全文获取类型
收费全文 | 3076篇 |
免费 | 193篇 |
国内免费 | 92篇 |
专业分类
电工技术 | 313篇 |
技术理论 | 1篇 |
综合类 | 268篇 |
化学工业 | 251篇 |
金属工艺 | 88篇 |
机械仪表 | 150篇 |
建筑科学 | 494篇 |
矿业工程 | 210篇 |
能源动力 | 369篇 |
轻工业 | 80篇 |
水利工程 | 187篇 |
石油天然气 | 95篇 |
武器工业 | 17篇 |
无线电 | 313篇 |
一般工业技术 | 183篇 |
冶金工业 | 100篇 |
原子能技术 | 34篇 |
自动化技术 | 208篇 |
出版年
2024年 | 6篇 |
2023年 | 28篇 |
2022年 | 57篇 |
2021年 | 66篇 |
2020年 | 75篇 |
2019年 | 52篇 |
2018年 | 37篇 |
2017年 | 76篇 |
2016年 | 73篇 |
2015年 | 88篇 |
2014年 | 216篇 |
2013年 | 154篇 |
2012年 | 208篇 |
2011年 | 242篇 |
2010年 | 220篇 |
2009年 | 188篇 |
2008年 | 169篇 |
2007年 | 257篇 |
2006年 | 184篇 |
2005年 | 148篇 |
2004年 | 121篇 |
2003年 | 141篇 |
2002年 | 94篇 |
2001年 | 70篇 |
2000年 | 85篇 |
1999年 | 63篇 |
1998年 | 37篇 |
1997年 | 29篇 |
1996年 | 26篇 |
1995年 | 37篇 |
1994年 | 27篇 |
1993年 | 24篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1979年 | 2篇 |
1962年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有3361条查询结果,搜索用时 834 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(40):17737-17748
Due to problems such as pores on surface-treated coatings, the corrosion resistance of pure titanium bipolar plates for proton-exchange membrane fuel cells can be further improved by increasing the corrosion resistance of pure titanium by using differential speed-rolling (DSR); however, these materials have not yet reached the standard requirements of bipolar plates (corrosion current density icorr<103 nA·cm?2). In this work, the corrosion resistance of pure titanium was improved by optimizing the DSR process while the strength was maintained. The best corrosion resistance of the DSR pure titanium was achieved when the roller speed ratio was 2, while icorr was 429 nA·cm?2 in a solution of 0.5 M H2SO4 and 2 mg/L HF at room temperature. The formability of the DSR pure titanium for bipolar plates was verified. The optimal holding pressure range was 6.8–7.0 kN. 相似文献
2.
《International Journal of Hydrogen Energy》2021,46(79):38983-38991
Water electrolysis is a process that can produce hydrogen in a clean way when renewable energy sources are used. This allows managing large renewable surpluses and transferring this energy to other sectors, such as industry or transport. Among the electrolytic technologies to produce hydrogen, proton exchange membrane (PEM) electrolysis is a promising alternative. One of the main components of PEM electrolysis cells are the bipolar plates, which are machined with a series of flow distribution channels, largely responsible for their performance and durability. In this work, AISI 316L stainless steel bipolar plates have been built by additive manufacturing (AM), using laser powder bed fusion (PBF-L) technology. These bipolar plates were subjected to ex-situ corrosion tests and assembled in an electrolysis cell to evaluate the polarization curve. Furthermore, the obtained results were compared with bipolar plates manufactured by conventional machining processes (MEC). The obtained experimental results are very similar for both manufacturing methods. This demonstrates the viability of the PBF-L technology to produce metal bipolar plates for PEM electrolyzers and opens the possibilities to design new and more complex flow distribution channels and to test these designs in initial phases before scaling them to larger surfaces. 相似文献
3.
采用了双极晶体管作为双极工艺的测试结构,将在线工艺的统计分析理论应用于双极工艺,研制了双极工艺的统计分析软件。最后给出了双极工艺的某些分析结果。 相似文献
4.
依托伊朗德黑兰地铁一、二号线工程 ,针对地铁单洞单线采用的轨道施工轨排法存在的不足 ,根据单洞双线隧道的特点 ,提出了利用组装好的轨排直接铺设在隧道结构底板上作为轨道平板车临时轨道的施工新方法 相似文献
5.
一级开发大柳树高坝原始库容比二级开发小观音高坝多 4 0亿m3 ,库容大带来的好处体现在 5~ 7月可多向下游增供水量 ,缓解下游河道断流 ;延长泄放清水时间 ;增加发电效益 ;满足宁蒙河段防凌要求 ;增加汛期集中泄水 ,减缓下游河道淤积萎缩 ;满足南水北调西线工程水量调节要求等。为了更好优化配置黄河水资源 ,从全局和长远利益考虑 ,应采用一级开发方案 ,修建大柳树高坝大库 相似文献
6.
D. Knig S. Carvajal-Gonzalez A. M. Downs J. Vassy P. Rigaut 《Journal of microscopy》1991,161(3):405-433
Within the concept of point processes, a review is presented of quantities which can be used in studies of three-dimensional (3-D) aggregates of particles. Suitable characteristics and estimators are given for both unmarked and marked point processes. To demonstrate the feasibility of such quantitative approaches, an application in histology, dealing with 3-D arrangements of cell nuclei in rat liver, is described. Using a confocal scanning light microscope, 3-D images are recorded and image analysis used to obtain the coordinates of the centroid, together with the volume and DNA content, of each cell nucleus. Examples of results are given, using both unmarked and marked point processes. In the latter case, cell type, nuclear volume and ploidy group are suitable marks. 相似文献
7.
Shear Bombs in Fibre Composites Despite an optimum external shape non‐load adapted internal fibre orientation can lead to the formation of shear cracks where crossing tension‐compression principal stress trajectories create localized shear peaks. Trees are subject to those failure because they cannot re‐arrange their fibres after wood formation. Bones can adjust their micro‐structure to changing load conditions and in this way can better control shear failure. The engineer working with fibre composites should be alert to avoid fibre arrangements not following the force flow. Localized shear zones may also form near notches similar to normal notch stresses, however they are not always situated at the contour line of the notch. 相似文献
8.
五强溪水电站主体工程混凝土浇筑垂直运输在大坝两岸分高、低层布置4台平移式20t缆索起重机。其中2台高缆从德国引进,属世界上首次采用全遥控的缆机,同时也是国内塔架最高的缆机;2台低缆属我国目前自行设计制造安装的规格最大、速度最高的缆机。 相似文献
9.
10.
深入贯彻十六大精神加速企业创新体系建设为全面实现"十五"目标而奋斗 总被引:1,自引:1,他引:0
总结了2001年以来冶金集团总公司的科技质量工作,指出了存在的主要问题,布署安排了今后两年的科技工作。 相似文献