全文获取类型
收费全文 | 97000篇 |
免费 | 9405篇 |
国内免费 | 4000篇 |
专业分类
电工技术 | 7006篇 |
技术理论 | 6篇 |
综合类 | 7794篇 |
化学工业 | 13074篇 |
金属工艺 | 6443篇 |
机械仪表 | 6689篇 |
建筑科学 | 7209篇 |
矿业工程 | 3440篇 |
能源动力 | 2839篇 |
轻工业 | 8343篇 |
水利工程 | 2770篇 |
石油天然气 | 4295篇 |
武器工业 | 1088篇 |
无线电 | 10374篇 |
一般工业技术 | 10456篇 |
冶金工业 | 4277篇 |
原子能技术 | 1613篇 |
自动化技术 | 12689篇 |
出版年
2025年 | 608篇 |
2024年 | 2279篇 |
2023年 | 2152篇 |
2022年 | 3372篇 |
2021年 | 4331篇 |
2020年 | 3478篇 |
2019年 | 2841篇 |
2018年 | 2794篇 |
2017年 | 3115篇 |
2016年 | 2869篇 |
2015年 | 4029篇 |
2014年 | 5036篇 |
2013年 | 5826篇 |
2012年 | 6881篇 |
2011年 | 7134篇 |
2010年 | 6577篇 |
2009年 | 6278篇 |
2008年 | 6207篇 |
2007年 | 5970篇 |
2006年 | 5280篇 |
2005年 | 4426篇 |
2004年 | 3301篇 |
2003年 | 2558篇 |
2002年 | 2654篇 |
2001年 | 2413篇 |
2000年 | 1899篇 |
1999年 | 1400篇 |
1998年 | 894篇 |
1997年 | 686篇 |
1996年 | 635篇 |
1995年 | 556篇 |
1994年 | 405篇 |
1993年 | 345篇 |
1992年 | 272篇 |
1991年 | 195篇 |
1990年 | 159篇 |
1989年 | 110篇 |
1988年 | 110篇 |
1987年 | 55篇 |
1986年 | 68篇 |
1985年 | 35篇 |
1984年 | 29篇 |
1983年 | 20篇 |
1982年 | 18篇 |
1981年 | 20篇 |
1980年 | 20篇 |
1979年 | 17篇 |
1977年 | 7篇 |
1959年 | 6篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Group interaction analysis in dynamic context. 总被引:1,自引:0,他引:1
Peng Dai Huijun Di Ligeng Dong Linmi Tao Guangyou Xu 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2008,38(1):275-282
Computer understanding of human actions and interactions is one of the key research issues in human computing. In this regard, context plays an essential role in semantic understanding of human behavioral and social signals from sensor data. This paper put forward an event-based dynamic context model to address the problems of context awareness in the analysis of group interaction scenarios. Event-driven multilevel dynamic Bayesian network is correspondingly proposed to detect multilevel events, which underlies the context awareness mechanism. Online analysis can be achieved, which is superior over previous works. Experiments in our smart meeting room demonstrate the effectiveness of our approach. 相似文献
43.
Dong RG Welcome DE Wu JZ 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2007,221(8):847-861
This study generally hypothesized that the vibration-induced biodynamic stress and number of its cycles in a substructure of the hand-arm system play an important role in the development of vibration-induced disorders in the substructure. As the first step to test this hypothesis, the specific aims of this study were to develop a practical method to quantify the biodynamic stress-cycle measure, to compare it with ISO-weighted and unweighted accelerations, and to assess its potential for applications. A mechanical-equivalent model of the system was established using reported experimental data. The model was used to estimate the average stresses in the fingers and palm. The frequency weightings of the stresses in these substructures were derived using the proposed stress-cycle measure. This study found the frequency dependence of the average stress distributed in the fingers is different from that in the palm. Therefore, this study predicted that the frequency dependencies of finger disorders could also be different from those of the disorders in the palm, wrist, and arms. If vibration-induced white finger (VWF) is correlated better with unweighted acceleration than with ISO-weighted acceleration, the biodynamic stress distributed in the fingers is likely to play a more important role in the development of VWF than is th e biodynamic stressdistributed in the other substructures of the hand-arm system. The results of this study also suggest that the ISO weighting underestimates the high-frequency effect on the finger disorder development but it may provide a reasonable risk assessment of the disorders in the wrist and arm. 相似文献
44.
