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1.
2.
Micheli E.D. Torre V. Uras S. 《IEEE transactions on pattern analysis and machine intelligence》1993,15(5):434-447
The accuracy and the dependence on parameters of a general scheme for the analysis of time-varying image sequences are discussed. The approach is able to produce vector fields from which it is possible to recover 3-D motion parameters such as time-to-collision and angular velocity. The numerical stability of the computed optical flow and the dependence of the recovery of 3-D motion parameters on spatial and temporal filtering is investigated. By considering optical flows computed on subsampled images or along single scanlines, it is also possible to recover 3-D motion parameters from reduced optical flows. An adequate estimate of time-to-collision can be obtained from sequences of images with spatial resolution reduced to 128×128 pixels or from sequences of single scanlines passing near the focus of expansion. The use of Kalman filtering increases the accuracy and the robustness of the estimation of motion parameters. The proposed approach seems to be able to provide not only a theoretical background but also practical tools that are adequate for the analysis of time-varying image sequences 相似文献
3.
Summary A survey is given of known continuity properties of solution concepts for cooperative games. Further continuity properties are derived for the bargaining set, the kernel, the equal division core, the least core, the least tax core, the-value and also for the core of non sidepayment games.
Zusammenfassung Die Arbeit gibt einen Überblick übebekannte Kontinuitätseigenschaften von Lösungsansätzen für kooperative Spiele. Weiter Kontinuitätseigenschaften werden abgeleitet für die Aushandlungsmenge, den Kernel, den Kern gleicher Aufteilungen, den kleinsten Kern, den kleinsten tax-Kern, den-Wert und den Kern von Spielen ohne Seitenzahlungen.相似文献
4.
Jose Gonzalez-Mora Fernando De la Torre Nicolas Guil Emilio L. Zapata 《Image and vision computing》2010
Over the last decade 3D face models have been extensively used in many applications such as face recognition, facial animation and facial expression analysis. 3D Morphable Models (MMs) have become a popular tool to build and fit 3D face models to images. Critical to the success of MMs is the ability to build a generic 3D face model. Major limitations in the MMs building process are: (1) collecting 3D data usually involves the use of expensive laser scans and complex capture setups, (2) the number of available 3D databases is limited, and typically there is a lack of expression variability and (3) finding correspondences and registering the 3D model is a labor intensive and error prone process. 相似文献
5.
Face recognition using Histograms of Oriented Gradients 总被引:2,自引:0,他引:2
6.
Although lexicographic (lex) variants of greedy algorithms are often P -complete, NC -algorithms are known for the following lex-search problems: lexicographic depth-first search (lex-dfs) for dags [12], [17], lexicographic breadth-first search (lex-bfs) for digraphs [12], [17], and lexicographic topological-first search (lex-tfs) for dags [12]. For the all-sources version of the problem for dense digraphs, the lex-dfs (lex-bfs, lex-tfs) in
[12] is (within a log factor of) work-optimal with respect to the all-sources sequential solution that performs a dfs (bfs,
tfs) from every vertex. By contrast, to solve the single-source lexicographic version on inputs of size n , all known NC -algorithms perform work that is at least an n factor away from the work performed by their sequential counterparts.
We present parallel algorithms that solve the single-source version of these lex-search problems in O(log
2
n) time using M(n) processors on the EREW PRAM. (M(n) denotes the number of processors required to multiply two n\times n integer matrices in O(log n) time and has O(n
2.376
) as tightest currently known bound.) They all offer a polynomial improvement in work-efficiency over that of their corresponding
best previously known and close the gap between the requirements of the best known parallel algorithms for the lex and the
nonlex versions of the problems.
Key to the efficiency of these algorithms is the novel idea of a lex-splitting tree and lex-conquer subgraphs of a dag G from source s . These structures provide a divide-and-conquer skeleton from which NC -algorithms for several lexicographic search problems emerge, in particular, an algorithm that places in the class NC the lex-dfs for reducible flow graphs—an interesting class of graphs which arise naturally in connection with code optimization and data flow analysis [4], [19].
A notable aspect of these algorithms is that they solve the lex-search problem instance at hand by efficiently transforming
solutions of appropriate instances of (nonlex) path problems. This renders them potentially capable of transferring significant
algorithmic advances—such as Driscoll et al.'s [14] single-source shortest paths algorithm and Ullman and Yannakakis' [34]
transitive closure algorithm—from fundamental (nonlex) path problems to lex-search problems.
Received January 9, 1994, and in revised form November 1997. Online publication July 20, 2001. 相似文献
7.
Farhad Shir Catherine Mavriplis Lawrence H. Bennett Edward Della Torre 《International Journal of Refrigeration》2005,28(4):1082
Results of a room temperature magnetic refrigeration test bed and an analysis using a computational model are presented. A detailed demonstration of the four sequential processes in the transient magnetocaloric regeneration process of a magnetic material is presented. The temperature profile during the transient approach to steady state operation was measured in detail. A 5 °C evolution of the difference of temperature between the hot end and the cold end of the magnetocaloric bed due to regeneration is reported. A model is developed for the heat transfer and fluid mechanics of the four sequential processes in each cycle of thermal wave propagation in the regenerative bed combined with the magnetocaloric effect. The basic equations that can be used in simulation of magnetic refrigeration systems are derived and the design parameters are discussed. 相似文献
8.
9.
A simple top-down fabrication technique that involves scanning probe lithography on Si is presented. The writing procedure consists of a chemically selective patterning in mesitylene. Operating in an organic media is possible to perform local oxidation or solvent decomposition during the same pass by tuning the applied bias. The layer deposited with a positively biased tip with sub-100-nm lateral resolution consists of nanocrystalline graphite, as verified by Raman spectroscopy. The oxide pattern obtained in opposite polarization is later used as a mask for dry etching, showing a remarkable selectivity in SF6 plasma, to produce Si nanofeatured molds. 相似文献
10.
Nitrogen adsorption isotherms at 77.7 K, over graphites with different surface homogeneity, are analyzed. Three of the samples exhibited the transition from a fluid to a bidimensional solid before the monolayer was completed. The apparent bidimensional critical temperature, deduced from the Hillde Boer equation (applied to experimental isotherms), is proposed as a criterion for surface homogeneity. The calculated values range from 61 K for the most homogeneous surface to 36 K for the less homogeneous one. The estimated degrees of homogeneity are in agreement with previous experimental evidence and the surface characteristics of these samples. 相似文献