全文获取类型
收费全文 | 8794篇 |
免费 | 413篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 118篇 |
综合类 | 38篇 |
化学工业 | 2251篇 |
金属工艺 | 226篇 |
机械仪表 | 184篇 |
建筑科学 | 601篇 |
矿业工程 | 20篇 |
能源动力 | 281篇 |
轻工业 | 838篇 |
水利工程 | 87篇 |
石油天然气 | 43篇 |
武器工业 | 1篇 |
无线电 | 660篇 |
一般工业技术 | 1449篇 |
冶金工业 | 548篇 |
原子能技术 | 58篇 |
自动化技术 | 1815篇 |
出版年
2023年 | 85篇 |
2022年 | 202篇 |
2021年 | 333篇 |
2020年 | 184篇 |
2019年 | 200篇 |
2018年 | 270篇 |
2017年 | 233篇 |
2016年 | 314篇 |
2015年 | 233篇 |
2014年 | 337篇 |
2013年 | 624篇 |
2012年 | 483篇 |
2011年 | 616篇 |
2010年 | 426篇 |
2009年 | 491篇 |
2008年 | 453篇 |
2007年 | 410篇 |
2006年 | 341篇 |
2005年 | 291篇 |
2004年 | 269篇 |
2003年 | 258篇 |
2002年 | 189篇 |
2001年 | 137篇 |
2000年 | 137篇 |
1999年 | 114篇 |
1998年 | 128篇 |
1997年 | 128篇 |
1996年 | 96篇 |
1995年 | 79篇 |
1994年 | 79篇 |
1993年 | 83篇 |
1992年 | 58篇 |
1991年 | 60篇 |
1990年 | 61篇 |
1989年 | 68篇 |
1988年 | 49篇 |
1987年 | 47篇 |
1986年 | 50篇 |
1985年 | 53篇 |
1984年 | 62篇 |
1983年 | 44篇 |
1982年 | 38篇 |
1981年 | 37篇 |
1980年 | 39篇 |
1979年 | 32篇 |
1978年 | 34篇 |
1977年 | 33篇 |
1976年 | 39篇 |
1975年 | 40篇 |
1973年 | 36篇 |
排序方式: 共有9218条查询结果,搜索用时 15 毫秒
91.
Peter E. Neerincx Martin Hofmann Oleksandr Gorodetskyi Kirill Feldman Jan Vermant Han E. H. Meijer 《Polymer Engineering and Science》2021,61(4):1257-1269
Relatively recently, we advanced a route to create, in a controlled fashion, combined horizontal and vertical stratified structures by simple and energy-efficient processing operations employing static mixing elements. While in state-of-the-art static mixing the focus is on layer multiplication, here the aim is to create hierarchical fractal structures. Therefore, the main question addressed in this article is how structures, rather than layers, can be multiplied. The key aspect is the addition of layers on the sides or in the midplane of the flow during the process; every addition step increases the hierarchy by one level. This article derives the general formalism for forming fractal structures with controlled hierarchy, and we develop the language required to design and construct the dies. The main part of the article addresses this main topic and is based on the splitting serpentine static mixer geometry that can be easily made on the parting surfaces of a mold on both the micro- and the macroscale. The second part of the article addresses the strategy to minimize the number of mirroring steps, eventually avoiding mirroring completely, and is based on the rotation-free multiflux static mixer geometry. With the design language derived, complex hierarchical fractal structures can be generated simply by changing the number and sequence of operators within extrusion dies or molds, providing a one-step solution to produce material structures for potential use in diverse applications ranging from advanced mechanical systems to photovoltaic devices, where controlled assembly of dissimilar materials, and the realization of huge interfaces and genuine cocontinuity throughout the cross section, is critical. 相似文献
92.
Đurović Gordana Van Neerbos Francine A. C. Bossaert Sofie Herrera-Malaver Beatriz Steensels Jan Arnó Judit Wäckers Felix Sobhy Islam S. Verstrepen Kevin J. Jacquemyn Hans Lievens Bart 《Journal of chemical ecology》2021,47(8-9):788-798
Journal of Chemical Ecology - There is increasing evidence that microorganisms, particularly fungi and bacteria, emit volatile compounds that mediate the foraging behaviour of insects and therefore... 相似文献
93.
