全文获取类型
收费全文 | 90393篇 |
免费 | 10389篇 |
国内免费 | 5662篇 |
专业分类
电工技术 | 7942篇 |
技术理论 | 3篇 |
综合类 | 7200篇 |
化学工业 | 13576篇 |
金属工艺 | 5167篇 |
机械仪表 | 5777篇 |
建筑科学 | 7281篇 |
矿业工程 | 2884篇 |
能源动力 | 2569篇 |
轻工业 | 7272篇 |
水利工程 | 2119篇 |
石油天然气 | 4521篇 |
武器工业 | 1100篇 |
无线电 | 11221篇 |
一般工业技术 | 9739篇 |
冶金工业 | 3549篇 |
原子能技术 | 1211篇 |
自动化技术 | 13313篇 |
出版年
2024年 | 636篇 |
2023年 | 2110篇 |
2022年 | 4208篇 |
2021年 | 5610篇 |
2020年 | 4060篇 |
2019年 | 3119篇 |
2018年 | 3274篇 |
2017年 | 3552篇 |
2016年 | 3182篇 |
2015年 | 4245篇 |
2014年 | 5148篇 |
2013年 | 5785篇 |
2012年 | 6591篇 |
2011年 | 6779篇 |
2010年 | 5980篇 |
2009年 | 5675篇 |
2008年 | 5572篇 |
2007年 | 5086篇 |
2006年 | 4727篇 |
2005年 | 4118篇 |
2004年 | 2665篇 |
2003年 | 2256篇 |
2002年 | 2235篇 |
2001年 | 1967篇 |
2000年 | 1638篇 |
1999年 | 1376篇 |
1998年 | 861篇 |
1997年 | 799篇 |
1996年 | 732篇 |
1995年 | 529篇 |
1994年 | 475篇 |
1993年 | 321篇 |
1992年 | 292篇 |
1991年 | 185篇 |
1990年 | 137篇 |
1989年 | 120篇 |
1988年 | 97篇 |
1987年 | 68篇 |
1986年 | 61篇 |
1985年 | 28篇 |
1984年 | 27篇 |
1983年 | 17篇 |
1982年 | 24篇 |
1981年 | 15篇 |
1980年 | 22篇 |
1979年 | 15篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1959年 | 13篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
1.
Data mining extracts implicit, previously unknown, and potentially useful information from databases. Many approaches have been proposed to extract information, and one of the most important ones is finding association rules. Although a large amount of research has been devoted to this subject, none of it finds association rules from directed acyclic graph (DAG) data. Without such a mining method, the hidden knowledge, if any, cannot be discovered from the databases storing DAG data such as family genealogy profiles, product structures, XML documents, task precedence relations, and course structures. In this article, we define a new kind of association rule in DAG databases called the predecessor–successor rule, where a node x is a predecessor of another node y if we can find a path in DAG where x appears before y. The predecessor–successor rules enable us to observe how the characteristics of the predecessors influence the successors. An approach containing four stages is proposed to discover the predecessor–successor rules. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 621–637, 2006. 相似文献
2.
提出了一种用于检测在役车辆车轴产生疲劳裂纹的超声波方法,设计了中心孔探头与斜角探头一起,完成了对车辆车轴的关键区域探伤。 相似文献
3.
4.
Nanofiber bundles of Ag2S, Ag2Se, and Ag have been successfully synthesized by making use of Ag2C2O4 template nanofiber bundles, utilizing both anion‐exchange and redox reactions. The obtained bundles were polycrystalline nanofibers composed of nanoparticles in which the precursor morphology was well‐preserved, indicating that Ag2C2O4 nanofiber bundles acted as a general sacrificial template for the synthesis of silver‐based semiconductor and metal nanofibers. Dispersing media and transforming reactants were found to be key factors influencing the chemical transformation in the system. In particular, separate single‐crystalline Ag nanofibers were obtained via a nontemplate route when ascorbic acid was used as a relatively weak reductant. An electrical transfer and switching device was built with the obtained Ag2S and Ag nanofiber bundles, utilizing the unique ion‐conductor nature of Ag2S and revealing their potential applications in electronics. 相似文献
5.
6.
Xin Qi Salapaka M.V. Voulgaris P.G. Khammash M. 《Automatic Control, IEEE Transactions on》2004,49(10):1623-1640
In this paper, the design of controllers that incorporate structural and multiobjective performance requirements is considered. The control structures under study cover nested, chained, hierarchical, delayed interaction and communications, and symmetric systems. Such structures are strongly related to several modern-day and future applications including integrated flight propulsion systems, platoons of vehicles, micro-electro-mechanical systems, networked control, control of networks, production lines and chemical processes. It is shown that the system classes presented have the common feature that all stabilizing controllers can be characterized by convex constraints on the Youla-Kucera parameter. Using this feature, a solution to a general optimal performance problem that incorporates time domain and frequency domain constraints is obtained. A synthesis procedure is provided which at every step yields a feasible controller together with a measure of its performance with respect to the optimal. Convergence to the optimal performance is established. An example of a multinode network congestion control problem is provided that illustrates the effectiveness of the developed methodology. 相似文献
7.
Yanqing Ji Hao Ying John Yen Shizhuo Zhu Daniel C. Barth‐Jones Richard E. Miller R. Michael Massanari 《国际智能系统杂志》2007,22(8):827-845
Discovering unknown adverse drug reactions (ADRs) in postmarketing surveillance as early as possible is highly desirable. Nevertheless, current postmarketing surveillance methods largely rely on spontaneous reports that suffer from serious underreporting, latency, and inconsistent reporting. Thus these methods are not ideal for rapidly identifying rare ADRs. The multiagent systems paradigm is an emerging and effective approach to tackling distributed problems, especially when data sources and knowledge are geographically located in different places and coordination and collaboration are necessary for decision making. In this article, we propose an active, multiagent framework for early detection of ADRs by utilizing electronic patient data distributed across many different sources and locations. In this framework, intelligent agents assist a team of experts based on the well‐known human decision‐making model called Recognition‐Primed Decision (RPD). We generalize the RPD model to a fuzzy RPD model and utilize fuzzy logic technology to not only represent, interpret, and compute imprecise and subjective cues that are commonly encountered in the ADR problem but also to retrieve prior experiences by evaluating the extent of matching between the current situation and a past experience. We describe our preliminary multiagent system design and illustrate its potential benefits for assisting expert teams in early detection of previously unknown ADRs. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 827–845, 2007. 相似文献
8.
9.
ATM局域网仿真体系结构的研究 总被引:4,自引:0,他引:4
本文在简要叙述了基于ATM技术进行局域网仿真的原理后,对局域网仿真体系结构作了一些探讨。考虑的重点是无连接服务和群播功能的实现 相似文献
10.
This paper shows that the mechanical and thermal properties of EPR cable dielectrics are very stable with temperature. Commercially available EPR and TRXLPE cable dielectrics typically have about the same thermal conductivity, although the thermal conductivity of TRXLPE above the melting point of the crystallites drops below that of the EPR dielectrics. The mechanical properties of EPR cable dielectrics are much more stable with temperature than those of the TRXLPE, as EPR polymer is essentially amorphous so that EPR cable dielectrics do not suffer from the very large thermal expansion of TRXLPE as its crystallites melt. 相似文献