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71.
The a contrario framework for the detection of convergences in an image consists in counting, for each tested point, the number of elementary linear structures that converge to it (up to a given precision), and when this number is high enough, the point is declared to be a meaningful point of convergence. This is so far analogous to a Hough transform, and the main contribution of the a contrario framework is to provide a statistical definition of what “high enough” means: it means large enough to ensure that in an image where all elementary structures are distributed according to a background noise model, there is, in expectation, less than 1 detection. Our aim in this paper is to discuss, from a methodological viewpoint, the choice and the influence of the background noise model. This model is generally taken as the uniform independent distribution on elementary linear structures, and here, we discuss the case of images that have a natural anisotropic distribution of structures. Our motivating example is the one of mammograms in which we would like to detect stellate patterns (that appear as local convergences of spicules), and in which the linear structures are naturally oriented towards the nipple. In this paper, we show how to tackle the two problems of (a) defining and estimating an anisotropic “normal” distribution from an image, and of (b) computing the probability that a random structure, following an anisotropic distribution, converges to any given convex region. We illustrate the whole approach with several examples.  相似文献   
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The interest in belite (Ca2SiO4 + impurities or dopants) phase increases significantly since new types of clinkers based essentially on this phase become promising alternatives to Portland clinker for reducing CO2 emission. Belite is also of interest as a biomedical cement. For the cement industry, stabilization of the β-polymorph is essential since the γ-polymorph has no hydraulic activity. In order to understand the mechanism of β-polymorph stabilization, this paper explores the addition of three dopants, namely P, B and S. It turns out that these dopants can modify the lattice parameters of Ca2SiO4 and induce specific twinning morphologies and surface relief, as well as grain boundaries deformations. A link between the addition of dopant leading to significant microstructural changes and the stabilization of β-polymorph has been established.  相似文献   
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Botryosphaeria dieback is a fungal grapevine trunk disease that currently represents a threat for viticulture worldwide because of the important economical losses due to reduced yield of affected plants and their premature death. Neofusicoccum parvum and Diplodia seriata are among the causal agents. Vine green stems were artificially infected with N. parvum or D. seriata at the onset of three different phenological stages (G stage (separated clusters), flowering and veraison). Highest mean lesion lengths were recorded at flowering. Major proteome changes associated to artificial infections during the three different phenological stages were also reported using two dimensional gel electrophoresis (2D)-based analysis. Twenty (G stage), 15 (flowering) and 13 (veraison) differentially expressed protein spots were subjected to nanoLC-MS/MS and a total of 247, 54 and 25 proteins were respectively identified. At flowering, a weaker response to the infection was likely activated as compared to the other stages, and some defense-related proteins were even down regulated (e.g., superoxide dismutase, major latex-like protein, and pathogenesis related protein 10). Globally, the flowering period seemed to represent the period of highest sensitivity of grapevine to Botryosphaeria dieback agent infection, possibly being related to the high metabolic activity in the inflorescences.  相似文献   
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The active layer of a polymer photovoltaic cell is mainly based on a blend of two components: a semiconducting polymer (electron donor) and a fullerene derivative (electron acceptor) to form the bulk heterojunction (BHJ). To offer optimum photovoltaic performances, the morphology of this layer has to be very carefully controlled at the nanoscale. The materials of the BHJ require specific phase segregation enabling the optimum photogenerated exciton diffusion and dissociation, and also to ensure pathways for charge carriers to electrodes. However, such a specific morphology is thermodynamically unstable over time and phase segregation occurs with thermal cycling under solar operating conditions inducing a decrease of solar cell efficiency. This review reports on the recent progress towards obtaining a stable optimized BHJ morphology and improved efficiency stability, using different chemical routes for crosslinking the organic semiconductors. © 2014 Society of Chemical Industry  相似文献   
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In this paper, results presented concern both the chemical and physical behaviours of hemp fibres in lime-based mineral matrix in order to better understand the role of chemical modifications of cellulosic fibres in the evolution of the macroscopic properties, essentially mechanical ones, of such composite materials. The role of fibres surface treatment has been also studied through various chemical treatments applied on hemp fibres. In a first step, the influence of such treatments on the fibre characteristics has been investigated by several means, such as scanning electron microscopy, thermal analysis, X-ray diffraction and FTIR spectroscopy, in order to evaluate their consequences on the fibre behaviour itself. Secondly, an attempt to characterise the influence of the various chemical treatments of fibres on the mechanical behaviour of hemp reinforced lime-based composites has been completed by a three points bending testing campaign. According to the results, it seems that the modifications induced by specific chemical treatments (EDTA, NaOH) on fibres play a major role in the strengthening of the lime/fibres interface but also in the improvement of the overall stiffness of the composite (with respect to the one reinforced by untreated fibres) most probably related to a specific stiffening process of the fibre itself.  相似文献   
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To provide more intuitive and easily interpretable representations of complex shapes/organs, medial manifolds should reach a compromise between simplicity in geometry and capability of restoring the anatomy/shape of the organ/volume. Existing morphological methods show excellent results when applied to 2D objects, but their quality drops across dimensions. This paper contributes to the computation of medial manifolds from a theoretical and a practical point of view. First, we introduce a continuous operator for accurate and efficient computation of medial structures of arbitrary dimension. Second, we present a validation protocol for assessing the suitability of medial surfaces for anatomical representation in medical applications. We evaluate quantitatively the performance of our method with respect to existing approaches and show its higher performance for medical imaging applications in terms of medial simplicity and capability of reconstructing the anatomical volume.  相似文献   
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