随着我国大中小型水利水电工程的不断发展,土石坝浇筑式沥青混凝土防渗心墙施工新技术得以广泛推广和应用,既消除了传统混凝土工程中的分层离析现象,既提高了混凝土整体的均匀性,又可以保证混凝土防渗心墙的可靠性与安全性。本文针对土石坝浇筑式沥青混凝土防渗心墙施工新技术的研究与应用作了四个方面的探讨。 相似文献
45.
介绍了大气污染控制工程课程教学改革研究的内容,提出了由教学内容、教学形式、教学平台与教学评价等4方面组成的立体化课程教学模式,并讨论了该模式下教学资源平台的建设,给出了大气污染控制工程课程的评价和考核方法.该模式在实践教学中取得了比较好的成效. 相似文献
46.
对上海市地铁列车中的三种不同车型的微机控制系统的总线进行分析与研究,并针对近年总线通信中出现的问题,提出改进方法。 相似文献
47.
Facial expression recognition using radial encoding of local Gabor features and classifier synthesis
Primarily motivated by some characteristics of the human visual cortex (HVC), we propose a new facial expression recognition scheme, involving a statistical synthesis of hierarchical classifiers. In this scheme, the input images of the database are first subjected to local, multi-scale Gabor-filter operations, and then the resulting Gabor decompositions are encoded using radial grids, imitating the topographical map-structure of the HVC. The codes are fed to local classifiers to produce global features, representing facial expressions. Experimental results show that such a hybrid combination of the HVC structure with a hierarchical classifier significantly improves expression recognition accuracy when applied to wide-ranging databases in comparison with the results in the literature. Furthermore, the proposed system is not only robust to corrupted data and missing information, but can also be generalized to cross-database expression recognition. 相似文献
48.
Haptic and audio cues now appear commonly in computer interfaces, partially due to inherent advantages such as their support for eyes-free interaction. Their invisible, unobservable nature also makes them ideal candidates for security interfaces in which users have to enter secret information such as passwords. In particular, researchers have explored this idea through the design of PIN entry authentication systems based on multi-modal combinations of visual and non-visual content or on the recognition of small sets of unimodal haptic or audio stimuli. This paper highlights the benefits and performance limitations of these approaches and introduces an alternative based on unimodal audio or haptic temporal numerosity – the ability to accurately and rapidly determine the number of cues presented in rapid temporal succession. In essence, in a numerosity interface, rather than recognizing distinct cues, users must count the number of times that a single cue occurs. In an iterative process of design and evaluation, three prototypes implementing this concept are presented and studies of their use reported. The results show the fastest PIN entry times and lowest error rates to be 8 s and 2%, figures that improve substantially on previous research. These results are attained while maintaining low levels of workload and substantial resistance to observation attack (as determined via camera attack security studies). In sum, this paper argues that unimodal audio and haptic numerosity is a valuable and relatively unexplored metaphor for non-visual input and demonstrates the validity of this claim in the demanding task of unobservable authentication systems. 相似文献
49.
文章立足于公共事业管理专业培养目标和实践教学的特点,分析了在公共事业管理专业开展《罗氏议事规则》实务训练的选题背景和必要性,论述了《罗氏规则》实训的设计方案及具体操作流程,总结了实训工作取得的成果,提出了增强实务训练效能的技巧和应注意的相关问题。 相似文献
50.
通过静力加载实验,并结合3维接触有限元数值计算,研究了由2个筒体和2根楔带装配组成的楔环连接结构试件的非线性静力学行为。结果表明,在轴向拉伸下,当拉力增大到一定值时,楔环连接结构的总拉力-总轴向伸长就表现出非线性关系;在轴向-横向力联合作用下,在载荷增大过程中,楔带与壳体的接触位置会发生变化,从而导致口盖孔邻近区域应力集中位置也会发生一定变化,进而引起结构上应力随载荷的非线性变化。对楔环结构的这些非线性行为的认识为结构的设计和使用提供了概念指导。 相似文献