全文获取类型
收费全文 | 8764篇 |
免费 | 1256篇 |
国内免费 | 944篇 |
专业分类
电工技术 | 444篇 |
技术理论 | 1篇 |
综合类 | 877篇 |
化学工业 | 72篇 |
金属工艺 | 41篇 |
机械仪表 | 285篇 |
建筑科学 | 176篇 |
矿业工程 | 142篇 |
能源动力 | 18篇 |
轻工业 | 48篇 |
水利工程 | 61篇 |
石油天然气 | 34篇 |
武器工业 | 58篇 |
无线电 | 3610篇 |
一般工业技术 | 251篇 |
冶金工业 | 87篇 |
原子能技术 | 20篇 |
自动化技术 | 4739篇 |
出版年
2024年 | 31篇 |
2023年 | 92篇 |
2022年 | 177篇 |
2021年 | 210篇 |
2020年 | 217篇 |
2019年 | 149篇 |
2018年 | 169篇 |
2017年 | 258篇 |
2016年 | 273篇 |
2015年 | 413篇 |
2014年 | 690篇 |
2013年 | 638篇 |
2012年 | 841篇 |
2011年 | 866篇 |
2010年 | 650篇 |
2009年 | 628篇 |
2008年 | 715篇 |
2007年 | 754篇 |
2006年 | 630篇 |
2005年 | 606篇 |
2004年 | 453篇 |
2003年 | 377篇 |
2002年 | 257篇 |
2001年 | 214篇 |
2000年 | 171篇 |
1999年 | 117篇 |
1998年 | 78篇 |
1997年 | 82篇 |
1996年 | 52篇 |
1995年 | 46篇 |
1994年 | 24篇 |
1993年 | 18篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
数字图像远程集中监控系统设计 总被引:1,自引:1,他引:0
方璐 《电信工程技术与标准化》2001,(1):19-20
随着网络技术、通信技术以及视频点插技术的发展与成熟,数字图像远程集中监控系统将是继Internet之后的亲一轮信息高速公路的应用主流。本主要介绍了数字图像远程集中监控系统的组成、工作原理以及应用前景。 相似文献
992.
针对小型视频工作站制作VCD视频光盘的特点,提出一种可行性加密方法,详细论述较为适合小型视频工作站的加密方法的研究过程。 相似文献
993.
I used data on handedness and pitching and hitting performance in annual cohorts of professional baseball players (1957-2005) to test the hypothesis that handedness among pitchers was subject to negative frequency-dependent selection. As predicted by this hypothesis, right-handed pitchers were more successful (i.e., opposing batters hit more poorly against them) when they were relatively rare in the population. Contrary to the predictions of this hypothesis, however, left-handed pitchers were more successful when they were relatively common. Both right- and left-handed batters performed better in years dominated by right-handed pitchers, despite the fact that right-handed batters perform relatively poorly against right-handed pitchers. I suggest that batters form cognitive representations based on pitcher handedness, and that these representations are strengthened by repeated exposure or priming. When the pitcher handedness polymorphism is more balanced (e.g., 67% right-handed, 33% left-handed), these cognitive representations are less effective, which leads to decreased batting averages and improved performance by all pitchers. Furthermore, these cognitive representations are likely to be more critical to the success of right-handed hitters, who have reduced visuomotor skills relative to left-handed hitters. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
994.
H. Gharavi S. M. Alamouti 《Journal of research of the National Institute of Standards and Technology》2001,106(2):455-469
This paper presents a twin-class unequal protected video transmission system over wireless channels. Video partitioning based on a separation of the Variable Length Coded (VLC) Discrete Cosine Transform (DCT) coefficients within each block is considered for constant bitrate transmission (CBR). In the splitting process the fraction of bits assigned to each of the two partitions is adjusted according to the requirements of the unequal error protection scheme employed. Subsequently, partitioning is applied to the ITU-T H.263 coding standard. As a transport vehicle, we have considered one of the leading third generation cellular radio standards known as WCDMA. A dual-priority transmission system is then invoked on the WCDMA system where the video data, after being broken into two streams, is unequally protected. We use a very simple error correction coding scheme for illustration and then propose more sophisticated forms of unequal protection of the digitized video signals. We show that this strategy results in a significantly higher quality of the reconstructed video data when it is transmitted over time-varying multipath fading channels. 相似文献
995.
DU Juan 《数字社区&智能家居》2008,(24)
我们知道,在很多情况下,电脑出现无法显示的故障并不是直接由显示硬件损坏所造成的,一些故障可以自己动手排除。本文为此根据介绍了与显卡有关的常见故障给出了现象、分析及其检修方法。 相似文献
996.
该文在分析了VOD视频点播系统的工作原理及特点基础上,对该技术在教育行业中的应用情况进行了阐述,同时指出应用中存在的问题及相应对策。 相似文献
997.
An object-oriented analysis-synthesis coder is presented which encodes arbitrarily shaped objects instead of rectangular blocks. The objects are described by three parameter sets defining their motion, shape and colour. Throughout this contribution, the colour parameters denote the luminance and chrominance values of the object surface. The parameter sets of each object are obtained by image analysis based on source models of moving 2D-objects and coded by an object-dependent parameter coding. Using the coded parameter sets an image can be reconstructed by model-based image synthesis. In order to cut down the generated bit-rate of the parameter coding, the colour updating of an object is suppressed if the modelling of the object by the source model is sufficiently exact, i.e., if only a relatively small colour update information would be needed for an errorless image synthesis. Omitting colour update information, small position errors of objects denoted as geometrical distortions are allowed for image synthesis instead of quantization error distortions. Tolerating geometrical distortions, the image area to be updated by colour coding can be decreased to 4% of the image size without introducing annoying distortions. As motion and shape parameters can efficiently be coded, about 1 bit per pel remains for colour updating in a 64 kbit/s coder compared to about 0.1 bit per pel in the standard reference coder (RM8) of the CCITT. Experimental results concerning the efficient coding of motion and shape parameters are given and discussed. The coding of the colour information will be dealt with in further research. 相似文献
998.
在Internet中很容易获得体育比赛的视频录像,这说明人们对体育比赛的视频录像有很大需求。分析了视频影像技术在体育教学中存在问题与困难,研发出一款教学辅助的软件,是一次把多媒体技术引入体育学科的实践,对体育辅助教学软件的研发有一定参考价值。 相似文献
999.
VOD系统中一种机顶盒的解决方案 总被引:2,自引:0,他引:2
提出了一种 VOD系统中机顶盒的解决方案 ,包括硬件和软件结构 .硬件包括网络接口 NIU和机顶单元 STU,NIU为一特定的 ATM接口 ,STU为一通用的与网络无关的硬件平台 .在软件结构中 ,详细描述了系统网络协议和 DAVID系统软件 . 相似文献
1000.
一种用于DRM的指纹嵌入和解密集成的实现方法研究 总被引:1,自引:0,他引:1
多播环境下,指纹嵌入应用技术是目前信息安全研究的焦点.在信源传输端嵌入指纹影响了系统的可扩展性;而在接收端嵌入指纹,系统增加了对用户的要求.综合考虑,本文针对DRM提出了一种新的指纹嵌入和解密集成的一体化技术实现方法.该方法嵌入的指纹是不对称密钥结构的相关函数,能满足通信时系统对实时性和鲁棒性的要求. 相似文献