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   48346篇
  免费   15589篇
  国内免费   502篇
电工技术   1581篇
技术理论   2篇
综合类   735篇
化学工业   18762篇
金属工艺   968篇
机械仪表   1461篇
建筑科学   2414篇
矿业工程   275篇
能源动力   1122篇
轻工业   7662篇
水利工程   493篇
石油天然气   684篇
武器工业   97篇
无线电   8178篇
一般工业技术   12730篇
冶金工业   1224篇
原子能技术   174篇
自动化技术   5875篇
  2024年   40篇
  2023年   226篇
  2022年   317篇
  2021年   677篇
  2020年   1776篇
  2019年   3415篇
  2018年   3403篇
  2017年   3764篇
  2016年   4166篇
  2015年   4366篇
  2014年   4388篇
  2013年   5551篇
  2012年   3347篇
  2011年   3153篇
  2010年   3239篇
  2009年   3115篇
  2008年   2707篇
  2007年   2556篇
  2006年   2284篇
  2005年   1933篇
  2004年   1725篇
  2003年   1682篇
  2002年   1707篇
  2001年   1453篇
  2000年   1310篇
  1999年   679篇
  1998年   260篇
  1997年   224篇
  1996年   195篇
  1995年   163篇
  1994年   147篇
  1993年   84篇
  1992年   86篇
  1991年   50篇
  1990年   30篇
  1989年   38篇
  1988年   32篇
  1987年   29篇
  1986年   20篇
  1985年   19篇
  1984年   14篇
  1983年   12篇
  1982年   9篇
  1980年   10篇
  1979年   3篇
  1977年   4篇
  1976年   11篇
  1975年   3篇
  1967年   3篇
  1957年   2篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
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   
2.
The effects of non-thermal plasma (NTP) on the physicochemical properties of wheat flour and the quality of fresh wet noodles ( FWN) were investigated. The results showed that NTP effectively decreased the total plate count (TPC), yeast and mould count (YMC) and Bacillus spp. in wheat flour. Wet gluten contents and the stability time reached the maximum when treated for 20 s. The viscosity of starch increased significantly after treatment due to the increased of damaged starch. The contents of secondary structure were altered to some extent, which was because that the ordered network structure of gluten protein broken. Furthermore, compared with the control, texture properties of FWN were enhanced significantly at 20 s, and the darkening rate of FWN was greatly inhibited due to the low polyphenol oxidase (PPO) activity. Consequently, the most suitable treatment was 500 W for 20 s, providing a basis for the application of NTP in flour products.  相似文献   
3.
安俊理 《机械管理开发》2021,36(4):140-141,161
以寺河矿南区回风大巷为工程背景,在分析巷道地质条件的基础上,通过理论计算分析了锚杆及锚索的主要支护参数,并确定了锚杆及锚索的型号;结合以往的生产实践经验,确定了巷道联合支护方案.实践表明,巷道支护方案合理,可以满足安全生产要求.  相似文献   
4.
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   
5.
6.
Tian  Dating  Zhou  Yuchi  An  Kai  Kang  Huiting 《Polymer Bulletin》2020,77(4):1847-1868
Polymer Bulletin - Preparation of konjac glucomannan-grafted poly(trimethyl allyl ammonium chloride) (KGM-g-PTMAAC) was carried out using KGM as polysaccharide matrix and TMAAC as cationic...  相似文献   
7.
In the future, hydrogen will be an important energy carrier and industrial raw material. Catalytic steam reforming of bio-oils is a promising and economically viable technology for hydrogen production. However, during the reforming process, the catalysts are rapidly deactivated due to coke formation and sintering. Thus, maintaining the activity and stability of catalysts is the key issue in this process. Optimized operation conditions could extend the catalyst lifetime by affecting the coke morphology or promoting coke gasification. This article summarizes the recent developments in the field of catalytic steam reforming of bio-oils, focusing on the operation conditions, the properties of the catalysts, and the effects of the catalyst supports. The expected insights into the catalytic steam reforming of bio-oils will provide further guidance for hydrogen production from bio-oils.  相似文献   
8.
Multimedia Systems - The preferences of Web information purchasers are changing. Cost-effectiveness (i.e., an emphasis on performance with respect to price) is becoming less regarded than...  相似文献   
9.
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