全文获取类型
收费全文 | 8158篇 |
免费 | 1085篇 |
国内免费 | 859篇 |
专业分类
电工技术 | 393篇 |
综合类 | 647篇 |
化学工业 | 143篇 |
金属工艺 | 221篇 |
机械仪表 | 763篇 |
建筑科学 | 253篇 |
矿业工程 | 84篇 |
能源动力 | 78篇 |
轻工业 | 95篇 |
水利工程 | 116篇 |
石油天然气 | 185篇 |
武器工业 | 59篇 |
无线电 | 1276篇 |
一般工业技术 | 546篇 |
冶金工业 | 59篇 |
原子能技术 | 15篇 |
自动化技术 | 5169篇 |
出版年
2024年 | 46篇 |
2023年 | 179篇 |
2022年 | 262篇 |
2021年 | 337篇 |
2020年 | 336篇 |
2019年 | 316篇 |
2018年 | 299篇 |
2017年 | 334篇 |
2016年 | 417篇 |
2015年 | 433篇 |
2014年 | 606篇 |
2013年 | 524篇 |
2012年 | 622篇 |
2011年 | 680篇 |
2010年 | 490篇 |
2009年 | 488篇 |
2008年 | 438篇 |
2007年 | 481篇 |
2006年 | 430篇 |
2005年 | 407篇 |
2004年 | 316篇 |
2003年 | 293篇 |
2002年 | 243篇 |
2001年 | 167篇 |
2000年 | 165篇 |
1999年 | 150篇 |
1998年 | 143篇 |
1997年 | 98篇 |
1996年 | 78篇 |
1995年 | 55篇 |
1994年 | 42篇 |
1993年 | 43篇 |
1992年 | 27篇 |
1991年 | 19篇 |
1990年 | 26篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1976年 | 6篇 |
1974年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Inverse surface design problems from light transport behavior specification usually represent extremely complex and costly processes, but their importance is well known. In particular, they are very interesting for lighting and luminaire design, in which it is usually difficult to test design decisions on a physical model in order to avoid costly mistakes. In this survey, we present the main ideas behind these kinds of problems, characterize them, and summarize existing work in the area, revealing problems that remain open and possible areas of further research. 相似文献
13.
Melt index is considered an important quality variable determining product specifications. Reliable prediction of melt index (MI) is crucial in quality control of practical propylene polymerization processes. In this paper a least squares support vector machines (LS‐SVM) soft‐sensor model of propylene polymerization process is developed to infer the MI of polypropylene from other process variables. Considering the use of a SSE cost function without regularization might lead to less robust estimates; the weighted least squares support vector machines (weighted LS‐SVM) approach of propylene polymerization process is further proposed to obtain a robust estimation of melt index. The performance of standard SVM model is taken as a basis of comparison. A detailed comparison research among the standard SVM, LS‐SVM, and weighted LS‐SVM models is carried out. The research results confirm the effectiveness of the presented methods. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 285–289, 2006 相似文献
14.
Claus Bahlmann Author Vitae 《Pattern recognition》2006,39(1):115-125
The selection of valuable features is crucial in pattern recognition. In this paper we deal with the issue that part of features originate from directional instead of common linear data. Both for directional and linear data a theory for a statistical modeling exists. However, none of these theories gives an integrated solution to problems, where linear and directional variables are to be combined in a single, multivariate probability density function. We describe a general approach for a unified statistical modeling, given the constraint that variances of the circular variables are small. The method is practically evaluated in the context of our online handwriting recognition system frog on hand and the so-called tangent slope angle feature. Recognition results are compared with two alternative modeling approaches. The proposed solution gives significant improvements in recognition accuracy, computational speed and memory requirements. 相似文献
16.
17.
Recently, efficient scheduling algorithms based on Lagrangian relaxation have been proposed for scheduling parallel machine
systems and job shops. In this article, we develop real-world extensions to these scheduling methods. In the first part of
the paper, we consider the problem of scheduling single operation jobs on parallel identical machines and extend the methodology
to handle multiple classes of jobs, taking into account setup times and setup costs. The proposed methodology uses Lagrangian
relaxation and simulated annealing in a hybrid framework. In the second part of the paper, we consider a Lagrangian relaxation
based method for scheduling job shops and extend it to obtain a scheduling methodology for a real-world flexible manufacturing
system with centralized material handling.
This research was supported in part by the Office of Naval Research and the Department of Science and Technology grant N00014-93-1017. 相似文献
18.
王振宇 《电气电子教学学报》2002,24(6):43-45
多级并接型权电阻解码网络结构简单,分析方便,文章给出了普通的和BCD码多级并接型权电阻解码网络,推导出了各级与运放的连接电阻的通用公式,并用EWB软件进行了电路模拟,这种方法对自行设计权电阻DAC有一定的参考价值。 相似文献
19.
In this paper, we propose an approach that combines the unsupervised and supervised learning techniques for unconstrained
handwritten numeral recognition. This approach uses the Kohonen self-organizing neural network for data classification in
the first stage and the learning vector quantization (LVQ) model in the second stage to improve classification accuracy. The
combined architecture performs better than the Kohonen self-organizing map alone. In the proposed approach, the collection
of centroids at different phases of training plays a vital role in the performance of the recognition system. Four experiments
have been conducted and experimental results show that the collection of centroids in the middle of the training gives high
performance in terms of speed and accuracy. The systems developed also resolve the confusion between handwritten numerals. 相似文献
20.