首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17920篇
  免费   1114篇
  国内免费   1037篇
电工技术   712篇
综合类   1673篇
化学工业   751篇
金属工艺   830篇
机械仪表   1691篇
建筑科学   1584篇
矿业工程   432篇
能源动力   444篇
轻工业   278篇
水利工程   222篇
石油天然气   236篇
武器工业   196篇
无线电   1213篇
一般工业技术   1298篇
冶金工业   487篇
原子能技术   200篇
自动化技术   7824篇
  2024年   42篇
  2023年   148篇
  2022年   217篇
  2021年   279篇
  2020年   357篇
  2019年   332篇
  2018年   288篇
  2017年   408篇
  2016年   514篇
  2015年   593篇
  2014年   959篇
  2013年   993篇
  2012年   993篇
  2011年   1152篇
  2010年   1023篇
  2009年   1206篇
  2008年   1190篇
  2007年   1324篇
  2006年   1299篇
  2005年   1072篇
  2004年   933篇
  2003年   827篇
  2002年   651篇
  2001年   538篇
  2000年   457篇
  1999年   437篇
  1998年   361篇
  1997年   292篇
  1996年   220篇
  1995年   187篇
  1994年   157篇
  1993年   119篇
  1992年   76篇
  1991年   70篇
  1990年   57篇
  1989年   62篇
  1988年   42篇
  1987年   19篇
  1986年   25篇
  1985年   22篇
  1984年   18篇
  1983年   10篇
  1982年   8篇
  1981年   9篇
  1980年   6篇
  1975年   7篇
  1964年   7篇
  1961年   7篇
  1956年   5篇
  1955年   7篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
依据《商品住宅性能评定方法和指标体系》正确地对商品住宅地性能进行评价 ,是评定商品住宅质量等级的重要依据。本文主要论述如何运用数学方法分析和处理住宅综合质量评定中大量存在的模糊问题以及如何建立相应的等级评价准则和进行等级评判  相似文献   
62.
模式识别催化剂生产调优   总被引:2,自引:0,他引:2  
本文介绍如何将模式识别应用于生产调优,着重讨论了多指标(优化目标)因素的分级,提出了用模糊综合评价度量和依有序聚类最小损失函数准则划类,并相继进行变量与样本筛选、信息压缩、特征提取和模拟仿真获得优区操作条件,实施效果显著。  相似文献   
63.
Annual growth increments were calculated for blue catfish (Ictalurus furcatus) and flathead catfish (Pylodictis olivaris) from the lower Mississippi River (LMR) to assess hypothesized relationships between fish growth and floodplain inundation as predicted by the Flood‐Pulse Concept. Variation in catfish growth increment was high for all age classes of both species, and growth increments were not consistently related to various measures of floodplain inundation. However, relationships became stronger, and usually direct, when water temperature was integrated with area and duration of floodplain inundation. Relationships were significant for four of six age classes for blue catfish, a species known to utilize floodplain habitats. Though similar in direction, relationships were weaker for flathead catfish, which is considered a more riverine species. Our results indicate the Flood‐Pulse Concept applies more strongly to temperate floodplain‐river ecosystems when thermal aspects of flood pulses are considered. We recommend that future management of the LMR should consider ways to ‘recouple’ the annual flood and thermal cycles. An adaptive management approach will allow further determination of important processes affecting fisheries production in the LMR. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
64.
基于概念网络的文本信息监控技术   总被引:1,自引:0,他引:1  
由于网上信息的迅速增长,文本信息监控已经成为网上信息管理中的热点研究课题。本文在模糊集和语义网络的理论基础上,构建了模糊值动态约束性概念网络,介绍了该概念网络的基本构建方法,并提出了基于概念网络的文本分析算法。  相似文献   
65.
