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91.
Yuanbin Guo Jianzhong Zhang Dennis McCain Joseph R. Cavallaro 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2007,54(2):122-126
A reduced complexity MIMO Kalman equalizer architecture is proposed in this brief by jointly considering the displacement structure and the block-Toeplitz structure. Numerical matrix-matrix multiplications with O(F3) complexity are eliminated by simple data loading process, where F is the spreading factor. Finally, an iterative Conjugate-Gradient based algorithm is proposed to avoid the inverse of the Hermitian symmetric innovation covariance matrix in Kalman gain processor. The proposed architecture not only reduces the numerical complexity from O(F2) to O(Flog2F) per chip, but also facilitates the parallel and pipelined VLSI implementation in real-time processing 相似文献
92.
Birgit Kanngießer Andreas-Germanos Karydas Dimosthenis Sokaras Stefan Röhrs Joseph Salomon 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,264(2):383-388
The paper describes a novel experiment characterized by the development of a confocal geometry in an external Micro-PIXE set-up. The position of X-ray optics in front of the X-ray detector and its proper alignment with respect to the proton micro-beam focus provided the possibility of carrying out 3D Micro-PIXE analysis. As a first application, depth intensity profiles of the major elements that compose the patina layer of a quaternary bronze alloy were measured. A simulation approach of the 3D Micro-PIXE data deduced elemental concentration profiles in rather good agreement with corresponding results obtained by electron probe micro-analysis from a cross-sectioned patina sample. With its non-destructive and depth-resolving properties, as well as its feasibility in atmospheric pressure, 3D Micro-PIXE seems especially suited for investigations in the field of cultural heritage. 相似文献
93.
John S. Wright Joseph M. Schwartz Lanny D. Schmidt Lorraine Falter Francis 《Journal of the American Ceramic Society》1995,78(9):2360-2366
The crystalline phase development and microstructural changes with heating of sol-gel-derived lead titanate (PT) particles and films on silica with and without a fugitive (or removable) diffusion barrier layer were investigated. Amorphous gel-derived PT particles were deposited on SiO2 -coated TEM grids with and without polyimide (PI) or carbon barrier layers between SiO2 and PT. TEM analysis showed that PI or carbon barriers prevented reaction between the gel-derived PT particles and SiO2 . PT particles crystallize and then the PI or carbon film decomposes. Sol-gel-derived PT films were deposited on oxidized Si substrates (Si/SiO2 ) with and without a PI barrier layer. Perovskite PT films were prepared on Si/SiO2 substrates with a PI barrier; however, some porosity remained in the films. Identically prepared films without the PI barrier formed a mixture of pyrochlore and perovskite. X-ray photoelectron spectroscopy results indicate that the PI film pre- vents the diffusion of Si into the PT film. 相似文献
94.
This paper describes the application of Fault Tree Analysis to the design phase of a robot manipulator for hazardous waste retrieval. The robot is to be deployed in single-shell under-ground storage tanks at the US Department of Energy (DOE) site in Hanford, Washington. These tanks contain a variety of highly radioactive waste types, necessitating extremely safe and reliable manipulator operation. Based on preliminary design drawings of this long-reach manipulator, fault trees were constructed for several critical failure scenarios. Analysis of the trees revealed a number of ways to improve the safety and reliability of the manipulator design. This paper presents a summary of the fault tree analysis, with a discussion of the applicability of qualitative and quantitative fault tree methods to hazardous waste robotics. 相似文献
95.
This study investigated the effectiveness of different types of on-line feedback following user errors for informing users of the information and functions available in a system with a natural language interface. Twenty-four individuals performed a task based on an industry cost savings program, in which they were given general goals to pursue with regard to the task. Three feedback levels which differed according to the type and amount of feedback provided, along with two levels of system complexity, were examined. In addition, subjects performed the task again after one week to determine the effects of feedback on retention. Results indicated that the subjects in the second level of feedback generally performed better with respect to accessing system functions and information than those in the first level. Although there was some performance improvement from the second to third level, it was not significant. However, the third level of feedback did significantly improve the efficiency with which subjects used information to complete the task during the return condition. Overall, feedback did not affect the errors made, though at certain more limited stages of the tasks this effect was observed. 相似文献
96.
Constant boost control of the Z-source inverter to minimize current ripple and voltage stress 总被引:2,自引:0,他引:2
Miaosen Shen Jin Wang Joseph A. Fang Zheng Peng Tolbert L.M. Adams D.J. 《Industry Applications, IEEE Transactions on》2006,42(3):770-778
This paper proposes two constant boost-control methods for the Z-source inverter, which can obtain maximum voltage gain at any given modulation index without producing any low-frequency ripple that is related to the output frequency and minimize the voltage stress at the same time. Thus, the Z-network requirement will be independent of the output frequency and determined only by the switching frequency. The relationship of voltage gain to modulation index is analyzed in detail and verified by simulation and experiments. 相似文献
97.
Joseph Leu 《软件工程师》2006,(4):55-57
Silicon Valley is hom e to the m ostdynam ic industries in the C aliforniaeconom y .These industries —— thehigh-tech sector—— are driven by in-novation,and each new wave of inno-vation is usually led by cre ativeentrepreneurs starting new firm s.D uri… 相似文献
98.
Joseph J. Niemela 《Journal of Low Temperature Physics》1997,109(5-6):709-732
Liquid Helium II drops, of diameter 1 mm or less, are charged with positive helium ions and subsequently levitated by static
electric fields. Stable levitation was achieved for drops of order 100–150 micrometers in diameter. The suspended drops could
be translated to arbitrary positions within the levitator using additional superimposed DC electric fields, and also could
be made to oscillate stably about their average positions by means of an applied time-varying electric field. A weak corona
discharge was used to produce the necessary ions for levitation. A novel superfluid film flow device, developed for the controlled
deployment of large charged drops, is described. Also discussed is an adjustable electric fountain that requires only a field
emission tip operating at modest potentials, and works in both Helium I and Helium II. 相似文献
99.
Joseph W. Burley 《乙烯基与添加剂工艺杂志》1996,2(4):282-286
Both the European and USA markets for liquid mixed metal stabilizers have moved or are moving to cadmium-free products. Self-lubricating products now dominate demanding areas such as calendering and extrusion in the European marketplace while the USA market has produced higher efficiency products by other means. In both markets, the use of organic costabilizers has played a major role in the formulation of cadmium-free products. The merits of self-lubricating technology and a new class of patented pyrrolidines are discussed here. 相似文献
100.