全文获取类型
收费全文 | 22625篇 |
免费 | 2765篇 |
国内免费 | 1859篇 |
专业分类
电工技术 | 1369篇 |
技术理论 | 1篇 |
综合类 | 2987篇 |
化学工业 | 1200篇 |
金属工艺 | 1392篇 |
机械仪表 | 2197篇 |
建筑科学 | 2359篇 |
矿业工程 | 738篇 |
能源动力 | 602篇 |
轻工业 | 865篇 |
水利工程 | 736篇 |
石油天然气 | 1435篇 |
武器工业 | 167篇 |
无线电 | 1896篇 |
一般工业技术 | 2032篇 |
冶金工业 | 711篇 |
原子能技术 | 219篇 |
自动化技术 | 6343篇 |
出版年
2024年 | 87篇 |
2023年 | 260篇 |
2022年 | 535篇 |
2021年 | 647篇 |
2020年 | 738篇 |
2019年 | 580篇 |
2018年 | 570篇 |
2017年 | 797篇 |
2016年 | 828篇 |
2015年 | 982篇 |
2014年 | 1428篇 |
2013年 | 1386篇 |
2012年 | 1684篇 |
2011年 | 1786篇 |
2010年 | 1440篇 |
2009年 | 1475篇 |
2008年 | 1458篇 |
2007年 | 1676篇 |
2006年 | 1487篇 |
2005年 | 1196篇 |
2004年 | 986篇 |
2003年 | 856篇 |
2002年 | 682篇 |
2001年 | 574篇 |
2000年 | 521篇 |
1999年 | 426篇 |
1998年 | 352篇 |
1997年 | 282篇 |
1996年 | 326篇 |
1995年 | 274篇 |
1994年 | 207篇 |
1993年 | 140篇 |
1992年 | 132篇 |
1991年 | 88篇 |
1990年 | 75篇 |
1989年 | 78篇 |
1988年 | 55篇 |
1987年 | 38篇 |
1986年 | 23篇 |
1985年 | 24篇 |
1984年 | 17篇 |
1983年 | 16篇 |
1982年 | 10篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 3篇 |
1959年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
赵惠琴 《有色冶金设计与研究》2004,25(4):4-8
根据所使用的低水泥浇注料的性能,对中铝山西分公司检修厂4号焙烧炉制定了合理的烘烤曲线,提高了耐火内衬的质量,延长了内衬的使用寿命。 相似文献
32.
Colin Fyfe 《Data mining and knowledge discovery》2007,14(2):207-224
We review a new form of self-organizing map which is based on a nonlinear projection of latent points into data space, identical
to that performed in the Generative Topographic Mapping (GTM) [Bishop et al. (1997) Neurl Comput 10(1): 215–234]. But whereas
the GTM is an extension of a mixture of experts, our new model is an extension of a product of experts [Hinton (2000) Technical
report GCNU TR 2000-004, Gatsby Computational Neuroscience Unit, University College, London]. We show visualisation results
on some real data sets and compare with the GTM. We then introduce a second mapping based on harmonic averages and show that
it too creates a topographic mapping of the data. We compare these mappings on real and artificial data sets.
Responsible editor: Soumen Chakrabarti. 相似文献
33.
