全文获取类型
收费全文 | 26191篇 |
免费 | 3115篇 |
国内免费 | 599篇 |
专业分类
化学 | 2081篇 |
晶体学 | 35篇 |
力学 | 553篇 |
综合类 | 252篇 |
数学 | 2159篇 |
物理学 | 3180篇 |
无线电 | 21645篇 |
出版年
2024年 | 96篇 |
2023年 | 433篇 |
2022年 | 829篇 |
2021年 | 1119篇 |
2020年 | 1069篇 |
2019年 | 584篇 |
2018年 | 527篇 |
2017年 | 889篇 |
2016年 | 1023篇 |
2015年 | 1105篇 |
2014年 | 1965篇 |
2013年 | 1730篇 |
2012年 | 1991篇 |
2011年 | 1852篇 |
2010年 | 1412篇 |
2009年 | 1308篇 |
2008年 | 1481篇 |
2007年 | 1454篇 |
2006年 | 1347篇 |
2005年 | 1126篇 |
2004年 | 1016篇 |
2003年 | 1057篇 |
2002年 | 791篇 |
2001年 | 696篇 |
2000年 | 629篇 |
1999年 | 470篇 |
1998年 | 378篇 |
1997年 | 322篇 |
1996年 | 310篇 |
1995年 | 232篇 |
1994年 | 186篇 |
1993年 | 139篇 |
1992年 | 89篇 |
1991年 | 53篇 |
1990年 | 45篇 |
1989年 | 30篇 |
1988年 | 28篇 |
1987年 | 10篇 |
1986年 | 20篇 |
1985年 | 17篇 |
1984年 | 13篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1979年 | 5篇 |
1977年 | 5篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1959年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 656 毫秒
991.
992.
针对视频监控领域的需求,采用TI公司C6000系列DSP芯片TMS320DM642作为核心处理芯片,搭建了一套基于B/S网络结构的嵌入式视频监控系统。系统包括多路视频采集、多路视频本地显示、系统存储器扩展、和视频网络传输部分。系统的软件编写采用了TI的嵌入式实时操作系统DSP/BIOS和网络开发套件NDK,对系统各个线程进行有序调度。试验证明该系统满足了视频图像采集和网络视频传输的实时性要求。 相似文献
993.
针对现代农业的发展,温室群智能监控成为当前现代农业建设的重点。毒刺本文设计一种基于 ZigBee 和Internet温室群环境远程监控,通过由若干个基于 ZigBee的独立温室网络,将不同温室的相关数据通过 Internet网络的方式接入到最终的管理服务平台,从而使得现代农业企业通过无线网络和因特尔网络实现对企业农业数据的智能监控。 相似文献
994.
The privacy protection in big data is a research hotspot in the field of cyberspace security.As a strict and provable definition of privacy protection,studying application status of differential privacy protection in big data environment can provide reference and guidance for its subsequent system applications.Based on the analysis of the related concepts and technical characteristics of differential privacy protection,the application of differential privacy protection technology was reviewed in data distribution and analysis,cloud computing and big data computing,location and trajectory services and social networks,which expounded the current representative research results and analyzed its existing problems.The research shows that the existing results have made effective innovation and exploration of differential privacy protection applications from the aspects of differential privacy protection mechanism,noise addition mechanism and location,and data processing methods,and the related results have been cross-applied in different scenarios.Finally,four major problems that need to be studied in the further systematic application of differential privacy protection in the big data environment are proposed. 相似文献
995.
E-Link是一种廉价、方便、小巧的串口以太网接口模块.随着Internet的蓬勃发展,人们在各个地点都可通过互联网来交换信息.各种智能仪器和设备都应具备入网的功能,通过E-link数据传输器,只需拥有串行口就可以使现有设备方便地接入网络,不再需要PC 网卡 设备接口卡,直接通过E-Link就可方便地接入以太网.利用廉价的"E-Link网络数据传输器",利用互联网取代现场总线,使原现场总线的分布式控制系统方便地转换成基于以太网的分布式控制系统. 相似文献
996.
With the continuous development of social network application,user’s personal social data is so sensitive that the problem of privacy protection needs to be solved urgently.In order to reduce the network data sensitivity,a differential privacy protection scheme BCPA based on edge betweenness model was proposed.The 2K sequence corresponding to the graph structure based on the dK model was captured,and 2K sequences based on the edge betweenness centrality were reordered.According to the result of reordering,the 2K sequence was grouped into several sub-sequences,and each sub-sequence was respectively added with noise by a dK perturbation algorithm.Finally,a social network graph satisfying differential privacy was generated according to the new 2K sequences after integration.Based on the real datasets,the scheme was compared with the classical schemes through simulation experiments.The results demonstrate that it improves the accuracy and usability of data while ensuring desired privacy protection level. 相似文献
997.
With rapid developments of digital photography and social networks,users of photo-sharing-supported social networking applications can easily forward photos across different social networks at the cost of their growing privacy concerns.To address this problem,a privacy-preserving photo sharing framework was proposed,which could apply to extended control and privacy invasion tracing.In extended control scheme,the following users on a dissemination chain was restrained by each user’s privacy policy.Then several privacy areas of photos were encrypted and the access control polices were bound to the uploaded photos,so that any privacy areas on the photos could be hidden away from unwanted viewers even across different social networks.On this basis,the behaviors of users were record by tracing scheme of privacy invasion,the integrality of records was protected by using nested signature algorithm.The correctness,security and performance of overhead of the scheme are then thoroughly analyzed and evaluated via detailed simulations. 相似文献
998.
999.
1000.