全文获取类型
收费全文 | 107234篇 |
免费 | 1859篇 |
国内免费 | 438篇 |
专业分类
电工技术 | 1080篇 |
综合类 | 2352篇 |
化学工业 | 16844篇 |
金属工艺 | 5120篇 |
机械仪表 | 3481篇 |
建筑科学 | 3428篇 |
矿业工程 | 656篇 |
能源动力 | 1712篇 |
轻工业 | 5418篇 |
水利工程 | 1490篇 |
石油天然气 | 412篇 |
无线电 | 10958篇 |
一般工业技术 | 20535篇 |
冶金工业 | 7106篇 |
原子能技术 | 448篇 |
自动化技术 | 28491篇 |
出版年
2023年 | 214篇 |
2022年 | 359篇 |
2021年 | 567篇 |
2020年 | 340篇 |
2019年 | 434篇 |
2018年 | 14822篇 |
2017年 | 13714篇 |
2016年 | 10466篇 |
2015年 | 1152篇 |
2014年 | 962篇 |
2013年 | 1596篇 |
2012年 | 4249篇 |
2011年 | 10767篇 |
2010年 | 9257篇 |
2009年 | 6478篇 |
2008年 | 7811篇 |
2007年 | 8753篇 |
2006年 | 1049篇 |
2005年 | 1948篇 |
2004年 | 1854篇 |
2003年 | 1803篇 |
2002年 | 1086篇 |
2001年 | 521篇 |
2000年 | 536篇 |
1999年 | 456篇 |
1998年 | 801篇 |
1997年 | 579篇 |
1996年 | 482篇 |
1995年 | 419篇 |
1994年 | 388篇 |
1993年 | 370篇 |
1992年 | 280篇 |
1991年 | 217篇 |
1990年 | 268篇 |
1989年 | 260篇 |
1988年 | 224篇 |
1987年 | 224篇 |
1986年 | 226篇 |
1985年 | 265篇 |
1984年 | 224篇 |
1983年 | 223篇 |
1982年 | 207篇 |
1981年 | 194篇 |
1980年 | 168篇 |
1979年 | 193篇 |
1978年 | 164篇 |
1977年 | 185篇 |
1976年 | 231篇 |
1975年 | 160篇 |
1974年 | 123篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
143.
Final-offer salary arbitration in major league baseball offers a unique institutional arrangement that creates a naturally occurring, non-equivalent-groups, repeated measures research design. The structural arrangements allow for examination of anticipatory expectancy effects and assessment of behavioral responses consistent with equity theory predictions. In addition, equity theory can be tested without the methodological problems inherent in defining the referent other. Performance and mobility were examined for major league baseball position players who won and lost their arbitration hearings. Prearbitration performance significantly predicted arbitration outcome. A significant relationship was noted between losing arbitration and postarbitration performance decline. Losers were significantly more likely to change teams and leave major league baseball. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
144.
Youngjohn James R.; Larrabee Glenn J.; Crook Thomas H. 《Canadian Metallurgical Quarterly》1992,4(1):54
The authors attempt to provide a better understanding of the differences between the normal memory decline characteristic of age-associated memory impairment (AAMI) and the pathological decline typical of mild Alzheimer's disease (AD). Batteries of traditional memory tests and computer-simulated everyday-memory tests discriminated between the 2 groups, which were matched on age, gender, and education, with reasonable degrees of accuracy (87.5% and 88.4%, respectively). False positives were the most frequent classification errors when using either battery. These results indicate that it is possible to use ecologically valid memory assessment paradigms without sacrificing discriminant validity. The clinical significance of discriminating mild AD from AAMI is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
145.
Bouchard Thomas J.; Arvey Richard D.; Keller Lauren M.; Segal Nancy L. 《Canadian Metallurgical Quarterly》1992,77(1):89
Responds to the points made by R. Cropanzano and K. James (see record 1991-00462-001) concerning the article by R. D. Arvey et al (1989). The authors acknowledge that the Arvey et al study is based on a single design, makes use of a small and special sample, and, as such, is vulnerable to threats of internal and external validity. Nevertheless, after providing a more comprehensive conceptual and empirical context for the study, and after reviewing a number of the issues raised by Cropanzano and James, the authors conclude that it is not premature to accept the idea that work attitudes are partially genetically influenced. Indeed, the authors use behavioral genetic theory, together with data gathered in the Arvey et al study, to make specific point predictions regarding the outcomes of an array of studies that easily can be undertaken. Finally, the authors acknowledge that the comments and issues raised by Cropanzano and James, along with the interchange, can offer directions for future research in this important area. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
146.
Keng Siau 《Requirements Engineering》2007,12(4):199-201
147.
Marcos Craizer Thomas Lewiner Jean-Marie Morvan 《Journal of Mathematical Imaging and Vision》2007,29(2-3):131-140
Image and geometry processing applications estimate the local geometry of objects using information localized at points. They usually consider information about the tangents as a side product of the points coordinates. This work proposes parabolic polygons as a model for discrete curves, which intrinsically combines points and tangents. This model is naturally affine invariant, which makes it particularly adapted to computer vision applications. As a direct application of this affine invariance, this paper introduces an affine curvature estimator that has a great potential to improve computer vision tasks such as matching and registering. As a proof-of-concept, this work also proposes an affine invariant curve reconstruction from point and tangent data. 相似文献
148.
149.
Phase-change read-and-write memory (PRAM) is a promising memory that can solve the problems of conventional memory—scalability, read/write speed, and reliability. We will review the opportunities and technical challenges of PRAM. The most important challenge of PRAM is the reduction of the writing current. Various approaches to reduce the writing current will be reviewed and the prospects of PRAM are discussed. 相似文献
150.