全文获取类型
收费全文 | 75537篇 |
免费 | 7666篇 |
国内免费 | 6688篇 |
专业分类
电工技术 | 6367篇 |
技术理论 | 15篇 |
综合类 | 7925篇 |
化学工业 | 3209篇 |
金属工艺 | 802篇 |
机械仪表 | 3248篇 |
建筑科学 | 3672篇 |
矿业工程 | 1251篇 |
能源动力 | 1677篇 |
轻工业 | 987篇 |
水利工程 | 1327篇 |
石油天然气 | 740篇 |
武器工业 | 1074篇 |
无线电 | 8814篇 |
一般工业技术 | 5011篇 |
冶金工业 | 2276篇 |
原子能技术 | 232篇 |
自动化技术 | 41264篇 |
出版年
2024年 | 245篇 |
2023年 | 1018篇 |
2022年 | 1304篇 |
2021年 | 1785篇 |
2020年 | 2154篇 |
2019年 | 1915篇 |
2018年 | 1783篇 |
2017年 | 2394篇 |
2016年 | 2729篇 |
2015年 | 2774篇 |
2014年 | 4978篇 |
2013年 | 5909篇 |
2012年 | 4847篇 |
2011年 | 5404篇 |
2010年 | 4068篇 |
2009年 | 4799篇 |
2008年 | 4981篇 |
2007年 | 5189篇 |
2006年 | 4626篇 |
2005年 | 4124篇 |
2004年 | 3523篇 |
2003年 | 3178篇 |
2002年 | 2522篇 |
2001年 | 2042篇 |
2000年 | 1800篇 |
1999年 | 1420篇 |
1998年 | 1152篇 |
1997年 | 986篇 |
1996年 | 877篇 |
1995年 | 719篇 |
1994年 | 666篇 |
1993年 | 606篇 |
1992年 | 453篇 |
1991年 | 423篇 |
1990年 | 323篇 |
1989年 | 260篇 |
1988年 | 228篇 |
1987年 | 183篇 |
1986年 | 152篇 |
1985年 | 199篇 |
1984年 | 213篇 |
1983年 | 188篇 |
1982年 | 161篇 |
1981年 | 109篇 |
1980年 | 84篇 |
1979年 | 99篇 |
1978年 | 64篇 |
1977年 | 72篇 |
1976年 | 21篇 |
1975年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Presents an obituary and information about the life and accomplishments of Josef Maria Bro?ek. Born August 14, 1913, in the ancient town of Melnik, in central Bohemia, today the Czech Republic, Josef spent his childhood in Poland (Warsaw, 1913- 1915) and in Siberia (1915-1920). His education in Czechoslovakia culminated with a thesis on "Memory, Its Measurement and Structure" and a PhD awarded in June 1937. In the history of psychology, his lifetime project bore the title "Historiography of Psychology Around the World," and it covered about 20 geographical areas. Extensive attention was devoted to institutional and organizational developments as journals, academic settings, archives, museums, research groups, conferences, and institutes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
82.
一种新颖的基于非压缩数字视频的水印盲检测算法 总被引:10,自引:0,他引:10
数字水印是一种嵌入到多媒体数据中用来进行版权标识的工具。在众多的宿主媒体中,数字视频因具有隐藏容量大、透明性好、鲁棒性强等诸多优点而受到日益广泛的关注。但是很多文献中提到的视频水印都是从数据流中提取单帧图像进行处理,这类算法与静态图像的水印方法如出一辙,没有充分利用视频文件的各种特性。而且对帧平均、视频压缩等常见的运动图像攻击方法十分敏感。针对这些问题,本文以非压缩视频文件为实验对象,结合人类视觉模型和彩色图像场景分割的方法,提出并实现了一种基于视频时间轴的数字水印盲检测算法。实验结果表明算法有效实用。 相似文献
83.
This paper proposes an original method for obtaining analytical approximations of the invariant probability density function of multi-dimensional Hamiltonian dissipative dynamic systems under Gaussian white noise excitations, with linear non-conservative parts and nonlinear conservative parts. The method is based on an exact result and a heuristic argument. Its pertinence is attested by numerical tests. 相似文献
84.
Research and Development of a Network—Based Intelligent Maintenance Information System 总被引:1,自引:0,他引:1
ZANGTie-gang YANGMing-zhong GUOShun-sheng 《国际设备工程与管理》2003,8(2):74-79
A maintenance information system is an important part of equipment management.An intelli-gent maintenance information system(IMIS)is a synthesis of network technology,information technology and intelligent technology.The IMIS in used to finish flexible maintenance decision-making and fast main-tenance planning,which helps enterprises to effectively reduce maintenance cost and increase working effi-ciency.Because the IMIS integrates advanced technologies,its performance is better than a traditional one.The difference between an IMIS and a traditional maintenance information system,and the functions,struc-ture,important realizations,and application of an IMIS are discussed in this paper. 相似文献
85.
MAX1773/MAX1773A是用于双电池系统的电源选择器,它允许外部控制器去管理双电池组、适配器输入、电池充电器和系统负载所需的电源连接。文中介绍了MAX1773/1773A的特点、引脚功能、内部结构和工作原理,给出了MAX1773/MAX1773A的典型工作电路。 相似文献
86.
Superconducting qubits are solid state electrical circuits fabricated using techniques borrowed from conventional integrated circuits. They are based on the Josephson tunnel junction, the only non-dissipative, strongly non-linear circuit element available at low temperature. In contrast to microscopic entities such as spins or atoms, they tend to be well coupled to other circuits, which make them appealling from the point of view of readout and gate implementation. Very recently, new designs of superconducting qubits based on multi-junction circuits have solved the problem of isolation from unwanted extrinsic electromagnetic perturbations. We discuss in this review how qubit decoherence is affected by the intrinsic noise of the junction and what can be done to improve it.
PACS: 03.67.-a, 03.65.Yz, 85.25.-j, 85.35.Gv 相似文献
87.
88.
89.
Many media processing applications create a load that varies significantly over time. Hence, if such an application is assigned a lower processing-time budget than needed in its worst-case load situation, deadline misses are likely to occur. This problem can be dealt with by designing media processing applications in a scalable fashion. A scalable media processing application can run in multiple qualities, leading to correspondingly different resource demands. The problem we consider is to find an accompanying quality control strategy, which minimizes both the number of deadline misses and the number of quality changes, while maximizing the quality of processing. We present an initial approach to the above problem by modeling it as a Markov decision process (MDP). Our model is based on measuring relative progress at milestones. Solving the MDP results in a quality control strategy that can be applied during runtime with only little overhead. We evaluate our approach by means of a practical example, which concerns a scalable MPEG-2 decoder. 相似文献
90.
着重阐明了偶氮聚合物光存储纪录的原理,分析了其双折射特性的微观机制,介绍了该课题近年来实验和理论上的最新进展,对这一充满希望和挑战的多学科交叉研究专题作了展望。 相似文献