In this article, we are combining minimization criteria in the colorant separation process for spectral color reproduction. The colorant separation is performed by inverting a spectral printer model: the spectral Yule‐Nielsen modified Neugebauer model. The inversion of the spectral printer model is an optimization operation in which a criterion is minimized at each iteration. The approach we proposed minimizes a criterion defined by the weighted sum of a spectral difference and a perceptual color difference. The weights can be tuned with a parameter α ∞ [0, 1]. Our goal is to decrease the spectral difference between the original data and its reproduction and also to consider perceptual color difference under different illuminant conditions. In order to find the best α value, we initially compare a pure colorimetric criterion and a pure spectral criterion for the reproduction, then we combine them. We perform four colorant separations: the first separation will minimize the 1976 CIELAB color difference where four illuminants are tested, the second separation will minimize an equally weighted summation of 1976 CIELAB color difference with the four illuminants tested independently, the third colorant separation will minimize a spectral difference, and the fourth colorant separation will combine a weighted sum of a spectral difference and one of the two first colorimetric differences previously introduced. This last colorant separation can be tuned with a parameter in order to emphasize on spectral or colorimetric difference. We use a six colorants printer with artificial inks for our experiments. The prints are simulated by the spectral Yule‐Nielsen modified Neugebauer model. Two groups of data are used for our experiments. The first group describes the data printed by our printing system, which is represented by a regular grid in colorant space of the printer and the second group describes the data which is not originally produced by our printing system but mapped to the spectral printer gamut. The Esser test chart and the Macbeth Color Checker test chart have been selected for the second group. Spectral gamut mapping of this data is carried out before performing colorant separation. Our results show improvement for the colorant separations combining a sum of 1976 CIELAB color difference for a set of illuminants and for the colorant separation combining a sum of 1976 CIELAB color difference and spectral difference, especially in the case of spectral data originally produced by the printer. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 494–504, 2008 相似文献
34.
The recommendation of the CIE has been followed as closely as possible to evaluate the accuracy of five color gamut mapping algorithms (GMAs)—two nonspatial and three spatial algorithms—by psychophysical experiments with 20 test images, 20 observers, one test done on paper and a second one on display. Even though the results do not show any overall “winner,” one GMA is definitely perceived as not accurate. The importance of a high number of test images to obtain robust evaluation is underlined by the high variability of the results depending on the test images. Significant correlations between the percentage of out‐of‐gamut pixels, the number of distinguishable pairs of GMAs, and the perceived difficulty to distinguish them have been found. The type of observers is also important. The experts, who prefer a spatial GMA, show a stronger consensus and look especially for a good rendering of details, whereas the nonexperts hardly make a difference between the GMAs. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 470–476, 2008 相似文献
35.
36.
A model-based autotuning method consists of an identification and a regulator tuning phase. To achieve satisfactory performance and robustness, it is advisable that both phases be tailored a priori to the characteristics of the observed process dynamics. Such characteristics include, but are not limited to, the model structure. For example, overdamped and underdamped models with the same pole-zero structure are parametrised and controlled in different ways. Step response data, that are typically used for the identification phase in the autotuning context, can also be pre-processed to reveal those characteristics. This paper presents a step response classification method suitable for the above purpose. The method is based on a polygonal curve approximation technique for data pre-processing, followed by a neural network classifier. Only normalised I/O data are employed, so that the neural network can be trained off-line with simulated data. Simulation results are reported to show the effectiveness of the proposed classification method in terms of the achievable tuning results. 相似文献
37.
陈训诰 《冶金标准化与质量》2004,42(1):37-40
分析材料试验机度盘偏转角度小 (准确度低 )、试样打滑、定义 (上屈服强度 -下屈服强度 -屈服强度 )模糊、不同应力速率等导致误读 ,并针对误读原因提出纠正方法。 相似文献
38.
Nalavany Blace A.; Ryan Scott D.; Gomory Tomi; Lacasse Jeffrey R. 《Canadian Metallurgical Quarterly》2005,14(1):27
In this pilot study, concept mapping, a methodological approach combining qualitative and quantitative analytic strategies, was used to identify the therapist qualities, competencies, and skills necessary for effective play therapy outcomes as perceived by a sub-sample of 28 experienced play therapists who are members of the Association for Play Therapy (APT). The clusters associated with the therapeutic relationship and facilitative skills (e.g., empathy, warmth, and genuineness) were rated as the most essential skills to possess and also as the most difficult to develop. In contrast, the clusters associated with play therapy interventions and theories were rated as the least important skills to possess but as the easiest to acquire. The findings are discussed, with implications for therapeutic practice, research, and policy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
39.
砼受压损伤力学本构模型的研究 总被引:15,自引:1,他引:14
本文利用MTS公司815.02型电液伺服试验系统对砼进行了等应变速率加载控制的应力一应变全曲线试验,应用不可逆热力学和内变量理论的成果建立了砼损伤力学模型,并用概率统计的观点分析了损伤的演化规律。由于考虑了不可逆变形的影响,本文所建本构模型与实验吻合较好。 相似文献
40.