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   37570篇
  免费   14806篇
  国内免费   3篇
电工技术   730篇
综合类   8篇
化学工业   17350篇
金属工艺   329篇
机械仪表   705篇
建筑科学   1694篇
矿业工程   3篇
能源动力   821篇
轻工业   7256篇
水利工程   283篇
石油天然气   44篇
无线电   6802篇
一般工业技术   11405篇
冶金工业   576篇
原子能技术   7篇
自动化技术   4366篇
  2024年   4篇
  2023年   17篇
  2022年   93篇
  2021年   376篇
  2020年   1455篇
  2019年   3193篇
  2018年   3124篇
  2017年   3442篇
  2016年   3903篇
  2015年   3971篇
  2014年   3895篇
  2013年   4996篇
  2012年   2707篇
  2011年   2346篇
  2010年   2645篇
  2009年   2524篇
  2008年   2064篇
  2007年   1887篇
  2006年   1646篇
  2005年   1361篇
  2004年   1323篇
  2003年   1305篇
  2002年   1251篇
  2001年   1091篇
  2000年   1061篇
  1999年   442篇
  1998年   44篇
  1997年   44篇
  1996年   24篇
  1995年   17篇
  1994年   18篇
  1993年   12篇
  1992年   13篇
  1991年   14篇
  1990年   10篇
  1989年   8篇
  1988年   4篇
  1987年   8篇
  1986年   6篇
  1985年   3篇
  1984年   6篇
  1983年   4篇
  1982年   3篇
  1981年   4篇
  1980年   2篇
  1979年   2篇
  1978年   4篇
  1977年   2篇
  1911年   2篇
  1890年   1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.
The aim of the present study was to determine mathematical relationships between pH changes in beef 24 h post-slaughter and changes in the intensity of electrical current flowing through bull and heifer carcasses during high-voltage electrical stimulation. The electrical stimulation was applied 40 min postmortem for 120 s. The pH values of m. longissimus thoracis et lumborum were analyzed in the function of electrical current intensity changes and its change during electrical stimulation. Mathematical linear correlations of the y = ax ± b type were demonstrated between pH values at 2, 6, and 24 h postmortem and the initial (Ii) and ultimate (Iu) electrical current intensity values, the difference between them and the initial pH values determined before electrical stimulation. High multiple correlation coefficients (R2 = 0.416, α ≤ 0.001) between Iu and pH values 24 h post-slaughter enabled concluding that there is a possibility to predict a pH value of stimulated carcass with high accuracy, and thus also beef quality, based merely on the ultimate electrical current intensity values.  相似文献   
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