques including elemental analytics, convergent-beam and nano-beam electron diffraction, and spectral imaging.  相似文献   
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Stream surfaces are a well‐studied and widely used tool for the visualization of 3D flow fields. Usually, stream surface seeding is carried out manually in time‐consuming trial and error procedures. Only recently automatic selection methods were proposed. Local methods support the selection of a set of stream surfaces, but, contrary to global selection methods, they evaluate only the quality of the seeding lines but not the quality of the whole stream surfaces. Global methods, on the other hand, only support the selection of a single optimal stream surface until now. However, for certain flow fields a single stream surface is not sufficient to represent all flow features. In our work, we overcome this limitation by introducing a global selection technique for a set of stream surfaces. All selected surfaces optimize global stream surface quality measures and are guaranteed to be mutually distant, such that they can convey different flow features. Our approach is an efficient extension of the most recent global selection method for single stream surfaces. We illustrate its effectiveness on a number of analytical and simulated flow fields and analyze the quality of the results in a user study.  相似文献   
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