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   159817篇
  免费   26657篇
  国内免费   7065篇
电工技术   8791篇
技术理论   9篇
综合类   9502篇
化学工业   36668篇
金属工艺   7476篇
机械仪表   8797篇
建筑科学   10991篇
矿业工程   3816篇
能源动力   4222篇
轻工业   17649篇
水利工程   2887篇
石油天然气   6885篇
武器工业   1346篇
无线电   20396篇
一般工业技术   24666篇
冶金工业   5516篇
原子能技术   1542篇
自动化技术   22380篇
  2024年   596篇
  2023年   2223篇
  2022年   4415篇
  2021年   6089篇
  2020年   5637篇
  2019年   6536篇
  2018年   6840篇
  2017年   7431篇
  2016年   7464篇
  2015年   9251篇
  2014年   10343篇
  2013年   12766篇
  2012年   11455篇
  2011年   12032篇
  2010年   11143篇
  2009年   10705篇
  2008年   10110篇
  2007年   9255篇
  2006年   8593篇
  2005年   7278篇
  2004年   5360篇
  2003年   4649篇
  2002年   4450篇
  2001年   3897篇
  2000年   3442篇
  1999年   2717篇
  1998年   1646篇
  1997年   1374篇
  1996年   1203篇
  1995年   1023篇
  1994年   864篇
  1993年   662篇
  1992年   487篇
  1991年   381篇
  1990年   292篇
  1989年   213篇
  1988年   178篇
  1987年   125篇
  1986年   101篇
  1985年   46篇
  1984年   39篇
  1983年   38篇
  1982年   39篇
  1981年   20篇
  1980年   30篇
  1979年   21篇
  1978年   11篇
  1977年   11篇
  1976年   13篇
  1951年   11篇
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
1.
Feng  Wenran  Li  Zhen  Chen  Yingying  Chen  Jinyang  Lang  Haoze  Wan  Jianghong  Gao  Yan  Dong  Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in...  相似文献   
2.
Xiao  Zhu  Chen  Yanxun  Jiang  Hongbo  Hu  Zhenzhen  Lui  John C. S.  Min  Geyong  Dustdar  Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of...  相似文献   
3.
4.
5.
Multimedia Tools and Applications - In geometry-based point cloud compression, the geometry information is typically compressed using octree coding. In octree coding, the size of the blocks in the...  相似文献   
6.
In this article, we present the optical design of a novel diagnostic on the HL-2 A tokamak, i.e. the20-channel edge Lyman-alpha beam emission spectroscopy, which is a promising solution for edge density turbulence research on tokamaks, as it offers the possibility of density fluctuation measurement with a 3.3 mm spatial resolution while maintains a high temporal resolution of1 μs. The optical path, including the reflective collection optics, the high-dispersion spectrometer, and the linear detector array, is carefully optimized to obtain a good image quality and a high throughput. The maximum root mean square radius of the collection optics is 64 μm.The detected photon flux is estimated to be about 10~(11) photons/s/channel.  相似文献   
7.
Sun  Junli  Wang  Huaibin  Li  Yang  Zhao  Min 《Journal of Porous Materials》2021,28(3):889-894
Journal of Porous Materials - Co3O4 has been widely investigated as a promising candidate anode material for lithium-ion batteries. We report on the porous Co3O4 column synthesized via a simple...  相似文献   
8.
9.
Recent advances in three‐dimensional (3D) printing have enabled the fabrication of interesting structures which are not achievable using traditional fabrication approaches. The 3D printing of carbon microtube composite inks allows fabrication of conductive structures for practical applications in soft robotics and tissue engineering. However, it is challenging to achieve 3D printed structures from solution‐based composite inks, which requires an additional process to solidify the ink. Here, we introduce a wet 3D printing technique which uses a coagulation bath to fabricate carbon microtube composite structures. We show that through a facile nanogrooving approach which introduces cavitation and channels on carbon microtubes, enhanced interfacial interactions with a chitosan polymer matrix are achieved. Consequently, the mechanical properties of the 3D printed composites improve when nanogrooved carbon microtubes are used, compared to untreated microtubes. We show that by carefully controlling the coagulation bath, extrusion pressure, printing distance and printed line distance, we can 3D print composite lattices which are composed of well‐defined and separated printed lines. The conductive composite 3D structures with highly customised design presented in this work provide a suitable platform for applications ranging from soft robotics to smart tissue engineering scaffolds. © 2019 Society of Chemical Industry  相似文献   
10.
The purpose of the current work was to research the effect of alkali metal oxide on the structure, thermal properties, viscosity and chemical stability in the glass system (R2O–CaO–B2O3–SiO2) systematically. Because the glass would emulsify when Li2O was added to the glass batch, this article did not discuss Li2O. The results showed that when the amount of Na2O was less than 4 mol.%, there was a higher interconnectivity of borate and silicate sub-networks in glass, as more mixed Si–O–B bonds were present in glass. The glass samples exhibited excellent thermal properties and chemical stabilities. As the amount of Na2O exceeded 4 mol.%, the interconnectivity of borate and silicate sub-networks was weakened. The thermal properties and chemical stabilities of the glass samples were reduced. The connectivity of the silicate sub-network was weakened slightly as the Na/K ratio varied, and the coefficient of thermal expansion (CTE) of the glass samples gradually increased, and the resistance to thermal shock (RTS) value gradually decreased. Moreover, the viscosity of the glass samples decreased with the ratio of Na/Si and Na/K increased.  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