全文获取类型
收费全文 | 6191篇 |
免费 | 600篇 |
国内免费 | 847篇 |
专业分类
电工技术 | 42篇 |
技术理论 | 1篇 |
综合类 | 209篇 |
化学工业 | 719篇 |
金属工艺 | 263篇 |
机械仪表 | 107篇 |
建筑科学 | 153篇 |
矿业工程 | 102篇 |
能源动力 | 392篇 |
轻工业 | 139篇 |
水利工程 | 72篇 |
石油天然气 | 267篇 |
武器工业 | 31篇 |
无线电 | 1201篇 |
一般工业技术 | 1357篇 |
冶金工业 | 159篇 |
原子能技术 | 318篇 |
自动化技术 | 2106篇 |
出版年
2024年 | 29篇 |
2023年 | 152篇 |
2022年 | 147篇 |
2021年 | 215篇 |
2020年 | 243篇 |
2019年 | 228篇 |
2018年 | 107篇 |
2017年 | 217篇 |
2016年 | 236篇 |
2015年 | 240篇 |
2014年 | 389篇 |
2013年 | 552篇 |
2012年 | 608篇 |
2011年 | 593篇 |
2010年 | 493篇 |
2009年 | 472篇 |
2008年 | 429篇 |
2007年 | 467篇 |
2006年 | 427篇 |
2005年 | 233篇 |
2004年 | 154篇 |
2003年 | 144篇 |
2002年 | 139篇 |
2001年 | 111篇 |
2000年 | 121篇 |
1999年 | 83篇 |
1998年 | 45篇 |
1997年 | 28篇 |
1996年 | 28篇 |
1995年 | 35篇 |
1994年 | 27篇 |
1993年 | 37篇 |
1992年 | 22篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 29篇 |
1987年 | 44篇 |
1986年 | 48篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
排序方式: 共有7638条查询结果,搜索用时 31 毫秒
41.
42.
43.
A 133-500 MHz,5.2 mW @500 MHz,0.021 mm2 all digital delay-locked loop(ADDLL)is presented.The power and area reduction of the proposed ADDLL are achieved by implementing a high frequency ring oscillator(ROSC)to count the reference clocks such that the one-clock cycle delay chain and the phase detector in a conventional Master block are no longer needed.The proposed ADDLL has better immunity to PVT(process,voltage,and temperature)than most conventional DLLs,which do not update the control word signals after the locking process,since the control signals for slave delay line are updated in every 256 reference cycles.Fabricated in 0.13 um CMOS process,the measured RMS jitter is 10.83 ps at 500 MHz while the RMS jitter of the input signal is 9.97 ps. 相似文献
44.
Qi Zhao Xuanzhe Liu Xingrun Chen Jiyu Huang Gang Huang Hong Mei 《Service Oriented Computing and Applications》2012,6(2):99-116
Facilitated by the SOA and new Web technologies, Service-Oriented Rich Clients (SORCs) compose various Web-delivered services in Web browser to create new applications. The SORCs support client-side data storage and manipulation and provide more features than traditional thin clients. However, the SORCs might suffer from data access issues, mainly due to both client-side incompatible data sources and server-side improper or even undesirable cache strategies. Addressing the data access issues, this paper proposes a data access framework for SORCs. The main contributions of this paper are as follows. First, the framework makes the SORCs accommodate heterogeneous local storage solutions and diverse Web browsers properly. The framework abstracts the underlying details of different local storages and selects the most proper data sources for current SORC in use. Secondly, the framework provides a cache mechanism, which supports client-side customized cache strategies. An adaptive technique for the strategies is also proposed to adjust cache strategies based on users?? historical actions to achieve better performance. 相似文献
45.
The advance of the Internet in the past decade has radically changed the way people communicate and col- laborate with each other. Physical distance is no more a barrier in online social networks, but cultural differences (at the individual, community, as well as societal levels) still govern human-human interactions and must be con- sidered and leveraged in the online world. The rapid de-ployment of high-speed Internet allows humans to interact using a rich set of multimedia data such as texts, pictures, and videos. This position paper proposes to define a new research area called ’connected multimedia’, which is the study of a collection of research issues of the super-area social media that receive little attention in the literature. By connected multimedia, we mean the study of the social and technical interactions among users, multimedia data, and devices across cultures and explicitly exploiting the cultural differences. We justify why it is necessary to bring attention to this new research area and what benefits of this new research area may bring to the broader scientific research community and the humanity. 相似文献
46.
随着手机GPS位置测定、导航以及摄像功能的普及,对于移动状态下的位置定位以及都市空间建筑物实时搜索等应用功能存在日益增长的需求。介绍了图像处理方式的城市建筑物识别方法,通过对两种图像匹配算法--SIFT和Local Search的比较分析表明,构造物轮廓线及其组合是一种相对稳定的几何特征,在匹配时受图像的仿射变换、画质变化以及镜头畸变等因素干扰较小,此外,基于轮廓的图像匹配指数还能反映摄影位置的变化。因此,对Local Search进行了改进,利用实时图的建筑物的特征轮廓线与从三维数据库中提取的建筑群特征轮廓线进行匹配,然后选择匹配指数高的记录作为识别结果。结果表明基于Local Search算法的建筑物识别技术可以很好地适应移动条件下建筑物快速识别的要求。 相似文献
47.
48.
Guozheng Qin Zhisheng Duan 《International Journal of Control, Automation and Systems》2012,10(3):651-658
In this paper, an output chattering attenuation scheme is proposed for two tracking controllers. The controllers have integral actions and are used to eliminate the steady-state tracking errors. By designing a compensator and reducing the discontinuous switching, the output chattering at the switching points can be attenuated significantly. Moreover, combining with the generalized Kalman-Yakubovich-Popov (KYP) lemma and the parameter-dependent Lyapunov function method, this problem can be characterized in terms of linear matrix inequality (LMI) formulation. Finally, the simulation results demonstrate the effectiveness of the proposed method. 相似文献
49.
针对目前已有社会化网络服务对社会影响的研究更侧重于青少年,对老年人群体研究相对较少的情况,本文研究了面向老年人的社会化网络服务平台,介绍了平台的体系结构,阐述了社交系统、数据分析和信息服务。此平台利用面向老年人的社交网络服务系统获得用户行为数据,在数据集成、时空数据仓库存储的基础上,通过建立老年人社会网络行为的数学模型,运用统计学方法进行建模分析,分析结果可为多层次人员提供不同的信息服务。 相似文献
50.
Shui-Jing Tang Paul H.Dannenberg Andreas C.Liapis Nicola Martino Yue Zhuo Yun-Feng Xiao Seok-Hyun Yun 《光:科学与应用(英文版)》2021,10(2):197-207
The ability to track individual cells in space over time is crucial to analyzing heterogeneous cell populations.Recently,microlaser particles have emerged as unique optical probes for massively multiplexed single-cell tagging.However,the microlaser far-field emission is inherently direction-dependent,which causes strong intensity fluctuations when the orientation of the particle varies randomly inside cells.Here,we demonstrate a general solution based on the incorporation of nanoscale light scatterers into microlasers.Two schemes are developed by introducing either boundary defects or a scattering layer into microdisk lasers.The resulting laser output is omnidirectional,with the minimum-to-maximum ratio of the angle-dependent intensity improving from 0.007(-24 dB)to>0.23(-6dB).After transfer into live cells in vitro,the omnidirectional laser particles within moving cells could be tracked continuously with high signal-to-noise ratios for 2 h,while conventional microlasers exhibited frequent signal loss causing tracking failure. 相似文献