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991.
Julia Clemente Jaime Ramírez Angélica de Antonio 《Expert systems with applications》2011,38(7):8066-8078
The advances in the educational field and the high complexity of student modeling have provoked it to be one of the aspects more investigated in Intelligent Tutoring Systems (ITSs). The Student Models (SMs) should not only represent the student’s knowledge, but rather they should reflect, as faithfully as possible, the student’s reasoning process. To facilitate this goal, in this article a new approach to student modeling is proposed that benefits from the advantages of Ontological Engineering, advancing in the pursue of a more granular and complete knowledge representation. It’s focused, mainly, on the SM cognitive diagnosis process, and we present a method providing a rich diagnosis about the student’s knowledge state – especially, about the state of learning objectives reached or not. The main goal is to achieve SMs with a good adaptability to the student’s features and a high flexibility for its integration in varied ITSs. 相似文献
992.
993.
Tommaso Mansi Xavier Pennec Maxime Sermesant Hervé Delingette Nicholas Ayache 《International Journal of Computer Vision》2011,92(1):92-111
Tracking soft tissues in medical images using non-linear image registration algorithms requires methods that are fast and
provide spatial transformations consistent with the biological characteristics of the tissues. LogDemons algorithm is a fast
non-linear registration method that computes diffeomorphic transformations parameterised by stationary velocity fields. Although
computationally efficient, its use for tissue tracking has been limited because of its ad-hoc Gaussian regularisation, which hampers the implementation of more biologically motivated regularisations. In this work, we
improve the logDemons by integrating elasticity and incompressibility for soft-tissue tracking. To that end, a mathematical
justification of demons Gaussian regularisation is proposed. Building on this result, we replace the Gaussian smoothing by
an efficient elastic-like regulariser based on isotropic differential quadratic forms of vector fields. The registration energy
functional is finally minimised under the divergence-free constraint to get incompressible deformations. As the elastic regulariser
and the constraint are linear, the method remains computationally tractable and easy to implement. Tests on synthetic incompressible
deformations showed that our approach outperforms the original logDemons in terms of elastic incompressible deformation recovery
without reducing the image matching accuracy. As an application, we applied the proposed algorithm to estimate 3D myocardium
strain on clinical cine MRI of two adult patients. Results showed that incompressibility constraint improves the cardiac motion
recovery when compared to the ground truth provided by 3D tagged MRI. 相似文献
994.
We address the self-calibration of a smooth generic central camera from only two dense rotational flows produced by rotations
of the camera about two unknown linearly independent axes passing through the camera centre. We give a closed-form theoretical
solution to this problem, and we prove that it can be solved exactly up to a linear orthogonal transformation ambiguity. Using
the theoretical results, we propose an algorithm for the self-calibration of a generic central camera from two rotational
flows. 相似文献
995.
Pablo Cascón Andrés Ortiz Julio Ortega Antonio F. Díaz Ignacio Rojas 《The Journal of supercomputing》2011,58(3):302-313
Hosts with several, possibly heterogeneous and/or multicore, processors provide new challenges and opportunities to accelerate
applications with high communications bandwidth requirements. Many opportunities to scale these network applications with the increase in the link bandwidths are related to the exploitation of the available parallelism provided by the presence
of several processing cores in the servers, not only for computing the workload of the user application but also for decreasing
the overhead associated to the network interface and the system software. 相似文献
996.
Francisco Almeida Domingo Giménez Jose J. López-Espín 《The Journal of supercomputing》2011,58(3):292-301
This paper presents a parameterized shared-memory scheme for parameterized metaheuristics. The use of a parameterized metaheuristic
facilitates experimentation with different metaheuristics and hybridation/combinations to adapt them to the particular problem
we are working with. Due to the large number of experiments necessary for the metaheuristic selection and tuning, parallelism
should be used to reduce the execution time. To obtain parallel versions of the metaheuristics and to adapt them to the characteristics
of the parallel system, a unified parameterized shared-memory scheme is developed. Given a particular computational system
and fixed parameters for the sequential metaheuristic, the appropriate selection of parameters in the unified parallel scheme
eases the development of parallel efficient metaheuristics. 相似文献
997.
