全文获取类型
收费全文 | 19267篇 |
免费 | 3511篇 |
国内免费 | 2438篇 |
专业分类
电工技术 | 2003篇 |
综合类 | 2216篇 |
化学工业 | 337篇 |
金属工艺 | 475篇 |
机械仪表 | 1598篇 |
建筑科学 | 366篇 |
矿业工程 | 177篇 |
能源动力 | 318篇 |
轻工业 | 132篇 |
水利工程 | 135篇 |
石油天然气 | 166篇 |
武器工业 | 514篇 |
无线电 | 4133篇 |
一般工业技术 | 1132篇 |
冶金工业 | 613篇 |
原子能技术 | 58篇 |
自动化技术 | 10843篇 |
出版年
2024年 | 129篇 |
2023年 | 467篇 |
2022年 | 725篇 |
2021年 | 749篇 |
2020年 | 740篇 |
2019年 | 675篇 |
2018年 | 554篇 |
2017年 | 767篇 |
2016年 | 890篇 |
2015年 | 1034篇 |
2014年 | 1316篇 |
2013年 | 1187篇 |
2012年 | 1539篇 |
2011年 | 1615篇 |
2010年 | 1289篇 |
2009年 | 1183篇 |
2008年 | 1297篇 |
2007年 | 1447篇 |
2006年 | 1236篇 |
2005年 | 1060篇 |
2004年 | 862篇 |
2003年 | 817篇 |
2002年 | 781篇 |
2001年 | 634篇 |
2000年 | 536篇 |
1999年 | 361篇 |
1998年 | 279篇 |
1997年 | 223篇 |
1996年 | 171篇 |
1995年 | 125篇 |
1994年 | 127篇 |
1993年 | 89篇 |
1992年 | 59篇 |
1991年 | 48篇 |
1990年 | 40篇 |
1989年 | 27篇 |
1988年 | 20篇 |
1987年 | 13篇 |
1986年 | 14篇 |
1985年 | 13篇 |
1984年 | 16篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1978年 | 3篇 |
1966年 | 3篇 |
1964年 | 6篇 |
1963年 | 4篇 |
1961年 | 4篇 |
1960年 | 4篇 |
1956年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
No authorship indicated 《Canadian Metallurgical Quarterly》1993,48(4):346
Recognizes Martha J. Farah for rigorous empirical and theoretical analysis of visual cognition, in which understanding of normal function and analysis of neurological deficits illuminate and strengthen one another. Applying diverse experimental techniques within an integrated approach to the study of mind and brain, she has sharpened and helped to answer fundamental questions about how humans generate and manipulate visual images, recognize objects, and attend to positions in space. Along with a citation, a biography is presented for Farah, as well as a bibliography of her works. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
83.
STN-LCD采用新的取向层,消除了残象;采用新的驱动波形,消除了串扰;采用二(口恶)烷、卤化物、链烯基、醚和二苯乙炔,改进了液晶料材的性能,使STN-LCD获得高的对比度、快的响应速度、低的驱动电压;采用有源矩阵驱动方法,消除了帧响应,使STN-LCD获得高的对比度、高的亮度及视频响应速度;使用温度跟踪电路,自动跟踪STN-LCD的阀值电压,使STN-LCD获得宽的工作温度。 相似文献
84.
采用二次回归正交设计进行烧结试验,获得了七个目标的数学模型,并验证了其可靠性,用多目标计算机选优法对四烧车间的工艺参数进行了选优。 相似文献
85.
Conditions for stability of the extended Kalman filter and their application to the frequency tracking problem 总被引:1,自引:0,他引:1
Barbara F. La Scala Robert R. Bitmead Matthew R. James 《Mathematics of Control, Signals, and Systems (MCSS)》1995,8(1):1-26
The error dynamics of the extended Kalman filter (EKF), employed as an observer for a general nonlinear, stochastic discrete time system, are analyzed. Sufficient conditions for the boundedness of the errors of the EKF are determined. An expression for the bound on the errors is given in terms of the size of the nonlinearities of the system and the error covariance matrices used in the design of the EKF. The results are applied to the design of a stable EKF frequency tracker for a signal with time-varying frequency.This research was supported by the Co-operative Research Centre for Robust and Adaptive Systems ((CR)2 ASys). The authors wish to acknowledge the funding of the activities of (CR)2 ASys by the Australian Commonwealth Government under the Co-operative Research Centre Program. 相似文献
86.
从侧钻井层、开窗工艺、井身剖面的优选和井眼轨迹控制、固井措施优化等方面,详细总结了套管开窗定向侧钻技术在吐哈油田老井改造中应用的经验,系统地描述了该技术应用的地质条件和工程要素,提出了吐哈侧钻井层优选的量化指标和固井质量的优化措施。近两年,该技术在老井治理、开采难动用储量、提高采收率、降低开发钻井成本等方面展现出广阔的前景。 相似文献
87.
88.
Gabriel Tsechpenakis Dimitris Metaxas Carol Neidle 《Computer Vision and Image Understanding》2006,104(2-3):140
We present a data-driven dynamic coupling between discrete and continuous methods for tracking objects of high dofs, which overcomes the limitations of previous techniques. In our approach, two trackers work in parallel, and the coupling between them is based on the tracking error. We use a model-based continuous method to achieve accurate results and, in cases of failure, we re-initialize the model using our discrete tracker. This method maintains the accuracy of a more tightly coupled system, while increasing its efficiency. At any given frame, our discrete tracker uses the current and several previous frames to search into a database for the best matching solution. For improved robustness, object configuration sequences, rather than single configurations, are stored in the database. We apply our framework to the problem of 3D hand tracking from image sequences and the discrimination between fingerspelling and continuous signs in American Sign Language. 相似文献
89.
When describing scenes, speakers gaze at objects while preparing their names (Z. M. Griffin & K. Bock, 2000). In this study, the authors investigated whether gazes to referents occurred in the absence of a correspondence between visual features and word meaning. Speakers gazed significantly longer at objects before intentionally labeling them inaccurately with the names of similar things (e.g., calling a horse a dog) than when labeling them accurately. This held for grammatical subjects and objects as well as agents and patients. Moreover, the time spent gazing at a referent before labeling it with a novel word or accurate name was similar and decreased as speakers gained experience using the novel word. These results suggest that visual attention in speaking may be directed toward referents in the absence of any association between their visual forms and the words used to talk about them. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
90.
Teaching-Material Design Center: An ontology-based system for customizing reusable e-materials 总被引:2,自引:1,他引:1
Use of electronic teaching materials (e-material) to support teaching is a trend. e-Material design is therefore an important issue. Currently, most e-material providers offer a package of solutions for different purposes. However, not all teachers and learners need everything from a single package. A preferable alternative is to find useful material from different packages and combine them for a particular course. Currently, most educators collect the material manually, which is time-consuming and may result in missed material. In this paper, we describe a system – the Teaching-Material Design Center, which follows the standard of Sharable Content Object Reference Model – to separate e-material for use as teaching templates and learning objects and to label the material with use of semantic metadata for searching. This system can find existing teaching templates and learning objects for e-material designers and provide a convenient environment for constructing customized e-material for different requirements. We describe the implementation and evaluation of the proposed system for a course. Our system is efficient in finding teaching templates and learning objects and shortening the e-material development process. 相似文献