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   42874篇
  免费   14937篇
  国内免费   16篇
电工技术   812篇
综合类   11篇
化学工业   18156篇
金属工艺   519篇
机械仪表   1062篇
建筑科学   1783篇
矿业工程   2篇
能源动力   1129篇
轻工业   7518篇
水利工程   297篇
石油天然气   50篇
武器工业   1篇
无线电   7762篇
一般工业技术   12543篇
冶金工业   1002篇
原子能技术   97篇
自动化技术   5083篇
  2024年   6篇
  2023年   85篇
  2022年   112篇
  2021年   420篇
  2020年   1564篇
  2019年   3280篇
  2018年   3232篇
  2017年   3571篇
  2016年   4054篇
  2015年   4092篇
  2014年   4103篇
  2013年   5344篇
  2012年   3104篇
  2011年   2779篇
  2010年   2930篇
  2009年   2824篇
  2008年   2397篇
  2007年   2118篇
  2006年   1857篇
  2005年   1574篇
  2004年   1504篇
  2003年   1453篇
  2002年   1391篇
  2001年   1210篇
  2000年   1165篇
  1999年   555篇
  1998年   243篇
  1997年   171篇
  1996年   133篇
  1995年   87篇
  1994年   70篇
  1993年   72篇
  1992年   42篇
  1991年   33篇
  1990年   30篇
  1989年   24篇
  1988年   24篇
  1987年   27篇
  1986年   13篇
  1985年   19篇
  1984年   12篇
  1983年   15篇
  1982年   6篇
  1981年   6篇
  1980年   12篇
  1978年   12篇
  1977年   10篇
  1976年   10篇
  1974年   7篇
  1972年   6篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
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   
3.
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   
4.
5.
6.
7.
8.
9.
Lobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product.  相似文献   
10.
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