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991.
We investigate families of finite initial segments of standard models for various arithmetics. We give an axiomatization of the theory of sentences true in almost all finite models with addition. We also characterize its complete extensions and relate its infinite models to models of Presburger arithmetic.We also estimate the complexity of complete extensions of the arithmetic with addition and multiplication. 相似文献
992.
We compare the fixed parameter complexity of various variants of coloring problems (including List Coloring, Precoloring Extension, Equitable Coloring, L(p,1)-Labeling and Channel Assignment) when parameterized by treewidth and by vertex cover number. In most (but not all) cases we conclude that parametrization by the vertex cover number provides a significant drop in the complexity of the problems. 相似文献
993.
994.
Lei?ChenEmail author Hung?Keng?Pung 《Annals of Mathematics and Artificial Intelligence》2008,52(1):67-80
Recently, a convex incremental algorithm (CI-ELM) has been proposed in Huang and Chen (Neurocomputing 70:3056–3062, 2007), which randomly chooses hidden neurons and then analytically determines the output weights connecting with the hidden layer
and the output layer. Though hidden neurons are generated randomly, the network constructed by CI-ELM is still based on the
principle of universal approximation. The random approximation theory breaks through the limitation of most conventional theories,
eliminating the need for tuning hidden neurons. However, due to the random characteristic, some of the neurons contribute
little to decrease the residual error, which eventually increase the complexity and computation of neural networks. Thus,
CI-ELM cannot precisely give out its convergence rate. Based on Lee’s results (Lee et al., IEEE Trans Inf Theory 42(6):2118–2132,
1996), we first show the convergence rate of a maximum CI-ELM, and then systematically analyze the convergence rate of an enhanced
CI-ELM. Different from CI-ELM, the hidden neurons of the two algorithms are chosen by following the maximum or optimality
principle under the same structure as CI-ELM. Further, the proof process also demonstrates that our algorithms achieve smaller
residual errors than CI-ELM. Since the proposed neural networks remove these “useless” neurons, they improve the efficiency
of neural networks. The experimental results on benchmark regression problems will support our conclusions.
The work is under the funding of Singapore MOE AcRF Tier 1 grant WBS No: R 252-000-221-112. 相似文献
995.
Agostinho de Medeiros Brito Junior Adri?o Duarte Dória Neto Jorge Dantas de Melo Luiz Marcos Garcia Goncalves 《Neural Networks, IEEE Transactions on》2008,19(6):1130-1140
In this paper, we propose a multiresolution approach for surface reconstruction from clouds of unorganized points representing an object surface in 3-D space. The proposed method uses a set of mesh operators and simple rules for selective mesh refinement, with a strategy based on Kohonen's self-organizing map (SOM). Basically, a self-adaptive scheme is used for iteratively moving vertices of an initial simple mesh in the direction of the set of points, ideally the object boundary. Successive refinement and motion of vertices are applied leading to a more detailed surface, in a multiresolution, iterative scheme. Reconstruction was experimented on with several point sets, including different shapes and sizes. Results show generated meshes very close to object final shapes. We include measures of performance and discuss robustness. 相似文献
996.
Abstract. This paper abstracts and generalizes the known approaches for proving lower bounds on the size of various variants of oblivious
branching programs (oblivious BPs for short), providing an easy-to-use technique which works for all nondeterministic and
randomized modes of acceptance. The technique is applied to obtain the following results concerning the power of nondeterminism
and randomness for oblivious BPs:
<p>— Oblivious read-once BPs, better known as OBDDs (ordered binary decision diagrams), are used in many applications and
their structure is well understood in the deterministic case. It has been open so far to compare the power of nondeterministic
OBDDs with so-called partitioned BDDs which are a variant of nondeterministic branching programs also used in practice. A
k -partitioned BDD has a nondeterministic node at the top by which one out of k deterministic OBDDs with possibly different variable orders is chosen. It is proven here that the two models are incomparable
as long as k is bounded by a logarithmic function in the input length. <p>— It is shown that deterministic oblivious read-k -times BPs for an explicitly defined function require superpolynomial size, for k logarithmic in the input length, while there are Las Vegas oblivious read-twice BPs of linear size for this function. This
is in contrast to the situation for OBDDs, for which the respective size measures are polynomially related. <p>— Furthermore,
an explicitly defined function is presented for which randomized oblivious read-k -times BPs with bounded error require exponential size, while the function as well as its complement can be represented in
polynomial size by nondeterministic oblivious read-k -times BPs and deterministic oblivious read-(k+1) -times BPs, where k=o(log n) . 相似文献
997.
998.
Detection and Tracking of Multiple,Partially Occluded Humans by Bayesian Combination of Edgelet based Part Detectors 总被引:6,自引:1,他引:5
Detection and tracking of humans in video streams is important for many applications. We present an approach to automatically
detect and track multiple, possibly partially occluded humans in a walking or standing pose from a single camera, which may
be stationary or moving. A human body is represented as an assembly of body parts. Part detectors are learned by boosting
a number of weak classifiers which are based on edgelet features. Responses of part detectors are combined to form a joint likelihood model that includes an analysis of possible
occlusions. The combined detection responses and the part detection responses provide the observations used for tracking.
Trajectory initialization and termination are both automatic and rely on the confidences computed from the detection responses.
An object is tracked by data association and meanshift methods. Our system can track humans with both inter-object and scene
occlusions with static or non-static backgrounds. Evaluation results on a number of images and videos and comparisons with
some previous methods are given.
Electronic Supplementary Material Supplementary material is available in the online version of this article at 相似文献
999.
The TGarden is a genre of responsive environment in which actor–spectators shape dense media sensitive to their movements. These dense fields of light, sound, and material also evolve according to their own composed dynamics, so the agency is distributed throughout the multiple media. These TGardens explore open-ended questions like the following: what makes some time-based, responsive environments compelling, and others flat? How can people improvise gestures without words, that are individually or collectively meaningful? When and how is a movement intentional, or collectively intentional? This paper introduces what has been at stake behind the experimental work: subjectivation, moving from technologies of representation to technologies of performance, and the potential for ethico-aesthetic novelty. 相似文献
1000.