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991.
L. H. Yang Randolph Q. Hood J. E. Pask J. E. Klepeis 《Journal of Computer-Aided Materials Design》2007,14(3):337-347
High-Z metals constitute a particular challenge for large-scale ab initio electronic-structure calculations, as they require high resolution due to the presence of strongly localized states and require
many eigenstates to be computed due to the large number of electrons and need to accurately resolve the Fermi surface. Here,
we report recent findings on high-Z metals, using an efficient massively parallel planewave implementation on some of the largest computational architectures
currently available. We discuss the particular architectures employed and methodological advances required to harness them
effectively. We present a pair-correlation function for U, calculated using quantum molecular dynamics, and discuss relaxations
of Pu atoms in the vicinity of defects in aged and alloyed Pu. We find that the self-irradiation associated with aging has
a negligible effect on the compressibility of Pu relative to other factors such as alloying.
The US Goverment’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
992.
L. Renaud F. Fouquet J. P. Millet H. Mazitle J. L. Crolet 《Materials and Manufacturing Processes》1991,6(2):315-330
It is possible to realize surface alloys by laser melting an electroless nickel layer containing chromium carbide particles predeposited on a mild steel substrate. By this way the surface alloy is expected to have not only a high nickel content but also an important chromium content in order to improve the corrosion resistance. The presence of chromium in solid solution results from the dissolution or melting of the carbide particles. Typical laser solidification microstructures are obtained. Dendrites consist of an austenitic Fe-Ni-Cr solid solution and interdendritic regions are constituted by an eutectic mixture containing the same austenitic solid solution and complex Fe, Ni, Cr carbides and phosphides. In comparison with a surface alloy obtained by laser melting of an electroless nickel layer without carbide particles, the corrosion resistance was slightly improved in saline aqueous solutions. The limited effect was due to the fact that the final chromium content in the present experimental conditions was not as high as that initially expected. 相似文献
993.
A novel soft-switching full-bridge DC/DC converter: analysis,design considerations, and experimental results at 1.5 kW, 100 kHz 总被引:1,自引:0,他引:1
The addition of an external commutating inductor and two clamp diodes to the phase-shifted PWM (pulsewidth modulated) full-bridge DC/DC converter substantially reduces the switching losses of the transistors and the rectifier diodes, under all loading conditions. The authors give analyses, practical design considerations, and experimental results for a 1.5 kW converter with 60 V, 25 A output, operating at 100 kHz clock frequency and 95% efficiency 相似文献
994.
995.
L. Bonci M. Gattobigio G. Iannaccone M. Macucci 《Journal of Computational Electronics》2002,1(1-2):49-53
We present a Monte Carlo simulation of two implementations of Quantum Cellular Automaton (QCA) circuits: one based on simple ground state relaxation and the other on the clocked cell scheme that has recently been proposed by Tóth and Lent. We focus on the time-dependent behavior of two basic circuits, a binary wire and a majority voting gate, and assess their maximum operating speed and temperature requirements for different sets of fabrication parameters. 相似文献
996.
S. R. Syrtsov V. N. Shut D. A. Il'yushchenko E. L. Gavrilenko 《Journal of Engineering Physics and Thermophysics》2002,75(5):1229-1233
The influence of the parameters of posistor elements and the conditions of their heat exchange on the electrical and dynamic characteristics of a posistor block have been investigated. Good agreement between calculation results and experimental data has been established. 相似文献
997.
998.
Bedload Transport in Alluvial Channels 总被引:1,自引:0,他引:1
Miguel Bravo-Espinosa W. R. Osterkamp Vicente L. Lopes 《Canadian Metallurgical Quarterly》2003,129(10):783-795
Hydraulic, sediment, land-use, and rock-erosivity data of 22 alluvial streams were used to evaluate conditions of bedload transport and the performance of selected bedload-transport equations. Transport categories of transport-limited (TL), partially transport-limited (PTL), and supply-limited (SL) were identified by a semiquantitative approach that considers hydraulic constraints on sediment movement and the processes that control sediment availability at the basin scale. Equations by Parker et al. in 1982, Schoklitsch in 1962, and Meyer-Peter and Muller in 1948 adequately predicted sediment transport in channels with TL condition, whereas the equations of Bagnold in 1980, and Schoklitsch, in 1962, performed well for PTL and SL conditions. Overall, the equation of Schoklitsch predicted well the measured bedload data for eight of 22 streams, and the Bagnold equation predicted the measured data in seven streams. 相似文献
999.
Mechanisms in damping of mechanical vibration by piezoelectric ceramic-polymer composite materials 总被引:5,自引:0,他引:5
The piezoelectric ceramic (piezoceramic) component of a polymer-piezoelectric ceramic composite converts mechanical energy
into electrical energy and this electrical energy is dissipated as heat in a load resistance, R
x, simulated by a shunted resistance, but provided in practice by a conductive polymer composite matrix. The composite therefore
dissipates the input mechanical energy via the damping mechanism provided by piezoelectric ceramic-conductive matrix material,
as well as the conventional viscoelastic damping provided by the polymer. Mathematical models have been developed to characterize
the damping behaviour of the composites, and the maximum damping ratio of composites can be as high as 23%. A two degrees-of-freedom
(2DOF) experimental setup was developed to test the validity of the models. The experimental results are in good agreement
with the theoretical predictions. 相似文献
1000.
The cellular neural network (CNN) architecture combines the best features from traditional fully-connected analog neural networks and digital cellular automata. The network can rapidly process continuous-valued (gray-scale) input signals (such as images) and perform many computation functions which traditionally were implemented in digital form. Here, we briefly introduce the the theory of CNN circuits, provide some examples of CNN applications to image processing, and discuss work toward a CNN implementation in custom CMOS VLSI. The role of analog computer-aided design (CAD) will be briefly presented as it relates to analog neural network implementation.This work is supported in part by the Office of Naval Research under Contract N00014-89-J1402, and the National Science Foundation under grant MIP-8912639. 相似文献