全文获取类型
收费全文 | 437410篇 |
免费 | 6185篇 |
国内免费 | 2319篇 |
专业分类
电工技术 | 8466篇 |
技术理论 | 5篇 |
综合类 | 1293篇 |
化学工业 | 68690篇 |
金属工艺 | 19383篇 |
机械仪表 | 13645篇 |
建筑科学 | 10151篇 |
矿业工程 | 3534篇 |
能源动力 | 9821篇 |
轻工业 | 36366篇 |
水利工程 | 5311篇 |
石油天然气 | 11957篇 |
武器工业 | 262篇 |
无线电 | 46514篇 |
一般工业技术 | 87626篇 |
冶金工业 | 78153篇 |
原子能技术 | 10840篇 |
自动化技术 | 33897篇 |
出版年
2021年 | 4232篇 |
2019年 | 3839篇 |
2018年 | 6478篇 |
2017年 | 6468篇 |
2016年 | 7013篇 |
2015年 | 4727篇 |
2014年 | 7763篇 |
2013年 | 19020篇 |
2012年 | 12459篇 |
2011年 | 16311篇 |
2010年 | 13074篇 |
2009年 | 14216篇 |
2008年 | 15110篇 |
2007年 | 15114篇 |
2006年 | 13192篇 |
2005年 | 11796篇 |
2004年 | 10665篇 |
2003年 | 10139篇 |
2002年 | 10005篇 |
2001年 | 10165篇 |
2000年 | 9482篇 |
1999年 | 9529篇 |
1998年 | 22188篇 |
1997年 | 16016篇 |
1996年 | 12268篇 |
1995年 | 9282篇 |
1994年 | 8300篇 |
1993年 | 8399篇 |
1992年 | 6498篇 |
1991年 | 6251篇 |
1990年 | 6262篇 |
1989年 | 6165篇 |
1988年 | 5869篇 |
1987年 | 5111篇 |
1986年 | 5174篇 |
1985年 | 5803篇 |
1984年 | 5563篇 |
1983年 | 5191篇 |
1982年 | 4669篇 |
1981年 | 4784篇 |
1980年 | 4582篇 |
1979年 | 4764篇 |
1978年 | 4692篇 |
1977年 | 4920篇 |
1976年 | 6183篇 |
1975年 | 4239篇 |
1974年 | 3945篇 |
1973年 | 4121篇 |
1972年 | 3567篇 |
1971年 | 3182篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
This article describes a test piece that minimizes the spread of the results of testing of composite materials on a metal base by extension in the direction of a reinforcing fiber and, from the results, determines the mechanical properties of intermediate and finished products made of these materials.Translated from Izmeritel'naya Tekhnika, No. 10, pp. 39–40, October, 1993. 相似文献
993.
W Matthiessen N Sch?nfeld H Mauch U Wahn A Grassot 《Canadian Metallurgical Quarterly》1993,118(5):139-144
The chest radiograph of a 35-year-old man with fatigue, exertional dyspnoea and haemoptyses revealed a cavity in the left upper lobe and a shrunken left lung with radiolucency greater than that on the right. Acid-fast rods in sputum were identified as Mycobacterium kansasii on culture. Scintigraphy showed a 9% residual perfusion on the left and abnormal ventilation, compatible with Swyer-James syndrome. This had favoured the development of a mycobacterial infection. There was also a decrease in ciliary function (rate of 4-7 Hz, normal: 10-11). Treatment, begun when tuberculosis had been suspected, was after sensitivity tests changed to a combination of rifampicin (600 mg), ethambutol (1600 mg) and protionamide (500 mg) daily. There was marked regression of the findings within 4 weeks, but treatment was prematurely stopped after 11 months. Two years later there was a recurrence which again responded well to the same drug regimen with additional sulphamethoxazole (1600 mg/d). 相似文献
994.
S. N. Syromyatnikov 《Journal of Engineering Physics and Thermophysics》1993,65(2):745-751
Nonlinear spherical vapor bubble oscillations in the main resonance region in a viscous incompressible fluid under the action of a periodically varying external pressure are considered using the multiscale method. Saddle-node type bifurcations that appear when the amplitude or frequency of the external effect changes are investigated.Institute of Thermal Physics of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 2, pp. 164–170, August, 1993. 相似文献
995.
In this paper a micromechanics model using the concentric cylinder assemblage model and the Mori-Tanaka average stress scheme is used to predict the static strength of unidirectional angle ply laminates. The predicted strengths agree with experimental results for Glass/Epoxy and Graphite/Epoxy systems. 相似文献
996.
An improved code density test for flash A/D converters is proposed, revealing some dynamic phenomena (e.g., missing codes) hidden by the conventional approach. Formulas are reported for obtaining, from code density, effective noise estimates fully consistent with those provided by waveform analysis. Finally, it is shown that the variance of noise estimates obtained by time-domain analysis may be unacceptably large if the observation window is not properly chosen 相似文献
997.
998.
N. A. Samoilov 《Chemical and Petroleum Engineering》2002,38(7-8):437-443
999.
Formulation of the problem of designing the optimal structure of an active system was considered within the framework of the game-theoretical model of interaction of its participants. Solution and the results of studying the control mechanisms in applications such as in-house management and multiagent systems were presented. 相似文献
1000.
Malyshev S.A. Galwas B.A. Piotrowski J. Chizh A.L. Szczepaniak Z.R. 《Microwave and Wireless Components Letters, IEEE》2002,12(6):201-203
A photovaractor for the remote optical control of microwave circuits was studied. The photovaractor was fabricated as a p-i-n photodiode placed in a pigtailed fiber optical module. The study of the impedance in the frequency range up to 3 GHz in darkness and under illumination has shown that the photovaractor capacitance strongly depends on the incident optical power. The capacitance variation of the photovaractor diode under illumination is discussed 相似文献