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   138689篇
  免费   14165篇
  国内免费   8591篇
电工技术   10250篇
技术理论   6篇
综合类   10915篇
化学工业   20355篇
金属工艺   8609篇
机械仪表   9379篇
建筑科学   11103篇
矿业工程   4382篇
能源动力   4201篇
轻工业   9659篇
水利工程   3337篇
石油天然气   7156篇
武器工业   1652篇
无线电   16892篇
一般工业技术   14968篇
冶金工业   5586篇
原子能技术   1918篇
自动化技术   21077篇
  2024年   665篇
  2023年   2106篇
  2022年   4143篇
  2021年   5868篇
  2020年   4365篇
  2019年   3514篇
  2018年   3924篇
  2017年   4466篇
  2016年   4031篇
  2015年   5861篇
  2014年   7518篇
  2013年   8615篇
  2012年   10139篇
  2011年   11101篇
  2010年   10292篇
  2009年   9543篇
  2008年   9747篇
  2007年   9257篇
  2006年   8706篇
  2005年   7063篇
  2004年   5083篇
  2003年   4172篇
  2002年   4059篇
  2001年   3455篇
  2000年   2881篇
  1999年   2433篇
  1998年   1628篇
  1997年   1340篇
  1996年   1165篇
  1995年   967篇
  1994年   778篇
  1993年   560篇
  1992年   435篇
  1991年   333篇
  1990年   244篇
  1989年   211篇
  1988年   149篇
  1987年   108篇
  1986年   99篇
  1985年   57篇
  1984年   50篇
  1983年   54篇
  1982年   39篇
  1981年   41篇
  1980年   36篇
  1979年   20篇
  1978年   15篇
  1977年   19篇
  1959年   19篇
  1951年   14篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
The application of deep learning in the field of object detection has experienced much progress. However, due to the domain shift problem, applying an off-the-shelf detector to another domain leads to a significant performance drop. A large number of ground truth labels are required when using another domain to train models, demanding a large amount of human and financial resources. In order to avoid excessive resource requirements and performance drop caused by domain shift, this paper proposes a new domain adaptive approach to cross-domain vehicle detection. Our approach improves the cross-domain vehicle detection model from image space and feature space. We employ objectives of the generative adversarial network and cycle consistency loss for image style transfer in image space. For feature space, we align feature distributions between the source domain and the target domain to improve the detection accuracy. Experiments are carried out using the method with two different datasets, proving that this technique effectively improves the accuracy of vehicle detection in the target domain.  相似文献   
82.
The electrochemical reduction of carbon dioxide (CO2) to hydrocarbons is a challenging task because of the issues in controlling the efficiency and selectivity of the products. Among the various transition metals, copper has attracted attention as it yields more reduced and C2 products even while using mononuclear copper center as catalysts. In addition, it is found that reversible formation of copper nanoparticle acts as the real catalytically active site for the conversion of CO2 to reduced products. Here, it is demonstrated that the dinuclear molecular copper complex immobilized over graphitized mesoporous carbon can act as catalysts for the conversion of CO2 to hydrocarbons (methane and ethylene) up to 60%. Interestingly, high selectivity toward C2 product (40% faradaic efficiency) is achieved by a molecular complex based hybrid material from CO2 in 0.1 m KCl. In addition, the role of local pH, porous structure, and carbon support in limiting the mass transport to achieve the highly reduced products is demonstrated. Although the spectroscopic analysis of the catalysts exhibits molecular nature of the complex after 2 h bulk electrolysis, morphological study reveals that the newly generated copper cluster is the real active site during the catalytic reactions.  相似文献   
83.
International Journal of Mechanics and Materials in Design - A simple iterative method is presented for cutting pattern optimization of frame-supported and pneumatic membrane structures for...  相似文献   
84.
85.
Wan  Huan  Wang  Hui  Scotney  Bryan  Liu  Jun  Ng  Wing W. Y. 《Multimedia Tools and Applications》2020,79(39-40):29327-29352
Multimedia Tools and Applications - In many real-world classification problems there exist multiple subclasses (or clusters) within a class; in other words, the underlying data distribution is...  相似文献   
86.
In the past two decades, brain science and robotics have made gigantic advances in their own fields, and their interactions have generated several interdisciplinary research fields. First, in the ‘understanding the brain by creating the brain’ approach, computational neuroscience models have been applied to many robotics problems. Second, such brain-motivated fields as cognitive robotics and developmental robotics have emerged as interdisciplinary areas among robotics, neuroscience and cognitive science with special emphasis on humanoid robots. Third, in brain–machine interface research, a brain and a robot are mutually connected within a closed loop. In this paper, we review the theoretical backgrounds of these three interdisciplinary fields and their recent progress. Then, we introduce recent efforts to reintegrate these research fields into a coherent perspective and propose a new direction that integrates brain science and robotics where the decoding of information from the brain, robot control based on the decoded information and multimodal feedback to the brain from the robot are carried out in real time and in a closed loop.  相似文献   
87.
88.
89.
In this study, yttrium iron garnet co-doped with Zn and Zr atoms with a chemical formula Y3ZnxZrxFe(5−2x)O12 (x = 0.0-0.3) has been successfully prepared by the solid-state reaction method. The effects of doping concentration on the microstructure, crystal structure, magnetic properties, and dielectric properties of Y3ZnxZrxFe(5−2x)O12 were investigated. The microstructure analysis indicates that co-doping of YIG with Zn and Zr can effectively reduce the grain size of the ceramic. The crystal structure results reveal that the doping concentration of Zn–Zr has substantial influence on the lattice parameters of YIG, such as, increases the lattice constant, crystal cell size, and interplanar spacing. However, the second phase of ZrO2 appears once ≥ 0.15. Additionally, the dielectric properties of YIG ferrite can be regulated using this Zn–Zr co-doping method. Zn–Zr co-doping can improve the dielectric stability and reduce the dielectric loss at high temperature. The magnetization measurement shows that the saturation magnetization is stabilized at x < 0.15, and the magnetic loss is decreased with the increase in the doping concentration. Overall, the findings show that the ceramic with x = 0.1 exhibits better properties included high saturation magnetization (24.607 emu/g), low magnetic loss (0.0025 @ 1 MHz), and relatively low dielectric loss (496 @ 400°C).  相似文献   
90.
基于图像增强方法,本文提出了一种使用亮度映射的图像去雾快速算法。此算法通过调整室外多雾场景图像的对比度,提高了雾中物体的辨识度。算法的复杂度低、处理延迟小,实时性高,利于FPGA的实现。实现时不需外存储器,延时为ns级,并提供了强度调节接口,以适应较广的应用环境。  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