全文获取类型
收费全文 | 1209篇 |
免费 | 58篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 281篇 |
金属工艺 | 7篇 |
机械仪表 | 14篇 |
建筑科学 | 34篇 |
矿业工程 | 2篇 |
能源动力 | 40篇 |
轻工业 | 88篇 |
水利工程 | 11篇 |
石油天然气 | 4篇 |
无线电 | 230篇 |
一般工业技术 | 142篇 |
冶金工业 | 55篇 |
原子能技术 | 4篇 |
自动化技术 | 341篇 |
出版年
2023年 | 14篇 |
2022年 | 37篇 |
2021年 | 48篇 |
2020年 | 41篇 |
2019年 | 41篇 |
2018年 | 36篇 |
2017年 | 45篇 |
2016年 | 41篇 |
2015年 | 33篇 |
2014年 | 58篇 |
2013年 | 91篇 |
2012年 | 72篇 |
2011年 | 85篇 |
2010年 | 57篇 |
2009年 | 84篇 |
2008年 | 71篇 |
2007年 | 74篇 |
2006年 | 42篇 |
2005年 | 26篇 |
2004年 | 31篇 |
2003年 | 20篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 16篇 |
1997年 | 10篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有1267条查询结果,搜索用时 15 毫秒
1.
2.
Yachao Dong Christos T. Maravelias Norman F. Jerome 《Optimization and Engineering》2018,19(4):937-976
We study a maritime inventory routing problem, in which shipments between production and consumption nodes are carried out by a fleet of vessels. The vessels have specific capacities and can be chartered under different agreements. The inventory levels of all consumption nodes and some production nodes should be maintained within specified bounds; for the remaining production nodes, orders should be picked up within pre-defined time windows. We propose a discrete-time mixed-integer programming model. In the face of new information and uncertainty, this optimization model has to be re-solved, as the horizon is rolled forward. We discuss how to account for different sources of uncertainty. We present a rolling-horizon reoptimization framework that allows us to study different policies that impact the quality of the implemented solution, so we can identify the optimal set of policies. 相似文献
3.
Christos Theoharatos Apostolos Ifantis Nikolaos A. Laskaris George Economou 《Computers & Geosciences》2008,34(6):625-634
An exploratory data analysis (EDA) framework was developed in order to investigate the presence of possible correlations in the long-term geoelectric potential (LTGP) signal, prior to significant seismic events in Western Greece. Experimental data, which had been collected continuously within a 6-year period (1998–2003) at the earthquake signal-acquisition center of the University of Patras Seismological Laboratory (UPSL), were studied. The multidimensional scaling (MDS) technique was used to detect putative clustering tendencies in the ensemble of time-series (TS) segments that could indicate the existence of a possible correlation between the geoelectric signal structure and the impending seismic activity. The end result is a 2-dimensional point diagram with the geometry reflecting important signal characteristics, directly related with the underlying seismic events. In addition, the “appending technique”, a well-suited data analysis methodology was incorporated as a means of relating any other TS segment directly with the pre-computed, via the MDS, point diagram. Using the proposed EDA framework, we examined the presence of similar temporal patterns in the recorded geoelectric TS field, 10 days before the occurrence of the major earthquakes. The presented experimental results indicated clearly the validity of the introduced approach and, further, motivated the use of such advanced visualization schemes for charting precursor trends of significance seismicity. 相似文献
4.
Christos Bouras Agisilaos Konidaris 《International Journal of Communication Systems》2005,18(2):119-142
Redundant data transfers over the Web, can be mainly attributed to the repeated transfers of unchanged data. Web caches and Web proxies are some of the solutions that have been proposed, to deal with the issue of redundant data transfers. In this paper we focus on the efficient estimation and reduction of redundant data transfers over the Web. We first prove that a vast amount of redundant data is transferred in Web pages that are considered to carry fresh data. We show this by following an approach based on Web page fragmentation and manipulation. Web pages are broken down to fragments, based on specific criteria. We then deal with these fragments as independent constructors of the Web page and study their change patterns independently and in the context of the whole Web page. After the fragmentation process, we propose solutions for dealing with redundant data transfers. This paper has been based on our previous work on ‘Web Components’ but also on related work by other researchers. It utilises a proxy based, client/server architecture, and imposes changes to the algorithms executed on the Proxy server and on clients. We show that our proposed solution can considerably reduce the amount of redundant data transferred on the Web. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
5.
