全文获取类型
收费全文 | 2657篇 |
免费 | 148篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 50篇 |
综合类 | 7篇 |
化学工业 | 728篇 |
金属工艺 | 67篇 |
机械仪表 | 67篇 |
建筑科学 | 171篇 |
矿业工程 | 2篇 |
能源动力 | 57篇 |
轻工业 | 215篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 238篇 |
一般工业技术 | 532篇 |
冶金工业 | 223篇 |
原子能技术 | 14篇 |
自动化技术 | 428篇 |
出版年
2022年 | 29篇 |
2021年 | 55篇 |
2020年 | 37篇 |
2019年 | 50篇 |
2018年 | 51篇 |
2017年 | 70篇 |
2016年 | 72篇 |
2015年 | 81篇 |
2014年 | 96篇 |
2013年 | 139篇 |
2012年 | 118篇 |
2011年 | 175篇 |
2010年 | 115篇 |
2009年 | 119篇 |
2008年 | 132篇 |
2007年 | 121篇 |
2006年 | 106篇 |
2005年 | 85篇 |
2004年 | 69篇 |
2003年 | 72篇 |
2002年 | 51篇 |
2001年 | 51篇 |
2000年 | 54篇 |
1999年 | 44篇 |
1998年 | 80篇 |
1997年 | 59篇 |
1996年 | 51篇 |
1995年 | 37篇 |
1994年 | 30篇 |
1993年 | 32篇 |
1992年 | 25篇 |
1991年 | 24篇 |
1990年 | 19篇 |
1989年 | 27篇 |
1988年 | 20篇 |
1987年 | 14篇 |
1986年 | 27篇 |
1985年 | 23篇 |
1984年 | 24篇 |
1983年 | 19篇 |
1982年 | 16篇 |
1981年 | 22篇 |
1980年 | 18篇 |
1979年 | 20篇 |
1978年 | 22篇 |
1977年 | 26篇 |
1976年 | 21篇 |
1975年 | 14篇 |
1974年 | 15篇 |
1973年 | 14篇 |
排序方式: 共有2807条查询结果,搜索用时 0 毫秒
31.
Nonparametric Bayesian Image Segmentation 总被引:1,自引:0,他引:1
Image segmentation algorithms partition the set of pixels of an image into a specific number of different, spatially homogeneous
groups. We propose a nonparametric Bayesian model for histogram clustering which automatically determines the number of segments
when spatial smoothness constraints on the class assignments are enforced by a Markov Random Field. A Dirichlet process prior
controls the level of resolution which corresponds to the number of clusters in data with a unique cluster structure. The resulting posterior is efficiently
sampled by a variant of a conjugate-case sampling algorithm for Dirichlet process mixture models. Experimental results are
provided for real-world gray value images, synthetic aperture radar images and magnetic resonance imaging data. 相似文献
32.
In this work we examine the influence of the diffusive motion of vortices in highly anisotropic high-Tc superconductors near the Berezinskii-Kosterlitz-Thouless (BKT) transition temperature T
bkt
on the spin-lattice relaxation rate T
1
–1
.We find a jump in T
1
–1
at the temperature T
bkt
. 相似文献
33.
Optimized Photoinitiator for Fast Two‐Photon Absorption Polymerization of Polyester‐Macromers for Tissue Engineering 下载免费PDF全文
34.
35.
Orphan detection in distributed systems is a well-researched field for which many solutions exist. These solutions exploit well defined parent-child relationships given in distributed systems. But they are not applicable in mobile agent systems, since no similar natural relationship between agents exist. Thus new protocols have to be developed. In this paper one such protocol for controlling mobile mobile agents and for orphan detection is presented. The shadow approach presented in this paper uses the idea of a placeholder (shadow) which is assigned by the agent system to each new agent. This defines an artificial relationship between agents and shadow. The shadow records the location of all dependent agents. Removing the root shadow implies that all dependent agents are declared orphan and are eventually be terminated. We introduce agent proxies that create a path from shadow to every agent. In an extension of the basic protocol we additionally allow the shadow to be mobile.The shadow approach can be used for termination of groups of agents even if the exact location of each single agent is not known. 相似文献
36.
