全文获取类型
收费全文 | 23967篇 |
免费 | 3974篇 |
国内免费 | 2686篇 |
专业分类
电工技术 | 1223篇 |
综合类 | 2197篇 |
化学工业 | 1043篇 |
金属工艺 | 634篇 |
机械仪表 | 1686篇 |
建筑科学 | 235篇 |
矿业工程 | 271篇 |
能源动力 | 124篇 |
轻工业 | 373篇 |
水利工程 | 109篇 |
石油天然气 | 420篇 |
武器工业 | 322篇 |
无线电 | 5531篇 |
一般工业技术 | 1392篇 |
冶金工业 | 970篇 |
原子能技术 | 76篇 |
自动化技术 | 14021篇 |
出版年
2024年 | 180篇 |
2023年 | 461篇 |
2022年 | 950篇 |
2021年 | 1086篇 |
2020年 | 1078篇 |
2019年 | 765篇 |
2018年 | 660篇 |
2017年 | 809篇 |
2016年 | 939篇 |
2015年 | 1027篇 |
2014年 | 1489篇 |
2013年 | 1334篇 |
2012年 | 1725篇 |
2011年 | 1848篇 |
2010年 | 1502篇 |
2009年 | 1525篇 |
2008年 | 1571篇 |
2007年 | 1742篇 |
2006年 | 1545篇 |
2005年 | 1358篇 |
2004年 | 1117篇 |
2003年 | 1046篇 |
2002年 | 840篇 |
2001年 | 587篇 |
2000年 | 517篇 |
1999年 | 508篇 |
1998年 | 411篇 |
1997年 | 331篇 |
1996年 | 267篇 |
1995年 | 214篇 |
1994年 | 187篇 |
1993年 | 161篇 |
1992年 | 139篇 |
1991年 | 63篇 |
1990年 | 70篇 |
1989年 | 82篇 |
1988年 | 56篇 |
1987年 | 31篇 |
1986年 | 27篇 |
1985年 | 41篇 |
1984年 | 39篇 |
1983年 | 47篇 |
1982年 | 40篇 |
1981年 | 36篇 |
1980年 | 28篇 |
1979年 | 22篇 |
1978年 | 23篇 |
1977年 | 27篇 |
1976年 | 23篇 |
1974年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
This paper presents an orientation-based representation for planar curves and shapes. The new representation can uniquely represent all types, of planar shapes, be it convex, nonconvex, polygonal, smoothly curved, or piecewise smooth shapes. It is based on a new parameterization, theabsolute integral orientation. This representation is invariant under translation and rotation. The absolute integral orientation is a parameter invariant under scaling. As a result, matching of similar shapes (i.e., determination of the relative orientation and the scaling factor) using the absolute integral orientation as the parameter is easier than using the arclength as the parameter. In addition, the new representation has the feature of adaptive sampling, making it more compact and efficient than arc-length-based representations. 相似文献
23.
生物超微弱发光的光子计数成象方法 总被引:1,自引:0,他引:1
介绍了我们研制和设计的用于测量生物超微弱发光的光子计数成象系统,包括光子成象头,高帧频CCD摄象机,图象采集系统和计算机,可以定量地探测出生物的发光强度分布 ,还能够显示出其发光的图象,确定发光的形状和位置,本系统的信噪比为10:1,最小探测功率达10^-16W,灵敏度高,动态范围大。 相似文献
24.
The cross-spectral estimation methods are efficient in estimating the parameters of sinusoidal signals embedded in colored noise. But up to now, only FPT and cross-periodogram methods are used in this field, the modern auto-spectral estimation method is introduced into cross-spectral estimation in this paper, meanwhile the cross-correlation based Yule-Walker equation is proposed theoretically and the moment and singular-value decomposition (SVD)) algorithms for cross-spectral estimation have been developed. Finally, a numerical example is given for comparing the presented methods with the well-known Cadzow's SVD method. 相似文献
25.
基于i860的存储器子系统设计 总被引:1,自引:0,他引:1
微处理机系统中的存储器子系统设计对整个系统性能的高低有重要的影响,尤其当微处理器的主频越来越高时。本文结合实际例子,给出了一个基于i860处理器(40MHz)的主存设计方案,讨论了实际中需仔细考虑的因素。该设计可为其它高性能RISC系统设计提供参考。 相似文献
26.
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
27.
28.
Reviews the book, Basic Processes in Reading Visual Word Recognition by Derek Besner and Glyn W. Humphreys (see record 1990-99017-000). While there has been an increase in the amount of work on many different aspects of reading, as Besner and Humphreys point out in the overview to their book, the vast majority of the research on the topic of reading in the past twenty years has been concerned with the processes involved in word recognition. For this reason, Besner and Humphreys have attempted to bring together studies on topics which are both relevant to current debates in the field of word recognition, and which are likely to be important for future developments in the field. They have compiled an edited volume consisting of their overview and eight additional chapters. The editors have attempted to span the continuum of processes involved in word recognition and thus have included chapters which cover topics ranging from the visual analysis of words, to those on the influence of semantic factors on word recognition. The authors of these chapters comprise an impressive list of researchers in the field of word recognition, with the majority of chapters being authored by leading researchers on the topic. Given the stature of the authors and the range of topics covered, in theory this volume should provide a very thorough overview of current theory and research on reading. There is no question that each of the chapters is interesting and important in its own right. However, in practice the volume as a whole fell somewhat short of my expectations. The different tacts taken by different authors has resulted in a very uneven coverage of the current debates in the field. Notwithstanding these criticisms, I am sure that the majority of researchers in this field will consider this volume to be an important contribution. The book would provide a very useful addition to graduate courses in cognitive sciences and as a supplemental text for an undergraduate course on the psychology of reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
29.
Document image analysis: A primer 总被引:1,自引:0,他引:1
30.
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