全文围绕树立和落实科学发展观这一主题 ,研究和探索如何在新时期、新阶段进一步做好国土资源管理工作的新思路、新途径和新方法。提出要进一步加强国土资源宏观管理 ,更好地为甘肃省经济社会的协调、可持续发展提供保障服务。  相似文献   
66.
T. Bag 《Information Sciences》2006,176(19):2910-2931
In this paper, definitions of strongly fuzzy convergent sequence, l-fuzzy weakly convergent sequence and l-fuzzy weakly compact set are given in a fuzzy normed linear space. The concepts of fuzzy normal structure, fuzzy non-expansive mapping, uniformly convex fuzzy normed linear space are introduced and fixed point theorems for fuzzy non-expansive mappings are proved.  相似文献   
67.
In this article, we analyze a co-operative multi-thread search-based optimization strategy, where each solver thread represents a different optimization algorithm (or the same one with different settings), and they are all controlled by a centralized co-ordinator. We also propose the use of memory to keep track of both the state of the individual threads and the obtained solutions. Based on this memory, a very simple fuzzy rule base is used to control the system behavior.We also present the results of three computational experiments. The first of these checks the strategy by comparing it with an independent search strategy and a sequential algorithm, and the superiority of the co-operative scheme is confirmed. The second analyzes how definition of the threads affects the quality of the results, and the importance of there being a balanced set between intensification and diversification is corroborated. The third explores the use of memory with two different fuzzy rules, and the results indicate that the best combination is to use memory together with two rules (solver dependent and solver independent ones) (although this combination should not be activated at the beginning of the search in order to avoid premature convergence).  相似文献   
68.
In this paper we have introduced a class of decision rules related to simple majority, by considering individual intensities of preference. These intensities will be shown by means of linguistic labels. In order to compare the amount of opinion obtained by each alternative, we have considered the total ordered monoid generated by the sums of the original labels, according to an addition and an ordering. In this general framework different sets of linguistic labels can be employed and these sets can be represented by means of diverse mathematical objects. Moreover, on these mathematical representations of linguistic labels several orderings can be considered. Thus, flexibility is an important feature of this new class of group decision making procedures. Some examples of putting in practice the simple majority decision rules based on linguistic labels are provided, and the main properties of these voting systems are analyzed. It is worth emphasizing that these properties are satisfied for any total ordered monoid, regardless of the mathematical representation of linguistic labels or the ordering used to compare collective opinions.  相似文献   
69.
In this paper, we propose and investigate a new category of neurofuzzy networks—fuzzy polynomial neural networks (FPNN) endowed with fuzzy set-based polynomial neurons (FSPNs) We develop a comprehensive design methodology involving mechanisms of genetic optimization, and genetic algorithms (GAs) in particular. The conventional FPNNs developed so far are based on the mechanisms of self-organization, fuzzy neurocomputing, and evolutionary optimization. The design of the network exploits the FSPNs as well as the extended group method of data handling (GMDH). Let us stress that in the previous development strategies some essential parameters of the networks (such as the number of input variables, the order of the polynomial, the number of membership functions, and a collection of the specific subset of input variables) being available within the network are provided by the designer in advance and kept fixed throughout the overall development process. This restriction may hamper a possibility of developing an optimal architecture of the model. The design proposed in this study addresses this issue. The augmented and genetically developed FPNN (gFPNN) results in a structurally optimized structure and comes with a higher level of flexibility in comparison to the one we encounter in the conventional FPNNs. The GA-based design procedure being applied at each layer of the FPNN leads to the selection of the most suitable nodes (or FSPNs) available within the FPNN. In the sequel, two general optimization mechanisms are explored. First, the structural optimization is realized via GAs whereas the ensuing detailed parametric optimization is carried out in the setting of a standard least square method-based learning. The performance of the gFPNN is quantified through experimentation in which we use a number of modeling benchmarks—synthetic and experimental data being commonly used in fuzzy or neurofuzzy modeling. The obtained results demonstrate the superiority of the proposed networks over the models existing in the references.  相似文献   
70.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号