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61.
Dae-Son Kim Hyun-Young Oh Hong-Yeop Song 《Communications Letters, IEEE》2008,12(3):203-205
In parallel-architecture turbo codes, the constituent interleavers must avoid memory collision. This paper proposes a collision-free interleaver structure composed of a Latin square (LS) and pre-designed interleavers. Our proposed interleavers can be easily optimized for various information block sizes and for various degrees of parallelism. Their performances were evaluated by computer simulation. 相似文献
62.
ZnO thin film was deposited on various metal electrodes by reactive sputtering, and c-axis preferred orientation of the film has been studied. ZnO, which has high piezoelectricity, is promising for oscillators or filter devices such as surface acoustic wave (SAW) device, gas sensor, and film bulk acoustic resonator (FBAR). But, for the application of ZnO film for these devices, the film should be grown with c-axis normal to the electrode. In this study, Pt, Al, and Au were deposited on Si wafer, and the surface roughness and crystal structure of the ZnO film on the electrode were investigated using AFM, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Columnar structures of ZnO films were grown with c-axis normal to all electrodes, and among them Pt electrode showed the highest preferred orientation of ZnO film. 相似文献
63.
Sun-Jung Kim Pyeong-Seok Cho Jong-Heun Lee Chong-Yun Kang Jin-Sang Kim Seok-Jin Yoon 《Ceramics International》2008,34(4):827-831
Various compositions of gas sensing films were prepared by the combinatorial deposition of SnO2, ZnO, and WO3 sol solutions and their gas sensing behaviors were investigated. The film composition could be manipulated conveniently via the alternate dropping of different oxide sol solutions. From the correlation between film compositions and gas sensitivities, the selective detection of C2H5OH and CH3COCH3 in the presence of CO, C3H8, H2, and NO2 could be attained. In addition, the discrimination between C2H5OH and CH3COCH3, which is a challenging issue due to their similar chemical nature, becomes possible. This research demonstrates the precise design of the sensor-material composition for the selective gas detection via the combinatorial approach. 相似文献
64.
Seung-Jean Kim In-Joong Ha 《Automatic Control, IEEE Transactions on》2004,49(7):1167-1171
In this note, we consider the existence of a Carathe/spl acute/odory solution in a single-input-single-output nonlinear system with a discontinuous switching feedback controller. The main contribution is to show that if the nonlinear system can be transformed into a global normal form, then we can specify the value of the discontinuous switching feedback controller on the switching hypersurface so that the closed-loop system has a Carathe/spl acute/odory solution. 相似文献
65.
The notion of knowledge-based economy premises that technological knowledge be created, accumulated and disseminated through
the interactive learning among principal actors in the national system. This paper analyzes, from a dynamic perspective, the
structure of inter-industrial technological knowledge. Both human-driven disembodied channel and capital-driven embodied channel
are investigated based on network analysis. The set of empirical data covers the Korean manufacturing sector during the 1980s.
Overall, density of network tends to be increasing over time, implying that knowledge network becomes expanded and intensified.
A number of distinctive features are identified between knowledge types and industrial categories. The findings in turn render
important policy implications that should be addressed when developing technology policy. Clearly, the policy framework needs
to be industry-specific and country-specific in accordance with the development stage and industrial structure of reference
time.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
66.
In developing an intelligent mobile construction robot, a navigation system that can provide an effective and efficient path-planning algorithm is a very important element. The purpose of a path-planning method for a mobile construction robot is to find a continuous collision-free path from the initial position of the construction robot to its target position. This paper presents an improved Bug-based algorithm, called SensBug, which can produce an effective path in an unknown environment with both stationary and movable obstacles. The contributions, which make it possible to generate an effective and short path, are an improved method to select local directions, a reverse mode, and a simple leaving condition. Some emerging technologies that can be used for implementing an intelligent construction robot are introduced in this paper. 相似文献
67.
