全文获取类型
收费全文 | 471073篇 |
免费 | 6215篇 |
国内免费 | 1368篇 |
专业分类
电工技术 | 8198篇 |
综合类 | 319篇 |
化学工业 | 73741篇 |
金属工艺 | 19196篇 |
机械仪表 | 14722篇 |
建筑科学 | 11339篇 |
矿业工程 | 2860篇 |
能源动力 | 11915篇 |
轻工业 | 41387篇 |
水利工程 | 5109篇 |
石油天然气 | 10043篇 |
武器工业 | 20篇 |
无线电 | 53380篇 |
一般工业技术 | 93423篇 |
冶金工业 | 84080篇 |
原子能技术 | 11287篇 |
自动化技术 | 37637篇 |
出版年
2021年 | 4091篇 |
2019年 | 3763篇 |
2018年 | 6444篇 |
2017年 | 6471篇 |
2016年 | 6935篇 |
2015年 | 4568篇 |
2014年 | 7662篇 |
2013年 | 20944篇 |
2012年 | 12328篇 |
2011年 | 16673篇 |
2010年 | 13360篇 |
2009年 | 15139篇 |
2008年 | 15301篇 |
2007年 | 14970篇 |
2006年 | 13091篇 |
2005年 | 12131篇 |
2004年 | 11436篇 |
2003年 | 11089篇 |
2002年 | 10866篇 |
2001年 | 10682篇 |
2000年 | 10258篇 |
1999年 | 10500篇 |
1998年 | 24848篇 |
1997年 | 18130篇 |
1996年 | 14253篇 |
1995年 | 10608篇 |
1994年 | 9623篇 |
1993年 | 9316篇 |
1992年 | 7191篇 |
1991年 | 7030篇 |
1990年 | 6689篇 |
1989年 | 6767篇 |
1988年 | 6590篇 |
1987年 | 5598篇 |
1986年 | 5539篇 |
1985年 | 6398篇 |
1984年 | 6035篇 |
1983年 | 5534篇 |
1982年 | 5102篇 |
1981年 | 5311篇 |
1980年 | 5053篇 |
1979年 | 5041篇 |
1978年 | 5115篇 |
1977年 | 5874篇 |
1976年 | 7658篇 |
1975年 | 4607篇 |
1974年 | 4389篇 |
1973年 | 4413篇 |
1972年 | 3781篇 |
1971年 | 3475篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
101.
G. A. Zeinalova A. E. Mushailov A. Kh. Mamedova É. A. Nagieva 《Chemistry and Technology of Fuels and Oils》1989,25(2):78-80
Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 14–15, February, 1989. 相似文献
102.
Dr. G. Pönisch 《Computing》1987,39(1):1-17
A direct method is described for computing a hysteresis point (double turning point) corresponding to a cusp point of a system ofn nonlinear equations inn variables depending on two parameters. By addition of two equations a minimally extended system ofn+2 nonlinear equations is constructed for which the hysteresis point is an isolated solution. An efficient implementation of Newton's method is presented not requiring evaluations of second derivatives of the original problem. Two numerical examples show the efficiency of theQ-quadratically convergent method. 相似文献
103.
104.
Consideration was given to the decision making procedures based on the fuzzy messages of experts whose preferences on the set of collective decisions can also be fuzzy. 相似文献
105.
I. N. Polandov V. K. Novik O. K. Gulish B. P. Bogomolov V. B. Morozov 《Measurement Techniques》1989,32(9):888-890
Translated from Izmeritel'naya Tekhnika, No. 9, pp. 34–35, September, 1989. 相似文献
106.
Flame structure and NO emission characteristics in counterflow diffusion flame of blended fuel of H2/CO2/Ar have been numerically simulated with detailed chemistry. The combination of H2, CO2 and Ar as fuel is selected to clearly display the contribution of hydrocarbon products to flame structure and NO emission characteristics due to the breakdown of CO2. A radiative heat loss term is involved to correctly describe the flame dynamics especially at low strain rates. The detailed chemistry adopts the reaction mechanism of GRI 2.11, which consists of 49 species and 279 elementary reactions. All mechanisms including thermal, NO2, N2O and Fenimore are taken into account to separately evaluate the effects of CO2 addition on NO emission characteristics. The increase of added CO2 quantity causes flame temperature to fall since at high strain rates a diluent effect is prevailing and at low strain rates the breakdown of CO2 produces relatively populous hydrocarbon products and thus the existence of hydrocarbon products inhibits chain branching. It is also found that the contribution of NO production by N2O and NO2 mechanisms are negligible and that thermal mechanism is concentrated on only the reaction zone. As strain rate and CO2 quantity increase, NO production is remarkably augmented. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
107.
108.
Fuzzy logic was first suggested as the mechanism by which humans drive cars. This paper addresses the use of fuzzy logic and algorithms towards the intelligent autonomous motion control of land vehicles. To cope with vehicle complexities, internal parametric changes, and with unpredictable environmental effects, the controllers that are presented, whilst heuristic in nature, are self-organizing or self-learning in that they generate automatically by observation an experiential rule base that models the vehicle, and via an appropriate performance index an optimal control rule base that is robust to large parametric changes. The methodology presented is applicable to any complex process which is too difficult to model or control using conventional methods, or which has relied on the experience of a human operator. An overview of fuzzy logic and static fuzzy logic control (akin to expert systems) is provided, together with illustrative examples. 相似文献
109.
Translated from Atomnaya Énergiya, Vol. 67, No. 2, pp. 97–100, August, 1989. 相似文献
110.