全文获取类型
收费全文 | 2059篇 |
免费 | 78篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 38篇 |
综合类 | 2篇 |
化学工业 | 427篇 |
金属工艺 | 10篇 |
机械仪表 | 30篇 |
建筑科学 | 45篇 |
能源动力 | 44篇 |
轻工业 | 156篇 |
水利工程 | 10篇 |
石油天然气 | 5篇 |
无线电 | 143篇 |
一般工业技术 | 207篇 |
冶金工业 | 798篇 |
原子能技术 | 8篇 |
自动化技术 | 216篇 |
出版年
2024年 | 5篇 |
2023年 | 27篇 |
2022年 | 59篇 |
2021年 | 95篇 |
2020年 | 46篇 |
2019年 | 49篇 |
2018年 | 50篇 |
2017年 | 37篇 |
2016年 | 50篇 |
2015年 | 34篇 |
2014年 | 80篇 |
2013年 | 82篇 |
2012年 | 87篇 |
2011年 | 101篇 |
2010年 | 81篇 |
2009年 | 58篇 |
2008年 | 51篇 |
2007年 | 59篇 |
2006年 | 58篇 |
2005年 | 34篇 |
2004年 | 30篇 |
2003年 | 32篇 |
2002年 | 20篇 |
2001年 | 21篇 |
2000年 | 9篇 |
1999年 | 25篇 |
1998年 | 209篇 |
1997年 | 129篇 |
1996年 | 92篇 |
1995年 | 56篇 |
1994年 | 45篇 |
1993年 | 45篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 15篇 |
1980年 | 16篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 68篇 |
1976年 | 92篇 |
1975年 | 4篇 |
1955年 | 1篇 |
排序方式: 共有2139条查询结果,搜索用时 31 毫秒
51.
Irene Taurino Sandro Carrara Mauro Giorcelli Alberto Tagliaferro Giovanni De MicheliAuthor vitae 《Sensors and actuators. B, Chemical》2011,160(1):327
In this study, we report on multi-walled carbon nanotubes fabricated on silicon substrate with four different orientations via chemical vapor deposition. It is well-known that chemical treatments improve the nanotube electrochemical reactivity by creating edge-like defects on their exposed sidewalls. Before use, we performed an acid treatment on carbon nanotubes. To prove the effect of the treatment on these nanostructured electrodes, contact angles were measured. Then, sensitivities and detection limits were evaluated performing cyclic voltammetry. Two target molecules were used: potassium ferricyanide, an inorganic electroactive molecule, and hydrogen peroxide that is a product of reactions catalyzed by many enzymes, such as oxidases and peroxidases. Carbon nanotubes with tilted tips become hydrophilic after the treatment showing a contact angle of 22° ± 2°. This kind of electrode has shown also the best electrochemical performance. Sensitivity and detection limit values are 110.0 ± 0.5 μA/(mM cm2) and 8 μM for potassium ferricyanide solutions and 16.4 ± 0.1 μA/(mM cm2) and 24 μM using hydrogen peroxide as target compound. Considering the results of wettability and voltammetric measurements, nanotubes with tilted tips-based electrodes are found to be the most promising for future biosensing applications. 相似文献
52.
53.
Sacchi M Spezzani C Carpentiero A Prasciolu M Delaunay R Lüning J Polack F 《The Review of scientific instruments》2007,78(4):043702
We have developed a setup for measuring holographically formed interference patterns using an integrated sample-mask design. The direct space image of the sample is obtained via a two-dimensional Fourier transform of the X-ray diffraction pattern. We present the details of our setup, commenting on the influence of geometrical parameters on the imaging capabilities. As an example, we present and discuss the results of test experiments on a patterned Co film. 相似文献
54.
A number of techniques that infer finite state automata from execution traces have been used to support test and analysis activities. Some of these techniques can produce automata that integrate information about the data-flow, that is, they also represent how data values affect the operations executed by programs.The integration of information about operation sequences and data values into a unique model is indeed conceptually useful to accurately represent the behavior of a program. However, it is still unclear whether handling heterogeneous types of information, such as operation sequences and data values, necessarily produces higher quality models or not.In this paper, we present an empirical comparative study between techniques that infer simple automata and techniques that infer automata extended with information about data-flow. We investigate the effectiveness of these techniques when applied to traces with different levels of sparseness, produced by different software systems. To the best of our knowledge this is the first work that quantifies both the effect of adding data-flow information within automata and the effectiveness of the techniques when varying sparseness of traces. 相似文献
55.
Lorenzo Repetto Mauro Parodi Marco Storace 《International Journal of Circuit Theory and Applications》2006,34(2):237-248
In this paper we propose a variational method to find out piecewise‐linear (PWL) approximations of non‐linear dynamical systems in view of their circuit implementations. The method is based on some significant trajectories of the dynamical system and provides reasonably accurate PWL approximations with a relatively low number of parameters. The effectiveness of the method is validated by applying it to the approximation of limit cycles (both stable and unstable) in the Bautin system. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
56.
The Unified Problem-Solving Method
Development Language UPML 总被引:2,自引:1,他引:2
57.
Storm overflow structures in combined sewers are used to separate sewage from storm water. For subcritical approach flow, sideweirs are currently used; however, they often behave hydraulically poor. This study was conducted to explore a combined storm overflow structure able to improve the hydraulic performance of sewer sideweirs. Such a structure consists of a low-crested sideweir and a bottom opening just downstream from the sideweir end. First, the hydraulic design procedure is described, and then, based on laboratory experiments and by using the governing flow equations, the main hydraulic features are highlighted. The results indicate that the proposed device has advantageous characteristics in terms of hydraulic efficiency, reliability, and maintenance. 相似文献
58.
In large‐scale fires, the input of energy to burning materials occurs predominantly by radiative transfer. The in‐depth (rather than just surface) absorption of radiant energy by a polymer influences its ignition time and burning rate. The present investigation examines two methods for obtaining the absorption coefficient of polymers for infrared radiation from high‐temperature sources: a broadband method and a spectral method. Data on the total average broadband transmittance for 11 thermoplastics are presented (as are reflectance data), and the absorption coefficient is found to vary with thickness. Implications for modeling of mass loss experiments are discussed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
59.
60.
Marco Cariglia Alfredo Vargas-Paredes Mauro M. Doria Antonio Bianconi Milorad V. Milošević Andrea Perali 《Journal of Superconductivity and Novel Magnetism》2016,29(12):3081-3086
Ultrathin superconductors of different materials are becoming a powerful platform to find mechanisms for enhancement of superconductivity, exploiting shape resonances in different superconducting properties. Here, we evaluate the superconducting gap and its spatial profile, the multiple gap components, and the chemical potential, of generic superconducting nanofilms, considering the pairing attraction and its energy scale as tunable parameters, from weak to strong coupling, at fixed electron density. Superconducting properties are evaluated at mean field level as a function of the thickness of the nanofilm, in order to characterize the shape resonances in the superconducting gap. We find that the most pronounced shape resonances are generated for weakly coupled superconductors, while approaching the strong coupling regime the shape resonances are rounded by a mixing of the subbands due to the large energy gaps extending over large energy scales. Finally, we find that the spatial profile, transverse to the nanofilm, of the superconducting gap acquires a flat behavior in the shape resonance region, indicating that a robust and uniform multigap superconducting state can arise at resonance. 相似文献