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   298246篇
  免费   23841篇
  国内免费   12167篇
电工技术   16403篇
技术理论   24篇
综合类   17770篇
化学工业   48783篇
金属工艺   17886篇
机械仪表   18606篇
建筑科学   19760篇
矿业工程   8006篇
能源动力   7769篇
轻工业   17617篇
水利工程   5445篇
石油天然气   18220篇
武器工业   2256篇
无线电   32318篇
一般工业技术   42356篇
冶金工业   17774篇
原子能技术   6412篇
自动化技术   36849篇
  2024年   1315篇
  2023年   4411篇
  2022年   8274篇
  2021年   11382篇
  2020年   8654篇
  2019年   7318篇
  2018年   8907篇
  2017年   9834篇
  2016年   8926篇
  2015年   10629篇
  2014年   13770篇
  2013年   16639篇
  2012年   17707篇
  2011年   19245篇
  2010年   16509篇
  2009年   15963篇
  2008年   15808篇
  2007年   15017篇
  2006年   14428篇
  2005年   12266篇
  2004年   9166篇
  2003年   9093篇
  2002年   9579篇
  2001年   8479篇
  2000年   7260篇
  1999年   6887篇
  1998年   5359篇
  1997年   4460篇
  1996年   4177篇
  1995年   3431篇
  1994年   2945篇
  1993年   2292篇
  1992年   1995篇
  1991年   1653篇
  1990年   1544篇
  1989年   1381篇
  1988年   1257篇
  1987年   1049篇
  1986年   917篇
  1985年   821篇
  1984年   788篇
  1983年   713篇
  1982年   725篇
  1979年   763篇
  1978年   782篇
  1977年   742篇
  1976年   769篇
  1975年   715篇
  1974年   722篇
  1973年   727篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The realization of liquid metal-based wearable systems will be a milestone toward high-performance, integrated electronic skin. However, despite the revolutionary progress achieved in many other components of electronic skin, liquid metal-based flexible sensors still suffer from poor sensitivity due to the insufficient resistance change of liquid metal to deformation. Herein, a nacre-inspired architecture composed of a biphasic pattern (liquid metal with Cr/Cu underlayer) as “bricks” and strain-sensitive Ag film as “mortar” is developed, which breaks the long-standing sensitivity bottleneck of liquid metal-based electronic skin. With 2 orders of magnitude of sensitivity amplification while maintaining wide (>85%) working range, for the first time, liquid metal-based strain sensors rival the state-of-art counterparts. This liquid metal composite features spatially regulated cracking behavior. On the one hand, hard Cr cells locally modulate the strain distribution, which avoids premature cut-through cracks and prolongs the defect propagation in the adjacent Ag film. On the other hand, the separated liquid metal cells prevent unfavorable continuous liquid-metal paths and create crack-free regions during strain. Demonstrated in diverse scenarios, the proposed design concept may spark more applications of ultrasensitive liquid metal-based electronic skins, and reveals a pathway for sensor development via crack engineering.  相似文献   
62.
63.
安全仪表功能(SIF)回路是为了降低特定场景的安全风险而设置的,定级报告中SIF回路的功能描述是工艺设计的完整逻辑要求,包含关键动作及附件动作。安全完整性等级(SIL)验证属于概率学领域研究范畴,影响失效率的因素多且复杂。如果SIL验证无法通过,将造成大量的设计变更,浪费工程投资,影响工期。设计人员应关注SIL定级报告中关键动作的识别、要求平均失效概率以及SIF回路架构的约束。按照文中方法优化测量元件、逻辑控制器、执行元件及辅助元件的设计,可增加通过验证的概率。在没有预验证及安全要求规格书时,可以参考文中典型可通过SIL验证的SIF回路的经验架构进行优化设计,以减少工程变更。  相似文献   
64.
Wei  Shaowei  Yu  Guoxian  Wang  Jun  Domeniconi  Carlotta  Zhang  Xiangliang 《Machine Learning》2021,110(6):1505-1526
Machine Learning - Traditional clustering algorithms focus on a single clustering result; as such, they cannot explore potential diverse patterns of complex real world data. To deal with this...  相似文献   
65.
With the emergence of large-scale knowledge base, how to use triple information to generate natural questions is a key technology in question answering systems. The traditional way of generating questions require a lot of manual intervention and produce lots of noise. To solve these problems, we propose a joint model based on semi-automated model and End-to-End neural network to automatically generate questions. The semi-automated model can generate question templates and real questions combining the knowledge base and center graph. The End-to-End neural network directly sends the knowledge base and real questions to BiLSTM network. Meanwhile, the attention mechanism is utilized in the decoding layer, which makes the triples and generated questions more relevant. Finally, the experimental results on SimpleQuestions demonstrate the effectiveness of the proposed approach.  相似文献   
66.
Qin  Yi  Tao  Xianping  Huang  Yu    Jian 《World Wide Web》2019,22(1):1-37
World Wide Web - Rule mechanism has been widely used in many areas, such as databases, artificial intelligent and pervasive computing. In a rule mechanism, rule activation decides which rules are...  相似文献   
67.
68.
69.
Fang  Zhiwei  Xing  Qiyu  Fernandez  Desiree  Zhang  Xiao  Yu  Guihua 《Nano Research》2020,13(5):1179-1190

Two-dimensional (2D) nanomaterials have attracted a great deal of attention since the discovery of graphene in 2004, due to their intriguing physicochemical properties and wide-ranging applications in catalysis, energy-related devices, electronics and optoelectronics. To maximize the potential of 2D nanomaterials for their technological applications, controlled assembly of 2D nanobulding blocks into integrated systems is critically needed. This mini review summarizes the reported strategies of 2D materials-based assembly into integrated functional nanostructures, from in-situ assembly method to post-synthesis assembly. The applications of 2D assembled integrated structures are also covered, especially in the areas of energy, electronics and sensing, and we conclude with discussion on the remaining challenges and potential directions in this emerging field.

  相似文献   
70.
Russian Journal of Non-Ferrous Metals - Rolling bearing rings comprise a large reserve for expanding powder metallurgy production. This reserve is being incompletely implemented. The hot forging 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