Myung-Sun Baek Hyung-Joon Kook Mi-Jeong Kim Young-Hwan You Hyoung-Kyu Song 《Broadcasting, IEEE Transactions on》2005,51(4):551-559
In this paper, we apply multi-antenna scheme to DAB system for high-rate transmission. In the MIMO-DAB system with a number of transmitting and receiving antennas increases the transmission rate efficiently with low multiplication operations. For channel estimation in the MIMO-DAB system, we propose a new PRS structure and evaluate the channel estimation performance. The proposed PRS structure can estimate multi-channel information based on the semi-blind processing. The performance of proposed PRS is compared with that of conventional training sequence employing Tarokh's transmission matrix. And also we investigate the performance limitation due to the imperfect channel estimation in a MIMO-DAB receiver. It has been shown that the MIMO-DAB system with multi-antennas can achieve the high-rate transmission for multimedia broadcasting and the performance of MIMO-DAB system is impaired by imperfect channel information. 相似文献
68.
This paper studies a Kansas Department of Transportation welded plate girder bridge that developed fatigue cracks at small web gaps close to the girder top flange. Repair had been previously performed by softening the connection plate end with a slot retrofit, but cracks were recently found to have reinitiated at some of the repaired details and are again propagating. A comprehensive finite-element method study was performed to investigate the cracking behavior observed in the bridge and to recommend appropriate measures for future bridge retrofit. The analytical results show that stresses developed at the top flange web gaps could exceed yielding under the loading of an HS15 fatigue truck. The current slot repair used in the bridge was found to have introduced higher magnitude fatigue stresses in the web gap. To achieve a permanent repair of the bridge, it is recommended that a welded connection plate to flange attachment be used during future bridge retrofit. The web gap details should be able to withstand unlimited number of load cycles once this additional repair is performed. 相似文献
69.
The ability to utilize fully automated flexible manufacturing systems (FMS) or develop reliable computer-integrated manufacturing (CIM) systems will depend on our ability to develop reliable and reusable software for large complex systems on a timely basis. To date, software design has not gone very far beyond the ad hoc trial-and-error stage. Consequently, the development of software is slow, expensive, unreliable, and unmanageable. The purpose of this paper is to provide a scientific basis for designing software. The approach used here is that of axiomatic design, which is based on two design axioms: the Independence Axiom and the Information Axiom. The axiomatic approach is based on the recognition of the following common elements in design: the existence of independent domains (i.e. the consumer domain, the functional domain, the physical domain, and the process domain); the need to map between various domains during the design process; the decomposition of the characteristic vectors (i.e. functional requirements, design parameters, and process variables) in their respective domains; the zig-zagging required between the domains for decomposition; and the need to satisfy the design axioms during the design process. The axiomatic approach discussed in this paper provides decision making tools for software design in addition to systematic means of knowledge and data representation, synthesis and analysis of software, and the construction of the module-junction structure diagram. 相似文献
70.
Nucleation of solidification in liquid droplets 总被引:2,自引:0,他引:2
Analytical and numerical methods have been developed to analyze the solidification kinetics of a mass of liquid droplets dispersed
in a fluid or solid matrix using classical nucleation theory. The resulting analytical expressions and numerical calculations
can be compared directly with calorimetric measurements of the droplet solidification exotherms to obtain information about
the nucleation mechanism. With increasing contact angle at the solid-liquid-matrix triple point, the solidification onset,
peak, and end temperatures and exothermic peak height all decrease sharply and the droplet solidification exotherms become
broader. Decreasing either the droplet radius or the number of potential catalytic nucleation sites produces a similar but
smaller effect. Distributions in droplet radius, contact angle, and nucleation sites have no effect on the solidification
peak temperature, but the droplet solidification exotherms become broader and more symmetric. The solidification onset temperature
is independent of cooling rate in the calorimeter, but the solidification peak and end temperatures decrease and the exothermic
peak height increases with increasing cooling rate. Predicted droplet solidification exotherms are in excellent agreement
with detailed experimental measurements on 10-nm-radius Cd droplets embedded in a solid Al matrix. Analytical predictions
give best-fit values of 43 deg and 430 for the contact angle and the number of potential catalytic nucleation sites per droplet,
respectively; numerical predictions give best-fit values of 43 deg and 750 for the contact angle and the number of potential
catalytic nucleation sites per droplet, respectively. 相似文献