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991.
The trend of digital convergence makes multitasking common in many digital electronic products. Some applications in those systems have inherent real‐time properties, while many others have few or no timeliness requirements. Therefore the embedded Linux kernels, which are widely used in those devices, provide real‐time features in many forms. However, providing real‐time scheduling usually induces throughput degradation in heavy multitasking due to the increased context switches. Usually the throughput degradation becomes a critical problem, since the performance of the embedded processors is generally limited for cost, design and energy efficiency reasons. This paper proposes schemes to lessen the throughput degradation, which is from real‐time scheduling, by suppressing unnecessary context switches and applying real‐time scheduling mechanisms only when it is necessary. Also the suggested schemes enable the complete priority inheritance protocol to prevent the well‐known priority inversion problem. We evaluated the effectiveness of our approach with open‐source benchmarks. By using the suggested schemes, the throughput is improved while the scheduling latency is kept same or better in comparison with the existing approaches. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
992.
A method of generating modified advancing layers mesh is proposed. In this paper the mesh generation process of semi-unstructured prismatic/tetrahedral mesh is presented for relatively thin three-dimensional geometries with variable thickness, as in the case of injection molding analysis. Prismatic meshes are generated by offsetting initial surface triangular meshes. During the mesh generation process, mesh quality is efficiently improved with the use of a new node relocation method. Finally, tetrahedral meshes are automatically generated in the rest of the domain. The mesh generating capability of the proposed algorithm is demonstrated with the several practical test cases. 相似文献
993.
In IEEE 802.16 networks, bandwidth request–grant schemes are employed for reducing data collision and supporting various QoS requirements. In this paper, we investigate the impact of such schemes on Best-Effort (BE) traffic. We examine three candidate schemes. In the first scheme, each Subscribe Station (SS) attempts to request bandwidth in every frame to reduce delay. In the second scheme, the number of bandwidth request is limited to avoid collisions in bandwidth request. In the third scheme, a base station allocates bandwidth to each SS based on the measured sending rate without explicit bandwidth request. We quantitatively analyze the performance of these schemes in terms of the collision rate and buffer length. We also present a simulation study to validate our analysis and to observe the impact of these schemes on BE traffic. This paper shows that IEEE 802.16 networks can be effectively managed through appropriate bandwidth request schemes. It is also shown that bandwidth allocation without request can be an alternative for increasing utilization. 相似文献
994.
Hyung-Soo Lee Daijin Kim 《IEEE transactions on pattern analysis and machine intelligence》2009,31(6):1102-1116
The active appearance model (AAM) is a well-known model that can represent a non-rigid object effectively. However, the fitting result is often unsatisfactory when an input image deviates from the training images due to its fixed shape and appearance model. To obtain more robust AAM fitting, we propose a tensor-based AAM that can handle a variety of subjects, poses, expressions, and illuminations in the tensor algebra framework, which consists of an image tensor and a model tensor. The image tensor estimates image variations such as pose, expression, and illumination of the input image using two different variation estimation techniques: discrete and continuous variation estimation. The model tensor generates variation-specific AAM basis vectors from the estimated image variations, which leads to more accurate fitting results. To validate the usefulness of the tensor-based AAM, we performed variation-robust face recognition using the tensor-based AAM fitting results. To do, we propose indirect AAM feature transformation. Experimental results show that tensor-based AAM with continuous variation estimation outperforms that with discrete variation estimation and conventional AAM in terms of the average fitting error and the face recognition rate. 相似文献
995.
In this paper, we propose a simple algorithm for detecting scanning worms with high detection rate and low false positive rate. The novelty of our algorithm is inspecting the frequency characteristic of scanning worms instead of counting the number of suspicious connections or packets from a monitored network. Its low complexity allows it to be used on any network-based intrusion detection system as a real-time detection module for high-speed networks.Our algorithm need not be adjusted to network status because its parameters depend on application types, which are generally and widely used in any networks such as web and P2P services. By using real traces, we evaluate the performance of our algorithm and compare it with that of SNORT. The results confirm that our algorithm outperforms SNORT with respect to detection rate and false positive rate. 相似文献
996.
Refinement algebras are abstract algebras for reasoning about programs in a total correctness framework. We extend a reduct of von Wright’s demonic refinement algebra with two operators for modelling enabledness and termination of programs. We show how the operators can be used for expressing relations between programs and apply the algebra to reasoning about action systems. 相似文献
997.
Myung Geol Choi Eunjung Ju Jung‐Woo Chang Jehee Lee Young J. Kim 《Computer Graphics Forum》2009,28(7):1773-1780
The standard C/C++ implementation of a spatial partitioning data structure, such as octree and quadtree, is often inefficient in terms of storage requirements particularly when the memory overhead for maintaining parent‐to‐child pointers is significant with respect to the amount of actual data in each tree node. In this work, we present a novel data structure that implements uniform spatial partitioning without storing explicit parent‐to‐child pointer links. Our linkless tree encodes the storage locations of subdivided nodes using perfect hashing while retaining important properties of uniform spatial partitioning trees, such as coarse‐to‐fine hierarchical representation, efficient storage usage, and efficient random accessibility. We demonstrate the performance of our linkless trees using image compression and path planning examples. 相似文献
998.
A formalism to describe design patterns based on role concepts 总被引:1,自引:0,他引:1
999.
This paper presents a wavelet-based texture segmentation method using multilayer perceptron (MLP) networks and Markov random
fields (MRF) in a multi-scale Bayesian framework. Inputs and outputs of MLP networks are constructed to estimate a posterior
probability. The multi-scale features produced by multi-level wavelet decompositions of textured images are classified at
each scale by maximum a posterior (MAP) classification and the posterior probabilities from MLP networks. An MRF model is
used in order to model the prior distribution of each texture class, and a factor, which fuses the classification information
through scales and acts as a guide for the labeling decision, is incorporated into the MAP classification of each scale. By
fusing the multi-scale MAP classifications sequentially from coarse to fine scales, our proposed method gets the final and
improved segmentation result at the finest scale. In this fusion process, the MRF model serves as the smoothness constraint
and the Gibbs sampler acts as the MAP classifier. Our texture segmentation method was applied to segmentation of gray-level
textured images. The proposed segmentation method shows better performance than texture segmentation using the hidden Markov
trees (HMT) model and the HMTseg algorithm, which is a multi-scale Bayesian image segmentation algorithm. 相似文献
1000.
Sang-Hoon Kim Jang Hyun Kim Junho Yang Hyunseok Yang Joo-Youn Park Young-Pil Park 《Microsystem Technologies》2009,15(10-11):1695-1700
Recently photopolymer with disk type substrate is selected as a media of the holographic data storage system. Because shape of the media is a disk, a disk tilt must be occur when the media rotates. When disk tilt occurs the angle between the reference beam and the media is changed by the tilt, thus the data can not be recorded with a right angle or another data page is retrieved. The holographic data storage system is very weak to the tilt disturbance by the Bragg effect, therefore it is necessary to detect the disk tilt angle and compensate it. In this study, we measure the amount of the tilt error using external photo detector and compensate it by rotating the angle of galvano mirror with our own algorithm. 相似文献