全文获取类型
收费全文 | 146646篇 |
免费 | 17484篇 |
国内免费 | 11305篇 |
专业分类
电工技术 | 13576篇 |
技术理论 | 2篇 |
综合类 | 14452篇 |
化学工业 | 18731篇 |
金属工艺 | 9582篇 |
机械仪表 | 10299篇 |
建筑科学 | 11105篇 |
矿业工程 | 4874篇 |
能源动力 | 4259篇 |
轻工业 | 17413篇 |
水利工程 | 5665篇 |
石油天然气 | 4381篇 |
武器工业 | 1940篇 |
无线电 | 15718篇 |
一般工业技术 | 13441篇 |
冶金工业 | 5622篇 |
原子能技术 | 2574篇 |
自动化技术 | 21801篇 |
出版年
2024年 | 811篇 |
2023年 | 2368篇 |
2022年 | 5376篇 |
2021年 | 6826篇 |
2020年 | 5033篇 |
2019年 | 3620篇 |
2018年 | 3826篇 |
2017年 | 4446篇 |
2016年 | 4083篇 |
2015年 | 6315篇 |
2014年 | 7954篇 |
2013年 | 9778篇 |
2012年 | 11605篇 |
2011年 | 12174篇 |
2010年 | 11740篇 |
2009年 | 11373篇 |
2008年 | 11714篇 |
2007年 | 11474篇 |
2006年 | 9943篇 |
2005年 | 8076篇 |
2004年 | 6228篇 |
2003年 | 4450篇 |
2002年 | 4543篇 |
2001年 | 4098篇 |
2000年 | 2963篇 |
1999年 | 1411篇 |
1998年 | 518篇 |
1997年 | 472篇 |
1996年 | 407篇 |
1995年 | 333篇 |
1994年 | 243篇 |
1993年 | 203篇 |
1992年 | 180篇 |
1991年 | 118篇 |
1990年 | 103篇 |
1989年 | 102篇 |
1988年 | 87篇 |
1987年 | 63篇 |
1986年 | 45篇 |
1985年 | 47篇 |
1984年 | 24篇 |
1983年 | 22篇 |
1982年 | 25篇 |
1981年 | 26篇 |
1980年 | 34篇 |
1979年 | 31篇 |
1977年 | 13篇 |
1976年 | 10篇 |
1959年 | 25篇 |
1951年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 25 毫秒
1.
2.
3.
5.
恶意代码数量已经呈现爆炸式增长,对于恶意代码的检测防护显得尤为重要.近几年,基于深度学习的恶意代码检测方法开始出现,基于此,提出一种新的检测方法,将恶意代码二进制文件转化为十进制数组,并利用一维卷积神经网络(1 Dimention Convolutional Neural Networks,1D CNN)对数组进行分类和识别.针对代码家族之间数量不平衡的现象,该算法选择在分类预测上表现良好的XGBoost,并对Vision Research Lab中的25个不同恶意软件家族的9458个恶意软件样本进行了实验.实验结果表明,所提的方法分类预测精度达到了97%. 相似文献
6.
Junjie Li Mei Liang Wanjing Cheng Shuhao Wang 《International Journal of Hydrogen Energy》2021,46(14):9553-9566
Electric vehicles (EVs) are considered a promising alternative to conventional vehicles (CVs) to alleviate the oil crisis and reduce urban air pollution and carbon emissions. Consumers usually focus on the tangible cost when choosing an EV or CV but overlook the time cost for restricting purchase or driving and the environmental cost from gas emissions, falling to have a comprehensive understanding of the economic competitiveness of CVs and EVs. In this study, a life cycle cost model for vehicles is conducted to express traffic and environmental policies in monetary terms, which are called intangible cost and external cost, respectively. Battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), and CVs are compared in four first-tier, four new first-tier, and 4 s-tier and below cities in China. The comparison shows that BEVs and FCEVs in most cities are incomparable with CVs in terms of tangible cost. However, the prominent traffic and environmental policies in first-tier cities, especially in Beijing and Shanghai, greatly increase the intangible and external costs of CVs, making consumers more inclined to purchase BEVs and FCEVs. The main policy benefits of BEVs and FCEVs come from three aspects: government subsidies, purchase and driving restrictions, and environmental taxes. With the predictable reduction in government subsidies, traffic and environmental policies present important factors influencing the competitiveness of BEVs and FCEVs. In first-tier cities, BEVs and FCEVs already have a competitive foundation for large-scale promotion. In new first-tier and second-tier and below cities, stricter traffic and environmental policies need to be formulated to offset the negative impact of the reduction in government subsidies on the competitiveness of BEVs and FCEVs. Additionally, a sensitivity analysis reveals that increasing the mileage and reducing fuel prices can significantly improve the competitiveness of BEVs and FCEVs, respectively. 相似文献
7.
8.
Tongling Xia Yue Qi Xilei Dai Jinyu Liu Can Xiao Ruoyu You Dayi Lai Junjie Liu Chun Chen 《Indoor air》2021,31(6):2020-2032
To evaluate the separate impacts on human health and establish effective control strategies, it is crucial to estimate the contribution of outdoor infiltration and indoor emission to indoor PM2.5 in buildings. This study used an algorithm to automatically estimate the long-term time-resolved indoor PM2.5 of outdoor and indoor origin in real apartments with natural ventilation. The inputs for the algorithm were only the time-resolved indoor/outdoor PM2.5 concentrations and occupants’ window actions, which were easily obtained from the low-cost sensors. This study first applied the algorithm in an apartment in Tianjin, China. The indoor/outdoor contribution to the gross indoor exposure and time-resolved infiltration factor were automatically estimated using the algorithm. The influence of outdoor PM2.5 data source and algorithm parameters on the estimated results was analyzed. The algorithm was then applied in four other apartments located in Chongqing, Shenyang, Xi'an, and Urumqi to further demonstrate its feasibility. The results provided indirect evidence, such as the plausible explanations for seasonal and spatial variation, to partially support the success of the algorithm used in real apartments. Through the analysis, this study also identified several further development directions to facilitate the practical applications of the algorithm, such as robust long-term outdoor PM2.5 monitoring using low-cost light-scattering sensors. 相似文献
9.
三维异质异构集成技术是实现电子信息系统向着微型化、高效能、高整合、低功耗及低成本方向发展的最重要方法,也是决定信息化平台中微电子和微纳系统领域未来发展的一项核心高技术。文章详细介绍了毫米波频段三维异质异构集成技术的优势、近年来的发展趋势以及面临的挑战。利用硅基MEMS 光敏复合薄膜多层布线工艺可实现异质芯片的低损耗互连,同时三维集成高性能封装滤波器、高辐射效率封装天线等无源元件,还能很好地处理布线间的电磁兼容和芯片间的屏蔽问题。最后介绍了一款新型毫米波三维异质异构集成雷达及其在远距离生命体征探测方面的应用。 相似文献
10.
黄江茵 《电气电子教学学报》2021,43(6):19-21,26
本文结合"计算机控制技术"课程的授课内容和学校的创新应用型人才培养目标,探索了一种线上线下混合式教学模式,将传统的线下课堂知识点传授与现代线上多媒体、多平台的信息共享、在线视频会议等相互融合,实践表明该教学模式有效调动了学生的学习积极性和主动性,获得了良好的授课效果. 相似文献