全文获取类型
收费全文 | 476篇 |
免费 | 21篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 157篇 |
金属工艺 | 25篇 |
机械仪表 | 19篇 |
建筑科学 | 7篇 |
矿业工程 | 2篇 |
能源动力 | 18篇 |
轻工业 | 9篇 |
水利工程 | 2篇 |
无线电 | 47篇 |
一般工业技术 | 87篇 |
冶金工业 | 11篇 |
原子能技术 | 4篇 |
自动化技术 | 101篇 |
出版年
2023年 | 3篇 |
2022年 | 32篇 |
2021年 | 28篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 21篇 |
2017年 | 13篇 |
2016年 | 21篇 |
2015年 | 17篇 |
2014年 | 26篇 |
2013年 | 45篇 |
2012年 | 27篇 |
2011年 | 45篇 |
2010年 | 21篇 |
2009年 | 38篇 |
2008年 | 26篇 |
2007年 | 21篇 |
2006年 | 16篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有497条查询结果,搜索用时 15 毫秒
111.
112.
Despite the sound theoretical, methodological, and experimental background inherited from 2D video, the stereoscopic video watermarking imposed itself as an open research topic. Paving the way towards practical deployment of such copyright protection mechanisms, the present paper is structured as a comparative study on the main classes of 2D watermarking methods (spread spectrum, side information, hybrid) and on their related optimal stereoscopic insertion domains (view or disparity based). The performances are evaluated in terms of transparency, robustness, and computational cost. First, the watermarked content transparency is assessed by both subjective protocols (according to ITU-R BT 500-12 and BT 1438 recommendations) and objective quality measures (five metrics based on differences between pixels and on correlation). Secondly, the robustness is objectively expressed by means of the watermark detection bit error rate against several classes of attacks, such as linear and nonlinear filtering, compression, and geometric transformations. Thirdly, the computational cost is estimated for each processing step involved in the watermarking chain. All the quantitative results are obtained out of processing two corpora of stereoscopic visual content: (1) the 3DLive corpus, summing up about 2 h of 3D TV content captured by French professionals, and (2) the MPEG 3D video reference corpus, composed of 17 min provided by both academic communities and industrials. It was thus established that for a fixed size of the mark, a hybrid watermark insertion performed into a new disparity map representation is the only solution jointly featuring imperceptibility (according to the subjective tests), robustness against the three classes of attacks, and nonprohibitive computational cost. 相似文献
113.
The preparation and characterization of new organic/inorganic composites by the consecutive adsorption of weak polyelectrolytes
on silica particles were studied in the article. Two polycations containing primary amine groups in the side chains, poly(vinylamine)
or poly[N(β-aminoethylene) acrylamide], and poly(acrylic acid) as polyanion were used for the hybrid materials construction. The stability
of the organic/inorganic composites has been increased by a heat-induced reaction at 150 °C. The organic/silica hybrids properties
were monitored by potentiometric titration, laser light scattering, infrared spectroscopy, and thermogravimetric analysis.
The adsorption of methylene blue by the composite materials has been tested. The dye adsorption capacity was strongly influenced
by the dye concentration, the nature of the last adsorbed layer, the polyions concentration, and the composite thermal treatment. 相似文献
114.
Mihai Nadin 《AI & Society》2018,33(4):467-485
The current assumptions of knowledge acquisition brought about the crisis in the reproducibility of experiments. A complementary perspective should account for the specific causality characteristic of life by integrating past, present, and future. A “second Cartesian revolution,” informed by and in awareness of anticipatory processes, should result in scientific methods that transcend the theology of determinism and reductionism. In our days, science, itself an expression of anticipatory activity, makes possible alternative understandings of reality and its dynamics. For this purpose, the study advances G-complexity for defining and comparing decidable and undecidable knowledge. AI and related computational expressions of knowledge could benefit from the awareness of what distinguishes the dynamics of life from any other expressions of change. 相似文献
115.
116.
117.
118.
The aricle presents the results of a research performed in order to establish whether drying lumber from frozen state (in winter) has repercussions upon its properties, compared to drying under the same conditions lumber parts originating from the same log and position within the log section but that were not frozen prior to drying. To this purpose, spruce (Picea abies L.) lumber specimens, 35 mm and 55 mm thick, cut from the same log, half frozen at - 30°C and half unfrozen, were dried under the same conditions in a climate chamber. Some mechanical properties (hardness, bending strength, and modulus elasticity in static bending), as well as workability (expressed by means of the absorbed power and specific resistance to cutting during milling), were determined The results revealed slight differences between the frozen and the unfrozen samples both during the drying process and afterwards. It was noticed that a significant amount of water was removed from wood during the very beginning of the heating phase (thawing). With regards to wood properties after drying, a slight lowering of the mechanical properties and better workability could be established for the initially frozen samples. 相似文献
119.
120.
Kyle P. Schmitt Mihai Anitescu Dan Negrut 《International journal for numerical methods in engineering》2009,80(5):537-564
We present two methods for efficiently sampling the response (trajectory space) of multibody systems operating under spatial uncertainty, when the latter is assumed to be representable with Gaussian processes. In this case, the dynamics (time evolution) of the multibody systems depends on spatially indexed uncertain parameters that span infinite‐dimensional spaces. This places a heavy computational burden on existing methodologies, an issue addressed herein with two new conditional sampling approaches. When a single instance of the uncertainty is needed in the entire domain, we use a fast Fourier transform technique. When the initial conditions are fixed and the path distribution of the dynamical system is relatively narrow, we use an incremental sampling approach that is fast and has a small memory footprint. Both methods produce the same distributions as the widely used Cholesky‐based approaches. We illustrate this convergence at a smaller computational effort and memory cost for a simple non‐linear vehicle model. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献