全文获取类型
收费全文 | 36074篇 |
免费 | 1449篇 |
国内免费 | 60篇 |
专业分类
电工技术 | 369篇 |
综合类 | 29篇 |
化学工业 | 7134篇 |
金属工艺 | 724篇 |
机械仪表 | 738篇 |
建筑科学 | 1963篇 |
矿业工程 | 114篇 |
能源动力 | 1054篇 |
轻工业 | 2882篇 |
水利工程 | 430篇 |
石油天然气 | 117篇 |
武器工业 | 5篇 |
无线电 | 2469篇 |
一般工业技术 | 6112篇 |
冶金工业 | 6602篇 |
原子能技术 | 268篇 |
自动化技术 | 6573篇 |
出版年
2023年 | 201篇 |
2022年 | 349篇 |
2021年 | 680篇 |
2020年 | 461篇 |
2019年 | 617篇 |
2018年 | 780篇 |
2017年 | 693篇 |
2016年 | 833篇 |
2015年 | 754篇 |
2014年 | 1042篇 |
2013年 | 2373篇 |
2012年 | 1681篇 |
2011年 | 2091篇 |
2010年 | 1651篇 |
2009年 | 1547篇 |
2008年 | 1800篇 |
2007年 | 1774篇 |
2006年 | 1591篇 |
2005年 | 1439篇 |
2004年 | 1175篇 |
2003年 | 1123篇 |
2002年 | 1051篇 |
2001年 | 702篇 |
2000年 | 549篇 |
1999年 | 595篇 |
1998年 | 583篇 |
1997年 | 574篇 |
1996年 | 549篇 |
1995年 | 572篇 |
1994年 | 525篇 |
1993年 | 510篇 |
1992年 | 500篇 |
1991年 | 288篇 |
1990年 | 418篇 |
1989年 | 389篇 |
1988年 | 319篇 |
1987年 | 355篇 |
1986年 | 310篇 |
1985年 | 418篇 |
1984年 | 416篇 |
1983年 | 318篇 |
1982年 | 295篇 |
1981年 | 281篇 |
1980年 | 269篇 |
1979年 | 270篇 |
1978年 | 247篇 |
1977年 | 225篇 |
1976年 | 206篇 |
1975年 | 194篇 |
1974年 | 173篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
Strategies for Expressing Concise, Helpful Answers 总被引:2,自引:0,他引:2
David N. Chin 《Artificial Intelligence Review》2000,14(4-5):333-350
An intelligent help system needs to take into account the user's knowledgewhen formulating answers. This allows the system to provide more conciseanswers, because it can avoid telling users things that they already know.Since these concise answers concentrate exclusively on pertinent newinformation, they are also easier to understand. Information about theuser's knowledge also allows the system to take advantage of the user'sprior knowledge in formulating explanations. The system can provide betteranswers by referring to the user's prior knowledge in the explanation(e.g., through use of similes). This process of refining answers is calledanswer expression.The process of answer expression has been implemented in the UCExpresscomponent of UC (UNIX Consultant), a natural language system that helps theuser solve problems in using the UNIX operating system. UCExpress separatesanswer expression into two phases: pruning and formatting.In the pruning phase, subconcepts of the answer are pruned by being markedas already known by the user (and hence do not need to be generated), ormarked as candidates for generating anaphora or ellipsis (since they arepart of the conversational context). In the formatting phase, UCExpressuses information about the user's prior domain knowledge to select amongspecialized expository formats,such as similes and examples, for expressing information to the user. Theseformats allow UCExpress to present different types of information to theuser in a clear, concise manner. The result of UCExpress' answer expressionprocess is an internal form that a tactical level generator can easily useto produce good English. 相似文献
942.
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
943.
Rahul Shringarpure Sameer Venugopal Korhan Kaftanoglu Lawrence T. Clark David R. Allee Edward Bawolek 《Journal of the Society for Information Display》2008,16(11):1147-1155
Abstract— A novel approach of modeling a‐Si:H TFTs with the industry‐standard BSIM3 compact model is presented. The described approach defines the a‐Si:H TFT drain current and terminal charges as explicit functions of terminal voltages using a minimum set of BSIM3 parameters. The set of BSIM3 parameters is chosen based on the electrical and physical characteristics of the a‐Si:H TFT and their values extracted from measured data. By using the selected BSIM3 model parameters, the a‐Si:H TFT is simulated inside SPICE to fit the simulated I‐V and C‐V curves with the measured results. Finally, the extracted BSIM3 model is validated by simulating the kickback voltage effect in an AMLCD pixel array. 相似文献
944.
