全文获取类型
收费全文 | 1229篇 |
免费 | 80篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 282篇 |
金属工艺 | 23篇 |
机械仪表 | 24篇 |
建筑科学 | 44篇 |
矿业工程 | 1篇 |
能源动力 | 57篇 |
轻工业 | 86篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 117篇 |
一般工业技术 | 256篇 |
冶金工业 | 135篇 |
原子能技术 | 12篇 |
自动化技术 | 250篇 |
出版年
2023年 | 14篇 |
2022年 | 25篇 |
2021年 | 48篇 |
2020年 | 26篇 |
2019年 | 47篇 |
2018年 | 44篇 |
2017年 | 34篇 |
2016年 | 48篇 |
2015年 | 44篇 |
2014年 | 59篇 |
2013年 | 91篇 |
2012年 | 87篇 |
2011年 | 132篇 |
2010年 | 77篇 |
2009年 | 72篇 |
2008年 | 86篇 |
2007年 | 54篇 |
2006年 | 59篇 |
2005年 | 39篇 |
2004年 | 25篇 |
2003年 | 26篇 |
2002年 | 17篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 15篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1958年 | 2篇 |
1954年 | 3篇 |
1948年 | 2篇 |
1947年 | 2篇 |
1946年 | 2篇 |
排序方式: 共有1310条查询结果,搜索用时 15 毫秒
41.
Julien Mouli-Castillo Stuart R. Haszeldine Kevin Kinsella Mark Wheeldon Angus McIntosh 《International Journal of Hydrogen Energy》2021,46(29):16217-16231
The increased reliance on natural gas for heating worldwide makes the search for carbon-free alternatives imperative, especially if international decarbonisation targets are to be met. Hydrogen does not release carbon dioxide (CO2) at the point of use which makes it an appealing candidate to decarbonise domestic heating. Hydrogen can be produced from either 1) the electrolysis of water with no associated carbon emissions, or 2) from methane reformation (using steam) which produces CO2, but which is easily captured and storable during production. Hydrogen could be transported to the end-user via gas distribution networks similar to, and adapted from, those in use today. This would reduce both installation costs and end-user disruption. However, before hydrogen can provide domestic heat, it is necessary to assess the ‘risk’ associated with its distribution in direct comparison to natural gas. Here we develop a comprehensive and multi-faceted quantitative risk assessment tool to assess the difference in ‘risk’ between current natural gas distribution networks, and the potential conversion to a hydrogen based system. The approach uses novel experimental and modelling work, scientific literature, and findings from historic large scale testing programmes. As a case study, the risk assessment tool is applied to the newly proposed H100 demonstration (100% hydrogen network) project. The assessment includes the comparative risk of gas releases both upstream and downstream of the domestic gas meter. This research finds that the risk associated with the proposed H100 network (based on its current design) is lower than that of the existing natural gas network by a factor 0.88. 相似文献
42.
Petty corruption is a barrier to entrepreneurship in emerging countries, justifying to investigate its determinants. Using data on 1,240 entrepreneurs across Indonesian regions, we analyse the effects of social capital. Two-evel ordered probit regressions show that weak-ties discourage entrepreneurs' bribing, strong-ties encourage it, whereas this latter effect is moderated by the quality of access to formal credit. Bribing banks or turning to relatives for external funding are alternative solutions for entrepreneurs facing poor access to formal credit, a common feature in emerging countries, and the second solution is preferred given the risk and psychological costs of corruption. 相似文献
43.
44.
An extended state observer (ESO)-based loop flter is designed for the phase-locked loop (PLL) involved in a disturbed gridconnected converter (GcC). This ESO-based design enhances the performances and robustness of the PLL, and, therefore, improves control performances of the disturbed GcCs. Besides, the ESO-based LF can be applied to PLLs with extra flters for abnormal grid conditions. The unbalanced grid is particularly taken into account for the performance analysis. A tuning approach based on the well-designed PI controller is discussed, which results in a fair comparison with conventional PItype PLLs. The frequency domain properties are quantitatively analysed with respect to the control stability and the noises rejection. The frequency domain analysis and simulation results suggest that the performances of the generated ESO-based
controllers are comparable to those of the PI control at low frequency, while have better ability to attenuate high-frequency measurement noises. The phase margin decreases slightly, but remains acceptable. Finally, experimental tests are conducted with a hybrid power hardware-in-the-loop benchmark, in which balanced/unbalanced cases are both explored. The obtained results prove the efectiveness of ESO-based PLLs when applied to the disturbed GcC. 相似文献
45.