This paper reexamines the construction of indicators of standards of living, by focussing on the challenges raised by the
subjectivity and the multidimensionality of living conditions. For that purpose, we apply Choquet integral-based multiattribute
value theory to the elicitation, from rankings of multiattribute hypothetical societies, of individual preferences on different
dimensions of living conditions. A simple application of the proposed approach highlights that preferences on multiattribute
societies cannot, in general, be represented by an additive value model, as there exist complementarities and redundancies
between different dimensions of standards of living. Our elicitation exercise reveals also a strong heterogeneity of individual
preferences on hypothetical societies. Finally, we explore how elicited preferences can be used to cast a new light on the
ranking of actual societies. 相似文献
998.
The paper deals with the problem of motion planning of anthropomorphic mechanical hands avoiding collisions and trying to
mimic real human hand postures. The approach uses the concept of “principal motion directions” to reduce the dimension of
the search space in order to obtain results with a compromise between motion optimality and planning complexity (time). Basically,
the work includes the following phases: capturing the human hand workspace using a sensorized glove and mapping it to the
mechanical hand workspace, reducing the space dimension by looking for the most relevant principal motion directions, and
planning the hand movements using a probabilistic roadmap planner. The approach has been implemented for a four finger anthropomorphic
mechanical hand (17 joints with 13 independent degrees of freedom) assembled on an industrial robot (6 independent degrees
of freedom), and experimental examples are included to illustrate its validity. 相似文献
999.
Daniel Ruiz Vicente Berenguer Antonio Soriano Belén Sánchez 《Expert systems with applications》2011,38(12):15217-15223
Melanoma is the most deathful of all skin cancers and the number of cases grows every year. The extirpation in early phases implies a high degree of survival so it is fundamental to diagnose it as soon as possible. In this paper we present a clinical decision support system for melanoma diagnosis using as input an image set of the skin lesion to be diagnosed. The system analyses the image sequence to extract the affected area, determinates the characteristics which indicate the degree of damage and, according to them, it makes a decision. Several methods of classification are proposed: a multilayered perceptron, a Bayesian classifier and the algorithm of the K nearest neighbours. These methods work independently and also in combination making a collaborative decision support system. The classification rates obtained are around 87%. 相似文献
1000.
I. Werbrouck M. Antrop V. Van Eetvelde C. Stal Ph. De Maeyer M. Bats J. Bourgeois M. Court-Picon Ph. Crombé J. De Reu Ph. De Smedt P.A. Finke M. Van Meirvenne J. Verniers A. Zwertvaegher 《Expert systems with applications》2011,38(7):8178-8185
This paper discusses the generation of a high precision DEM (Digital Elevation Model) based on high density airborne LiDAR (Light Detection and Ranging) data for an interdisciplinary landscape archaeological study concerning the settlement history and environment in Sandy Flanders, a region to the north of Ghent (Belgium). The objective was to create a detailed topographical surface free of artificial features and topographical artefacts, in the form of a DEM, visualizing the natural and current topography through the implementation of true ground points only. The semi-automatical removal of these features and artefacts was based on topographical vector data, visual interpretations and slope analysis. Ultimately two DEM’s were constructed (1) a TIN (Triangulated Irregular Network) model, whereby the inherent large file format restricts the usability to large scale and (2) a grid model which can be used for small-, medium- and large-scale applications. Both datasets were used as an image that is interpreted using ancillary data from historical sources. Its usefulness is illustrated in a case of field pattern and microfield topography. Starting from this DEM, the approach of this landscape historical study is mainly retrogressive, i.e. starting from the landscape structures and elements that are still present in the contemporary landscape and moving into the past. 相似文献