全文获取类型
收费全文 | 1074篇 |
免费 | 51篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 202篇 |
金属工艺 | 14篇 |
机械仪表 | 41篇 |
建筑科学 | 40篇 |
矿业工程 | 1篇 |
能源动力 | 15篇 |
轻工业 | 58篇 |
水利工程 | 6篇 |
武器工业 | 2篇 |
无线电 | 317篇 |
一般工业技术 | 144篇 |
冶金工业 | 143篇 |
自动化技术 | 135篇 |
出版年
2023年 | 9篇 |
2022年 | 22篇 |
2021年 | 30篇 |
2020年 | 22篇 |
2019年 | 15篇 |
2018年 | 25篇 |
2017年 | 21篇 |
2016年 | 27篇 |
2015年 | 26篇 |
2014年 | 31篇 |
2013年 | 63篇 |
2012年 | 61篇 |
2011年 | 53篇 |
2010年 | 53篇 |
2009年 | 53篇 |
2008年 | 52篇 |
2007年 | 53篇 |
2006年 | 45篇 |
2005年 | 35篇 |
2004年 | 35篇 |
2003年 | 30篇 |
2002年 | 28篇 |
2001年 | 37篇 |
2000年 | 30篇 |
1999年 | 28篇 |
1998年 | 72篇 |
1997年 | 47篇 |
1996年 | 27篇 |
1995年 | 23篇 |
1994年 | 13篇 |
1993年 | 12篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1973年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有1129条查询结果,搜索用时 31 毫秒
101.
102.
Autofocusing for tissue microscopy 总被引:12,自引:0,他引:12
This paper describes the implementation of autofocusing for tissue microscopy. We first investigate the suitability of several criterion functions for the evaluation of image sharpness. Since tissue sections are invariably stained, we also discuss the selection of the colour component on which autofocusing will be performed. In tissue microscopy, where a section generally comprises multiple layers, it is often not possible to obtain an image that is well focused over the field of view because of the limited depth of field of the objective. We describe focus enhancement algorithms, closely related to the autofocus system, which may be employed to obtain an entirely sharp image. 相似文献
103.
Automatic parsing and indexing of news video 总被引:9,自引:0,他引:9
Automatic construction of content-based indices for video source material requires general semantic interpretation of both images and their accompanying sounds; but such a broadly-based semantic analysis is beyond the capabilities of the current technologies of machine vision and audio signal analysis. However, if one can assume a limited and well-demarcated body of domain knowledge for describing the content of a body of video, then it becomes easier to interpret a video source in terms of that domain knowledge. This paper presents our work on using domain knowledge to parse news video programs and to index them on the basis of their visual content. Models based on both the spatial structure of image frames and the temporal structure of the entire program have been developed for news videos, along with algorithms that apply these models by locating and identifying instances of their elements. Experimental results are also discussed in detail to evaluate both the models and the algorithms that use them. Finally, proposals for future work are summarized. 相似文献
104.
Ozanyan K.B. Yeo T.L. Hindle F.P. Poolton N.R.J. McCann H. Tan K.L. 《IEEE sensors journal》2004,4(5):681-690
We report on an optical fiber probe, coupled to a 404-nm laser diode, as a fluorescence sensor for monitoring of commercial gasolines. The principle of operation of the sensor is based on quantifying the intensity of the Stokes-shifted fluorescence from some of the heavier polycyclic aromatic hydrocarbons C/sub x/H/sub y/,(x,y) /spl ges/ (14,10) present in gasolines as minor constituents. The normalized efficiency of the optical fiber probe, as a function of its geometry, is calculated in the cases of single-fiber and parallel dual-fiber designs. The spatial and temporal resolutions achievable by the sensor are discussed as a function of design parameters The performance of the sensor is investigated experimentally for commercial gasolines in the liquid and gas phase. The optimal excitation wavelength for such sensors is investigated in the range of 350-400 nm. The linear sensitivity to vapor concentrations of retail gasoline fuel is demonstrated in the range of 4%-125% of combustion stoichiometry at 10 bar and 180/spl deg/C. Statistical processing of the data from the sensor allows distinction to be made between different forecourt gasoline suppliers, as well as fuel varieties (unleaded, low sulfur, etc.). 相似文献
105.