This report summarizes the 2nd International Summer School on Network and Service Management (ISSNSM’08), which was held at
the Communication Systems Group (CSG) of the Department of Informatics (IFI), University of Zurich, Switzerland, on 2–6 June
2008. Supported by the European FP6 Network of Excellence for the Management of Internet Technologies and Complex Services
(EMANICS), the ISSNSM presented within 5 days eight different topics, covering the areas of (1) security, (2) virtualization
and simulations, and (3) network monitoring and management. All of these run for a full or half day, including a short theoretical
introduction and larger practical lab course components, respectively.
相似文献
David HausheerEmail: |
945.
Acevedo D Jackson CD Drury F Laidlaw DH 《IEEE transactions on visualization and computer graphics》2008,14(4):877-884
We describe an experiment in which art and illustration experts evaluated six 2D vector visualization methods. We found that these expert critiques mirrored previously recorded experimental results; these findings support that using artists, visual designers and illustrators to critique scientific visualizations can be faster and more productive than quantitative user studies. Our participants successfully evaluated how well the given methods would let users complete a given set of tasks. Our results show a statistically significant correlation with a previous objective study: designers' subjective predictions of user performance by these methods match users measured performance. The experts improved the evaluation by providing insights into the reasons for the effectiveness of each visualization method and suggesting specific improvements. 相似文献
946.
Williams D Grimm S Coto E Roudsari A Hatzakis H 《IEEE transactions on visualization and computer graphics》2008,14(1):109-119
Curved Planar Reformation (CPR) has proved to be a practical and widely used tool for the visualization of curved tubular structures within the human body. It has been useful in medical procedures involving the examination of blood vessels and the spine. However, it is more difficult to use it for large, tubular, structures such as the trachea and the colon because abnormalities may be smaller relative to the size of the structure and may not have such distinct density and shape characteristics. Our new approach improves on this situation by using volume rendering for hollow regions and standard CPR for the surrounding tissue. This effectively combines gray scale contextual information with detailed color information from the area of interest. The approach is successfully used with each of the standard CPR types and the resulting images are promising as an alternative to virtual endoscopy. Because the CPR and the volume rendering are tightly coupled, the projection method used has a significant effect on properties of the volume renderer, such as distortion and isometry. We describe and compare the different CPR projection methods and how they affect the volume rendering process. A version of the algorithm is also presented which makes use of importance driven techniques; this ensures the users attention is always focused on the area of interest and also improves the speed of the algorithm. 相似文献
947.
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
948.
Koop D Scheidegger CE Callahan SP Freire J Silva CT 《IEEE transactions on visualization and computer graphics》2008,14(6):1691-1698
Building visualization and analysis pipelines is a large hurdle in the adoption of visualization and workflow systems by domain scientists. In this paper, we propose techniques to help users construct pipelines by consensus--automatically suggesting completions based on a database of previously created pipelines. In particular, we compute correspondences between existing pipeline subgraphs from the database, and use these to predict sets of likely pipeline additions to a given partial pipeline. By presenting these predictions in a carefully designed interface, users can create visualizations and other data products more efficiently because they can augment their normal work patterns with the suggested completions. We present an implementation of our technique in a publicly-available, open-source scientific workflow system and demonstrate efficiency gains in real-world situations. 相似文献
949.
Keefe DF Acevedo D Miles J Drury F Swartz SM Laidlaw DH 《IEEE transactions on visualization and computer graphics》2008,14(4):835-847
We present four studies investigating tools and methodologies for artist-scientist-technologist collaboration in designing multivariate, virtual reality (VR) visualizations. Design study 1 identifies the promise of 3D drawing-style interfaces for VR design and also establishes limitations of these tools with respect to precision and support for animation. Design study 2 explores animating artist-created visualization designs with scientific 3D fluid flow data. While results captured an accurate sense of flow that was advantageous as compared to the results of study 1, the potential for visual exploration using the design tools tested was limited. Design study 3 reveals the importance of a new 3D interface that overcomes the precision limitation found in study 1 while remaining accessible to artist collaborators. Drawing upon previous results, design study 4 engages collaborative teams in a design process that begins with traditional paper sketching and moves to animated, interactive, VR prototypes "sketched" by designers in VR using interactive 3D tools. Conclusions from these four studies identify important characteristics of effective artist-accessible VR visualization design tools and lead to a proposed formalized methodology for successful collaborative design that we expect to be useful in guiding future collaborations. We call this proposed methodology Scientific Sketching. 相似文献
950.
David Kan 《CAD/CAM与制造业信息化》2008,(5):20-21
随着计算机技术的迅速发展,在工程领域中,有限元分析(FEA)越来越多地用于仿真模拟,来求解真实的工程问题。这些年来,越来越多的工程师、应用数学家和物理学家已经证明这种采用求解偏微分方程(PDE)的方法可以求解许多物理现象,这些偏微 相似文献