全文获取类型
收费全文 | 16060篇 |
免费 | 2929篇 |
国内免费 | 2259篇 |
专业分类
电工技术 | 776篇 |
技术理论 | 3篇 |
综合类 | 1428篇 |
化学工业 | 1508篇 |
金属工艺 | 257篇 |
机械仪表 | 628篇 |
建筑科学 | 1017篇 |
矿业工程 | 671篇 |
能源动力 | 159篇 |
轻工业 | 777篇 |
水利工程 | 332篇 |
石油天然气 | 524篇 |
武器工业 | 84篇 |
无线电 | 1912篇 |
一般工业技术 | 1416篇 |
冶金工业 | 933篇 |
原子能技术 | 199篇 |
自动化技术 | 8624篇 |
出版年
2024年 | 110篇 |
2023年 | 503篇 |
2022年 | 844篇 |
2021年 | 1387篇 |
2020年 | 952篇 |
2019年 | 762篇 |
2018年 | 723篇 |
2017年 | 732篇 |
2016年 | 741篇 |
2015年 | 845篇 |
2014年 | 1124篇 |
2013年 | 998篇 |
2012年 | 1139篇 |
2011年 | 1303篇 |
2010年 | 978篇 |
2009年 | 973篇 |
2008年 | 969篇 |
2007年 | 1071篇 |
2006年 | 857篇 |
2005年 | 718篇 |
2004年 | 640篇 |
2003年 | 516篇 |
2002年 | 472篇 |
2001年 | 333篇 |
2000年 | 253篇 |
1999年 | 244篇 |
1998年 | 166篇 |
1997年 | 117篇 |
1996年 | 118篇 |
1995年 | 101篇 |
1994年 | 96篇 |
1993年 | 58篇 |
1992年 | 32篇 |
1991年 | 29篇 |
1990年 | 35篇 |
1989年 | 34篇 |
1988年 | 20篇 |
1987年 | 20篇 |
1986年 | 21篇 |
1985年 | 27篇 |
1984年 | 18篇 |
1983年 | 25篇 |
1982年 | 13篇 |
1981年 | 15篇 |
1980年 | 10篇 |
1979年 | 13篇 |
1978年 | 10篇 |
1964年 | 7篇 |
1958年 | 8篇 |
1957年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
81.
Measurement selection for parametric IC fault diagnosis 总被引:1,自引:0,他引:1
This article presents experimental results which show feedforward neural networks are well-suited for analog IC fault diagnosis. Boundary band data (BBD) measurement selection is used to reduce the computational overhead of the FFN training phase. We compare the diagnostic accuracy between traditional statistical classifiers and feedforward neural networks trained with various measurement selection criteria. The feedforward networks consistently perform as well as or better than the other classifiers in term of accuracy. Training using BBD consistently reduces the FFN training efforts without degrading the performance. Experimental results suggest that feedforward networks provide a cost efficient method for IC fault diagnosis in a large scale production testing environment.This work is supported by NSF-IUC CDADIC, Project 90-1. 相似文献
82.
Reviews the book, Language in the Americas by Joseph H. Greenberg (1987). Greenberg's work on universals of language has crossed disciplinary boundaries to become known to many psychologists interested in language. His equally important work in language classification, of which Language in the Americas is one part, remains unfamiliar to psychologists. This book is a pioneering work in that it is the first genetic classification of the indigenous languages of both North and South America. Greenberg maintains that all of the languages of the Americas belong to three families: Eskimo-Aleut, Na-Dene, and a family that he has named Amerind. This assertion is both important and controversial; the controversy lies in the grouping of most of the languages including all of those of South and Central America into the Amerind family. Most of Language in the Americas consists of the Amerind etymological dictionary, arranged so that the reader can assess lexical similarities within and between subgroups. Greenberg's discussion is informed, articulate, profound, and to the point. He draws on relevant sources and examples from diverse fields of knowledge. The depth and breadth of his scholarship and the clarity of his presentation create a work that is an intellectual pleasure to read. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
83.
This paper deals with the pricing and investment decision problem of multi-modal transportation systems in which the congestion
is a significant factor in the assessment of system costs. This study approaches this congestion pricing problem with a number
of social welfare maximization problems, all of which have the identical structure except financial constraints. One welfare
maximization problem examined in this study yields the pricing and investment decision, which can attain the first-best social
optimality for multi-modal transportation systems. Other welfare maximization problems show he second-best optimal solutions
that can address two policy questions in transportation economics, namely, the cross-subsidy between competing modes and peak-period
congestion charges on a single highway link.