Effect of artificial aging on intergranular corrosion of extruded AlMgSi alloy with small Cu content
The effect of artificial aging parameters on the corrosion performance of air cooled AlMgSi(Cu) model alloy extrusions was investigated. Accelerated corrosion test revealed that the extrusions were highly susceptible to intergranular corrosion (IGC) in the naturally aged condition. However, IGC susceptibility was reduced, and finally eliminated, by artificial aging. Overaging introduced slight pitting susceptibility. EDS X-ray mapping in FE-TEM revealed Mg2Si and Q-phase (Al4Cu2Mg8Si7) grain boundary precipitates and a continuous Cu-enriched grain boundary film. IGC susceptibility was related to the Cu-enriched grain boundary film. Increased IGC resistance was caused by coarsening of the grain boundary film by aging. Pitting susceptibility by over aging evolved due to coarsening of the Q-phase particles in the grain bodies. 相似文献
94.
Cathodic disbonding and charge transport through paint films were studied as a function of polarization potential, temperature, dry-film thickness and cation type in the electrolyte. It was found that both the disbonding rate and the charge transport were linearly related to the polarization potential. The activation energy for the disbonding process and the charge transport were quite different. The disbonding rate was linearly related to the dry-film thickness and was dependent on the cation type in the electrolyte. This was not the case for the charge transport. The results indicate a rate controlling factor for the disbonding process involving transport of cations through the film where the film is already disbonded. A fundamental difference in the conductive properties of the paint film on either side of the disbonding front is also proposed. 相似文献
95.
Hiroaki Tsuchiya Jan M. Macak Andrei Ghicov Luciano Taveira Patrik Schmuki 《Corrosion Science》2005,47(12):3324-3335
The present work investigates the electrochemical formation of self-organized high aspect ratio TiO2 and ZrO2 nanotube layers. The formation and growth of a self-organized porous layer can be achieved directly by anodization without any templates in fluoride containing electrolytes. The morphology of the porous layers is affected by the electrochemical conditions such as the electrolyte composition, the pH and the exact polarization treatment (such as the potential sweep rate from the open-circuit potential to the anodizing potential). For Ti, nanotube layers are formed with diameters varying from approx. 20 nm to 100 nm and lengths from approx. 0.25 μm to 2.5 μm depending on the electrolytes and pH. On the other hand, for Zr, tubes of 50 nm in diameter and up to approx. 17 μm in length can be grown—a key parameter in this case is the potential sweep rate. The large difference between Ti and Zr in the achievable thickness of nanotube layers indicates a difference in the growth mechanism which may be based on the different chemical dissolution rates of electrochemically formed oxides. 相似文献
96.
97.
A discrete Laplace‐Beltrami operator is called perfect if it possesses all the important properties of its smooth counterpart. It is known which triangle meshes admit perfect Laplace operators and how to fix any other mesh by changing the combinatorics. We extend the characterization of meshes that admit perfect Laplacians to general polygon meshes. More importantly, we provide an algorithm that computes a perfect Laplace operator for any polygon mesh without changing the combinatorics, although, possibly changing the embedding. We evaluate this algorithm and demonstrate it at applications. 相似文献
98.
99.
Robustness of ISS systems to inputs with limited moving average: Application to spacecraft formations 下载免费PDF全文
Esten Ingar Grøtli Elena Panteley Antoine Chaillet Jan Tommy Gravdahl 《国际强度与非线性控制杂志
》2016,26(4):816-833
》2016,26(4):816-833
We provide a theoretical framework that fits realistic challenges related to spacecraft formation with disturbances. We show that the input‐to‐state stability of such systems guarantees some robustness with respect to a class of signals with bounded average‐energy, which encompasses the typical disturbances acting on spacecraft formations. Solutions are shown to converge to the desired formation, up to an offset, which is somewhat proportional to the considered moving average of disturbances. In the presence of fast peaking perturbations, the approach provides a tighter evaluation of the disturbances' influence, which allows for the use of more parsimonious control gains. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
100.
Global polynomial optimization can be a powerful tool when applied to engineering problems. One of the most successful methods for solving such problems is based on convex linear matrix inequality (LMI) relaxations. Software implementations of this approach can be found for example in Matlab toolboxes GloptiPoly and YALMIP. Matlab language makes it very easy when it comes to modelling polynomial problems. However, when using these toolboxes, Matlab is also required for the problem solving. GpoSolver aims at bridging this gap by providing a Matlab-based problem modelling toolbox supplemented by a problem-solving back end in a form of a C++ template library. Once a problem is conveniently modelled and parametrized in Matlab, a C++ class is automatically generated by GpoSolver. This class can be easily included into an existing codebase and used to solve different instances of the problem based on the supplied parameters. 相似文献