全文获取类型
收费全文 | 2970篇 |
免费 | 125篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 21篇 |
综合类 | 1篇 |
化学工业 | 600篇 |
金属工艺 | 50篇 |
机械仪表 | 99篇 |
建筑科学 | 62篇 |
矿业工程 | 3篇 |
能源动力 | 81篇 |
轻工业 | 421篇 |
水利工程 | 29篇 |
石油天然气 | 17篇 |
无线电 | 254篇 |
一般工业技术 | 427篇 |
冶金工业 | 559篇 |
原子能技术 | 35篇 |
自动化技术 | 438篇 |
出版年
2024年 | 6篇 |
2023年 | 32篇 |
2022年 | 89篇 |
2021年 | 108篇 |
2020年 | 65篇 |
2019年 | 80篇 |
2018年 | 85篇 |
2017年 | 86篇 |
2016年 | 99篇 |
2015年 | 57篇 |
2014年 | 108篇 |
2013年 | 185篇 |
2012年 | 164篇 |
2011年 | 209篇 |
2010年 | 146篇 |
2009年 | 142篇 |
2008年 | 125篇 |
2007年 | 111篇 |
2006年 | 76篇 |
2005年 | 86篇 |
2004年 | 55篇 |
2003年 | 62篇 |
2002年 | 48篇 |
2001年 | 33篇 |
2000年 | 32篇 |
1999年 | 43篇 |
1998年 | 195篇 |
1997年 | 116篇 |
1996年 | 93篇 |
1995年 | 45篇 |
1994年 | 50篇 |
1993年 | 48篇 |
1992年 | 18篇 |
1991年 | 13篇 |
1990年 | 12篇 |
1989年 | 22篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 12篇 |
1985年 | 17篇 |
1984年 | 5篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1977年 | 8篇 |
1976年 | 15篇 |
1969年 | 4篇 |
1967年 | 7篇 |
排序方式: 共有3097条查询结果,搜索用时 15 毫秒
1.
2.
Shanchieh Jay Yang Gustavo de Veciana 《Networking, IEEE/ACM Transactions on》2004,12(2):349-360
With a view on improving user-perceived performance on networks supporting best effort flows, e.g., multimedia/data file transfers, we propose a family of bandwidth allocation criteria that depends on the residual work of on-going transfers. Analysis and simulations show that allocating bandwidth in this fashion can significantly improve the user-perceived delay, bit transmission delay, and throughput over traditional approaches, e.g., by 58% on an 80% loaded linear network. A simple implementation based on TCP Reno, exemplifies how one might approach practically realizing such gains. We discuss several other advantages of incorporating such differentiation at the transport level. In particular we make the case that favoring small transfers combined with user impatience or peak rate constraints, both of which are natural mechanisms for users to express the utility of completing transfers, offers a lightweight approach to achieving good overall network goodput and/or utility for best effort networks. 相似文献
3.
We study the mechanical and conformational properties of networks of helical polymers with a combination of Monte Carlo simulations based on the Wang-Landau algorithm and the three-chain model. We find that the stress-strain behavior of these networks has novel features not observed in typical networks made of synthetic polymers. In particular, we find that as these networks are stretched they first strengthen, then soften and finally strengthen again. This non-monotonic behavior of the stress correlates with the one of the helical content and is rationalized by the elongation-induced formation and melting of the helical structure of the polymer. We complement these results with a study of other conformational properties of the polymer strands that clarify the molecular mechanisms behind the mechanical behavior of these networks. Finally, we present a qualitative comparison of some of our results with the theoretical ones recently reported by Kutter and Terentjev. 相似文献
4.
Sebastián López Gustavo M. Callicó Félix Tobajas Valentín de Armas José F. López Roberto Sarmiento 《ETRI Journal》2008,30(6):862-864
This letter presents a novel approach for organizing computational resources into groups within H.264/AVC motion estimation architectures, leading to reductions of up to 75% in the equivalent gate count with respect to state‐of‐the‐art designs. 相似文献
5.
The paper describes an experimental investigation of the diamond-like carbon deposition process from methane precursor with an innovative high-density inductively coupled plasma source. It appears that a high plasma density allows a fast growth of diamond-like carbon coatings exhibiting a high hardness. In contrast to what is usually found in the literature, it seems that the ion species participate significantly to the growth of the carbon film when exposed to a high ion flux. 相似文献
6.
The purpose of the current study was to describe four models of cognitive deficit and to outline the statistical hypotheses underlying each model. The four models of cognitive deficit were (a) specific deficit; (b) subgroup deficit; (c) a syndrome dissociation model; and (d) a global function dissociation model. Neuropsychological data are analyzed to examine each of these four models in a sample of mild Multiple Sclerosis (MS) patients. The results suggest that for these subjects and tests, the specific deficit model best fits the data. The results are reviewed initially in the context of MS. There follows a consideration of statistical caveats and finally, general applications of the proposed procedures. 相似文献
7.
8.
9.
Inverse surface design problems from light transport behavior specification usually represent extremely complex and costly processes, but their importance is well known. In particular, they are very interesting for lighting and luminaire design, in which it is usually difficult to test design decisions on a physical model in order to avoid costly mistakes. In this survey, we present the main ideas behind these kinds of problems, characterize them, and summarize existing work in the area, revealing problems that remain open and possible areas of further research. 相似文献
10.
On the basis of a geological - volcanological - geophysical survey, integrated with petrological and geochronological data, a structural model, including a shallow magmatic body, was defined for the Ribeira Grande area, Sao Miguel island (Azores). Two series of production tests were carried out in the Pico Vermelho 1 and Ribeira Grande 1 wells, which led to a preliminary definition of the deep fluid circulation. The data obtained from these studies were used to reconstruct a preliminary model of the Ribeira Grande geothermal field. 相似文献