全文获取类型
收费全文 | 702406篇 |
免费 | 17908篇 |
国内免费 | 7065篇 |
专业分类
电工技术 | 18598篇 |
技术理论 | 9篇 |
综合类 | 9169篇 |
化学工业 | 112354篇 |
金属工艺 | 30982篇 |
机械仪表 | 26818篇 |
建筑科学 | 22013篇 |
矿业工程 | 7834篇 |
能源动力 | 17879篇 |
轻工业 | 54972篇 |
水利工程 | 9621篇 |
石油天然气 | 22233篇 |
武器工业 | 1084篇 |
无线电 | 75269篇 |
一般工业技术 | 134891篇 |
冶金工业 | 102830篇 |
原子能技术 | 17228篇 |
自动化技术 | 63595篇 |
出版年
2022年 | 8040篇 |
2021年 | 11206篇 |
2020年 | 8296篇 |
2019年 | 8785篇 |
2018年 | 13269篇 |
2017年 | 13876篇 |
2016年 | 13797篇 |
2015年 | 11136篇 |
2014年 | 16636篇 |
2013年 | 33747篇 |
2012年 | 24222篇 |
2011年 | 30073篇 |
2010年 | 24624篇 |
2009年 | 26250篇 |
2008年 | 26429篇 |
2007年 | 25628篇 |
2006年 | 22878篇 |
2005年 | 20364篇 |
2004年 | 18151篇 |
2003年 | 17817篇 |
2002年 | 17455篇 |
2001年 | 16651篇 |
2000年 | 15507篇 |
1999年 | 14942篇 |
1998年 | 29899篇 |
1997年 | 21863篇 |
1996年 | 17277篇 |
1995年 | 13498篇 |
1994年 | 12056篇 |
1993年 | 11552篇 |
1992年 | 9194篇 |
1991年 | 8805篇 |
1990年 | 8609篇 |
1989年 | 8332篇 |
1988年 | 7968篇 |
1987年 | 7181篇 |
1986年 | 6889篇 |
1985年 | 7705篇 |
1984年 | 6995篇 |
1983年 | 6698篇 |
1982年 | 6067篇 |
1981年 | 6188篇 |
1980年 | 5903篇 |
1979年 | 6045篇 |
1978年 | 5993篇 |
1977年 | 6478篇 |
1976年 | 8016篇 |
1975年 | 5426篇 |
1974年 | 5202篇 |
1973年 | 5291篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 95–112, March–April, 1994. 相似文献
73.
74.
A. G. Strunina 《Journal of Engineering Physics and Thermophysics》1993,65(4):953-956
The process of combustion of homogeneous and heterogeneous nongasifying and slightly gasifying systems over the range of a number of parameters characterizing the reactive composition and the conditions for the arrangement of the combustion process is studied by using thermocouple and optical methods. The regions of the implementation of different combustion regimes, namely, steady, pulsating, multiple-point, and spin, are determined experimentally.Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 4, pp. 407–411, October, 1993. 相似文献
75.
An extended logistic model with a varying asymptotic upper bound for long-range peak demand forecasting is described. The model has been applied to a typical fast growing system, the Saudi Consolidated Electric Company. The forecasts are compared with actual demands and with those obtained from classical forecasting methods. The model gave relatively accurate peak demand forecasts compared with other classical methods. The model with a single load observation is capable of producing several peak demand forecasts corresponding to different levels of maximum temperature and various levels of social activity. The forecasts produced by the model were also stable irrespective of the length of the ex-post simulation period 相似文献
76.
Furst C. Leitenstorfer A. Laubereau A. 《IEEE journal of selected topics in quantum electronics》1996,2(3):473-479
An experimental and theoretical analysis of the nonlinear coupling mechanism between the two solitary pulses circulating in a two-color femtosecond laser is presented. Two operation regimes; synchronized; and nonsynchronized; and a hysteresis of the transition between the two regimes are clearly observed; while independent modelocking and tunability of the output pulse trains is found in both regimes. Pulses in the range from 15 to 100 fs are synchronized with a timing jitter below 2 fs. The combined effects of cross-phase modulation and negative group velocity dispersion are shown to be responsible for the strong pulse correlation in the synchronized regime. Our experimental observations are in agreement with numerical simulations, thus confirming the theoretical model 相似文献
77.
78.
79.
A systematic and straightforward procedure is developed for the synthesis and analysis of transformer-isolated power converters. The procedure can be used to determine the ranges of duty-ratio over which the transformer-isolated power converters of a given class can be operated without transformer saturation. The procedure can also be used to study the dependence of the power converter switch stresses on duty-ratios. This information is useful in the selection of the transformer-isolated power converter most suitable for a given application and in the design of this power converter with minimum switch stresses, high power density, and low cost 相似文献
80.
Carboxyl-terminated butadiene-acrylonitrile-rubber decreases modulus and yield stress of the studied epoxy but increases fracture toughness. The addition of glass bead compensates for the loss in modulus but has little effect on yield stress. However, it significantly contributes to the fracture toughness by providing additional mechanisms for toughening of both the unmodified and rubber-modified epoxy. For the toughened epoxies studied, fracture surfaces gave only limited information on fracture mechanisms since significant energy absorption also occurs in the material below the fracture surface. Suggestions for suitable material compositions for fiber composite matrices are given. 相似文献