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   58031篇
  免费   15283篇
  国内免费   56篇
电工技术   1032篇
综合类   27篇
化学工业   21602篇
金属工艺   1227篇
机械仪表   2075篇
建筑科学   2071篇
矿业工程   9篇
能源动力   1723篇
轻工业   8675篇
水利工程   368篇
石油天然气   68篇
无线电   9937篇
一般工业技术   15451篇
冶金工业   2088篇
原子能技术   318篇
自动化技术   6699篇
  2024年   11篇
  2023年   276篇
  2022年   316篇
  2021年   911篇
  2020年   1842篇
  2019年   3519篇
  2018年   3656篇
  2017年   3919篇
  2016年   4444篇
  2015年   4361篇
  2014年   4656篇
  2013年   6240篇
  2012年   4095篇
  2011年   4116篇
  2010年   3866篇
  2009年   3763篇
  2008年   3233篇
  2007年   2779篇
  2006年   2444篇
  2005年   2044篇
  2004年   1968篇
  2003年   1858篇
  2002年   1823篇
  2001年   1587篇
  2000年   1490篇
  1999年   876篇
  1998年   758篇
  1997年   468篇
  1996年   421篇
  1995年   276篇
  1994年   196篇
  1993年   168篇
  1992年   132篇
  1991年   118篇
  1990年   88篇
  1989年   93篇
  1988年   76篇
  1987年   74篇
  1986年   62篇
  1985年   46篇
  1984年   40篇
  1983年   32篇
  1982年   31篇
  1981年   27篇
  1980年   30篇
  1979年   13篇
  1977年   24篇
  1976年   33篇
  1975年   18篇
  1974年   13篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
2.
Food Science and Biotechnology - Various hilling materials (rice hulls, pine sawdust, and perlite) were compared to produce sprout vegetables using beach silvertop (Glehnia littoralis Fr. Schm. ex...  相似文献   
3.
International Journal of Information Security - Machine learning techniques have been widely used and shown remarkable performance in various fields. Along with the widespread utilization of...  相似文献   
4.
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   
5.
The production of hydrogen, a favourable alternative to an unsustainable fossil fuel remains as a significant hurdle with the pertaining challenge in the design of proficient, highly productive and sustainable electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, the dysprosium (Dy) doped copper oxide (Cu1-xDyxO) nanoparticles were synthesized via solution combustion technique and utilized as a non-noble metal based bi-functional electrocatalyst for overall water splitting. Due to the improved surface to volume ratio and conductivity, the optimized Cu1-xDyxO (x = 0.01, 0.02) electrocatalysts exhibited impressive HER and OER performance respectively in 1 M KOH delivering a current density of 10 mAcm?2 at a potential of ?0.18 V vs RHE for HER and 1.53 V vs RHE for OER. Moreover, the Dy doped CuO electrocatalyst used as a bi-functional catalyst for overall water splitting achieved a potential of 1.56 V at a current density 10 mAcm?2 and relatively high current density of 66 mAcm?2 at a peak potential of 2 V. A long term stability of 24 h was achieved for a cell voltage of 2.2 V at a constant current density of 30 mAcm?2 with only 10% of the initial current loss. This showcases the accumulative opportunity of dysprosium as a dopant in CuO nanoparticles for fabricating a highly effective and low-cost bi-functional electrocatalyst for overall water splitting.  相似文献   
6.
7.
The aim of this exploratory study has been to investigate the fire properties and environmental aspects of different upholstery material combinations, mainly for domestic applications. An analysis of the sustainability and circularity of selected textiles, along with lifecycle assessment, is used to qualitatively evaluate materials from an environmental perspective. The cone calorimeter was the primary tool used to screen 20 different material combinations from a fire performance perspective. It was found that textile covers of conventional fibres such as wool, cotton and polyester, can be improved by blending them with fire resistant speciality fibres. A new three‐dimensional web structure has been examined as an alternative padding material, showing preliminary promising fire properties with regard to ignition time, heat release rates and smoke production.  相似文献   
8.
9.
10.
Food Science and Biotechnology - Aluminum based reflective nanolens arrays were developed via a series of aluminum electropolishing and anodization steps with subsequent selective dissolution of...  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