Received: February 2001/Accepted: December 2001
This work was supported in part by funds from BK21 Research Division of Seoul National University for Social Infrastructure
and Construction Technology. 相似文献
84.
This issue begins with an invited paper by Ronald Melzack, continuing the "Distinguished Contribution Series" begun in 1990 by my predecessor, Gordon Winocur. Professor Melzack is known world-wide for his research on pain. In 1965, together with Patrick Wall, he proposed the gate control theory, an entirely new conception of pain. For the first time, there was an explicit physiological model emphasizing the role played by the brain as well as by the spinal cord, leading to a new integration of psychological and physiological contributions to pain, as well as to new avenues for the control of pain. This theory has been highly influential, as a quick look in virtually any textbook in biology or medicine will confirm. Professor Melzack's continuing development of his ideas is presented with remarkable clarity in his books and in his many journal articles. It is, therefore, especially exciting for CJEP to be the first to publish a sketch of his new neuromatrix theory. When the book developing this theory is published, it too will no doubt have an immediate and major impact. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
雷达目标识别技术综述 总被引:25,自引:7,他引:18
针对雷达自动目标识别技术进行了简要回顾。讨论了目前理论研究和应用比较成功的4类目标识别方法:基于目标运动的回波起伏和调制谱特性的目标识别方法、基于极点分布的目标识别方法、基于高分辨雷达成像的目标识别方法和基于极化特征的目标识别方法,同时讨论了应用于雷达目标识别中的4种模式识别技术:统计模式识别方法、模糊模式识别方法、基于模型和基于知识的模式识别方法以及神经网络模式识别方法。最后分析了问题的可能解决思路。 相似文献
86.
87.
In this paper, we present an approach toward pedestrian detection and tracking from infrared imagery using joint shape and appearance cues. A layered representation is first introduced and a generalized expectation-maximization (EM) algorithm is developed to separate infrared images into background (still) and foreground (moving) layers regardless of camera panning. In the two-pass scheme of detecting pedestrians from the foreground layer: shape cue is first used to eliminate non-pedestrian moving objects and then appearance cue helps to locate the exact position of pedestrians. Templates with varying sizes are sequentially applied to detect pedestrians at multiple scales to accommodate different camera distances. To facilitate the task of pedestrian tracking, we formulate the problem of shot segmentation and present a graph matching-based tracking algorithm that jointly exploits the shape, appearance and distance information. Experimental results with both OSU Infrared Image Database and WVU Infrared Video Database are reported to demonstrate the accuracy and robustness of our algorithm. 相似文献
88.
Reports an error in "Learning myopia: An adaptive recency effect in category learning" by Matt Jones and Winston R. Sieck (Journal of Experimental Psychology: Learning, Memory, and Cognition, 2003[Jul], Vol 29[4], 626-640). On page 633, Table 2, the values in columns (T, P) and (P, T) in the dual condition row incorrectly read .10 and .90, respectively. The correct values are .90 and .10, respectively. (The following abstract of the original article appeared in record 2003-06626-013.) Recency effects (REs) have been well established in memory and probability learning paradigms but have received little attention in category learning research. Extant categorization models predict REs to be unaffected by learning, whereas a functional interpretation of REs, suggested by results in other domains, predicts that people are able to learn sequential dependencies and incorporate this information into their responses. These contrasting predictions were tested in 2 experiments involving a classification task in which outcome sequences were autocorrelated. Experiment 1 showed that reliance on recent outcomes adapts to the structure of the task, in contrast to models' predictions. Experiment 2 provided constraints on how sequential information is learned and suggested possible extensions to current models to account for this learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
90.
文本索引词项相对权重计算方法与应用 总被引:4,自引:0,他引:4
文本索引词权重计算方法决定了文本分类的准确率。该文提出一种文本索引词项相对权重计算方法,即文本索引词项权重根据索引词项在该文本中的出现频率与在整个文本空间出现的平均频率之间的相对值进行计算。该方法能有效地提高索引词对文本内容识别的准确性。 相似文献