全文获取类型
收费全文 | 46822篇 |
免费 | 4659篇 |
国内免费 | 3331篇 |
专业分类
电工技术 | 3006篇 |
技术理论 | 8篇 |
综合类 | 5956篇 |
化学工业 | 5431篇 |
金属工艺 | 1658篇 |
机械仪表 | 2646篇 |
建筑科学 | 3725篇 |
矿业工程 | 1417篇 |
能源动力 | 1595篇 |
轻工业 | 1458篇 |
水利工程 | 1093篇 |
石油天然气 | 1411篇 |
武器工业 | 670篇 |
无线电 | 5023篇 |
一般工业技术 | 5138篇 |
冶金工业 | 2715篇 |
原子能技术 | 568篇 |
自动化技术 | 11294篇 |
出版年
2024年 | 183篇 |
2023年 | 740篇 |
2022年 | 992篇 |
2021年 | 1244篇 |
2020年 | 1400篇 |
2019年 | 1258篇 |
2018年 | 1300篇 |
2017年 | 1542篇 |
2016年 | 1753篇 |
2015年 | 1753篇 |
2014年 | 2626篇 |
2013年 | 3234篇 |
2012年 | 3012篇 |
2011年 | 3519篇 |
2010年 | 2832篇 |
2009年 | 3001篇 |
2008年 | 2938篇 |
2007年 | 3146篇 |
2006年 | 2944篇 |
2005年 | 2426篇 |
2004年 | 1982篇 |
2003年 | 1732篇 |
2002年 | 1452篇 |
2001年 | 1164篇 |
2000年 | 1005篇 |
1999年 | 871篇 |
1998年 | 646篇 |
1997年 | 595篇 |
1996年 | 482篇 |
1995年 | 448篇 |
1994年 | 363篇 |
1993年 | 324篇 |
1992年 | 284篇 |
1991年 | 229篇 |
1990年 | 169篇 |
1989年 | 190篇 |
1988年 | 147篇 |
1987年 | 81篇 |
1986年 | 109篇 |
1985年 | 82篇 |
1984年 | 75篇 |
1983年 | 54篇 |
1982年 | 58篇 |
1981年 | 49篇 |
1980年 | 38篇 |
1979年 | 32篇 |
1978年 | 30篇 |
1977年 | 26篇 |
1964年 | 26篇 |
1955年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
This paper describes the theory and implementation ofBabel, a system which explores the hypothesis that much of the differences in the world's languages may be characterized by the inventory and properties of the lexical items and functional categories of those languages. The structure ofBabel assumes that functional categories are originally lacking in a child's syntax, and are acquired through a statistical induction process of lexical acquisition.Babel then uses information induced from the structure of the lexicon to create a model of syntax via a deductive, rule-based process. This model makes a number of predictions about the time course of language acquisition. These predictions are tested by runningBabel as a simulation of child language acquisition, using large samples of adult speech to children as input. The simulation results are shown to highly correlate to longitudinal studies of child language acquisition in English and Polish. Finally, the approach to handling noisy data withBabel is detailed. 相似文献
142.
Bachant Janet L.; Lynch Arthur A.; Richards Arnold D. 《Canadian Metallurgical Quarterly》1996,13(1):153
The authors respond to the "relational" issue of Psychoanalytic Psychology (PP; Vol. 12, No. 1) and support Karol Marshall's remonstration about the need to clarify what exactly the category relational refers to. It is noteworthy that in this issue of PP the relational thinkers do not engage the specific topics of our essay. The author's article attempted to review the most comprehensive relational thinkers of that time across theoretical variables. Relationalists have begun to spell out the technical consequences of their perspective in recent discussions of neutrality, authority, and self-disclosure, among other issues. This is a useful trend in the relational literature, and we hope it continues. We are concerned, however, that the relational thinkers writing in this issue tend to dismiss the contributions to PP 12(1) because the perspectives presented there did not satisfy the relationalist vision of how scientific exchange should be undertaken. Although we feel that it is important for emerging points of view to be able to elaborate assumptions, constructs, and principles within their own framework and in their own way, constructive dialogue, much less a comparative analysis of the contributions and limitations of different points of view, requires that we have some common ground. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
143.
144.
D. Scida Z. Aboura M.L. Benzeggagh E. Bocherens 《Composites Science and Technology》1998,57(12):2733-1740
A micromechanical model called MESOTEX is presented for prediction of the elastic behaviour of composites reinforced with non-hybrid weave (plain weave, satin weave and twill weave) and hybrid weave (hybrid plain weave and hybrid twill weave) fabrics. By using the classical thin laminate theory applied to each woven structure, this analytical model takes into account the strand undulations in the two directions and also integrates the geometrical and mechanical parameters of each constituent (resin, fill and warp strands). A representative volume is chosen for each woven composite and the fibre architecture is described by several functions. To determine the effectiveness of this analysis, the elastic properties predicted for each woven composite are compared with experimental results and results extracted from the literature. This correlation shows excellent agreement between measured and predicted values, with a very low calculation cost (CPU time of less than 0·01 s). 相似文献
145.
146.
147.
148.
任雪莲 《电脑编程技巧与维护》2012,(8):135-136
根据《Flash动画制作》课程在教学实践中的特点,提出构建"理实同步,实例引导,任务驱动"的教学模式,在教学内容、教学方法等方面进行教学改革,并阐述了在Flash教学中的具体实施方法,提高了学生动手能力及综合素质。 相似文献
149.
目前反倾岩质边坡弯曲倾倒破坏分析方法仍以基于极限平衡理论的悬臂梁模型为主,但大多未考虑坡脚岩层的剪切破坏。为准确评价该类边坡的稳定性,建立考虑坡脚岩层剪切破坏的分析计算方法。首先,根据岩层变形破坏特征,将边坡分为后缘稳定区、中部弯曲倾倒区和前缘剪切区3个区域;其次,建立弯曲倾倒-剪切滑移破坏模式的稳定性分析方法;最后,通过工程实例验证,并进行参数分析。研究结果表明:提出的分析方法与工程实际符合性较好;边坡在倾角较陡、坡角较大时稳定性最差,坡角对边坡稳定性影响大于岩层倾角的影响;岩层厚度及层面内摩擦角增加有利于边坡稳定性,且会扩大坡脚剪切区范围。研究成果对反倾岩质边坡破坏的防治具有实践指导意义。 相似文献
150.
Thermal conductivity, viscosity, and self-diffusion coefficient data for liquid n-alkanes are satisfactorily correlated simultaneously by a method based on the hard-sphere theory of transport properties. Universal curves are developed for the reduced transport properties
*,
*, and D
* as a function of the reduced volume. A consistent set of equations is derived for the characteristic volume and for the parameters R
, R
, and R
D, introduced to account for the nonsphericity and roughness of the molecules. The temperature range of the above scheme extends from 110 to 370 K, and the pressure range up to 650 MPa. 相似文献