Maurus Biedermann Konrad Grob Carlo Mariani Joachim P. Schmidt 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1996,202(3):199-204
Adulteration of expensive edible oils, such as olive oil, often involves desterolized oils in order to render the adulteration undetectable. Sunflower oil contains characteristic 7-sterols, which are readily removed upon strong bleaching. It is shown that these 7-sterols do not primarily dehydrate (as do 5-sterols), but isomerize to 8(14)- and 14-sterols. These compounds can be analysed by LC on silica gel or GC on capillary columns with stationary phases of intermediate to high polarity. 相似文献
37.
Anselm Grundhöfer Daniel Kurz Sebastian Thiele Oliver Bimber 《The Visual computer》2010,26(9):1167-1176
In this article we show how temporal backdrops that alternately change their color rapidly at recording rate can aid chroma
keying by transforming color spill into a neutral background illumination. Since the chosen colors sum up to white, the chromatic
(color) spill component is neutralized when integrating over both backdrop states. The ability to separate both states additionally
allows to compute high-quality alpha mattes. Besides the neutralization of color spill, our method is invariant to foreground
colors and supports applications with real-time demands. In this article, we explain different realizations of temporal backdrops
and describe how keying and color spill neutralization are carried out, how artifacts resulting from rapid motion can be reduced,
and how our approach can be implemented to be compatible with common real-time post-production pipelines. 相似文献
38.
The use of RFID middleware to support application development for and integration of RFID hardware into information systems
has become quite common in RFID applications where reader devices remain stationary, which currently represents the largest
part of all RFID applications in use. Another field for applying RFID technology which is offering a huge set of novel possibilities
and applications are mobile applications, where readers are no longer fixed. In order to address the specific issues of mobile RFID-enabled applications
and to support developers in rapid application development, we present ID-Services, an architecture for an RFID middleware that is designed to support mobile applications. The ID-Services approach has been used to implement MoVIS (Mobile Visitor Information System), a mobile application which allows museum visitors to request individually adapted multimedia
information about exhibits in an intuitive way. 相似文献
39.
Modelling water dynamics with DNDC and DAISY in a soil of the North China Plain: A comparative study
Roland Kröbel Qinping Sun Joachim Ingwersen Xinping Chen Fusuo Zhang Torsten Müller Volker Römheld 《Environmental Modelling & Software》2010,25(4):583-601
The performance of the DNDC and Daisy model to simulate the water dynamics in a floodplain soil of the North China Plain was tested and compared. While the DNDC model uses a simple cascade approach, the Daisy model applies the physically based Richard's equation for simulating water movement in soil. For model testing a three years record of the soil water content from the Dong Bei Wang experimental station near Beijing was used. There, the effect of nitrogen fertilization, irrigation and straw removal on soil water and nitrogen dynamics was investigated in a three factorial field experiment applying a split-split-plot design with 4 replications. The dataset of one treatment was used for model testing and calibration. Two other independent datasets from further treatments were employed for validating the models. For both models, the simulation results were not satisfying using default parameters. After parameter optimisation and the use of site-specific van Genuchten parameters, however, the Daisy model performed well. But, for the DNDC model, parameter optimisation failed to improve the simulation result. Owing to the fact that many biological processes such as plant growth, nitrification or denitrification depend strongly on the soil water content, our findings bring us to the conclusion that the site-specific suitability of the DNDC model for simulating the soil water dynamics should be tested before further simulation of other processes. 相似文献
40.
For the development of practical semantic applications, ontologies are commonly used with rule extensions. Prominent examples of semantic applications not only are Semantic Wikis, Semantic Desktops, but also advanced Web Services and agents. The application of rules increases the expressiveness of the underlying knowledge in many ways. Likewise, the integration not only creates new challenges for the design process of such ontologies, but also existing evaluation methods have to cope with the extension of ontologies by rules.Since the verification of Owl ontologies with rule extensions is not tractable in general, we propose to verify ontologies at the symbolic level by using a declarative approach: With the new language Datalog?, known anomalies can be easily specified and tested in a compact manner. We introduce supplements to existing verification techniques to support the design of ontologies with rule enhancements, and we focus on the detection of anomalies that especially occur due to the combined use of rules and ontological definitions. 相似文献