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151.
After the liberalization of the Japanese telecommunications market in 1985, the market went through a first phase of competition, which focused on domestic telephony services, in both the long distance (domestic and international) and mobile segments. However, the growth of the Internet and the full digitalization of NTT's telecommunications network are ushering in a digital era and a second phase of competition. This article describes the current Japanese telecommunications market and the direction it is taking by referring to key statistical indicators 相似文献
152.
M. S. Han S. R. Hahn H. C. Kwon Y. Bin T. W. Kang J. H. Leem Y. B. Hou H. C. Jeon J. K. Hyun Y. T. Jeoung H. K. Kim J. M. Kim T. W. Kim 《Journal of Electronic Materials》1998,27(6):680-683
Double-crystal x-ray rocking curve (DCRC) and secondary-ion mass-spectroscopy (SIMS) measurements have been performed to investigate the effect of rapid thermal annealing on the interdiffusion behavior of Hg in HgTe/CdTe superlattices grown on Cd0.96Zn0.04Te (211)B substrates by molecular beam epitaxy. The sharp satellite peaks of the DCRC measurements on a 100-period HgTe/CdTe (100Å/100Å) superlattice show a periodic arrangement of the superlattice with high-quality interfaces. The negative direction of the entropy change obtained from the diffusion coefficients as a function of the reciprocal of the temperature after RTA indicates that the Hg diffusion for the annealed HgTe/CdTe superlattice is caused by an interstitial mechanism. The Cd and the Hg concentration profiles near the annealed HgTe/CdTe superlattice interfaces, as measured by SIMS, show a nonlinear behavior for Hg, originating from the interstitial diffusion mechanism of the Hg composition. These results indicate that a nonlinear interdiffusion behavior is dominant for HgTe/CdTe superlattices annealed at 190°C and that the rectangular shape of HgTe/CdTe superlattices may change to a parabolic shape because of the intermixing of Hg and Cd due to the thermal treatment. 相似文献
153.
The spherical-multipole analysis of scalar scattering by an acoustically soft or hard elliptic cone, and of electromagnetic scattering by a perfectly conducting elliptic cone, are presented. The series expansions of the exact solutions are of poor convergence, if both source and field points are far from the cone's tip. A mathematical transformation for the acceleration of convergence-due to Euler-is applied to these expansions, to numerically determine the scattering cross sections of these objects. This powerful method can also be used for the numerical evaluation of diffraction coefficients. The paper contains a review of scientific work concerning scattering by objects with edges, corners, tips, etc 相似文献
154.
A technique for SiO2 formation by liquid-phase deposition (LPD) at nearly room temperature for low-temperature processed (LTP) polysilicon thin-film transistor (poly-Si TFT) was developed. LPD SiO2 film with a lower P-etch rate shows a dense structure. LPD SiO2 also exhibits good electrical characteristics. LTP poly-Si thin-film transistors (TFTs) with LPD SiO 2 as the gate insulator have been fabricated and investigated. Their characteristics indicate performance adequate for their use as pixel transistors in liquid crystal displays (LCDs) 相似文献
155.
156.
Arithmetic coding for data compression 总被引:17,自引:0,他引:17
Howard P.G. Vitter J.S. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1994,82(6):857-865
Arithmetic coding provides an effective mechanism for removing redundancy in the encoding of data. We show how arithmetic coding works and describe an efficient implementation that uses table lookup as a first alternative to arithmetic operations. The reduced-precision arithmetic has a provably negligible effect on the amount of compression achieved. We can speed up the implementation further by use of parallel processing. We discuss the role of probability models and how they provide probability information to the arithmetic coder. We conclude with perspectives on the comparative advantages and disadvantages of arithmetic coding 相似文献
157.
This research extends previous work with dynamic models to manage groundwater quality by using the consumptive nitrate use rate instead of the nitrate application rate. The analysis indicates that misspecification results in overestimation of economic benefits, and supra-optimum nitrogen fertilizer application rates and groundwater nitrate stocks at a steady state. 相似文献
158.
To model effectively the output waveform and propagation delay of a CMOS gate, knowledge of the time point at which it starts to conduct is essential. An efficient method for calculating analytically this time point taking into account the structure of the gate and the input waveform, is introduced. Such a method can easily be integrated into a timing analysis system 相似文献
159.
P Sallagoity F Gaillard M Rivoire M Paoli M Haond S McClathie 《Microelectronics Reliability》1998,38(2):700
This paper presents Shallow Trench Isolation (STI) process steps for sub-1/4 μ CMOS technologies. Dummy active areas, vertical trench sidewalls, excellent gap filling, counter mask etch step and CMP end point detection, have been used for a 0.18 μm CMOS technology. Electrical results obtained with a 5.5 nm gate oxide thickness show good isolation down to 0.3 μm spacing. Good transistor performances have been demonstrated. 相似文献
160.
S. Arimoto T. Nakayama 《Mechatronics, IEEE/ASME Transactions on》1996,1(2):168-180
Dynamics and control of nonlinear mechanical systems and advanced mechatronic systems can be investigated more vividly and efficiently by using corresponding nonlinear position-dependent circuits that describe Lagrange's equations of motions and interactions with objects or/and task environments. Such expressions of Lagrange's equations via nonlinear circuits are indebted to lumped-parameter discretization of mechanical systems as a set of rigid bodies through equations of motion due to Newton's second law. This observation is quite analogous to validity of electric circuits that can be derived as lumped parameter versions of Maxwell's equations of electromagnetic waves. Couplings of nonlinear mechanical circuits with electrical circuits through actuator dynamics are also discussed. In such electromechanical circuits the passivity should be a generalization of impedance concept in order to cope with general nonlinear position-dependent circuits and play a crucial role in their related motion control problems. In particular, it is shown that the passivity as an input-output property gives rise to a necessary and sufficient characterization of H/sub /spl infin//-tuning for disturbance attenuation of robotic systems, which can give another system theoretic interpretation of the energy conservation law. 相似文献