全文获取类型
收费全文 | 268169篇 |
免费 | 2032篇 |
国内免费 | 621篇 |
专业分类
电工技术 | 3731篇 |
综合类 | 3121篇 |
化学工业 | 40619篇 |
金属工艺 | 15162篇 |
机械仪表 | 9400篇 |
建筑科学 | 5762篇 |
矿业工程 | 2726篇 |
能源动力 | 4025篇 |
轻工业 | 13471篇 |
水利工程 | 4375篇 |
石油天然气 | 10046篇 |
武器工业 | 99篇 |
无线电 | 24629篇 |
一般工业技术 | 57671篇 |
冶金工业 | 31668篇 |
原子能技术 | 7839篇 |
自动化技术 | 36478篇 |
出版年
2021年 | 1925篇 |
2019年 | 1991篇 |
2018年 | 17650篇 |
2017年 | 16714篇 |
2016年 | 13650篇 |
2015年 | 2754篇 |
2014年 | 3699篇 |
2013年 | 7206篇 |
2012年 | 8007篇 |
2011年 | 15325篇 |
2010年 | 13122篇 |
2009年 | 10910篇 |
2008年 | 12123篇 |
2007年 | 13024篇 |
2006年 | 4677篇 |
2005年 | 5318篇 |
2004年 | 5102篇 |
2003年 | 5110篇 |
2002年 | 4589篇 |
2001年 | 4085篇 |
2000年 | 3817篇 |
1999年 | 3441篇 |
1998年 | 7166篇 |
1997年 | 5298篇 |
1996年 | 3986篇 |
1995年 | 3034篇 |
1994年 | 2697篇 |
1993年 | 2837篇 |
1992年 | 2382篇 |
1991年 | 2440篇 |
1990年 | 2532篇 |
1989年 | 2475篇 |
1988年 | 2461篇 |
1987年 | 2331篇 |
1986年 | 2376篇 |
1985年 | 2442篇 |
1984年 | 2360篇 |
1983年 | 2302篇 |
1982年 | 2142篇 |
1981年 | 2325篇 |
1980年 | 2208篇 |
1979年 | 2429篇 |
1978年 | 2636篇 |
1977年 | 2632篇 |
1976年 | 3297篇 |
1975年 | 2440篇 |
1974年 | 2539篇 |
1973年 | 2565篇 |
1972年 | 2364篇 |
1971年 | 2108篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Generation of self-oscillations under unstable stationary states of nonlinear control systems, which may contain delay of complicated nature (the Andronov–Hopf bifurcation), and approximate design of self-oscillating states and their asymptotes are studied with the help of pulse-frequency characteristics of the linear component of a system. 相似文献
103.
A. I. Ivaneshkin 《Cybernetics and Systems Analysis》1991,27(6):833-840
The paper considers integrated optimization of a single-server semi-Markov queue with input conflicts, controllable message size, and a finite buffer with different types of storage organization. The optimization is based on an additive performance criterion.Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 45–53, November–December, 1991. 相似文献
104.
105.
The paper briefly reviews the major forms of optical bistability in active optical devices compatible for use in gigabit optical communication systems, and reports an entirely new optical bistability for the first time. Unlike previous devices, the two bistable states of the optical device are each a series of picosecond optical pulses at 1 GHz or greater repetition rates, and are distinguished by a half period temporal shift between their temporal positions in relation to a clock pulse. The bistable device is based on a gain switched semiconductor laser. Theoretical studies suggest 100-ps switching speeds might be achieved, and experimental results are reported indicating optically triggered switching times of 500 ps. 相似文献
106.
107.
108.
O. A. Teplov I. G. Voropaev V. G. Dyubanov L. I. Leont’ev 《Russian Metallurgy (Metally)》2007,(4):268-275
The interaction of hydrogen with the zinc-containing electrometallurgical slime of the Severstal’ metallurgical works has been studied. The sequence of transformations in the slime heated to 1100°C in hydrogen or air has been established. The experimental and calculated weight losses coincide. Some of the carbonates are shown to decompose in the temperature range 300–700°C, and most iron and zinc oxides are reduced to a metal. In the temperature range 650–850°C, zinc is almost completely sublimated. At temperatures above 800°C, complex oxides are reduced and calcium and magnesium carbonates and sulfates are likely to decompose. Experimental digital data on the zinc sublimation rate are processed by the least squares method with approximating equations used in thermal analysis. The kinetics of nonisothermal zinc sublimation is comprehensively analyzed using a unique procedure developed for taking into account the background of a peak and the effect of accompanying processes. An equation for the calculation of the zinc sublimation rate under experimental conditions (fluidized bed) is given and tested. 相似文献
109.
V. A. Borodulya Yu. S. Teplitskii Yu. G. Epanov I. I. Markevich 《Journal of Engineering Physics and Thermophysics》1987,53(6):1393-1396
Experimental data was obtained on external heat transfer in infiltrated granular beds of coarse particles. It was determined that calcualtions with the proposed model agree satisfactorily with the experimental results.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 6, pp. 919–923, December, 1988. 相似文献
110.