全文获取类型
收费全文 | 3012篇 |
免费 | 201篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 47篇 |
综合类 | 16篇 |
化学工业 | 692篇 |
金属工艺 | 88篇 |
机械仪表 | 74篇 |
建筑科学 | 271篇 |
矿业工程 | 24篇 |
能源动力 | 90篇 |
轻工业 | 147篇 |
水利工程 | 28篇 |
石油天然气 | 2篇 |
无线电 | 232篇 |
一般工业技术 | 671篇 |
冶金工业 | 133篇 |
原子能技术 | 11篇 |
自动化技术 | 694篇 |
出版年
2024年 | 5篇 |
2023年 | 66篇 |
2022年 | 90篇 |
2021年 | 117篇 |
2020年 | 106篇 |
2019年 | 102篇 |
2018年 | 120篇 |
2017年 | 95篇 |
2016年 | 148篇 |
2015年 | 134篇 |
2014年 | 155篇 |
2013年 | 221篇 |
2012年 | 235篇 |
2011年 | 266篇 |
2010年 | 173篇 |
2009年 | 164篇 |
2008年 | 162篇 |
2007年 | 163篇 |
2006年 | 98篇 |
2005年 | 85篇 |
2004年 | 76篇 |
2003年 | 51篇 |
2002年 | 64篇 |
2001年 | 28篇 |
2000年 | 26篇 |
1999年 | 29篇 |
1998年 | 32篇 |
1997年 | 32篇 |
1996年 | 22篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 15篇 |
1992年 | 17篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1972年 | 2篇 |
1961年 | 2篇 |
排序方式: 共有3220条查询结果,搜索用时 15 毫秒
991.
992.
Christoph Schneeweiß 《OR Spectrum》1994,16(2):161-168
Zusammenfassung Die Arbeit stellt einen konzeptionellen Rahmen zur Modellierung hierarchischer Planungsprobleme bereit, indem sie die Ebenen der hierarchischen Planung als Stufen eines dynamischen Programms interpretiert. Wesentlich ist hierbei, daß die unteren Ebenen zunächst nur approximativ antizipiert werden und eine genauere Beschreibung erst in nach unten fortschreitender (rollierender) Planung erfolgt. An einigen Beispielen wird gezeigt, wie sich die vorhandenen hierarchischen Modelle in dem allgemeinen Rahmen beschreiben lassen, und es wird angedeutet, welcher Zusammenhang zu hierarchischen Algorithmen, Agency-Fragestellungen und hierarchischen Aushandlungen besteht. 相似文献
993.
Christoph Schnörr 《Journal of Mathematical Imaging and Vision》1994,4(2):189-198
We propose the minimization of a nonquadratic functional or, equivalently, a nonlinear diffusion model to smooth noisy image functionsg: R
n R while preserving significant transitions of the data. The model is chosen such that important properties of the conventional quadratic-functional approach still hold: (1) existence of a unique solution continuously depending on the datag and (2) stability of approximations using the standard finite-element method. Relations with other global approaches for the segmentation of image data are discussed. Numerical experiments with real data illustrate this approach.This work was supported by the ESPRIT project SUBSYM. 相似文献
994.
Manman Hu Andi Muhammad Risqi Jianchang Wu Liang Chen Jaewang Park Seung-Un Lee Hyun-Sung Yun Byung-Wook Park Christoph J. Brabec Sang Il Seok 《Advanced functional materials》2023,33(29):2300693
Improving the performance, reproducibility, and stability of Sn-based perovskite solar cells (PSCs) with n–i–p structures is an important challenge. Spiro-OMeTAD [2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene], a hole transporting material (HTM) with n–i–p structure, requires the oxygen exposure after addition of Li-TFSI [Lithium bis(trifluoromethanesulfonyl)imide] as a dopant to increase the hole concentration. In Sn-based PSC, Sn2+ is easily oxidized to Sn4+ under such a condition, resulting in a sharp decrease in efficiency. Herein, a formamidinium tin triiodide (FASnI3)-based PSCs fabricated using DPI-TPFB [4-Isopropyl-4′-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate] instead of Li-TFSI are reported as a dopant in Spiro-OMeTAD. The DPI-TPFB enables the fabrication of PSCs with an efficiency of up to 10.9%, the highest among FASnI3-based PSCs with n–i–p structures. Moreover, ≈80% of the initial efficiency is maintained even after 1,597 h under maximum power point tracking conditions. In particular, the encapsulated device does not show any decrease in efficiency even after holding for 50 h in the 85 °C/85% RH condition. The high efficiency and excellent stability of PSCs prepared by doping with DPI-TPFB are attributed to not only increasing electrical conductivity by acting as a Lewis acid, but also stabilizing Sn2+ through coordination with Sn2+ on the surface of FASnI3. 相似文献
995.