46.
47.
A new method is developed to obtain guaranteed error bounds on pointwise quantities of interest for linear transient viscodynamics
problems. The calculation of strict error bounds is based on the concept of “constitutive relation error” (CRE) and the solution
of an adjoint problem. The central and original point of this work is the treatment of the singularity in space and time introduced
by the loading of the adjoint problem. Hence, the adjoint solution is decomposed into two parts: (i) an analytical part determined
from Green’s functions; (ii) a residual part approximated with classical numerical tools (finite element method, Newmark integration
scheme). The capabilities and the limits of the proposed approach are analyzed on a 2D example. 相似文献
48.
Pierre Melchior Mathieu Pellet Julien Petit Jean-Marie Cabelguen Alain Oustaloup 《Signal, Image and Video Processing》2012,6(3):421-428
Muscle models are useful in bio-inspired robotic, because they allow to reproduce accurately natural motion. When they are used for robotic issue, they need to be compact and embeddable. The non-integer model order has the advantage to ensure a parametrical parsimony that permits to implant it easily on an embedded system. Thus, a fractional multi-model of muscle was identified and presented in later paper. This model is able to predict the response of a motor unit to an electrical stimulation, considering isometric contractions (that is to say, muscle length is constant). There are three different physiological types of motor unit (FR, FF, and S). The aim of this work is to study muscle length impact on the multi-model and the limitations of the linear multi-model. Previous paper was published using FR type motor unit. In this paper, the results of the study using S type motor unit are presented. 相似文献
49.
A comparison of partially acetylated nanocellulose,nanocrystalline cellulose,and nanoclay as fillers for high‐performance polylactide nanocomposites
下载免费PDF全文
![点击此处可从《应用聚合物科学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jon Trifol David Plackett Cecile Sillard Ole Hassager Anders Egede Daugaard Julien Bras Peter Szabo 《应用聚合物科学杂志》2016,133(14)
Partially acetylated cellulose nanofibers (CNF) were chemically extracted from sisal fibers and the performance of those CNF as nanofillers for polylactide (PLA) for food packaging applications was evaluated. Three PLA nanocomposites; PLA/CNF (cellulose nanofibers), PLA/CNC (nanocrystalline cellulose), and PLA/C30B (CloisiteTM 30B, an organically modified montmorillonite clay) were prepared and their properties were evaluated. It was found that CNF reinforced composites showed a larger decrease on oxygen transmission rate (OTR) than the clay‐based composites; (PLA/CNF 1% nanocomposite showed a 63% of reduction at 23°C and 50% RH while PLA/C30B 1% showed a 26% decrease) and similar behavior on terms of water vapor barrier properties with 46 and 43%, respectively of decrease on water vapor transmission rate at 23°C and 50% RH (relative humidity). In terms of mechanical and thermomechanical properties, CNF‐based nanocomposites showed better performance than clay‐based composites without affecting significantly the optical transparency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43257. 相似文献
50.
Nanocomposites of PBAT and cellulose nanocrystals modified by in situ polymerization and melt extrusion 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Polymer Engineering and Science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Carolina L. Morelli Mohamed N. Belgacem Márcia C. Branciforti Marie C. B. Salon Julien Bras Rosario E. S. Bretas 《Polymer Engineering and Science》2016,56(12):1339-1348
Cellulose nanocrystals (CNC) were successfully grafted with a low molecular weight poly(butylene glutarate) through an in situ polymerization procedure. The grafting treatment decreased the CNC hydrophilic character and increased the onset of their thermal degradation by approximately 20°C, thus increasing the possibilities of CNC application. Composites of grafted and nongrafted CNC with a poly(butylene‐adipate‐co‐terephthalate) (PBAT) matrix were prepared by melt extrusion. The CNC addition led to an increase of 50% of the tensile elastic modulus of the PBAT. In addition, dynamic mechanical thermal analysis showed that the composite with CNC retained its high modulus even at temperatures far above the glass transition temperature of PBAT. At 60°C the storage modulus of the composite with CNC was approximately 200% higher than that of the pure PBAT. Thus, in this work, nanocomposites of improved properties were obtained through a combination of in situ polymerization and melt extrusion. POLYM. ENG. SCI., 56:1339–1348, 2016. © 2016 Society of Plastics Engineers 相似文献