全文获取类型
收费全文 | 1998篇 |
免费 | 152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 | 551篇 |
金属工艺 | 44篇 |
机械仪表 | 33篇 |
建筑科学 | 79篇 |
矿业工程 | 1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 | 20篇 |
2022年 | 48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2156条查询结果,搜索用时 0 毫秒
91.
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
92.
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
93.
The optical sectioning property of the confocal microscope offers a breakthrough from the classic observation of the hair in a scanning electron microscope (SEM). Confocal microscopy requires minimal sampling preparation, and the hair can be observed in its natural environment with less damage than by other microscopic methods such as SEM. While used in the reflection mode, the true morphology of the cuticle and the various exogenous deposits at the surface can be identified and quantified. This relatively noninvasive, nondestructive technique is routinely used by us to monitor the efficiency of cleansing shampoos, to assess the homogeneity of layering polymers, and to evaluate the changes they induce in the optical properties of the hair surface in terms of opacity, transparency, and brilliancy. A second important field of investigation uses the fluorescence channel which reveals the internal structure of the hair. Fluorescent probes (rhodamine and its derivatives) demonstrate the routes of penetration and outline the geometry of cortical cells and of the medulla according to their lipophilic or hydrophilic properties. A volume rendering of a hair cylinder provides a better understanding of the interrelationships between cuticle cells, cortical cells, and the medullar channel. This recent technology is becoming an invaluable tool for the cosmetic assessment of the hair. 相似文献
94.
We present a manufacturing method based on the dynamic use of phase plates to photowrite Bragg gratings. This process allows for control of the local value of the index modulation envelope in the grating. The application to apodized fiber Bragg gratings is discussed. 相似文献
95.
Linear-correlation amplitude changes when the intensity level of the input image is modified. As recognition is often based on the correlation-peak level, a change of the input illumination may result in a false recognition. We propose an illumination-change compensation by a post processing of the correlation distribution that is based on statistical measures of the correlation histograms. The theoretical background and simulation results are provided in the frame of an actual application in biology. 相似文献
96.
Nyström B Becker-Van Slooten K Bérard A Grandjean D Druart JC Leboulanger C 《Water research》2002,36(8):2020-2028
Irgarol 1051 is a recent herbicidal compound, inhibitor of photosynthesis, used in antifouling paints. This toxic is persistent in aquatic environments, with low abiotic and biotic degradation, highly phytotoxic, and has already been detected in estuaries and coastal areas, with suspected negative impacts on non-target organisms (aquatic plants and algae). We measured the toxicity of Irgarol 1051 to macrophytes and phytoplankton from Lake Geneva (between Switzerland and France) by determining chlorophyll fluorescence yield, and phytoplankton primary production. Long-term toxicity for phytoplankton was estimated in a microcosm study, and growth inhibition tests were performed with isolated algal strains. The concentration of Irgarol 1051 was analysed in the water, and the most polluted site showed a higher level (up to 135 ng/L) than the lowest observed effect concentration for phytoplankton (8-80 ng/L), while the macrophytes appeared to be more tolerant to Irgarol 1051 in short-term tests. The microcosm study showed that phytoplankton structure might be even more sensitive to Irgarol 1051. 相似文献
97.
An optimized explicit low-storage fourth-order Runge–Kutta algorithm is proposed in the present work for time integration. Dispersion and dissipation of the scheme are minimized in the Fourier space over a large range of frequencies for linear operators while enforcing a wide stability range. The scheme remains of order four with nonlinear operators thanks to the low-storage algorithm. Linear and nonlinear propagation problems are finally solved to illustrate the accuracy of the present Runge–Kutta scheme. 相似文献
98.
Franois Charollais Sophie Fonquernie Christophe Perrais Marc Perez Olivier Dugne Franois Cellier Grard Harbonnier Marie-Pierre Vitali 《Nuclear Engineering and Design》2006,236(5-6):534-2004
In the framework of the French V/HTR fuel development and qualification program, the Commissariat à l’Energie Atomique (CEA) and AREVA are conducting R&D projects covering the mastering of UO2 coated particle and fuel compact fabrication technology. To fulfill this task, a review of past knowledge, of existing technologies and a preliminary laboratory-scale work program have been conducted with the aim of retrieving the know-how on HTR coated particle and compact manufacture:
- • The different stages of UO2 kernel fabrication GSP process have been reviewed, reproduced and improved.
- • The experimental conditions for the chemical vapor deposition of coatings have been defined on dummy kernels and development of innovative characterization methods has been carried out.
- • Former CERCA compacting process has been reviewed and updated.
- • to recover and validate past knowledge,
- • to produce representative HTR TRISO fuel meeting industrial standards,
- • to permit the optimization of reference fabrication processes for kernels and coatings defined previously at a laboratory-scale and the investigation of alternative and innovative fuel design (UCO kernel, ZrC coating),
- • to test alternative compact process options and
- • to fabricate and characterize fuel required for irradiation and qualification purpose.
99.
Volume-Surface Trees 总被引:2,自引:0,他引:2
Tamy Boubekeur Wolfgang Heidrich Xavier Granier Christophe Schlick 《Computer Graphics Forum》2006,25(3):399-406
Many algorithms in computer graphics improve their efficiency by using Hierarchical Space Subdivision Schemes (HS3), such as octrees, kD‐trees or BSP trees. Such HS3 usually provide an axis‐aligned subdivision of the 3D space embedding a scene or an object. However, the purely volume‐based behavior of these schemes often leads to strongly imbalanced surface clustering. In this article, we introduce the VS‐Tree, an alternative HS3 providing efficient and accurate surface‐based hierarchical clustering via a combination of a global 3D decomposition at coarse subdivision levels, and a local 2D decomposition at fine levels near the surface. First, we show how to efficiently construct VS‐Trees over meshes and point‐based surfaces, and analyze the improvement it offers for cluster‐based surface simplification methods. Then we propose a new surface reconstruction algorithm based on the volume‐surface classification of the VS‐Tree. This new algorithm is faster than state‐of‐the‐art reconstruction methods and provides a final semi‐regular mesh comparable to the output of remeshing algorithms. 相似文献
100.
Bernadette Bouchon-Meunier Giulianella Coletti Christophe Marsala 《Annals of Mathematics and Artificial Intelligence》2002,35(1-4):107-123
There is not a unique definition of a conditional possibility distribution since the concept of conditioning is complex and many papers have been conducted to define conditioning in a possibilistic framework. In most cases, independence has been also defined and studied by means of a kind of analogy with the probabilistic case. In [2,4], we introduce conditional possibility as a primitive concept by means of a function whose domain is a set of conditional events. In this paper, we define a concept of independence associated with this form of conditional possibility and we show that classical properties required for independence concepts are satisfied. 相似文献