Christos C. Agrafiotis Chrysoula Pagkoura Souzana Lorentzou Margaritis Kostoglou Athanasios G. Konstandopoulos 《Catalysis Today》2007,127(1-4):265-277
The present work summarizes the recent activities of our laboratory in the field of solar-aided hydrogen production with structured monolithic solar reactors. This reactor concept, “transferred” from the well-known automobile exhaust catalytic after-treatment systems, employs ceramic supports optimized to absorb effectively solar radiation and develop sufficiently high temperatures, that are coated with active materials capable to perform/catalyze a variety of “solar-aided” reactions for the production of hydrogen such as water splitting or natural gas reforming. Our work evolves in an integrated approach starting from the synthesis of active powders tailored to particular hydrogen production reactions, their deposition upon porous absorbers, testing of relevant properties of merit such as thermomechanical stability and hydrogen yield and finally to the design, operation simulation and performance optimization of structured monolithic solar hydrogen production reactors. This approach, among other things, has culminated to the world's first closed, solar-thermochemical cycle in operation that is capable of continuous hydrogen production employing entirely renewable and abundant energy sources and raw materials – solar energy and water, respectively – without any CO2 emissions and holds, thus, a significant potential for large-scale, emissions-free hydrogen production, particularly for regions of the world that lack indigenous resources but are endowed with ample solar energy. 相似文献
6.
The authors examined students' understanding of hypotheses as beliefs that can be empirically verified. Thirty second graders and 30 sixth graders considered cases of disagreement about foods and colors that reflected either alternative hypotheses or different preferences. Their task was to decide whether the validity of each expressed belief could be determined and to justify their decision. Younger students considered both hypotheses and preferences as empirically verifiable, whereas older students were better able to recognize in some cases that preferences are legitimately variable. This lack of distinction may reflect limited metaconceptual ability or a deterministic epistemological view, both of which might interfere with the understanding of the hypothesis-testing process. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Surface waves due to a current source on a grounded ferrite slab are investigated. Electromagnetic fields of the structure are in terms of a continuous plane wave spectrum. The spectrum of each field component is obtained numerically through the exponential-matrix method. The surface waves of the structure are extracted from the continuous spectrum by using the residue theorem and the method of steepest descent. Two types of surface waves are found and their properties are described. The surface wave modes found include dynamic surface wave modes which are closely related to the surface waves of a grounded dielectric slab, and magnetostatic surface wave modes which are related to the solution of Laplace's equation for the magnetic potential 相似文献
8.
Christos Koulamas 《IIE Transactions》1994,26(4):87-90
This note incorporates tool life variability in the geometric programming formulation of machining economics problems by transforming the probability of tool failure while machining a part to a function of the cutting variables for both Markovian and non-Markovian tool failure processes. Numerical examples show that the stochastic nature of tool life cannot be ignored, since it results in different optimal cutting variable values compared to the deterministic tool life case. 相似文献
9.
10.
Microstructured and Electro-Assisted High-Temperature Wettability of MgO in Contact with a Silicate Slag-Based on Fayalite 总被引:1,自引:0,他引:1
Christos G. Aneziris Michael Hampel 《International Journal of Applied Ceramic Technology》2008,5(5):469-479
In this work, MgO samples have been microstructured by laser treatment and surfaces with a controlled stripe design have been manufactured. Sessile drop wetting measurements were performed in a special heating microscope by determining horizontal contact angles as well as contact angles as a function of surface inclination angles. In a further step, voltage was applied to ground MgO surfaces and the wetting behavior was registered as a function of the voltage level. Activation energy analysis was conducted for all the experiments. 相似文献