全文获取类型
收费全文 | 1253篇 |
免费 | 59篇 |
专业分类
电工技术 | 10篇 |
综合类 | 1篇 |
化学工业 | 310篇 |
金属工艺 | 27篇 |
机械仪表 | 33篇 |
建筑科学 | 43篇 |
矿业工程 | 2篇 |
能源动力 | 60篇 |
轻工业 | 104篇 |
水利工程 | 6篇 |
石油天然气 | 6篇 |
无线电 | 115篇 |
一般工业技术 | 258篇 |
冶金工业 | 98篇 |
原子能技术 | 11篇 |
自动化技术 | 228篇 |
出版年
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 31篇 |
2020年 | 25篇 |
2019年 | 19篇 |
2018年 | 22篇 |
2017年 | 35篇 |
2016年 | 37篇 |
2015年 | 30篇 |
2014年 | 39篇 |
2013年 | 84篇 |
2012年 | 74篇 |
2011年 | 76篇 |
2010年 | 68篇 |
2009年 | 76篇 |
2008年 | 74篇 |
2007年 | 60篇 |
2006年 | 62篇 |
2005年 | 53篇 |
2004年 | 37篇 |
2003年 | 35篇 |
2002年 | 31篇 |
2001年 | 20篇 |
2000年 | 13篇 |
1999年 | 24篇 |
1998年 | 33篇 |
1997年 | 19篇 |
1996年 | 18篇 |
1995年 | 17篇 |
1994年 | 16篇 |
1993年 | 14篇 |
1992年 | 9篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 4篇 |
排序方式: 共有1312条查询结果,搜索用时 156 毫秒
91.
Gilles Rochefort Frédéric Champagnat Guy Le Besnerais Jean-Fran?ois Giovannelli 《IEEE transactions on image processing》2006,15(11):3325-3337
Super-resolution (SR) techniques make use of subpixel shifts between frames in an image sequence to yield higher resolution images. We propose an original observation model devoted to the case of nonisometric inter-frame motion as required, for instance, in the context of airborne imaging sensors. First, we describe how the main observation models used in the SR literature deal with motion, and we explain why they are not suited for nonisometric motion. Then, we propose an extension of the observation model by Elad and Feuer adapted to affine motion. This model is based on a decomposition of affine transforms into successive shear transforms, each one efficiently implemented by row-by-row or column-by-column one-dimensional affine transforms. We demonstrate on synthetic and real sequences that our observation model incorporated in a SR reconstruction technique leads to better results in the case of variable scale motions and it provides equivalent results in the case of isometric motions. 相似文献
92.
Constraint Programming (CP) offers a rich modeling language of constraints embedding efficient algorithms to handle complex and heterogeneous combinatorial problems. To solve hard combinatorial optimization problems using CP alone or hybrid CP-ILP decomposition methods, costs also have to be taken into account within the propagation process. Optimization constraints, with their cost-based filtering algorithms, aim to apply inference based on optimality rather than feasibility. This paper introduces a new optimization constraint, cost-regular. Its filtering algorithm is based on the computation of shortest and longest paths in a layered directed graph. The support information is also used to guide the search for solutions. We believe this constraint to be particularly useful in modeling and solving Column Generation subproblems and evaluate its behaviour on complex Employee Timetabling Problems through a flexible CP-based column generation approach. Computational results on generated benchmark sets and on a complex real-world instance are given.A preliminary version of this paper appeared as [7]. This research was supported by the Mathematics of Information Technology and Complex Systems (MITACS) Internship program in association with Omega Optimisation Inc. (CA). 相似文献
93.
94.
