首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   590篇
  免费   13篇
电工技术   39篇
化学工业   219篇
金属工艺   14篇
机械仪表   22篇
建筑科学   8篇
能源动力   14篇
轻工业   17篇
无线电   28篇
一般工业技术   105篇
冶金工业   6篇
原子能技术   22篇
自动化技术   109篇
  2023年   2篇
  2022年   7篇
  2021年   5篇
  2020年   7篇
  2019年   5篇
  2018年   11篇
  2017年   5篇
  2016年   11篇
  2015年   10篇
  2014年   19篇
  2013年   27篇
  2012年   24篇
  2011年   37篇
  2010年   21篇
  2009年   39篇
  2008年   56篇
  2007年   36篇
  2006年   21篇
  2005年   25篇
  2004年   20篇
  2003年   12篇
  2002年   23篇
  2001年   10篇
  2000年   7篇
  1999年   10篇
  1998年   15篇
  1997年   11篇
  1996年   18篇
  1995年   7篇
  1994年   9篇
  1993年   8篇
  1992年   7篇
  1991年   4篇
  1990年   10篇
  1989年   4篇
  1988年   6篇
  1987年   3篇
  1986年   4篇
  1985年   7篇
  1984年   6篇
  1983年   7篇
  1980年   1篇
  1979年   2篇
  1978年   2篇
  1977年   6篇
  1976年   9篇
  1973年   1篇
  1972年   2篇
  1968年   1篇
  1967年   1篇
排序方式: 共有603条查询结果,搜索用时 15 毫秒
51.
iopeNet及其目的   总被引:1,自引:0,他引:1  
我们已经提出的新的开放式区域控制网络“iopeNet”是一个全新的概念,与现有的设备控制网络没有冲突。本资料就此加以阐释。  相似文献   
52.
Acidic hydrothermal degradation of glucose was examined in the presence of HCl, H2SO4, and H3PO4 with pH varying from 1.5 to 2.5 and reaction time varying from 1 to 10 min at 523 K, to investigate the effect of different acid catalysts and acid concentration on the production of 5-hydroxymethyl-2-furaldehyde (HMF) and levulinic acid from glucose. At lower acidities of pH 2.5, a considerably higher amount of HMF was produced. The increase in acid concentration accelerated the conversion of HMF to levulinic acid. The order for the production of HMF using the three acids is in the sequence of H3PO4 > H2SO4 > HCl. On the contrary, the order for production of levulinic acid follows HCl > H2SO4 > H3PO4. In the experimental conditions used in this study, the highest yield of levulinic acid is about 55%, which was obtained at pH 1.5 for 5 min in the case of HCl as an acid catalyst, and the total highest yields of HMF and levulinic acid are about 50%, which occurred at pH 2.0 for 5 min in the case of H3PO4 as an acid catalyst.  相似文献   
53.
通信协议标准规格   总被引:4,自引:4,他引:0  
开放式综合设备网络可以满足建筑物节能、引进设备控制网络、连接现有的各种电气设备网络协议、通过扩展因特网的方式构建广域建筑设备控制网络等要求。 本文将对目前正在研究的,可望满足上述要求的设备控制网络的标准规格进行简要介绍。  相似文献   
54.
55.
We have developed a mobile global positioning system (GPS) that operates on just photovoltaic (PV) cells. The system receives wireless signals from satellites and shows one's present location accurately on a map without the need for a battery. A PV display module, which combines a transparent LCD with a-Si PV cells and has a power generation function, is added to ordinary PV cells to increase the total amount of power generated. The PV display module enables 40% more power generation than a system without the module.  相似文献   
56.
