全文获取类型
收费全文 | 350474篇 |
免费 | 1360篇 |
国内免费 | 666篇 |
专业分类
化学 | 132618篇 |
晶体学 | 4192篇 |
力学 | 20929篇 |
综合类 | 7篇 |
数学 | 70262篇 |
物理学 | 96996篇 |
无线电 | 27496篇 |
出版年
2020年 | 2065篇 |
2019年 | 2584篇 |
2018年 | 20869篇 |
2017年 | 21150篇 |
2016年 | 13665篇 |
2015年 | 3379篇 |
2014年 | 4318篇 |
2013年 | 7923篇 |
2012年 | 12873篇 |
2011年 | 27012篇 |
2010年 | 17752篇 |
2009年 | 18105篇 |
2008年 | 21840篇 |
2007年 | 26989篇 |
2006年 | 6631篇 |
2005年 | 12564篇 |
2004年 | 9777篇 |
2003年 | 9994篇 |
2002年 | 7336篇 |
2001年 | 5873篇 |
2000年 | 4822篇 |
1999年 | 3482篇 |
1998年 | 3269篇 |
1997年 | 3027篇 |
1996年 | 2893篇 |
1995年 | 2546篇 |
1994年 | 2483篇 |
1993年 | 2493篇 |
1992年 | 2443篇 |
1991年 | 2756篇 |
1990年 | 2732篇 |
1989年 | 2770篇 |
1988年 | 2651篇 |
1987年 | 2577篇 |
1986年 | 2411篇 |
1985年 | 2938篇 |
1984年 | 2942篇 |
1983年 | 2563篇 |
1982年 | 2575篇 |
1981年 | 2480篇 |
1980年 | 2275篇 |
1979年 | 2597篇 |
1978年 | 2745篇 |
1977年 | 2737篇 |
1976年 | 2863篇 |
1975年 | 2658篇 |
1974年 | 2572篇 |
1973年 | 2789篇 |
1972年 | 2241篇 |
1971年 | 2037篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Tereshchenko E. D. Cherniakov S. M. Yurik R. Yu. Rietveld M. T. Häggström I. 《Radiophysics and Quantum Electronics》2020,62(10):667-676
Radiophysics and Quantum Electronics - We present the results of comparing the total electron content measurements based on GLONASS satellite signals and the EISCAT UHF incoherent scatter radar... 相似文献
142.
143.
144.
Radiophysics and Quantum Electronics - We consider whether it is possible in principle to retrieve the key parameters of the mixed layer in the upper ocean (its thickness, bulk eddy viscosity and... 相似文献
145.
Siberian Mathematical Journal - Under study are the right-symmetric algebras over a field $ F $ which possess a “unital” matrix subalgebra $... 相似文献
146.
147.
V. A. Babenko V. V. Grigor’yants I. P. Shilov 《Journal of Communications Technology and Electronics》2006,51(6):618-630
Basic definitions related to the main electrodynamic characteristics of surface space-charge waves are formulated. These characteristics and their relationships with the geometric dimensions of guiding structures (a dielectric cylinder and a planar metal-dielectric waveguide) are determined. 相似文献
148.
Stievano I.S. Maio I.A. Canavero F.G. Siviero C. 《Advanced Packaging, IEEE Transactions on》2006,29(1):31-38
This paper addresses the impact of device macromodels on the accuracy of signal integrity and performance predictions for critical digital interconnecting systems. It exploits nonlinear parametric models for both single-ended and differential devices, including the effects of power supply fluctuations and receiver bit detection. The analysis demonstrates that the use of well-designed macromodels dramatically speeds up the simulation as well it preserves timing accuracy even for long bit sequences. 相似文献
149.
Yang Aiying Wang Ziyu Zhang Zhaoyi Chen Zhangyuan Wu Deming 《电子科学学刊(英文版)》2003,20(6):461-466
A 10Gbit/s recirculating system is configured with Chirped Fiber Bragg Grating (CFBG) for the dispersion compensation. For the first time, the transmission distance in the loop reaches 1000km with bit error rate of 10-9. The effect of the group delay ripple of the fiber grating is also investigated in the recirculating systems, and it is shown that the transmission distance is limited to 4 cycles (4×167.1km ) in the loop with the power penalty fluctuation below 1.0dB. Thus the group delay ripple should be reduced to allow for the wavelength drift of±5GHz. At the end of this letter, the principles are given for designing long haul recirculating systems with dispersion compensation CFBG. 相似文献
150.
V. G. Deibuk 《Semiconductors》2003,37(10):1151-1155
The miscibility gaps and the critical temperatures of spinodal decomposition of ternary semiconducting Ga-In-Sb, Ga-In-P, and In-As-Sb systems are calculated by taking into account the deformation energy and the effect of plastic relaxation caused by the misfit dislocations. It is shown that taking into consideration elastic energy narrows the ranges of spinodal decomposition and lowers its critical temperature. The introduction of the phenomenological parameter into Matthews-Blakeslee formula makes it possible to reach a satisfactory agreement between theoretically calculated values of critical thickness of epitaxial films and the experimental data. 相似文献