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排序方式: 共有674条查询结果,搜索用时 15 毫秒
11.
A surface active pyrrole, which has a long hydrophobic chain attached to the 3 position of the pyrrole ring, is used to modify the surface properties of the pores of a porous, crosslinked polystyrene. The latter is prepared starting from a concentrated emulsion (an emulsion with a large volume fraction of the dispersed phase, here 0.81) of water dispersed in a continuous medium composed of styrene, divinyl benzene, a suitable surfactant, an initiator, and the surface active pyrrole. This modified crosslinked porous medium is emplyed as the host for a polypyrrole composite that is prepared first by imbibing the host with a solution of pyrrole and subsequently with an oxidant solution. The latter plays the role of catalyst for polymerization as well as the role of dopant. The presence of the head groups of 3-alkyl pyrrole molecules on the surface of the pores of the host polymer increases the affinity of the surface for pyrrole. The improved wetting thus achieved for the pyrrole solution ensures a higher connectivity among the pyrrole films present on the internal surface of the host polymer and increases the conductivity of the polypyrrole composites by a factor of 2 to 14, depending upon the solvents employed for pyrrole and oxidant. 相似文献
12.
Flaxer E 《Ultramicroscopy》2008,108(12):1536-1539
In order to protect the sample and the tip against current transients in a scanning tunneling microscope, which in most cases damages the scanned surface and the tip, when using a bias higher than 1V, we have designed a simple and low-cost circuit that limits the tunneling current. During the evolution of the current transient, when the current exceeds a pre-determined value, a fast feedback control mechanism immediately reduces the bias and prevents the current transient from developing. In addition, we designed a fast pre-amplifier that works with this controller. We have shown that this mechanism provides a better scanning image compared to a system without such a mechanism. 相似文献
13.
14.
Defect‐Laden MoSe2 Quantum Dots Made by Turbulent Shear Mixing as Enhanced Electrocatalysts
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Chongyang Zhu Yuan Huang Feng Xu Peng Gao Binghui Ge Jing Chen Haibo Zeng Eli Sutter Peter Sutter Litao Sun 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(27)
A high density of edge sites and other defects can significantly improve the catalytic activity of layered 2D materials. Herein, this study demonstrates a novel top‐down strategy to maximize catalytic edge sites of MoSe2 by breaking up bulk MoSe2 into quantum dots (QDs) via “turbulent shear mixing” (TSM). The ultrasmall size of the MoSe2 QDs provides a high fraction of atoms in reactive edge sites, thus significantly improving the catalytic activities. The violent TSM further introduces abundant defects as additional active sites for electrocatalytic reactions. These edge‐proliferated and defect‐laden MoSe2 QDs are found to be efficient electrocatalysts for the hydrogen evolution reaction, and useful as counter electrodes in dye‐sensitized solar cells. The work provides a new paradigm for creating edge‐proliferated and defect‐rich QDs from bulk layered materials. 相似文献
15.
16.
Yehuda Afek Eli Gafni Sergio Rajsbaum Michel Raynal Corentin Travers 《Distributed Computing》2010,22(3):185-195
This paper introduces and investigates the k-simultaneous consensus task: each process participates at the same time in k independent consensus instances until it decides in any one of them. It is shown that the k-simultaneous consensus task is equivalent to the k-set agreement task in the wait-free read/write shared memory model, and furthermore k-simultaneous consensus possesses properties that k-set does not. In particular we show that the multivalued version and the binary version of the k-simultaneous consensus task are wait-free equivalent. These equivalences are independent of the number of processes. Interestingly, this provides us with a new characterization of the k-set agreement task that is based on the fundamental binary consensus problem. 相似文献
17.
Li‐Qian Ma Jue Wang Eli Shechtman Kalyan Sunkavalli Shi‐Min Hu 《Computer Graphics Forum》2016,35(7):189-197
Shadow removal is a challenging problem and previous approaches often produce de‐shadowed regions that are visually inconsistent with the rest of the image. We propose an automatic shadow region harmonization approach that makes the appearance of a de‐shadowed region (produced using any previous technique) compatible with the rest of the image. We use a shadow‐guided patch‐based image synthesis approach that reconstructs the shadow region using patches sampled from non‐shadowed regions. This result is then refined based on the reconstruction confidence to handle unique textures. Qualitative comparisons over a wide range of images, and a quantitative evaluation on a benchmark dataset show that our technique significantly improves upon the state‐of‐the‐art. 相似文献
18.
In their recent paper “Do Accelerating Turing Machines Compute the Uncomputable?” Copeland and Shagrir (Minds Mach 21:221–239, 2011) draw a distinction between a purist conception of Turing machines, according to which these machines are purely abstract, and Turing machine realism according to which Turing machines are spatio-temporal and causal “notional" machines. In the present response to that paper we concede the realistic aspects of Turing’s own presentation of his machines, pointed out by Copeland and Shagrir, but argue that Turing's treatment of symbols in the course of that presentation opens the door for later purist conceptions. Also, we argue that a purist conception of Turing machines (as well as other computational models) plays an important role not only in the analysis of the computational properties of Turing machines, but also in the philosophical debates over the nature of their realization. 相似文献
19.
Eli Rohn 《Knowledge and Information Systems》2011,28(1):175-196
The move toward automatic data integration from autonomous and heterogeneous sources is viewed as a transition from a closed
to an open system, which is in essence an adaptive information processing system. Data definition languages from various computing
eras spanning almost 50 years to date are examined, assessing if they have moved from closed systems to open systems paradigm.
The study proves that contemporary data definition languages are indistinguishable from older ones using measurements of Variety,
Tension and Entropy, three characteristics of complex adaptive systems (CAS). The conclusion is that even contemporary data
definition languages designed for such integration exhibit closed systems characteristics along with open systems aspirations
only. Plenty of good will is insufficient to make them more suitable for automatic data integration than their oldest predecessors.
A previous report and these new findings set the stage for the development and proposal of a mathematically sound data definition
language based on CAS, thus potentially making it better suited for automatic data integration from autonomous heterogeneous
sources. 相似文献
20.
Spoken dialogue systems (SDSs) can be used to operate devices, e.g. in the automotive environment. People using these systems usually have different levels of experience. However, most systems do not take this into account. In this paper, we present a method to build a dialogue system in an automotive environment that automatically adapts to the user’s experience with the system. We implemented the adaptation in a prototype and carried out exhaustive tests. Our usability tests show that adaptation increases both user performance and user satisfaction. We describe the tests that were performed, and the methods used to assess the test results. One of these methods is a modification of PARADISE, a framework for evaluating the performance of SDSs [Walker MA, Litman DJ, Kamm CA, Abella A (Comput Speech Lang 12(3):317–347, 1998)]. We discuss its drawbacks for the evaluation of SDSs like ours, the modifications we have carried out, and the test results.
相似文献
Eli HagenEmail: |