全文获取类型
收费全文 | 18529篇 |
免费 | 1339篇 |
国内免费 | 391篇 |
专业分类
电工技术 | 996篇 |
技术理论 | 4篇 |
综合类 | 1161篇 |
化学工业 | 3091篇 |
金属工艺 | 901篇 |
机械仪表 | 993篇 |
建筑科学 | 1415篇 |
矿业工程 | 470篇 |
能源动力 | 555篇 |
轻工业 | 1055篇 |
水利工程 | 297篇 |
石油天然气 | 1137篇 |
武器工业 | 108篇 |
无线电 | 2198篇 |
一般工业技术 | 2631篇 |
冶金工业 | 767篇 |
原子能技术 | 210篇 |
自动化技术 | 2270篇 |
出版年
2025年 | 44篇 |
2024年 | 407篇 |
2023年 | 367篇 |
2022年 | 497篇 |
2021年 | 711篇 |
2020年 | 549篇 |
2019年 | 544篇 |
2018年 | 534篇 |
2017年 | 526篇 |
2016年 | 493篇 |
2015年 | 632篇 |
2014年 | 796篇 |
2013年 | 891篇 |
2012年 | 1033篇 |
2011年 | 1127篇 |
2010年 | 1002篇 |
2009年 | 993篇 |
2008年 | 945篇 |
2007年 | 903篇 |
2006年 | 947篇 |
2005年 | 830篇 |
2004年 | 551篇 |
2003年 | 538篇 |
2002年 | 476篇 |
2001年 | 403篇 |
2000年 | 450篇 |
1999年 | 470篇 |
1998年 | 420篇 |
1997年 | 401篇 |
1996年 | 362篇 |
1995年 | 328篇 |
1994年 | 234篇 |
1993年 | 190篇 |
1992年 | 154篇 |
1991年 | 90篇 |
1990年 | 105篇 |
1989年 | 104篇 |
1988年 | 68篇 |
1987年 | 32篇 |
1986年 | 28篇 |
1985年 | 22篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1959年 | 1篇 |
1953年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
In recent years, metric learning in the semisupervised setting has aroused a lot of research interest. One type of semisupervised metric learning utilizes supervisory information in the form of pairwise similarity or dissimilarity constraints. However, most methods proposed so far are either limited to linear metric learning or unable to scale well with the data set size. In this letter, we propose a nonlinear metric learning method based on the kernel approach. By applying low-rank approximation to the kernel matrix, our method can handle significantly larger data sets. Moreover, our low-rank approximation scheme can naturally lead to out-of-sample generalization. Experiments performed on both artificial and real-world data show very promising results. 相似文献
2.
Huang Huajie Dai Junjie Dou Long Liu Junfu Liu Yunpeng Chen Taotao Wu Tianxiang Li Junhui 《Journal of Electronic Testing》2022,38(2):195-203
Journal of Electronic Testing - In order to control the stable and controllable loading of the wafer level microprobe test bench, the magnetorheological (MR) damper used in the existing research... 相似文献
3.
4.
Summary Poly(phenylene sulfide) (PPS) was cured in the melt and solid states under air and/or nitrogen environments. Crystallization behavior of such cured materials as a function of cure time at 320°C and 255°C was studied via differential scanning calorimetry. It was found, on general, that while short-time curing leads to an increase in crystallization rate, prolonged curing leads to a decrease in both crystallinity and crystallization rate. In contrast to the enhanced crystallization rate caused by curing in nitrogen at the melt state, no significant change of crystallization rate is observed while curing is done in the solid state (in nitrogen). 相似文献
5.
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
6.
探索了一种在多媒体环境下进行计算机及外部设备维修教学、训练的新方法 ,介绍了计算机维修模拟训练系统的设计与实现 ,给出了主要的设计思想、总体结构及关键技术。 相似文献
7.
Dai J Feng J Zhou J 《IEEE transactions on pattern analysis and machine intelligence》2012,34(8):1618-1632
During the past decade, many efforts have been made to use palmprints as a biometric modality. However, most of the existing palmprint recognition systems are based on encoding and matching creases, which are not as reliable as ridges. This affects the use of palmprints in large-scale person identification applications where the biometric modality needs to be distinctive as well as insensitive to changes in age and skin conditions. Recently, several ridge-based palmprint matching algorithms have been proposed to fill the gap. Major contributions of these systems include reliable orientation field estimation in the presence of creases and the use of multiple features in matching, while the matching algorithms adopted in these systems simply follow the matching algorithms for fingerprints. However, palmprints differ from fingerprints in several aspects: 1) Palmprints are much larger and thus contain a large number of minutiae, 2) palms are more deformable than fingertips, and 3) the quality and discrimination power of different regions in palmprints vary significantly. As a result, these matchers are unable to appropriately handle the distortion and noise, despite heavy computational cost. Motivated by the matching strategies of human palmprint experts, we developed a novel palmprint recognition system. The main contributions are as follows: 1) Statistics of major features in palmprints are quantitatively studied, 2) a segment-based matching and fusion algorithm is proposed to deal with the skin distortion and the varying discrimination power of different palmprint regions, and 3) to reduce the computational complexity, an orientation field-based registration algorithm is designed for registering the palmprints into the same coordinate system before matching and a cascade filter is built to reject the nonmated gallery palmprints in early stage. The proposed matcher is tested by matching 840 query palmprints against a gallery set of 13,736 palmprints. Experimental results show that the proposed matcher outperforms the existing matchers a lot both in matching accuracy and speed. 相似文献
8.
In breast cancer research, it is of great interest to identify genomic markers associated with prognosis. Multiple gene profiling studies have been conducted for such a purpose. Genomic markers identified from the analysis of single datasets often do not have satisfactory reproducibility. Among the multiple possible reasons, the most important one is the small sample sizes of individual studies. A cost-effective solution is to pool data from multiple comparable studies and conduct integrative analysis. In this study, we collect four breast cancer prognosis studies with gene expression measurements. We describe the relationship between prognosis and gene expressions using the accelerated failure time (AFT) models. We adopt a 2-norm group bridge penalization approach for marker identification. This integrative analysis approach can effectively identify markers with consistent effects across multiple datasets and naturally accommodate the heterogeneity among studies. Statistical and simulation studies demonstrate satisfactory performance of this approach. Breast cancer prognosis markers identified using this approach have sound biological implications and satisfactory prediction performance. 相似文献
9.
Qing Dai Menzies D. Qiang Wang Ostafin A. E. Brown S. N. Meisel D. Maginn E. J. 《Nanotechnology, IEEE Transactions on》2006,5(6):677-682
A novel technique to monitor the synthesis process of encapsulated acetylacetonatocarbonyl triphenylphosphinerhodium within a microsilica nanoshell has been studied using inductively coupled plasma (ICP) techniques. Nanospheres sized around 50-100 nm were obtained and ICP was used to quantify the exact composition of rhodium, phosphorous, and silicon with differing digestion solvents. In addition, ICP was used to detect rhodium and phosphorous in the nano core-shell catalysts as a quality control procedure 相似文献
10.