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31.
Amphiphilic copolymers using hydrophilic N,N‐dimethylacrylamide (DMA), hydrophobic methyl methacrylate (MMA) and a crosslinkable monomer, 3‐methacryloyloxypropyl trimethoxysilane (MTSi), were synthesized and evaluated as coating materials for leukocyte removal filters for whole blood. When filters composed of non‐woven fabrics were coated with crosslinked synthesized copolymers, the elution ratios of the copolymers to water were adequately low because of the crosslinking with trimethoxysilane groups of MTSi units in the copolymers. Filters coated with crosslinked poly(DMA‐co‐MTSi) having a 0.96 mole fraction of DMA units showed a 0.35 ± 0.44% platelet permeation ratio and a logarithmic reduction of 4.0 ± 0.68 for leukocytes. On the other hand, an increase in the content of MMA units in the DMA‐containing copolymers improved the permeation ratio of the platelets dramatically. Filters coated with crosslinked poly(DMA‐co‐MMA‐co‐MTSi) containing a 0.39 mole fraction of MMA units and a 0.58 mole fraction of DMA units showed an 86 ± 3.0% platelet permeation ratio and a logarithmic reduction of 2.1 ± 1.2 for leukocytes. This indicates that an adequate content of hydrophobic monomer units, such as MMA units, is necessary for effective platelet permeation. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
32.
Ali Kircay Ugur Cam 《AEUE-International Journal of Electronics and Communications》2006,60(6):471-474
This paper proposes a first-order allpass log-domain filter, which is systematically derived using the state-space synthesis procedure. To the best knowledge of the authors, the filter is the first log-domain first-order allpass filter in the literature. The proposed filter has a simple structure and can be electronically tuned. PSPICE simulations are given to confirm the theoretical analysis. 相似文献
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The combination of a high‐order unstructured spectral difference (SD) spatial discretization scheme with sub‐grid scale (SGS) modeling for large‐eddy simulation is investigated with particular focus on the consistent implementation of a structural mixed model based on the scale similarity hypothesis. The difficult task of deriving a consistent formulation for the discrete filter within the SD element of arbitrary order led to the development of a new class of three‐dimensional constrained discrete filters. The discrete filters satisfy a set of selected criteria and are completely local within the SD element. Their weights can be automatically computed at run time from the number of solution points within each element and the expected filter cutoff length scale. The novel discrete filters can be applied to any SGS model involving explicit filtering and to a broad class of high‐order discontinuous finite element numerical schemes. The code is applied to the computation of turbulent channel flows at three Reynolds numbers, namely Reτ = 180, 395, and 590 (based on the friction velocity uτ and channel half‐width δ). Results from computations with and without the SGS model are compared against results from direct numerical simulation. The numerical experiments suggest that the results are sensitive to the use of the SGS model, even when a high‐order numerical scheme is used, especially when the grid resolution is kept relatively low and mostly in terms of resolved Reynolds stresses. Results obtained using existing filters based on the projection of the solution over lower‐order polynomial bases are also shown and demonstrate that these filters are inadequate for SGS modeling purposes, mostly because of their inability to enforce the selected cutoff length scale with sufficient accuracy. The use of the similarity mixed formulation proved to be particularly accurate in reproducing SGS interactions, confirming that its well‐known potential can be realized in conjunction with state‐of‐the‐art high‐order numerical schemes.Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
37.
This paper proposes a fast super-resolution (SR) algorithm using content-adaptive two-dimensional (2D) finite impulse response (FIR) filters based on a rotation-invariant classifier. The proposed algorithm consists of a learning stage and an inference stage. In the learning stage, we cluster a sufficient number of low-resolution (LR) and high-resolution (HR) patch pairs into a specific number of groups using the rotation-invariant classifier, and choose a specific number of dominant clusters. Then, we compute the optimal 2D FIR filter(s) to synthesize a high-quality HR patch from an LR patch per cluster, and finally store the patch-adaptive 2D FIR filters in a dictionary. Also, we present a smart hierarchical addressing method for effective dictionary exploration in the inference stage. In the inference stage, the ELBP of each input LR patch is extracted in the same way as the learning stage, and the best matched FIR filter(s) to the input LR patch is found from the dictionary by the hierarchical addressing. Finally, we synthesize the HR patch by using the optimal 2D FIR filter. The experimental results show that the proposed algorithm produces better HR images than the existing SR methods, while providing fast running time. 相似文献
38.
The extraction of vein traits from venation networks is of great significance to the development of a variety of research fields, such as evolutionary biology. However, traditional studies normally target to the extraction of reticulate structure traits (ReSTs), which is not sufficient enough to distinguish the difference between vein orders. For hierarchical structure traits (HiSTs), only a few tools have made attempts with human assistance, and obviously are not practical for large-scale traits extraction. Thus, there is a necessity to develop the method of automated vein hierarchy classification, raising a new challenge yet to be addressed. We propose a novel vein hierarchy classification method based on directional morphological filtering to automatically classify vein orders. Different from traditional methods, our method classify vein orders from highly dense venation networks for the extraction of traits with ecological significance. To the best of our knowledge, this is the first attempt to automatically classify vein hierarchy. To evaluate the performance of our method, we prepare a soybean transmission image dataset (STID) composed of 1200 soybean leaf images and the vein orders of these leaves are manually coarsely annotated by experts as ground truth. We apply our method to classify vein orders of each leaf in the dataset. Compared with ground truth, the proposed method achieves great performance, while the average deviation on major vein is less than 5 pixels and the average completeness on second-order veins reaches 54.28%. 相似文献
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Image fusion methods based on multiscale transform (MST) suffer from high computational load due to the use of fast Fourier transforms (ffts) in the lowpass and highpass filtering steps. Lifting wavelet scheme which is based on second generation wavelets has been proposed as a solution to this issue. Lifting Wavelet Transform (LWT) is composed of split, prediction and update operations all implemented in the spatial domain using multiplications and additions, thus computation time is highly reduced. Since image fusion performance benefits from undecimated transform, it has later been extended to Stationary Lifting Wavelet Transform (SLWT). In this paper, we propose to use the lattice filter for the MST analysis step. Lattice filter is composed of analysis and synthesis parts where simultaneous lowpass and highpass operations are performed in spatial domain with the help of additions/multiplications and delay operations, in a recursive structure which increases robustness to noise. Since the original filter is designed for the undecimated case, we have developed undecimated lattice structures, and applied them to the fusion of multifocus images. Fusion results and evaluation metrics show that the proposed method has better performance especially with noisy images while having similar computational load with LSWT based fusion method. 相似文献
40.
Quantum dot infrared photodetectors can be coupled with micro‐structured filters to create narrowband sensors. Guided‐mode resonance filters based on a high‐index dielectric slab can exhibit bandpass characteristics that are suitable for monolithic integration with focal‐plane arrays. Here, patterned Ge filters were integrated with InGaAs/GaAs quantum dot detectors to linearly tune their 77 K photoresponse peaks from 5.6 µm to 6.2 µm. The dark current was not influenced by these filters but the ability to narrow the photoresponse linewidth was limited by substrate scattering, which is often encountered with front‐side illumination architectures. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献