全文获取类型
收费全文 | 20609篇 |
免费 | 2185篇 |
国内免费 | 1163篇 |
专业分类
电工技术 | 1398篇 |
综合类 | 1720篇 |
化学工业 | 3129篇 |
金属工艺 | 957篇 |
机械仪表 | 1098篇 |
建筑科学 | 1502篇 |
矿业工程 | 437篇 |
能源动力 | 437篇 |
轻工业 | 2882篇 |
水利工程 | 519篇 |
石油天然气 | 630篇 |
武器工业 | 142篇 |
无线电 | 2211篇 |
一般工业技术 | 2231篇 |
冶金工业 | 787篇 |
原子能技术 | 279篇 |
自动化技术 | 3598篇 |
出版年
2024年 | 137篇 |
2023年 | 418篇 |
2022年 | 863篇 |
2021年 | 1015篇 |
2020年 | 809篇 |
2019年 | 704篇 |
2018年 | 699篇 |
2017年 | 883篇 |
2016年 | 750篇 |
2015年 | 1099篇 |
2014年 | 1290篇 |
2013年 | 1538篇 |
2012年 | 1689篇 |
2011年 | 1736篇 |
2010年 | 1519篇 |
2009年 | 1414篇 |
2008年 | 1389篇 |
2007年 | 1210篇 |
2006年 | 1104篇 |
2005年 | 879篇 |
2004年 | 570篇 |
2003年 | 399篇 |
2002年 | 316篇 |
2001年 | 286篇 |
2000年 | 237篇 |
1999年 | 180篇 |
1998年 | 123篇 |
1997年 | 88篇 |
1996年 | 81篇 |
1995年 | 64篇 |
1994年 | 46篇 |
1993年 | 45篇 |
1992年 | 48篇 |
1991年 | 20篇 |
1990年 | 32篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 19篇 |
1986年 | 23篇 |
1985年 | 14篇 |
1984年 | 22篇 |
1983年 | 15篇 |
1982年 | 15篇 |
1981年 | 8篇 |
1980年 | 22篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1974年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Xiang‐Dan Li Zhen‐Xin Zhong Sang‐Hoon Han Seung Hee Lee Myong‐Hoon Lee 《Polymer International》2005,54(2):406-411
From chloromethylated polyimide, a useful starting material for modification of aromatic polyimides, a thermocurable transparent polyimide having acrylate side groups was prepared. In the presence of 1,8‐diazabicyclo[5,4,0]undec‐7‐ene, chloromethylated polyimide was esterified with acrylic acid to synthesize poly(imide methylene acrylate). The polymer was soluble in organic solvent, which makes it possible to prepare a planar film by spin coating. The polymer film became insoluble after thermal treatment at 230 °C for 30 min. Optical transparency of the film at 400 nm (for 1 µm thickness) was higher than 98 % and not affected by further heating at 230 °C for 250 min. Adhesion properties measured by the ASTM D3359‐B method ranged from 4B to 5B. Preliminary results of planarization testing showed a high degree of planarization (DOP) value (>0.53). These properties demonstrate that poly(imide methylene acrylate) could be utilized as a thermocurable transparent material in fabricating display devices such as TFT‐LCD. Copyright © 2004 Society of Chemical Industry 相似文献
2.
Dan Strassberg 《电子设计技术》2005,12(8):66-72
在高达每路2Gbps的数据速率上,几乎没有什么技术能使信号完整性有很大的不同。哪种技术能真正提高性能?或者是只能使性能更差?专家们意见不一。 相似文献
3.
4.
对在五坐标数控加工中心上铣制三元流叶轮时出现的叶轮附面尺寸误差问题,进行了详细分析,并提出了问题的解决方法,有效地避免了加工中产生的超差。 相似文献
5.
6.
River ice jams are a common occurrence on northern rivers, and their formation can present a severe flood risk to nearby communities. As more and more river regulation projects are developed to provide an alternative to fossil fuels for electrical power-generating capacity, our need to understand the mechanisms associated with ice jam formation under variable flow conditions becomes more vital. This is because, at present, hydropeaking operations are often severely curtailed during the ice-affected seasons due to concerns that sudden flow fluctuations might instigate ice jams and associated flooding. Here, an experimental investigation explores the effects of rapid increases in discharge on ice jam formation and evolution. It is found that the thickness of ice jams formed under highly dynamic flow conditions tend to be slightly thinner than those formed during steady carrier flows for comparable discharges. Also, despite the highly dynamic nature of these consolidation events, the resulting ice thicknesses appear reasonably well approximated by steady flow theory. 相似文献
7.
In this article, a new algorithm based on an artificial potential field and hierarchical cell decomposition technique is developed to solve the find-path problem for a mobile robot. The complete map of the workspace including obstacle locations is assumed to be known a priori. The basic cell structure used for decomposition is a hexagon. The artificial potential field is based on an attractive force from the goal position and repelling forces from the obstacles. Computer simulations of the algorithm for various obstacle scenarios are also presented. © 1994 John Wiley & Sons, Inc. 相似文献
8.
Chemical mechanical polishing of polymer films 总被引:2,自引:0,他引:2
Strategies to reduce capacitance effects associated with shrinking integrated circuit (IC) design rules include incorporating
low resistivity metals and insulators with low dielectric values, or “low-κ” materials. Using such materials in current IC
fabrication schemes necessitates the development of reliable chemical mechanical polishing (CMP) processes and process consumables
tailored for them. Here we present results of CMP experiments performed on FLARE™ 2.0 using a specialized zirconium oxide
(ZrO2) polishing slurry. FLARE™ 2.0 is a poly(arylene) ether from AlliedSignal, Inc. with a nominal dielectric constant of 2.8.
In addition, we provide insight into possible removal mechanisms during the CMP of organic polymers by examining the performance
of numerous abrasive slurries. Although specific to a limited number of polymers, the authors suggest that the information
presented in this paper is relevant to the CMP performance of many polymer dielectric materials. 相似文献
9.
Since electronic switching systems usually require very strict reliability requirements as well as good performance objectives, we need to jointly analyse the performance and reliability of switching systems. In this paper, we compare conventional time–space–time switches with single space switches with those with multiple separated space switches, from the viewpoints of reliability and performance. We consider time–space–time switching networks which consist of N incoming time switches, i.e. one NxN space switch, two (N/2)x(N/2) space switches, and four (N/4)x(N/4) space switches. We introduce a Markov reliability model to study the effect of failures and analyse the reliability and performance of three different types of switching networks in terms of average blocking probability and the mean time to unreliable operation, as we vary the offered traffic. As a result, T–S–T switching networks with multiple separated space switches exhibit better performance and reliability than those with single space switches. 相似文献
10.
Dan Strassberg 《电子设计技术》2006,13(7):56-64
有了合适的协议以后(如ZigBee),无需经常与外界交流的传感器就不会消耗过多能量。有时,一节碱性电池就可以为它们提供长达十年的能量。 相似文献