Smillie Luke D.; Yeo Gillian B.; Furnham Adrian F.; Jackson Chris J. 《Canadian Metallurgical Quarterly》2006,91(1):139
The authors evaluate a model suggesting that the performance of highly neurotic individuals, relative to their stable counterparts, is more strongly influenced by factors relating to the allocation of attentional resources. First, an air traffic control simulation was used to examine the interaction between effort intensity and scores on the Anxiety subscale of Eysenck Personality Profiler Neuroticism in the prediction of task performance. Overall effort intensity enhanced performance for highly anxious individuals more so than for individuals with low anxiety. Second, a longitudinal field study was used to examine the interaction between office busyness and Eysenck Personality Inventory Neuroticism in the prediction of telesales performance. Changes in office busyness were associated with greater performance improvements for highly neurotic individuals compared with less neurotic individuals. These studies suggest that highly neurotic individuals outperform their stable counterparts in a busy work environment or if they are expending a high level of effort. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
Hill Dina E.; Yeo Ronald A.; Campbell Richard A.; Hart Blaine; Vigil Janet; Brooks William 《Canadian Metallurgical Quarterly》2003,17(3):496
This study compared magnetic resonance imaging size differences in several brain regions and neurocognitive function in a group of male and female children with attention-deficit/hyperactivity disorder (ADHD) with no comorbid learning disorders with a normal control group of children. The ADHD group demonstrated smaller total brain, superior prefrontal, and right superior prefrontal volumes, as well as significantly smaller areas for cerebellar lobules I-V and VIII-X, total corpus callosum area, and splenium. No group differences were observed for the inferior prefrontal, caudate, or cerebellar volumes, or for the area of cerebellar lobules VI-VII. In the ADHD group but not in the control group, greater right superior prefrontal volume predicted poorer performance on a test of sustained attention. Patterns of brain abnormality did not differ in male and female children with ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
Other researchers have observed that eccentric irises possess certain advantageous features that may lead designers to prefer them over the conventional concentric irises. The least-squares boundary residual method (LSBRM) is utilized in this paper to analyze the behavior of such an eccentric-iris structure (of nonzero thickness). Tests have confirmed that the computer model thus obtained is capable of yielding numerical results that are accurate to within ⊥1% 相似文献
108.
A Tournament-Based Competitive Coevolutionary Algorithm 总被引:1,自引:0,他引:1
For an efficient competitive coevolutionary algorithm, it is important that competing populations be capable of maintaining a coevolutionary balance and hence, continuing evolutionary arms race to increase the levels of complexity. We propose a competitive coevolutionary algorithm that combines the strategies of neighborhood-based evolution, entry fee exchange tournament competition (EFE-TC) and localized elitism. An emphasis is placed on analyzing the effects of these strategies on the performance of competitive coevolutionary algorithms. We have tested the proposed algorithm with two adversarial problems: sorting network and Nim game problems that have different characteristics. The experimental results show that the interacting effects of the strategies appear to promote a balanced evolution between host and parasite populations, which naturally leads them to keep on evolutionary arms race. Consequently, the proposed algorithm provides good quality solutions with a little computation time. 相似文献
109.
Jong Bum Hong Student Member IEEE Yeong Bae Yeo Byoung Yoon Kim Fellow IEEE 《战术导弹控制技术》2002,(2):55-58
通过采用锁相放大器,演示了一种性能明显提高的锁模光纤激光陀螺.结果表明锁相放大器的输出与转动速率之间具有理想的线性关系,并对两脉冲(在时间间隔测量过程中引起相位误差)之间的光强差不敏感.与以往报道的时间间隔测量相比,演示了长期稳定性提高了二个数量级. 相似文献
110.
On the basis of prior studies of handedness, it was predicted that variations from modal asymmetry scores on cognitive tasks, in either direction from the mean, would be associated with an elevated incidence of classic markers of developmental instability (minor physical anomalies and fluctuating anatomic asymmetries). University students (N = 146) were administered 4 tasks that typically reveal functional asymmetries: the fused rhymed words dichotic listening task, the line bisection task, the chimeric faces task, and the cartoon faces task. A composite measure of developmental instability was computed from minor physical anomalies and fluctuating asymmetries. Participants with greater evidence of developmental instability had more atypical lateralization scores, deviating more from the sample mean, in either direction. Directional asymmetries were unrelated to developmental instability. These results suggest that developmental instability influences variation in the lateralization of cognitive skills as well as handedness. 相似文献