Virtual Reality - A “virtual mirror” is a promising interface for virtual or augmented reality applications in which users benefit from seeing themselves within the environment, such as... 相似文献
996.
A visual short-term memory task was more strongly disrupted by visual than spatial interference, and a spatial memory task was simultaneously more strongly disrupted by spatial than visual interference. This double dissociation supports a fractionation of visuospatial short-term memory into separate visual and spatial components. In 6 experiments, this interpretation could be defended against alternative explanations in terms of trade-offs in resource allocation between memory tasks and interference tasks, in terms of an involvement of short-term consolidation and long-term memory, in terms of differential phonological-loop and central-executive involvement, and in terms of similarity-based interference. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
997.
Gamma oscillations and stimulus selection 总被引:1,自引:0,他引:1
More coherent excitatory stimuli are known to have a competitive advantage over less coherent ones. We show here that this advantage is amplified greatly when the target includes inhibitory interneurons acting via GABA(A)-receptor-mediated synapses and the coherent input oscillates at gamma frequency. We hypothesize that therein lies, at least in part, the functional significance of the experimentally observed link between attentional biasing of stimulus competition and gamma frequency rhythmicity. 相似文献
998.
Suter SK Guitián JA Marton F Agus M Elsener A Zollikofer CP Gopi M Gobbetti E Pajarola R 《IEEE transactions on visualization and computer graphics》2011,17(12):2135-2143
Large scale and structurally complex volume datasets from high-resolution 3D imaging devices or computational simulations pose a number of technical challenges for interactive visual analysis. In this paper, we present the first integration of a multiscale volume representation based on tensor approximation within a GPU-accelerated out-of-core multiresolution rendering framework. Specific contributions include (a) a hierarchical brick-tensor decomposition approach for pre-processing large volume data, (b) a GPU accelerated tensor reconstruction implementation exploiting CUDA capabilities, and (c) an effective tensor-specific quantization strategy for reducing data transfer bandwidth and out-of-core memory footprint. Our multiscale representation allows for the extraction, analysis and display of structural features at variable spatial scales, while adaptive level-of-detail rendering methods make it possible to interactively explore large datasets within a constrained memory footprint. The quality and performance of our prototype system is evaluated on large structurally complex datasets, including gigabyte-sized micro-tomographic volumes. 相似文献
999.
Wei Ding Christoph F. Eick Xiaojing Yuan Jing Wang Jean-Philippe Nicot 《GeoInformatica》2011,15(1):1-28
The motivation for regional association rule mining and scoping is driven by the facts that global statistics seldom provide
useful insight and that most relationships in spatial datasets are geographically regional, rather than global. Furthermore,
when using traditional association rule mining, regional patterns frequently fail to be discovered due to insufficient global
confidence and/or support. In this paper, we systematically study this problem and address the unique challenges of regional
association mining and scoping: (1) region discovery: how to identify interesting regions from which novel and useful regional
association rules can be extracted; (2) regional association rule scoping: how to determine the scope of regional association
rules. We investigate the duality between regional association rules and regions where the associations are valid: interesting
regions are identified to seek novel regional patterns, and a regional pattern has a scope of a set of regions in which the
pattern is valid. In particular, we present a reward-based region discovery framework that employs a divisive grid-based supervised
clustering for region discovery. We evaluate our approach in a real-world case study to identify spatial risk patterns from
arsenic in the Texas water supply. Our experimental results confirm and validate research results in the study of arsenic
contamination, and our work leads to the discovery of novel findings to be further explored by domain scientists. 相似文献
1000.