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   108326篇
  免费   14383篇
  国内免费   7728篇
电工技术   6595篇
技术理论   3篇
综合类   11801篇
化学工业   5679篇
金属工艺   2831篇
机械仪表   5968篇
建筑科学   14730篇
矿业工程   2662篇
能源动力   2192篇
轻工业   14945篇
水利工程   4810篇
石油天然气   2878篇
武器工业   1041篇
无线电   13533篇
一般工业技术   7468篇
冶金工业   4611篇
原子能技术   702篇
自动化技术   27988篇
  2024年   359篇
  2023年   1807篇
  2022年   3104篇
  2021年   3984篇
  2020年   3797篇
  2019年   3164篇
  2018年   2923篇
  2017年   3504篇
  2016年   3974篇
  2015年   4442篇
  2014年   7824篇
  2013年   7048篇
  2012年   8536篇
  2011年   9010篇
  2010年   7311篇
  2009年   7463篇
  2008年   7126篇
  2007年   7978篇
  2006年   6926篇
  2005年   5762篇
  2004年   4786篇
  2003年   4068篇
  2002年   3410篇
  2001年   2534篇
  2000年   1981篇
  1999年   1525篇
  1998年   1104篇
  1997年   896篇
  1996年   761篇
  1995年   637篇
  1994年   515篇
  1993年   398篇
  1992年   329篇
  1991年   239篇
  1990年   206篇
  1989年   178篇
  1988年   150篇
  1987年   111篇
  1986年   93篇
  1985年   88篇
  1984年   74篇
  1983年   62篇
  1982年   46篇
  1981年   31篇
  1980年   35篇
  1979年   12篇
  1977年   9篇
  1965年   20篇
  1964年   8篇
  1959年   16篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
传统的汉字书写教学方法具有一定的局限性,为此人们开始关注计算机辅助的汉字书写教学技术。它主要研究汉字书写规范的智能化、自动化评判方法以及可视化的反馈形式。对近20年来计算机辅助汉字书写教学技术的发展情况进行了综述;详细介绍了数字化展示、书写评判、水平评测等几个研究分支的特点、关键问题以及主要成果;结合相关技术的发展和需求的变化,提出了汉字书写数字化教学技术在未来的发展方向。  相似文献   
92.
93.
Low-light images enhancement is a challenging task because enhancing image brightness and reducing image degradation should be considered simultaneously. Although existing deep learning-based methods improve the visibility of low-light images, many of them tend to lose details or sacrifice naturalness. To address these issues, we present a multi-stage network for low-light image enhancement, which consists of three sub-networks. More specifically, inspired by the Retinex theory and the bilateral grid technique, we first design a reflectance and illumination decomposition network to decompose an image into reflectance and illumination maps efficiently. To increase the brightness while preserving edge information, we then devise an attention-guided illumination adjustment network. The reflectance and the adjusted illumination maps are fused and refined by adversarial learning to reduce image degradation and improve image naturalness. Experiments are conducted on our rebuilt SICE low-light image dataset, which consists of 1380 real paired images and a public dataset LOL, which has 500 real paired images and 1000 synthetic paired images. Experimental results show that the proposed method outperforms state-of-the-art methods quantitatively and qualitatively.  相似文献   
94.
95.
With the growing availability of hand-held cameras in recent years, more and more images and videos are taken at any time and any place. However, they usually suffer from undesirable blur due to camera shake or object motion in the scene. In recent years, a few modern video deblurring methods are proposed and achieve impressive performance. However, they are still not suitable for practical applications as high computational cost or using future information as input. To address the issues, we propose a sequentially one-to-one video deblurring network (SOON) which can deblur effectively without any future information. It transfers both spatial and temporal information to the next frame by utilizing the recurrent architecture. In addition, we design a novel Spatio-Temporal Attention module to nudge the network to focus on the meaningful and essential features in the past. Extensive experiments demonstrate that the proposed method outperforms the state-of-the-art deblurring methods, both quantitatively and qualitatively, on various challenging real-world deblurring datasets. Moreover, as our method deblurs in an online manner and is potentially real-time, it is more suitable for practical applications.  相似文献   
96.
97.
Heat capacity data for compounds located in the binary CaO–SiO2, CaO–Al2O3 and MgO–Al2O3 systems are fitted by Debye-Einstein integrals. Starting from the fitted heat capacities, the standard values of the thermodynamic functions of these compounds are calculated. In almost all cases investigated, the derived standard entropies are within the uncertainties of the values provided in literature. The Debye-Einstein coefficients obtained in this thermodynamic assessment can be used to approximate the heat capacities, enthalpies and entropies of these compounds in the temperature range from 0 to 298.15 K.  相似文献   
98.
99.
基于GA-BP的汽车风振噪声声品质预测模型   总被引:1,自引:1,他引:0  
目前对于汽车风振噪声的优化研究主要以声压级(Sound pressure level,SPL)作为单一评价指标,既不能全面反映噪声的物理属性,也无法考虑人耳对噪声的主观认知过程。为准确评价风振噪声,引入声品质,运用大涡模拟(Large eddy simulation,LES)对风振噪声进行数值仿真,根据实车道路试验判断仿真的准确性;对仿真结果进行声品质客观评价与主观评价,综合声品质客观评价参数与声品质主观评价试验结果建立BP神经网络预测模型;利用遗传算法(Genetic algorithm,GA),进一步对BP神经网络的结构参数进行优化,建立GA-BP声品质预测模型。研究结果表明,GA-BP声品质预测模型在训练速度和预测精度上都优于BP神经网络预测模型。预测模型基于声品质主客观评价结果,其预测值可以代替传统的声压级评价指标,为风振噪声提供更为准确合理的评价。  相似文献   
100.
Blowdown testing offers a cost-effective experimental tool to replicate the aerothermal conditions in numerous high speed systems. The wind tunnel must replicate the inlet operating conditions, while the spatial and time dependent inlet flow conditions should be assessed carefully. This paper provides a design methodology and rules that ensure adequate flow conditioning in high inlet pressure wind tunnels suitable for subsonic and supersonic operation with mass-flow limits ranging from 1 kg/s to 25 kg/s, Reynolds numbers from 103 (1/m) to 4x107 (1/m), and Mach numbers from 0.01 up to 6. The quality of the proposed flow conditioning system was evaluated using stereo PIV measurements combined with hotwire, Pitot probe, and total flow temperature traverses.  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