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   104965篇
  免费   9095篇
  国内免费   4631篇
电工技术   6188篇
技术理论   6篇
综合类   6677篇
化学工业   17118篇
金属工艺   6677篇
机械仪表   7436篇
建筑科学   8671篇
矿业工程   3752篇
能源动力   3102篇
轻工业   6681篇
水利工程   1835篇
石油天然气   7758篇
武器工业   874篇
无线电   11256篇
一般工业技术   12184篇
冶金工业   5088篇
原子能技术   1097篇
自动化技术   12291篇
  2024年   390篇
  2023年   1860篇
  2022年   3053篇
  2021年   4641篇
  2020年   3573篇
  2019年   2856篇
  2018年   3135篇
  2017年   3491篇
  2016年   3269篇
  2015年   4435篇
  2014年   5273篇
  2013年   6218篇
  2012年   6772篇
  2011年   7248篇
  2010年   6215篇
  2009年   5894篇
  2008年   5746篇
  2007年   5416篇
  2006年   5762篇
  2005年   4965篇
  2004年   3167篇
  2003年   2992篇
  2002年   2800篇
  2001年   2527篇
  2000年   2464篇
  1999年   2815篇
  1998年   2159篇
  1997年   1818篇
  1996年   1760篇
  1995年   1465篇
  1994年   1190篇
  1993年   758篇
  1992年   665篇
  1991年   457篇
  1990年   361篇
  1989年   307篇
  1988年   230篇
  1987年   144篇
  1986年   114篇
  1985年   74篇
  1984年   48篇
  1983年   40篇
  1982年   44篇
  1981年   26篇
  1980年   26篇
  1979年   19篇
  1978年   1篇
  1965年   1篇
  1959年   5篇
  1951年   2篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
21.
22.
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   
23.
The severe environmental pollution in many countries is caused by indiscriminate discharge of large quantities of food waste (FW), fat oil and grease (FOG) and sewage sludge (SS) to the environment. There are many possible treatment routes, but anaerobic digestion (AD) is now well accepted for treating several kinds of organic wastes. But AD of FW alone presents some operational challenges because of substrates and variability. Anaerobic co-digestion of two or more substrates is better than single substrate digestion. This can use a plant’s unused capacity, in line with the trend to renewable energy. Co-digestion technology, although well established in many European countries, is still in its infancy in Ireland. There are problems with different regulatory arrangements. They should be resolved. The paper reviews anaerobic co-digestion technology is reviewed, with special focus on possible application in Ireland.  相似文献   
24.
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   
25.
In this article, an adaptive fuzzy output feedback control method is presented for nonlinear time-delay systems with time-varying full state constraints and input saturation. To overcome the problem of time-varying constraints, the integral barrier Lyapunov functions (IBLFs) integrating with dynamic surface control (DSC) are applied for the first time to keep the state from violating constraints. The effects of unknown time delays can be removed by using designed Lyapunov-Krasovskii functions (LKFs). An auxiliary design system is introduced to solve the problem of input saturation. The unknown nonlinear functions are approximated by the fuzzy logic systems (FLS), and the unmeasured states are estimated by a designed fuzzy observer. The novel controller can guarantee that all signals remain semiglobally uniformly ultimately bounded and satisfactory tracking performance is achieved. Finally, two simulation examples illustrate the effectiveness of the presented control methods.  相似文献   
26.
Yan  Jing  Zhu  Rongying  Wu  Fan  Zhao  Ziyin  Ye  Huan  Hou  Mengying  Liu  Yong  Yin  Lichen 《Nano Research》2020,13(10):2706-2715
Nano Research - Insufficient intratumoral penetration greatly hurdles the anticancer performance of nanomedicine. To realize highly efficient tumor penetration in a precisely and spatiotemporally...  相似文献   
27.
28.
29.
SDN中基于KMOBPSO的高可靠性控制器部署算法   总被引:1,自引:0,他引:1  
针对SDN中控制器系统的单节点故障问题,兼顾系统成本和系统时延,应用N+1冗余备份模型来提高SDN控制器部署的可靠性,并将其抽象为多目标优化问题.同时,提出了一种融合K-means聚类算法和遗传算子的多目标二进制粒子群算法——KMOBPSO算法,以求解SDN控制器高可靠性部署问题的解.仿真结果表明,所提算法具有求解精度高、分布均匀、沿Pareto前沿面覆盖广的特点,能够显著提高SDN中控制器部署的可靠性.  相似文献   
30.
Lin  Haicheng  Huang  Wantong  Zhao  Kun  Qiao  Shuang  Liu  Zheng  Wu  Jian  Chen  Xi  Ji  Shuai-Hua 《Nano Research》2020,13(1):133-137
Nano Research - The isostructural and isoelectronic transition-metal-dichalcogenides 1T-TaS2 and 1T-TaSe2 are layered materials with intricate electronic structures. Combining the molecular beam...  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