全文获取类型
收费全文 | 291520篇 |
免费 | 4698篇 |
国内免费 | 906篇 |
专业分类
电工技术 | 5074篇 |
综合类 | 221篇 |
化学工业 | 43128篇 |
金属工艺 | 10189篇 |
机械仪表 | 8263篇 |
建筑科学 | 7275篇 |
矿业工程 | 952篇 |
能源动力 | 7982篇 |
轻工业 | 26159篇 |
水利工程 | 2554篇 |
石油天然气 | 3380篇 |
武器工业 | 19篇 |
无线电 | 36477篇 |
一般工业技术 | 56814篇 |
冶金工业 | 58312篇 |
原子能技术 | 5252篇 |
自动化技术 | 25073篇 |
出版年
2022年 | 1752篇 |
2021年 | 3008篇 |
2020年 | 2270篇 |
2019年 | 2572篇 |
2018年 | 4725篇 |
2017年 | 4756篇 |
2016年 | 4912篇 |
2015年 | 3281篇 |
2014年 | 5301篇 |
2013年 | 14083篇 |
2012年 | 8509篇 |
2011年 | 10659篇 |
2010年 | 8545篇 |
2009年 | 9346篇 |
2008年 | 10128篇 |
2007年 | 9800篇 |
2006年 | 8486篇 |
2005年 | 7435篇 |
2004年 | 7155篇 |
2003年 | 7327篇 |
2002年 | 6725篇 |
2001年 | 6946篇 |
2000年 | 6405篇 |
1999年 | 6949篇 |
1998年 | 19586篇 |
1997年 | 13267篇 |
1996年 | 10006篇 |
1995年 | 7312篇 |
1994年 | 6513篇 |
1993年 | 6443篇 |
1992年 | 4328篇 |
1991年 | 4229篇 |
1990年 | 4065篇 |
1989年 | 3849篇 |
1988年 | 3736篇 |
1987年 | 3179篇 |
1986年 | 3110篇 |
1985年 | 3409篇 |
1984年 | 3099篇 |
1983年 | 2952篇 |
1982年 | 2787篇 |
1981年 | 2703篇 |
1980年 | 2602篇 |
1979年 | 2422篇 |
1978年 | 2215篇 |
1977年 | 2792篇 |
1976年 | 3949篇 |
1975年 | 1848篇 |
1974年 | 1794篇 |
1973年 | 1732篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
We recorded the highest age at the time of death for both men and women in Norway for the years 1970 to 1995. During this period longevity increased by approximately one year; for women from 106 to 107 years and for men from 105 to 106 years. Based on Gumbel's theory, we have estimated the most probable highest age for the next 10, 20, and 100 years. For women this was found to be 109, 110 and 113 years, respectively; for men the corresponding ages were 108, 109 and 112 years. Our aim must be that as many men and women as possible live to a high age, that their latter years are meaningful, and that they enjoy a high standard of living. 相似文献
993.
We compared the performance of patients with frontal excisions, patients with temporal excisions and controls in tasks involving speeded choice responses in which a number of variables were manipulated including: perceptual difficulty, stimulus and response set-size, associative complexity, and spatial stimulus-response compatibility. Response times were sensitive to all manipulations but did not show any group differences. The error rates of the three groups were equally affected by perceptual difficulty and response set-size but frontals were preferentially affected by spatial S-R compatibility, associative complexity, and the number of stimuli per response. The results are consistent with a basic deficit in response selection processes which could underly many problems produced by frontal lesions. 相似文献
994.
The 1,3-specific lipase-catalyzed interesterified fats were distinguished from chemically catalyzed products by the fatty
acids in the 2-position. The fatty acid contents in the 2-position of the 1,3-lipase-catalyzed and the original triglycerides
were similar but different from that of chemically interesterified fat. Also, the saturated-to-unsaturated fatty acid ratio
in the 2-monoglycerides was lower for the 1,3-specific lipase-catalyzed interesterified fats than for the corresponding chemical
products. 相似文献
995.
996.
T. A. Bykhovskaya K. P. Zakharova T. T. Karpova O. L. Masanov A. A. Orlova O. M. Khimchenko 《Atomic Energy》1995,79(3):606-608
Main Science Center of the Russian Federation, A. A. Bochvara All-Russia Scientific-Research Institute of Standardization
in Machine Engineering. Atomnaya énergiya, Vol. 79, No. 3, pp. 197–200, September, 1995. 相似文献
997.
L. D. Panteleev L. N. Konovalov I. I. Konovalov S. A. Krylov V. B. Malygin K. I. Naboichenko 《Atomic Energy》1994,77(2):613-617
A. A. Bochvar All-Union Scientific-Research Institute of Standardization in Machine Engineering. Moscow Engineering Physics
Institute. Translated from Atomnaya énergiya, Vol. 77, No. 2, pp. 123–129, August, 1994. 相似文献
998.
A male patient with green hair is described. The cause was exogenous deposition of copper from domestic tap water which contained an increased copper concentration. The discolouration disappeared promptly following the use of a penicillamine containing shampoo. 相似文献
999.
1000.
Criteria for evaluating flexibility of a generation mix are presented, and an efficient computational algorithm for determining a flexible generation mix considering uncertainties in the power system expansion planning is developed. The flexible generation mix problem is formulated as a multiobjective optimization problem and solved by the dynamic programming technique in which type of generation plant is selected as a stage and generation capacity is selected as a state. The proposed method can treat easily not only the uncertainties but also many constraints of generation planning such as integer solutions of generation capacities, reliability constraints, and so on. The effectiveness and feasibility of the proposed method are demonstrated on a typical power system model 相似文献