全文获取类型
收费全文 | 4344篇 |
免费 | 171篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 61篇 |
综合类 | 9篇 |
化学工业 | 593篇 |
金属工艺 | 77篇 |
机械仪表 | 107篇 |
建筑科学 | 311篇 |
矿业工程 | 15篇 |
能源动力 | 164篇 |
轻工业 | 415篇 |
水利工程 | 49篇 |
石油天然气 | 21篇 |
无线电 | 356篇 |
一般工业技术 | 744篇 |
冶金工业 | 556篇 |
原子能技术 | 23篇 |
自动化技术 | 1023篇 |
出版年
2023年 | 24篇 |
2022年 | 38篇 |
2021年 | 80篇 |
2020年 | 59篇 |
2019年 | 81篇 |
2018年 | 124篇 |
2017年 | 133篇 |
2016年 | 126篇 |
2015年 | 112篇 |
2014年 | 129篇 |
2013年 | 323篇 |
2012年 | 249篇 |
2011年 | 305篇 |
2010年 | 240篇 |
2009年 | 220篇 |
2008年 | 287篇 |
2007年 | 242篇 |
2006年 | 226篇 |
2005年 | 175篇 |
2004年 | 131篇 |
2003年 | 128篇 |
2002年 | 134篇 |
2001年 | 78篇 |
2000年 | 86篇 |
1999年 | 72篇 |
1998年 | 80篇 |
1997年 | 68篇 |
1996年 | 59篇 |
1995年 | 63篇 |
1994年 | 41篇 |
1993年 | 38篇 |
1992年 | 40篇 |
1991年 | 24篇 |
1990年 | 20篇 |
1989年 | 24篇 |
1988年 | 21篇 |
1987年 | 24篇 |
1986年 | 18篇 |
1985年 | 21篇 |
1984年 | 23篇 |
1983年 | 12篇 |
1982年 | 16篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 15篇 |
1978年 | 15篇 |
1977年 | 10篇 |
1976年 | 14篇 |
1974年 | 6篇 |
1972年 | 6篇 |
排序方式: 共有4524条查询结果,搜索用时 0 毫秒
81.
We shall present an algorithm for determining whether or not a given planar graph H can ever be a subgraph of a 4-regular planar graph. The algorithm has running time O(|H|2.5) and can be used to find an explicit 4-regular planar graph G⊃H if such a graph exists. It shall not matter whether we specify that H and G must be simple graphs or allow them to be multigraphs. 相似文献
82.
Len Seligman Paul Lehner Ken Smith Chris Elsaesser David Mattox 《Journal of Intelligent Information Systems》2000,14(1):29-50
We are interested in information management for decision support applications, especially those that monitor distributed, heterogeneous databases to assess time-critical decisions. Users of such applications can easily be overwhelmed with data that may change rapidly, may conflict, and may be redundant. Developers are faced with a dilemma: either filter out most information and risk excluding critical items, or gather possibly irrelevant or redundant information, and overwhelm the decision maker. This paper describes a solution to this dilemma called decision-centric information monitoring (DCIM). First, we observe that decision support systems should monitor only information that can potentially change some decision. We present an architecture for DCIM that meets the requirements implied by this observation. We describe techniques for identifying the highest value information to monitor and techniques for monitoring that information despite autonomy, distribution, and heterogeneity of data sources. Finally, we present lessons learned from building LOOKOUT, which is to our knowledge the first implementation of a top-to-bottom system performing decision-centric information monitoring. 相似文献
83.
Using the classical Parzen window (PW) estimate as the target function, the sparse kernel density estimator is constructed in a forward-constrained regression (FCR) manner. The proposed algorithm selects significant kernels one at a time, while the leave-one-out (LOO) test score is minimized subject to a simple positivity constraint in each forward stage. The model parameter estimation in each forward stage is simply the solution of jackknife parameter estimator for a single parameter, subject to the same positivity constraint check. For each selected kernels, the associated kernel width is updated via the Gauss-Newton method with the model parameter estimate fixed. The proposed approach is simple to implement and the associated computational cost is very low. Numerical examples are employed to demonstrate the efficacy of the proposed approach. 相似文献
84.
Large datasets typically contain coarse features comprised of finer sub-features. Even if the shapes of the small structures are evident in a 3D display, the aggregate shapes they suggest may not be easily inferred. From previous studies in shape perception, the evidence has not been clear whether physically-based illumination confers any advantage over local illumination for understanding scenes that arise in visualization of large data sets that contain features at two distinct scales. In this paper we show that physically-based illumination can improve the perception for some static scenes of complex 3D geometry from flow fields. We perform human-subjects experiments to quantify the effect of physically-based illumination on participant performance for two tasks: selecting the closer of two streamtubes from a field of tubes, and identifying the shape of the domain of a flow field over different densities of tubes. We find that physically-based illumination influences participant performance as strongly as perspective projection, suggesting that physically-based illumination is indeed a strong cue to the layout of complex scenes. We also find that increasing the density of tubes for the shape identification task improved participant performance under physically-based illumination but not under the traditional hardware-accelerated illumination model. 相似文献
85.
Graphical histories for visualization: supporting analysis, communication, and evaluation 总被引:1,自引:0,他引:1
Heer J Mackinlay J Stolte C Agrawala M 《IEEE transactions on visualization and computer graphics》2008,14(6):1189-1196
Interactive history tools, ranging from basic undo and redo to branching timelines of user actions, facilitate iterative forms of interaction. In this paper, we investigate the design of history mechanisms for information visualization. We present a design space analysis of both architectural and interface issues, identifying design decisions and associated trade-offs. Based on this analysis, we contribute a design study of graphical history tools for Tableau, a database visualization system. These tools record and visualize interaction histories, support data analysis and communication of findings, and contribute novel mechanisms for presenting, managing, and exporting histories. Furthermore, we have analyzed aggregated collections of history sessions to evaluate Tableau usage. We describe additional tools for analyzing users’ history logs and how they have been applied to study usage patterns in Tableau. 相似文献
86.
Network data frequently arises in a wide variety of fields, and node-link diagrams are a very natural and intuitive represen- tation of such data. In order for a node-link diagram to be effective, the nodes must be arranged well on the screen. While many graph layout algorithms exist for this purpose, they often have limitations such as high computational complexity or node colocation. This paper proposes a new approach to graph layout through the use of space filling curves which is very fast and guarantees that there will be no nodes that are colocated. The resulting layout is also aesthetic and satisfies several criteria for graph layout effectiveness. 相似文献
87.
Structured decomposition of adaptive applications 总被引:1,自引:0,他引:1
88.
This paper contextualises, describes and discusses a student project which takes a particular exploratory approach to using
mathematical surface definition as a language and vehicle for co-rational design co-authorship for architecture and engineering.
The project has two authors, one from an architectural and one from an engineering educational background. It investigates
the metaphorical and operational role of mathematics in the design process and outcomes. 相似文献
89.
90.
El Rube I Ahmed M Kamel M 《IEEE transactions on pattern analysis and machine intelligence》2006,28(2):323-327
In this paper, new wavelet-based affine invariant functions for shape representation are presented. Unlike the previous representation functions, only the approximation coefficients are used to obtain the proposed functions. One of the derived functions is computed by applying a single wavelet transform; the other function is calculated by applying two different wavelet transforms with two different wavelet families. One drawback of the previously derived detail-based invariant representation functions is that they are sensitive to noise at the finer scale levels, which limits the number of scale levels that can be used. The experimental results in this paper demonstrate that the proposed functions are more stable and less sensitive to noise than the detail-based functions. 相似文献