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   823061篇
  免费   13178篇
  国内免费   2480篇
电工技术   15336篇
综合类   739篇
化学工业   125949篇
金属工艺   33463篇
机械仪表   29424篇
建筑科学   19975篇
矿业工程   3449篇
能源动力   22512篇
轻工业   67378篇
水利工程   7642篇
石油天然气   10345篇
武器工业   32篇
无线电   101843篇
一般工业技术   163028篇
冶金工业   144476篇
原子能技术   14627篇
自动化技术   78501篇
  2022年   4503篇
  2021年   7349篇
  2020年   5403篇
  2019年   6775篇
  2018年   16298篇
  2017年   16730篇
  2016年   14938篇
  2015年   8552篇
  2014年   13453篇
  2013年   38165篇
  2012年   23754篇
  2011年   35658篇
  2010年   28718篇
  2009年   30788篇
  2008年   31428篇
  2007年   32162篇
  2006年   23743篇
  2005年   23823篇
  2004年   21708篇
  2003年   21170篇
  2002年   19681篇
  2001年   18992篇
  2000年   17793篇
  1999年   18619篇
  1998年   44405篇
  1997年   31562篇
  1996年   24586篇
  1995年   18712篇
  1994年   16639篇
  1993年   16304篇
  1992年   11975篇
  1991年   11357篇
  1990年   11023篇
  1989年   10498篇
  1988年   10070篇
  1987年   8668篇
  1986年   8502篇
  1985年   9973篇
  1984年   9265篇
  1983年   8171篇
  1982年   7558篇
  1981年   7599篇
  1980年   7106篇
  1979年   6900篇
  1978年   6633篇
  1977年   7818篇
  1976年   10401篇
  1975年   5621篇
  1974年   5353篇
  1973年   5305篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Journal of Mechanical Science and Technology - The shape of the combustion chamber plays an important role in the formation of the air-fuel mixture in the chamber, which has a great influence on...  相似文献   
82.
Topics in Catalysis - In this work, a simple thermal-catalytic system was used to valorize peanut shells (Arachis hypogaea), the residual biomass from the peanut industry. To accomplish this...  相似文献   
83.
84.
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with...  相似文献   
85.
Debittered trub (brewing waste) is an important source of protein source (70.26%). Trub and whey protein were used for 5% protein enrichment of ice cream frozen by liquid nitrogen. Three formulations were elaborated: ice cream standard (ICS), ice cream with whey protein (ICW) and ice cream with trub (ICT). Chemical composition, rheological properties, texture, overrun, melting rate, scanning electron microscopy and a sensorial test were performed. Results showed that ICT presented a higher viscosity, obtained on the upward curve up to 6.76 Pa s−1, consistency index (22.96 (Pa s−1)n), hysteresis area (140.40 mPa s−1) and hardness (31113.33 g) but a lower melting rate (0.38 g min−1), overrun (13.92%) and sensorial acceptability than the other formulations. The addition of trub debittered for protein enrichment improved ice cream properties and demonstrated that it could be used as a food ingredient.  相似文献   
86.
Journal of Communications Technology and Electronics - Abstract—The article presents a rigorous numerical solution, using the Wiener–Hopf method, to the problem of plane wave...  相似文献   
87.
The proliferating need for sustainability intervention in food grain transportation planning is anchoring the attention of researchers in the interests of stakeholders and environment at large. Uncertainty associated with food grain supply further intensifies the problem steering the need for designing robust, cost-efficient and sustainable models. In line with this, this paper aims to develop a robust and sustainable intermodal transportation model to facilitate single type of food grain commodity shipments while considering procurement uncertainty, greenhouse gas emissions, and intentional hub disruption. The problem is designed as a mixed integer non-linear robust optimisation model on a hub and spoke network for evaluating near optimal shipment quantity, route selection and hub location decisions. The robust optimisation approach considers minimisation of total relative regret associated with total cost subject to several real-time constraints. A version of Particle Swarm Optimisation with Differential Evolution is proposed to tackle the resulting NP-hard problem. The model is tested with two other state-of the art meta-heuristics for small, medium, and large datasets subject to different procurement scenarios inspired from real time food grain operations in Indian context. Finally, the solution is evaluated with respect to total cost, model and solution robustness for all instances.  相似文献   
88.
The Fourth Industrial Revolution – also known as Industry 4.0 (i4.0) – comprises the digitalisation of the industrial sector. This paper uses the theoretical lens of supply chain innovation (SCI) to investigate the implications of i4.0 on supply chain management. For these purposes, the method of structured content analysis is applied to more than 200 use cases of i4.0-enabled SCI introduced by both established and startup companies. i4.0-enabled SCI manifests along three dimensions: process, technology, and business architecture. The key findings of this study can be summarised as follows: first, i4.0-enabled SCI extends the initial focus on productivity improvements in SC processes towards scalability and flexibility. Second, extant i4.0 solutions rely mostly on analytics and smart things while omitting smart people technology and the human-centric approach associated with the i4.0 paradigm. Third, established companies adopt i4.0 merely to sustain their existing business architectures while startup companies radically change their operating models, relying heavily on data analytics and the platform economy. Consequently, established companies pursue a problem-driven, engineering-based approach to SCI while startup companies follow an ‘asset-light’, business-driven approach. Lastly, there are two distinct approaches to digitalising operational SC processes: platform-based crowdsourcing of standard processes and on-demand provision of customised services.  相似文献   
89.
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   
90.
Wireless Personal Communications - The rapid development of Information and Communication Technology and the growing number of devices connected to the Internet make the Internet of Things (IoT) as...  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