全文获取类型
收费全文 | 1975篇 |
免费 | 163篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 24篇 |
综合类 | 2篇 |
化学工业 | 540篇 |
金属工艺 | 44篇 |
机械仪表 | 33篇 |
建筑科学 | 79篇 |
能源动力 | 72篇 |
轻工业 | 238篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 211篇 |
一般工业技术 | 394篇 |
冶金工业 | 49篇 |
原子能技术 | 36篇 |
自动化技术 | 414篇 |
出版年
2024年 | 1篇 |
2023年 | 18篇 |
2022年 | 38篇 |
2021年 | 65篇 |
2020年 | 51篇 |
2019年 | 45篇 |
2018年 | 62篇 |
2017年 | 72篇 |
2016年 | 67篇 |
2015年 | 78篇 |
2014年 | 103篇 |
2013年 | 160篇 |
2012年 | 137篇 |
2011年 | 221篇 |
2010年 | 146篇 |
2009年 | 135篇 |
2008年 | 126篇 |
2007年 | 86篇 |
2006年 | 88篇 |
2005年 | 79篇 |
2004年 | 58篇 |
2003年 | 63篇 |
2002年 | 45篇 |
2001年 | 24篇 |
2000年 | 20篇 |
1999年 | 29篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 23篇 |
1995年 | 6篇 |
1994年 | 17篇 |
1993年 | 15篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有2144条查询结果,搜索用时 640 毫秒
111.
112.
Mechanochemical degradation of poly(vinyl fluoride) by sodium hydroxide measured by microindentation
Mohamad Alchikh Christophe Fond Yves Frère Hervé Pelletier 《Journal of Materials Science》2010,45(9):2311-2316
The degradation of the mechanical properties of deformed PVDF during its mechanochemical ageing in sodium hydroxide (soda) was followed by microindentation measurements, especially the local reduction of the elastic modulus and the hardness. This allows measurements on a local scale of the mechanical properties on the surface and in-depth as a function of the strain level and the ageing time. Microindentation tests with Berkovich indenter have been performed with a Nanoindenter XP® (MTS). Measurements are made at penetration depth less than 2 μm for an applied load of 10 mN. During ageing in soda (Ph 14) at 90 °C up to 16 days, various deformations ε (0, 22 and 38%) are imposed on PVDF tensile specimen. For the first two imposed deformations (ε = 0 and ε = 22%), mechanical degradation is limited to some percent (less than 7%). For the greatest deformation (ε = 38%), mechanical degradation continues to decrease with ageing time (more than 21%). Microindentation tests show that a range of low deformations exists in which the mechanochemical degradation is limited and no limitation is observed for larger imposed deformation. 相似文献
113.
The aim of this paper is to provide new empirical evidence on the relationship between energy consumption and economic growth for 21 African countries over the period from 1970 to 2006, using recently developed panel cointegration and causality tests. The countries are divided into two groups: net energy importers and net energy exporters. It is found that there exists a long-run equilibrium relationship between energy consumption, real GDP, prices, labor and capital for each group of countries as well as for the whole set of countries. This result is robust to possible cross-country dependence and still holds when allowing for multiple endogenous structural breaks, which can differ among countries. Furthermore, we find that decreasing energy consumption decreases growth and vice versa, and that increasing energy consumption increases growth, and vice versa, and that this applies for both energy exporters and importers. Finally, there is a marked difference in the cointegration relationship when country groups are considered. 相似文献
114.
Laurent Mezeix Christophe Bouvet Julitte Huez Dominique Poquillon 《Journal of Materials Science》2009,44(14):3652-3661
Entangled fibrous materials have been manufactured from different fibers: metallic fibers, glass fibers, and carbon fibers.
Specimens have been produced with and without cross-links between fibers. Cross-links have been achieved using epoxy spraying.
The scope of this article is to analyze the mechanical behavior of these materials and to compare it with available models.
The first part of this article deals with entangled fibrous materials without cross-link between fibers. Compression tests
are detailed and test reproducibility is checked. In the second part, compression tests were performed on materials manufactured
with cross-linked fibers. The specific mechanical behavior obtained is discussed. 相似文献
115.
