全文获取类型
收费全文 | 6744篇 |
免费 | 210篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 80篇 |
综合类 | 1篇 |
化学工业 | 1359篇 |
金属工艺 | 128篇 |
机械仪表 | 111篇 |
建筑科学 | 340篇 |
矿业工程 | 19篇 |
能源动力 | 156篇 |
轻工业 | 684篇 |
水利工程 | 52篇 |
石油天然气 | 42篇 |
武器工业 | 1篇 |
无线电 | 416篇 |
一般工业技术 | 1107篇 |
冶金工业 | 1374篇 |
原子能技术 | 44篇 |
自动化技术 | 1055篇 |
出版年
2023年 | 44篇 |
2022年 | 71篇 |
2021年 | 115篇 |
2020年 | 96篇 |
2019年 | 82篇 |
2018年 | 119篇 |
2017年 | 88篇 |
2016年 | 148篇 |
2015年 | 106篇 |
2014年 | 193篇 |
2013年 | 396篇 |
2012年 | 289篇 |
2011年 | 388篇 |
2010年 | 264篇 |
2009年 | 236篇 |
2008年 | 320篇 |
2007年 | 287篇 |
2006年 | 233篇 |
2005年 | 232篇 |
2004年 | 184篇 |
2003年 | 183篇 |
2002年 | 180篇 |
2001年 | 116篇 |
2000年 | 101篇 |
1999年 | 118篇 |
1998年 | 200篇 |
1997年 | 168篇 |
1996年 | 130篇 |
1995年 | 110篇 |
1994年 | 84篇 |
1993年 | 101篇 |
1992年 | 99篇 |
1991年 | 69篇 |
1990年 | 70篇 |
1989年 | 69篇 |
1988年 | 79篇 |
1987年 | 68篇 |
1986年 | 83篇 |
1985年 | 95篇 |
1984年 | 78篇 |
1983年 | 88篇 |
1982年 | 69篇 |
1981年 | 55篇 |
1980年 | 61篇 |
1979年 | 70篇 |
1978年 | 59篇 |
1977年 | 66篇 |
1976年 | 72篇 |
1975年 | 47篇 |
1973年 | 35篇 |
排序方式: 共有6969条查询结果,搜索用时 15 毫秒
31.
Philip M. Stone Yong-Ki Kim J. P. Desclaux 《Journal of research of the National Institute of Standards and Technology》2002,107(4):327-337
Electron-impact excitation cross sections are presented for the dipole- and spin allowed transitions from the ground states to the np
2P states for hydrogen and lithium, and to the 1snp
1P states for helium, n = 2 through 10. Two scaling formulas developed earlier by Kim [Phys. Rev. A 64, 032713 (2001)] for plane-wave Born cross sections are used. The scaled Born cross sections are in excellent agreement with available theoretical and experimental data. 相似文献
32.
33.
Examined intake profiles of 54 depressed women survivors of child sexual abuse presenting for a specialized group therapy program at a community mental health center. The 32 therapy completers were compared with the 22 dropouts. Both groups possessed extensive and severe childhood and adult abuse histories. Both were extremely socially disadvantaged and clinically impaired as measured on the Millon Clinical Multiaxial Inventory (MCMI). Dropouts were more likely to have been battered as children and to have been sexually abused only within the family. Completers were more likely to have been multiply offended both by intrafamilial and extrafamilial perpetrators. The groups differed in terms of marital status and extent of economic dependence on spouse. Dropouts appeared to be more actively enmeshed in the abuse cycle at the time of therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
34.
An estimate is made of the motion of a rigid body from two noisy 2-D perspective projections using the least-squares method and the algebra of R.Y. Tsai and T.S. Huang (1984). The accuracy of the estimated motion parameters is influenced by the position of the features of the object used in the calculation. Four test variables are derived that indicate how the accuracy is affected, and they are used for discarding inaccurate estimates. Monte Carlo tests demonstrate the obtained accuracy 相似文献
35.
36.
Distributed Multirobot Exploration and Mapping 总被引:3,自引:0,他引:3
Fox D. Ko J. Konolige K. Limketkai B. Schulz D. Stewart B. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2006,94(7):1325-1339
Efficient exploration of unknown environments is a fundamental problem in mobile robotics. We present an approach to distributed multirobot mapping and exploration. Our system enables teams of robots to efficiently explore environments from different, unknown locations. In order to ensure consistency when combining their data into shared maps, the robots actively seek to verify their relative locations. Using shared maps, they coordinate their exploration strategies to maximize the efficiency of exploration. This system was evaluated under extremely realistic real-world conditions. An outside evaluation team found the system to be highly efficient and robust. The maps generated by our approach are consistently more accurate than those generated by manually measuring the locations and extensions of rooms and objects. 相似文献
37.
Investigated, in 4 experiments, the time course of semantic priming effects during 2 forms of visual word identification, lexical decision and pronunciation. On each trial, a target letter string was preceded by a single-word priming context. The effects of varying the stimulus onset asynchrony between the prime and the target indicated that the time course of semantic priming was equivalent for young and older adults. There were no consistent differences between lexical decision and pronunciation in the time course of semantic priming. The age differences associated with response selection were greater than would be predicted by generalized age-related slowing. The semantic priming effects were also inconsistent with a generalized slowing model, but the reliability of these effects was substantially lower than the reliability of the other task-related variables. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
38.
Lutgendorf Susan K.; Russell Daniel; Ullrich Philip; Harris Tamara B.; Wallace Robert 《Canadian Metallurgical Quarterly》2004,23(5):465
This study prospectively examined the relationship between religious attendance, interleukin-6 (IL-6) levels, and mortality rates in a community-based sample of 557 older adults. Attending religious services more than once weekly was a significant predictor of lower subsequent 12-year mortality and elevated IL-6 levels (> 3.19 pg/mL), with a mortality ratio of .32 (95% confidence interval [CI] = 0.15,0.72; p 相似文献
39.
40.
Schulz Laura E.; Bonawitz Elizabeth Baraff; Griffiths Thomas L. 《Canadian Metallurgical Quarterly》2007,43(5):1124
Causal learning requires integrating constraints provided by domain-specific theories with domain-general statistical learning. In order to investigate the interaction between these factors, the authors presented preschoolers with stories pitting their existing theories against statistical evidence. Each child heard 2 stories in which 2 candidate causes co-occurred with an effect. Evidence was presented in the form: AB→E; CA→E; AD→E; and so forth. In 1 story, all variables came from the same domain; in the other, the recurring candidate cause, A, came from a different domain (A was a psychological cause of a biological effect). After receiving this statistical evidence, children were asked to identify the cause of the effect on a new trial. Consistent with the predictions of a Bayesian model, all children were more likely to identify A as the cause within domains than across domains. Whereas 3.5-year-olds learned only from the within-domain evidence, 4- and 5-year-olds learned from the cross-domain evidence and were able to transfer their new expectations about psychosomatic causality to a novel task. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献