Royer P Barchiesi D Lerondel G Bachelot R 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2004,362(1817):821-842
We present a particular approach and the associated results allowing the nanostructuration of a thin photosensitive polymer film. This approach based on a scanning near-field optical microscopy configuration uses the field-enhancement (FE) effect, a so-called lightning-rod effect appearing at the extremity of a metallic tip when illuminated with an incident light polarized along the tip axis. The local enhancement of the electromagnetic field straight below the tip's apex is observed directly through a photoisomerization reaction, inducing the growth of a topographical nanodot characterized in situ by atomic-force microscopy using the same probe. From a survey of the literature, we first review the different experimental approaches offered to nanostructure materials by near-field optical techniques. We describe more particularly the FE effect approach. An overview of the theoretical approach of this effect is then given before presenting some experimental results so as theoretical results using the finite-element method. These results show the influence on the nanostructuration of the polymer of a few experimental parameters such as the polarization state, the illumination mode and the tip's geometry. Finally, the potentiality of this technique for some applications in the field of lithography and high-density data storage is shown via the fabrication of nano-patterns. 相似文献
95.
Protective layers typically act in a passive way by simply separating two sides. Protection is only efficient as long as the layers are intact. If a high level of protection has to be achieved by thin layers, complementary measures need to be in place to ensure safety, even after breakage of the layer-an important issue in medical applications. Here, we present a novel approach for integrating a biocide liquid into a protective film (about 300-500 microm thick), which guarantees that a sufficient amount of biocide is rapidly released when the film is punctured. The film is composed of a middle layer, containing the liquid in droplet-like compartments, sandwiched between two elastomeric boundary layers. When the film is punctured, the liquid squirts out of the middle layer. A theoretical model was used to determine the size and density of droplets that are necessary to ensure a sufficient quantity of biocide is expelled from an adequately elastic matrix to provide protection at the site of damage. We demonstrate the utility of this approach for the fabrication of surgical gloves. 相似文献
96.
BCI Competition 2003--Data set IIa: spatial patterns of self-controlled brain rhythm modulations 总被引:6,自引:0,他引:6
A brain-computer interface (BCI) is a system that should in its ultimate form translate a subject's intent into a technical control signal without resorting to the classical neuromuscular communication channels. By using that signal to, e.g., control a wheelchair or a neuroprosthesis, a BCI could become a valuable tool for paralyzed patients. One approach to implement a BCI is to let users learn to self-control the amplitude of some of their brain rhythms as extracted from multichannel electroencephalogram. We present a method that estimates subject-specific spatial filters which allow for a robust extraction of the rhythm modulations. The effectiveness of the method was proved by achieving the minimum prediction error on data set IIa in the BCI Competition 2003, which consisted of data from three subjects recorded in ten sessions. 相似文献
97.
We measure with a gated intensified CCD camera the cross-polarized backscattered light from a linearly polarized laser beam penetrating a cloud made of spherical particles. In accordance with previously published results we observe a clear azimuthal pattern in the recorded images. We show that the pattern is symmetrical, that it originates from second-order scattering, and that higher-order scattering causes blurring that increases with optical depth. We also find that the contrast in the symmetrical features can be related to measurement of the optical depth. Moreover, when the blurring contributions are identified and subtracted, the resulting pattern provides a pure second-order scattering measurement that can be used for retrieval of droplet size. 相似文献
98.
99.
New compounds MIIThNb2O8 with MII = Ca, Sr, Cd, and CaUNb2O8 have been prepared by solid state reaction. These compounds isotypic with the rare-earth niobates LnNbO4 cristallize in a monoclinic system with space group I2/c. Like the niobates LnNbO4, they present a displacive and non quenchable transition (monoclinic to tetragonal) which is probably of second order. 相似文献
100.
The effects of the albino gene on mouse behavior were examined, particularly its possible interactions with nonallelic genes (epistasis). More generally, the possible effects of genetic background (inbreeding depression or hybrid vigor) on the effects of the mutation were also considered. Tasks requiring either predominantly motor or predominantly cognitive capacity were studied for coisogenic albino and pigmented mice from either an inbred strain (C57BL/6 c/c vs C57BL/6 +/c) or an F? heterozygous generation (F? c/c vs F? +/c) from a BALB/c?×?C57BL/6 +/c cross. Results show a clear albino gene effect in the 2 lines and provide further evidence that the gene is the effective factor. There was no significant interaction between the mutation and the genotypic group (C57BL/6 or F?), which indicates that the effects of the mutation act approximately in an additive fashion between loci in these groups. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献