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991.
Surface Reconstruction based on Lower Dimensional Localized Delaunay Triangulation 总被引:14,自引:0,他引:14
We present a fast, memory efficient algorithm that generates a manifold triangular mesh S passing through a set of unorganized points P R 3 . Nothing is assumed about the geometry, topology or presence of boundaries in the data set except that P is sampled from a real manifold surface. The speed of our algorithm is derived from a projection-based approach we use to determine the incident faces on a point. We define our sampling criteria to sample the surface and guarantee a topologically correct mesh after surface reconstruction for such a sampled surface. We also present a new algorithm to find the normal at a vertex, when the surface is sampled according our given criteria. We also present results of our surface reconstruction using our algorithm on unorganized point clouds of various models. 相似文献
992.
Klosowski J.T. Silva C.T. 《IEEE transactions on visualization and computer graphics》2001,7(4):365-379
We propose a novel conservative visibility culling technique based on the Prioritized-Layered Projection (PLP) algorithm. PLP is a time-critical rendering technique that computes, for a given viewpoint, a partially correct image by rendering only a subset of the geometric primitives, those that PLP determines to be most likely visible. Our new algorithm builds on PLP and provides an efficient way of finding the remaining visible primitives. We do this by adding a second phase to PLP which uses image-space techniques for determining the visibility status of the remaining geometry. Another contribution of our work is to show how to efficiently implement such image-space visibility queries using currently available OpenGL hardware and extensions. We report on the implementation of our techniques on several graphics architectures, analyze their complexity, and discuss a possible hardware extension that has the potential to further increase performance 相似文献
993.
Towards a Reference Model for Surveying Mobile Agent Systems 总被引:2,自引:1,他引:1
994.
Outdoor Visual Position Estimation for Planetary Rovers 总被引:2,自引:0,他引:2
This paper describes (1) a novel, effective algorithm for outdoor visual position estimation; (2) the implementation of this algorithm in the Viper system; and (3) the extensive tests that have demonstrated the superior accuracy and speed of the algorithm. The Viper system (Visual Position Estimator for Rovers) is geared towards robotic space missions, and the central purpose of the system is to increase the situational awareness of a rover operator by presenting accurate position estimates. The system has been extensively tested with terrestrial and lunar imagery, in terrains ranging from moderate—the rounded hills of Pittsburgh and the high deserts of Chile—to rugged—the dramatic relief of the Apollo 17 landing site—to extreme—the jagged peaks of the Rockies. Results have consistently demonstrated that the visual estimation algorithm estimates position with an accuracy and reliability that greatly surpass previous work. 相似文献
995.
996.
Juan Francisco Gómez-Lopera José Martínez-Aroza Aureliano M. Robles-Pérez Ramón Román-Roldán 《Journal of Mathematical Imaging and Vision》2000,13(1):35-56
This work constitutes a theoretical study of the edge-detection method by means of the Jensen-Shannon divergence, as proposed by the authors. The overall aim is to establish formally the suitability of the procedure of edge detection in digital images, as a step prior to segmentation. In specific, an analysis is made not only of the properties of the divergence used, but also of the method's sensitivity to the spatial variation, as well as the detection-error risk associated with the operating conditions due to the randomness of the spatial configuration of the pixels. Although the paper deals with the procedure based on the Jensen-Shannon divergence, some problems are also related to other methods based on local detection with a sliding window, and part of the study is focused to noisy and textured images. 相似文献
997.
J.L. Díaz De León S. J.H. Sossa-Azuela 《Journal of Mathematical Imaging and Vision》2000,12(2):137-154
Mathematical Morphology (MM) is a general method for image processing based on set theory. The two basic morphological operators are dilation and erosion. From these, several non linear filters have been developed usually with polynomial complexity, and this because the two basic operators depend strongly on the definition of the structural element. Most efforts to improve the algorithm's speed for each operator are based on structural element decomposition and/or efficient codification.A new framework and a theoretical basis toward the construction of fast morphological operators (of zero complexity) for an infinite (countable) family of regular metric spaces are presented in work. The framework is completely defined by the three axioms of metric. The theoretical basis here developed points out properties of some metric spaces and relationships between metric spaces in the same family, just in terms of the properties of the four basic metrics stated in this work. Concepts such as bounds, neighborhoods and contours are also related by the same framework.The presented results, are general in the sense that they cover the most commonly used metrics such as the chamfer, the city block and the chess board metrics. Generalizations and new results related with distances and distance transforms, which in turn are used to develop the morphologic operations in constant time, in contrast with the polynomial time algorithms are also given. 相似文献
998.
Koop D Scheidegger CE Callahan SP Freire J Silva CT 《IEEE transactions on visualization and computer graphics》2008,14(6):1691-1698
Building visualization and analysis pipelines is a large hurdle in the adoption of visualization and workflow systems by domain scientists. In this paper, we propose techniques to help users construct pipelines by consensus--automatically suggesting completions based on a database of previously created pipelines. In particular, we compute correspondences between existing pipeline subgraphs from the database, and use these to predict sets of likely pipeline additions to a given partial pipeline. By presenting these predictions in a carefully designed interface, users can create visualizations and other data products more efficiently because they can augment their normal work patterns with the suggested completions. We present an implementation of our technique in a publicly-available, open-source scientific workflow system and demonstrate efficiency gains in real-world situations. 相似文献
999.
José A. Macías 《World Wide Web》2008,11(2):253-286
Since its emergence in the early 1990s, the WWW has become not only an information system of unprecedented size, but a universal
platform for the development of services and applications. However, most of the advances in web technologies are intended
for professional developers, paying poor attention to end-users with no programming abilities but with explicit needs of creating
and customizing web-based presentations. This provides a strong motivation for end-users to act as designers at some point,
leading to an emerging role of new computing-related professionals to be considered. This paper is an effort to leverage such
difficulties by providing intelligent mechanism to assist end-users in web-based authoring tasks. To carry out such a challenge,
intelligent user-monitoring techniques are exploited to obtain high-level information that will be used to infer the user’s
preferences and assist him throughout the interaction. Furthermore, we report on how iteration patterns can be applied to avoid repetitive tasks that are automatically carried out on behalf of the user. In order to bring off
a feasible trade-off between expressivity and ease of use, a user experiment to obtain the user’s perception and evaluate
the hit-rate of our system is also presented. 相似文献
1000.
Erick Corrêa da Silva Aristófanes Corrêa Silva Anselmo Cardoso de Paiva Rodolfo Acatauassu Nunes 《Pattern Analysis & Applications》2008,11(1):89-99
This paper analyzes the application of Moran’s index and Geary’s coefficient to the characterization of lung nodules as malignant
or benign in computerized tomography images. The characterization method is based on a process that verifies which combination
of measures, from the proposed measures, has been best able to discriminate between the benign and malignant nodules using
stepwise discriminant analysis. Then, a linear discriminant analysis procedure was performed using the selected features to
evaluate the ability of these in predicting the classification for each nodule. In order to verify this application we also
describe tests that were carried out using a sample of 36 nodules: 29 benign and 7 malignant. A leave-one-out procedure was
used to provide a less biased estimate of the linear discriminator’s performance. The two analyzed functions and its combinations
have provided above 90% of accuracy and a value area under receiver operation characteristic (ROC) curve above 0.85, that
indicates a promising potential to be used as nodules signature measures. The preliminary results of this approach are very
encouraging in characterizing nodules using the two functions presented.
相似文献
Rodolfo Acatauassu NunesEmail: |