Christophe Rapine Nadia Brauner Gerd Finke Vassilissa Lebacque 《Journal of Scheduling》2012,15(2):127-139
For an industrial application in the chemical industry, we were confronted with the planning of experiments, where human intervention
of a chemist is required to handle the starting and termination of each of the experiments. This gives rise to a new type
of scheduling problem, namely problems of finding schedules with time periods when the tasks can neither start nor finish.
We consider in this paper the natural case of small periods where the duration of the periods is smaller than any processing time. This assumption corresponds to our chemical
experiments lasting several days, whereas the operator unavailability periods are typically single days or week-ends. These
problems are analyzed on a single machine with the makespan as criterion. 相似文献
116.
Christophe Charrier Olivier Lézoray Gilles Lebrun 《Signal Processing: Image Communication》2012,27(3):209-219
A crucial step in image compression is the evaluation of its performance, and more precisely, available ways to measure the quality of compressed images. In this paper, a machine learning expert, providing a quality score is proposed. This quality measure is based on a learned classification process in order to respect human observers. The proposed method namely Machine Learning-based Image Quality Measure (MLIQM) first classifies the quality using multi-Support Vector Machine (SVM) classification according to the quality scale recommended by the ITU. This quality scale contains 5 ranks ordered from 1 (the worst quality) to 5 (the best quality). To evaluate the quality of images, a feature vector containing visual attributes describing images content is constructed. Then, a classification process is performed to provide the final quality class of the considered image. Finally, once a quality class is associated to the considered image, a specific SVM regression is performed to score its quality. Obtained results are compared to the one obtained applying classical Full-Reference Image Quality Assessment (FR-IQA) algorithms to judge the efficiency of the proposed method. 相似文献
117.
Christos Baloukas Author Vitae Jose L. Risco-Martin Author Vitae Christophe Poucet Author Vitae Lazaros Papadopoulos Author Vitae Juan Lanchares Author Vitae 《Journal of Systems and Software》2009,82(4):590-602
Modern multimedia application exhibit high resource utilization. In order to efficiently run this kind of applications in embedded systems, the dynamic memory subsystem needs to be optimized. A key role in this optimization is played by the dynamic data structures that reside in every real-life application. This paper presents a novel and automated way to optimize dynamic data structures. The search space is pruned using genetic algorithms that converge to the best multilayered data structure implementation for the targeted applications. 相似文献
118.
Niamh Harbourne Eunice Marete Jean Christophe Jacquier Dolores O'Riordan 《Food research international (Ottawa, Ont.)》2013,50(2):480-486
Recently phytochemical constituents have attracted a lot of interest as sources of functional ingredients in food product formulations. However, before being incorporated into foods or beverages the stability of these bioactive constituents during post-harvest preservation procedures, in food matrices and during processing and storage must be considered. This review will focus on the stability of phytochemical constituents of herbs with anti-inflammatory properties, including chamomile, meadowsweet, feverfew and willow. These herbs contain a relatively high content of phenolic compounds in comparison to common fruits and vegetables. They have been traditionally used to make teas or infusions that are consumed as a remedy for pain and inflammation. Effects of preservation and extraction conditions on the level of bioactive constituents will be reviewed. The storage conditions (temperature) and thermal processing at pH levels encountered in food products will also be examined. 相似文献
119.
120.
Ferrari CP Dommergue A Veysseyre A Planchon F Boutron CF 《The Science of the total environment》2002,287(1-2):61-69
Snow samples have been collected in the French Alps in 1998, 1999 and 2000 in order to measure both total Hg (HgT) and reactive Hg (HgR). Concentrations of HgT were between 13 and 130 pg g(-1) and HgR concentrations were below the detection limit (approximately 0.8 pg g(-1)). Hg speciation in snow was evaluated on the basis of ionic complexation equilibrium with chloride, hydroxide, oxalate. The pH of the snow was found to be an important parameter for Hg speciation. For pH values near 3, HgC2O4 is predominant in snow samples except for snow strongly influenced by anthropogenic sources (in which case HgCl2 predominates). When pH > 4, Hg(OH)2 and HgOHCl are predominant. These latter pH values are observed for precipitation not influenced by anthropogenic sources but more by soil erosion, e.g. Saharan dusts. The knowledge of Hgr speciation in snow is a key question for understanding the mechanisms of transformation of these complexes in snow after precipitation. 相似文献