全文获取类型
收费全文 | 22003篇 |
免费 | 3783篇 |
国内免费 | 2606篇 |
专业分类
电工技术 | 1033篇 |
综合类 | 2173篇 |
化学工业 | 1047篇 |
金属工艺 | 468篇 |
机械仪表 | 1281篇 |
建筑科学 | 406篇 |
矿业工程 | 224篇 |
能源动力 | 114篇 |
轻工业 | 412篇 |
水利工程 | 109篇 |
石油天然气 | 424篇 |
武器工业 | 286篇 |
无线电 | 4274篇 |
一般工业技术 | 1267篇 |
冶金工业 | 901篇 |
原子能技术 | 51篇 |
自动化技术 | 13922篇 |
出版年
2024年 | 94篇 |
2023年 | 412篇 |
2022年 | 871篇 |
2021年 | 1005篇 |
2020年 | 999篇 |
2019年 | 723篇 |
2018年 | 610篇 |
2017年 | 751篇 |
2016年 | 867篇 |
2015年 | 937篇 |
2014年 | 1369篇 |
2013年 | 1229篇 |
2012年 | 1590篇 |
2011年 | 1729篇 |
2010年 | 1425篇 |
2009年 | 1445篇 |
2008年 | 1516篇 |
2007年 | 1687篇 |
2006年 | 1472篇 |
2005年 | 1263篇 |
2004年 | 1042篇 |
2003年 | 961篇 |
2002年 | 778篇 |
2001年 | 530篇 |
2000年 | 466篇 |
1999年 | 420篇 |
1998年 | 357篇 |
1997年 | 271篇 |
1996年 | 222篇 |
1995年 | 210篇 |
1994年 | 166篇 |
1993年 | 146篇 |
1992年 | 124篇 |
1991年 | 66篇 |
1990年 | 54篇 |
1989年 | 76篇 |
1988年 | 51篇 |
1987年 | 27篇 |
1986年 | 27篇 |
1985年 | 39篇 |
1984年 | 38篇 |
1983年 | 50篇 |
1982年 | 44篇 |
1981年 | 35篇 |
1980年 | 32篇 |
1979年 | 25篇 |
1978年 | 26篇 |
1977年 | 29篇 |
1976年 | 24篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
71.
地震数据油气预测中的属性优化方法 总被引:20,自引:4,他引:16
本文简单介绍了智能信息处理中新出现的RoughSet(RS)理论及属性选择方法,从双相介质地震波传播理论角度,探讨了地震数据油气预测属性优化原理,提出了基于RS理论的地震数据油气预测属性优化方法。实际应用表明;本方法速度快、易实现,而且在优选属性、最大程度地减少提取地震属性种数、提高分类正确率等方面,明显优于其它方法。本方法将成为地震数据油气预测的一种有效手段。 相似文献
72.
73.
介绍了一种适用于模式识别的新型神经网络模型--局部有监督特征映射(Reglonal Supervised Feature Mapping,RSFM)网络,描述了该网络的拓扑结构和学习算法,研究了网络的基本性能,最后将其应用到了信号滤波中.理论研究和仿真实验表明,该网络结构简单、算法简洁,收敛速度快、识别精度高,适用于需要大样本训练、随机干扰严重的复杂模式的分类与识别. 相似文献
74.
The tree representation of evolutionary relationship oversimplifies the view of the process of evolution as it cannot take into account the events such as horizontal gene transfer, hybridization, homoplasy and genetic recombination. Several algorithms exist for constructing phylogenetic networks which result from events such as horizontal gene transfer, hybridization and homoplasy. Very little work has been published on the algorithmic detail of phylogenetic networks with constrained recombination. The problem of minimizing the number of recombinations in a phylogenetic network, constructed using binary DNA sequences, is NP-hard. In this paper, we propose a pattern recognition-based O(n2) time approach for constructing the phylogenetic network, where n is the number of nodes or sequences in the input data. The network is constructed with the restriction that no two cycles in the network share a common node. 相似文献
75.
76.
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
77.
78.
Tang Yuanyan 《Frontiers of Computer Science in China》2007,1(2):123-125
This paper gives an introduction and remarks on two review papers for Chinese character recognition. One review is made by
Chinese authors, another is from American scientists. They investigate Chinese character from different language environments;
they do the research from different points of view. Thus, a more comprehensive view on Chinese character recognition, which
is an important branch of pattern recognition, can be provided to the readers. Meantime, one article pays attention to online
process, and other paper deals with offline recognition, which complement each other.
The author is the Associate Editor-in-Chief of Frontiers of Computer Science in China 相似文献
79.
Mulligan Neil W.; Lozito Jeffrey P.; Rosner Zachary A. 《Canadian Metallurgical Quarterly》2006,32(4):836
Generation enhances memory for occurrence but may not enhance other aspects of memory. The present study further delineates the negative generation effect in context memory reported in N. W. Mulligan (2004). First, the negative generation effect occurred for perceptual attributes of the target item (its color and font) but not for extratarget aspects of context (location and background color). Second, nonvisual generation tasks with either semantic or nonsemantic generation rules (antonym and rhyme generation, respectively) produced the same pattern of results. In contrast, a visual (or data-driven) generation task (letter transposition) did not disrupt context memory for color. Third, generating nonwords produced no effect on item memory but persisted in producing a negative effect on context memory for target attributes, implying that (a) the negative generation effect in context memory is not mediated by semantic encoding, and (b) the negative effect on context memory can be dissociated from the positive effect on item memory. The results are interpreted in terms of the processing account of generation. The original, perceptual-conceptual version of this account is too narrow, but a modified processing account, based on a more generic visual versus nonvisual processing distinction, accommodates the results. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
80.
李涛 《信息技术与信息化》2007,10(3):76-78
版面分析过程可以理解为同模式类对象间聚类(合并)的过程,而这种聚类存在的风险(hazard)是伴随整个聚类过程中的。而且越是在后期,该风险值越高,即一旦出现聚类错误则将导致前期正确的聚类结果付诸东流。该文将就此问题展开关于版面分析中的聚类稳定性问题的探讨,并提出相应的逻辑规则——逻辑判别函数(logic differentiation function)用来指导聚类和其在聚类算法中的应用;实验结果表明,建立在定性分析基础上的该规则能解决聚类过程的稳定性问题,同时该规则可以应用在存在若干模式类对象聚类的场合中。 相似文献