全文获取类型
收费全文 | 379篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 96篇 |
金属工艺 | 8篇 |
机械仪表 | 20篇 |
建筑科学 | 4篇 |
矿业工程 | 2篇 |
能源动力 | 33篇 |
轻工业 | 27篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 47篇 |
一般工业技术 | 68篇 |
冶金工业 | 10篇 |
原子能技术 | 1篇 |
自动化技术 | 72篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 18篇 |
2021年 | 10篇 |
2020年 | 13篇 |
2019年 | 13篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 20篇 |
2015年 | 9篇 |
2014年 | 22篇 |
2013年 | 40篇 |
2012年 | 37篇 |
2011年 | 30篇 |
2010年 | 29篇 |
2009年 | 14篇 |
2008年 | 17篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 4篇 |
2003年 | 8篇 |
2002年 | 12篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1990年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有399条查询结果,搜索用时 0 毫秒
31.
Vojislav V. Mitic Zoran S. Nikolic Vladimir B. Pavlovic Vesna Paunovic Miroslav Miljkovic Branka Jordovic Ljiljana Zivkovic 《Journal of the American Ceramic Society》2010,93(1):132-137
In this article, ytterbium and erbium oxides are used as doping materials for barium titanate (BaTiO3 ) materials. The amphoteric behavior of these rare-earth ions leads to the increase of dielectric permittivity and decrease of dielectric losses. BaTiO3 ceramics doped with 0.01–0.5 wt% of Yb2 O3 and Er2 O3 were prepared by conventional solid-state procedure and sintered at 1320°C for 4 h. In BaTiO3 doped with a low content of rare-earth ions (0.01 wt%) the grain size ranged between 10 and 25 μm. With the higher dopant concentration of 0.5 wt%, the abnormal grain growth is inhibited and the grain size ranged between 2 and 10 μm. The measurements of capacitance and dielectric losses as a function of frequency and temperature have been carried out in order to correlate the microstructure and dielectric properties of doped BaTiO3 ceramics. The temperature dependence of the dielectric constant as a function of dopant amount has been investigated. 相似文献
32.
33.
34.
In this paper we present an electromagnetism (EM) metaheuristic for solving NP hard Maximum Betweenness Problem (MBP). A new encoding scheme with appropriate objective functions is implemented. Specific representation of the individuals enables the EM operators to explore the searching space in a way that achieves high quality solutions. An effective 1-swap based local search procedure improved by the specific caching technique is performed on each EM point. The algorithm is tested both on real and artificial instances from the literature. Experimental results show that the proposed EM approach achieves all previously known optimal solutions, except one, and achieves the best-known solutions or outperforms other approaches on all large-scale instances, except two. Provided statistical analysis indicates that the EM approach is significantly better than other approaches. 相似文献
35.
Aleksandar Jovanović Aleksandar Perović Wlodzimierz Klonowski Wlodzisław Duch Zoran Đorđević Slađana Spasić 《Journal of Signal Processing Systems》2010,60(1):115-129
In this article structures in biological signals are treated. The simpler—directly visible in the signals, which still demand
serious methods and algorithms in the feature detection, similarity investigation and classification. The major actions in
this domain are of geometric, thus simpler sort, though there are still hard problems related to simple situations. The other
large class of less simple signals unsuitable for direct geometric or statistic approach, are signals with interesting frequency
components and behavior, those suitable for spectroscopic analysis. Semantics of spectroscopy, spectroscopic structures and
research demanded operations and transformations on spectra and time spectra are presented. The both classes of structures
and related analysis methods and tools share a large common set of algorithms, all of which aiming to the full automatization.
Some of the signal features present in the brain signal patterns are demonstrated, with the contexts relevant in BCI, brain
computer interfaces. Mathematical representations, invariants and complete characterization of structures in broad variety
of biological signals are in the central focus. 相似文献
36.
Antoine Doucet Gabriella Kazai Bodin Dresevic Aleksandar Uzelac Bogdan Radakovic Nikola Todic 《International Journal on Document Analysis and Recognition》2011,14(1):45-52
This paper describes the setup of the Book Structure Extraction competition run at ICDAR 2009. The goal of the competition
was to evaluate and compare automatic techniques for deriving structure information from digitized books, which could then
be used to aid navigation inside the books. More specifically, the task that participants faced was to construct hyperlinked
tables of contents for a collection of 1,000 digitized books. This paper describes the setup of the competition and its challenges.
It introduces and discusses the book collection used in the task, the collaborative construction of the ground truth, the
evaluation measures, and the evaluation results. The paper also introduces a data set to be used freely for research evaluation
purposes. 相似文献
37.
Aleksandar Dedic 《Drying Technology》1997,15(10):2557-2564
This paper presents the specific methods to obtain sorption isotherms. Sorption isotherms were first obtained experimentally for 20°C and 100°C and then, by using the presented method, isotherms were also obtained for 50°C and 80°C. The same treatment can be applied in finding any isotherm sorption in the temperature range between 20°Cand 100°C.
The experiments were carried out on beech (Fagus moesiaca) and sample dimensions were 3×3×3cm. Based on the results of the experiment, by regression analysis, the most suitable analytic formula was proposed. It relsites temperature and air humidity with the equilibrium moisture content in wood. Experimental results were compared with psychrometric tables and Bramhall's formula for desorption curves with good agreement. This proves that the method presented in this paper is precise and efficient to decrease the lime needed to obtain sorption isotherms experimentally. 相似文献
The experiments were carried out on beech (Fagus moesiaca) and sample dimensions were 3×3×3cm. Based on the results of the experiment, by regression analysis, the most suitable analytic formula was proposed. It relsites temperature and air humidity with the equilibrium moisture content in wood. Experimental results were compared with psychrometric tables and Bramhall's formula for desorption curves with good agreement. This proves that the method presented in this paper is precise and efficient to decrease the lime needed to obtain sorption isotherms experimentally. 相似文献
38.
39.
Vehicle‐to‐grid presents a mechanism to meet the key requirements of an electric power system, using electric vehicles (EVs) when they are parked. The most economic ancillary service is that of frequency regulation, which imposes some constraints regarding the period and duration of time the vehicles have to be connected to the grid. The majority of research explores the profitability of the aggregator, while the perspective of the EV fleet owner, in terms of their need for usage of their fleet, remains neglected. In this paper, the optimal allocation of available vehicles on a day‐ahead basis using queuing theory and fuzzy multi‐criteria methodology has been determined. The proposed methodology is illustrated on the daily scheduling of EVs in an electricity distribution company. 相似文献
40.
Dragica Lj. Stojić Tomislav D. Grozdić Milica P. Marčeta Kaninski Aleksandar D. Maksić Nataša D. Simić 《International Journal of Hydrogen Energy》2006
Intermetallics phases along Mo–Pt phase diagram have been investigated as cathode materials for the production of hydrogen by electrolysis from water KOH solutions, in an attempt to increase the electrolytic process efficiency. These materials were compared with conventional cathodes (Fe and Ni), often used in the alkaline electrolysis, and also with the intermetallic Ti–Pt. An significant upgrade of the electrolytic efficiency using intermetallics in pure KOH electrolyte was achieved in comparison with conventional cathode materials. 相似文献