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   60047篇
  免费   15343篇
  国内免费   68篇
电工技术   1050篇
综合类   30篇
化学工业   21896篇
金属工艺   1381篇
机械仪表   2217篇
建筑科学   2119篇
矿业工程   9篇
能源动力   1850篇
轻工业   8860篇
水利工程   377篇
石油天然气   68篇
无线电   10203篇
一般工业技术   15935篇
冶金工业   2220篇
原子能技术   333篇
自动化技术   6910篇
  2024年   15篇
  2023年   322篇
  2022年   320篇
  2021年   1000篇
  2020年   1912篇
  2019年   3569篇
  2018年   3734篇
  2017年   3984篇
  2016年   4509篇
  2015年   4389篇
  2014年   4733篇
  2013年   6342篇
  2012年   4247篇
  2011年   4316篇
  2010年   4008篇
  2009年   3899篇
  2008年   3325篇
  2007年   2872篇
  2006年   2516篇
  2005年   2108篇
  2004年   1986篇
  2003年   1911篇
  2002年   1869篇
  2001年   1622篇
  2000年   1507篇
  1999年   904篇
  1998年   797篇
  1997年   500篇
  1996年   444篇
  1995年   295篇
  1994年   199篇
  1993年   194篇
  1992年   136篇
  1991年   119篇
  1990年   88篇
  1989年   100篇
  1988年   91篇
  1987年   79篇
  1986年   72篇
  1985年   59篇
  1984年   51篇
  1983年   36篇
  1982年   37篇
  1981年   33篇
  1980年   38篇
  1979年   17篇
  1977年   30篇
  1976年   45篇
  1975年   19篇
  1974年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
6.
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   
7.
Antimony triselenide (Sb2Se3) nanoflake-based nitrogen dioxide (NO2) sensors exhibit a progressive bifunctional gas-sensing performance, with a rapid alarm for hazardous highly concentrated gases, and an advanced memory-type function for low-concentration (<1 ppm) monitoring repeated under potentially fatal exposure. Rectangular and cuboid shaped Sb2Se3 nanoflakes, comprising van der Waals planes with large surface areas and covalent bond planes with small areas, can rapidly detect a wide range of NO2 gas concentrations from 0.1 to 100 ppm. These Sb2Se3 nanoflakes are found to be suitable for physisorption-based gas sensing owing to their anisotropic quasi-2D crystal structure with extremely enlarged van der Waals planes, where they are humidity-insensitive and consequently exhibit an extremely stable baseline current. The Sb2Se3 nanoflake sensor exhibits a room-temperature/low-voltage operation, which is noticeable owing to its low energy consumption and rapid response even under a NO2 gas flow of only 1 ppm. As a result, the Sb2Se3 nanoflake sensor is suitable for the development of a rapid alarm system. Furthermore, the persistent gas-sensing conductivity of the sensor with a slow decaying current can enable the development of a progressive memory-type sensor that retains the previous signal under irregular gas injection at low concentrations.  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