Two-dimensional monoclinic WO(3) nanoplates with high specific surface areas are synthesized through a novel conversion process using tungstate-based inorganic-organic hybrid micro/nanobelts as precursors. The process developed involves a topochemical transformation of tungstate-based inorganic-organic hybrid belts into WO(3) nanoplates via an intermediate product of H(2)WO(4) nanoplates, utilizing the similarity of the W-O octahedral layers in both H(2)WO(4) and WO(3). The as-obtained WO(3) nanoplates show a single-crystalline nanostructure with the smallest side along the [001] direction. The WO(3) nanoplates are 200-500 nm x 200-500 nm x 10-30 nm in size, and their specific surface areas are up to 180 m(2) g(-1). Photocatalytic measurements of visible-light-driven oxidation of water for O(2) generation in the presence of Ag(+) ions indicate that the activity of the as-obtained WO(3) nanoplates is one order of magnitude higher than that of commercially available WO(3) powders.  相似文献   
57.
Both silicon carbide and aluminum silicon carbide have simultaneously been obtained directly from naturally occurring aluminosilicate by carbothermal reduction for the first time. A precursor of a montmorillonite–polyacrylonitrile (PAN) intercalation compound was heated at 1700°C in Ar. For comparison, montmorillonite–carbon mixtures were similarly heated. α-SiC, β-SiC, and Al4Si2C5 formed from the montmorillonite–PAN intercalation compound. Mainly α-Al4SiC4 was obtained with ternary carbides from the montmorillonite–carbon mixtures in addition to a large amount of β-SiC. Hence, aluminum silicon carbide formation was affected by the mixing condition of the starting materials.  相似文献   
58.
Autonomous control of vehicles has recently attracted considerable attention. In this sense, vehicle merging has become an important topic in this field of research. However, in conventional studies, the controlled vehicle must calculate the movement of other surrounding vehicles to complete the merge, requiring high computational costs. In this paper, we focus on dragonfly behavior to solve this issue. Indeed, insects can behave adaptively in the complex real world in spite of the limited size of their brains. They reduce the computational requirements of their brain by relying on different properties of their surroundings, basing their intelligent behaviors on simple strategies. The behavior of a dragonfly when chasing a prey is an example of these strategies. In this study, we address the vehicle merging maneuver by applying dragonfly’s strategies to control the movement of the merging vehicle. We propose a simple control method inspired by the aforementioned strategies and, finally, we present simulation results that were conducted to demonstrate the effectiveness of this method.  相似文献   
59.
In this study, we focus on the intelligent behavior of an octopus and describe the development of a flexible manipulator. To realize the intelligent behavior, we employ sponges, rubbers and wires instead of electrical computers. The manipulator is controlled by the dynamics of the body such as the flexibility of the sponges, resilience of the rubbers and constraint by the wires. To demonstrate the effectiveness of the proposed manipulator, we conducted experiment for grasping various objects. We confirmed that grasping behaviors similar to those of an octopus can be realized by the dynamics of the body without electrical computers.  相似文献   
60.
Simple glycolipid N‐alkaroyl‐β‐D‐glucopyranosylamine 1(n) selectively self‐assembles into sheets in water, nanotubes in alcohols, and helical nanocoils in toluene. All self‐assemblies consist of bilayer membranes in which 1(n) packed in an interdigitated fashion. The outer surface of the sheet is covered with the hydrophilic glucose headgroup of 1(n), whereas those of the nanotube and helical nanocoil are covered with the hydrophobic alkyl‐chain tail of 1(n). Heat treatment of the nanotube in the presence of water induces a rearrangement of the molecular packing of the outermost surface that allows the nanotube to become an effective nanocontainer for the dispersion of fullerene (C60) in water, a result of the ability of the hydrophilic outer surface of the nanotube and the hydrophobic nanochannel to encapsulate C60. The nanotube also exhibits photothermal characteristics after being hybridized with Au nanoparticles (AuNPs). The photothermal effect of the AuNPs allows the nanotube to unfold its tubular morphology and leads to compulsive release of the encapsulated C60 to the bulk water. Application of other nanotubes with similar photostimulated transformation ability should facilitate control of the dispersion/aggregation of other carbon nanomaterials, functional aromatic compounds, and drugs with low solubility in water.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号