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   55471篇
  免费   15324篇
  国内免费   45篇
电工技术   952篇
综合类   24篇
化学工业   20522篇
金属工艺   786篇
机械仪表   1096篇
建筑科学   2615篇
矿业工程   108篇
能源动力   1399篇
轻工业   8582篇
水利工程   449篇
石油天然气   113篇
无线电   8209篇
一般工业技术   14558篇
冶金工业   3983篇
原子能技术   125篇
自动化技术   7319篇
  2023年   120篇
  2022年   175篇
  2021年   529篇
  2020年   1635篇
  2019年   3392篇
  2018年   3412篇
  2017年   3755篇
  2016年   4243篇
  2015年   4235篇
  2014年   4331篇
  2013年   6125篇
  2012年   3481篇
  2011年   3424篇
  2010年   3370篇
  2009年   3282篇
  2008年   2951篇
  2007年   2742篇
  2006年   2391篇
  2005年   2098篇
  2004年   1918篇
  2003年   1825篇
  2002年   1777篇
  2001年   1417篇
  2000年   1354篇
  1999年   771篇
  1998年   400篇
  1997年   335篇
  1996年   347篇
  1995年   312篇
  1994年   308篇
  1993年   275篇
  1992年   274篇
  1991年   177篇
  1990年   242篇
  1989年   212篇
  1988年   173篇
  1987年   177篇
  1986年   167篇
  1985年   197篇
  1984年   208篇
  1983年   167篇
  1982年   175篇
  1981年   175篇
  1980年   147篇
  1979年   170篇
  1978年   133篇
  1977年   128篇
  1976年   170篇
  1975年   135篇
  1974年   113篇
排序方式: 共有10000条查询结果,搜索用时 343 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.
Number entry is a ubiquitous activity and is often performed in safety- and mission-critical procedures, such as healthcare, science, finance, aviation and in many other areas. We show that Monte Carlo methods can quickly and easily compare the reliability of different number entry systems. A surprising finding is that many common, widely used systems are defective, and induce unnecessary human error. We show that Monte Carlo methods enable designers to explore the implications of normal and unexpected operator behaviour, and to design systems to be more resilient to use error. We demonstrate novel designs with improved resilience, implying that the common problems identified and the errors they induce are avoidable.  相似文献   
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