全文获取类型
收费全文 | 17044篇 |
免费 | 1377篇 |
国内免费 | 740篇 |
专业分类
电工技术 | 907篇 |
技术理论 | 3篇 |
综合类 | 1152篇 |
化学工业 | 2992篇 |
金属工艺 | 827篇 |
机械仪表 | 927篇 |
建筑科学 | 1385篇 |
矿业工程 | 456篇 |
能源动力 | 494篇 |
轻工业 | 967篇 |
水利工程 | 282篇 |
石油天然气 | 1104篇 |
武器工业 | 109篇 |
无线电 | 2030篇 |
一般工业技术 | 2424篇 |
冶金工业 | 758篇 |
原子能技术 | 177篇 |
自动化技术 | 2167篇 |
出版年
2024年 | 60篇 |
2023年 | 284篇 |
2022年 | 442篇 |
2021年 | 663篇 |
2020年 | 454篇 |
2019年 | 442篇 |
2018年 | 489篇 |
2017年 | 484篇 |
2016年 | 438篇 |
2015年 | 599篇 |
2014年 | 768篇 |
2013年 | 881篇 |
2012年 | 1022篇 |
2011年 | 1113篇 |
2010年 | 992篇 |
2009年 | 986篇 |
2008年 | 941篇 |
2007年 | 895篇 |
2006年 | 948篇 |
2005年 | 829篇 |
2004年 | 549篇 |
2003年 | 536篇 |
2002年 | 471篇 |
2001年 | 403篇 |
2000年 | 447篇 |
1999年 | 464篇 |
1998年 | 414篇 |
1997年 | 397篇 |
1996年 | 358篇 |
1995年 | 326篇 |
1994年 | 234篇 |
1993年 | 189篇 |
1992年 | 149篇 |
1991年 | 86篇 |
1990年 | 101篇 |
1989年 | 104篇 |
1988年 | 67篇 |
1987年 | 31篇 |
1986年 | 28篇 |
1985年 | 21篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Jing-Shan Zhao Jian-Yi WangFulei Chu Zhi-Jing FengJian S. Dai 《Mechanism and Machine Theory》2011,46(7):998-1015
This paper proposes a foldable stair that can be deployed for use and folded for conservation and investigates the geometry and statics of the structure. It not only has the moving flexibility of a mechanism but also has the high stiffness and high strength of statically indeterminate structures. The primary linkage is a deployable scissor-like element which forms the staircase after expanding. This paper starts with the analysis of the geometry of planar four- and six-bar mechanisms and processes to synthesize the foldable stair and then investigates its statics. The paper further investigates redundant inner forces of every link based on the second Castigliano theorem, develops a foldable stair model, assembles and manufactures. Working experiments verify the theoretical results and the outstanding advantages over the general fixed stairs. 相似文献
132.
Song-Jeng?HuangEmail author Yeau-Ren?Jeng V.?I.?Semenov Yo-Zhi?Dai 《Tribology Letters》2011,42(1):79-87
This article investigated the particle size effect of micro-sized SiC on the tribological behavior of SiCp-reinforced AZ91D Mg-based metal–matrix composites (MMCs). The Mg MMCs were prepared by the melt-stirring technique for wear
tests. The hardness and coefficient of friction of Mg MMCs increases as particle size of SiC particle in MMCs increases, except
for the hardness tendency at the region between particle size of 11 and 15 μm. The SiCp/AZ91D MMCs exhibit superior wear resistance under lower and moderate sliding condition. However, the effects of the SiC particle
reinforcements on wear resistance are not as conclusive under severe sliding condition, since the matrix of MMCs were softened
at elevated temperature under such a severe condition. 相似文献
133.
134.
提出了如何设计开发网络设备配置信息备份系统,实现各种网络设备配置信息的远程备份,并用VBScript语言进行了具体实现。 相似文献
135.
办公自动化(OA--office Automation)是将现代化办公和计算机网络功能结合起来的一种新型的办公方式.如何更有效地将计算机网络应用到办公自动化系统中来至关重要.本文基于此,对办公自动化系统与计算机网络进行了较详尽的阐述,同时以高校办公为例,论述了如何设计才能够使计算机网络在办公自动化系统中得到有效地利用. 相似文献
136.
高校教育信息化的评价要受基础设施建设、信息资源建设、信息技术应用、信息化人才等因素的影响,而各影响因素不能都以定量的形式体现。采用定性分析与定量分析相结合的思路,给出了高校教育信息化的评价方法,较好地解决了高校教育信息化的评价问题。 相似文献
137.
戴安刚 《计算机光盘软件与应用》2010,(13)
本文介绍一种利用CPLD及专用集成电路实现的2M通道时隙提取设备,该设备实现将一路RS-232接口的串行数据复接到E1通道的一个选定时隙中,利用E1通道的空闲时隙实现RS232数据的组网及传输. 相似文献
138.
In recent years, metric learning in the semisupervised setting has aroused a lot of research interest. One type of semisupervised metric learning utilizes supervisory information in the form of pairwise similarity or dissimilarity constraints. However, most methods proposed so far are either limited to linear metric learning or unable to scale well with the data set size. In this letter, we propose a nonlinear metric learning method based on the kernel approach. By applying low-rank approximation to the kernel matrix, our method can handle significantly larger data sets. Moreover, our low-rank approximation scheme can naturally lead to out-of-sample generalization. Experiments performed on both artificial and real-world data show very promising results. 相似文献
139.
We consider the Sequential Monte Carlo (SMC) method for Bayesian inference applied to the problem of information-theoretic
distributed sensor collaboration in complex environments. The robot kinematics and sensor observation under consideration
are described by nonlinear models. The exact solution to this problem is prohibitively complex due to the nonlinear nature
of the system. The SMC method is, therefore, employed to track the probabilistic kinematics of the robot and to make the corresponding
Bayesian estimates and predictions. To meet the specific requirements inherent in distributed sensors, such as low-communication
consumption and collaborative information processing, we propose a novel SMC solution that makes use of the particle filter
technique for data fusion, and the density tree representation of the a posterior distribution for information exchange between
sensor nodes. Meanwhile, an efficient numerical method is proposed for approximating the information utility in sensor selection.
A further experiment, obtained with a real robot in an indoor environment, illustrates that under the SMC framework, the optimal
sensor selection and collaboration can be implemented naturally, and significant improvement in localization accuracy is achieved
when compared to conventional methods using all sensors. 相似文献
140.
策略翻译是目前策略管理研究的难点之一.针对以数据结构表示的策略,提出策略结构五元组概念,增设可扩展的词库,采用XML语言统一描述策略结构,设计通用的脚本分析模块,支持不同设备类型的策略结构,实现透明的策略翻译,提高了策略管理的伸缩性、统一性和透明性. 相似文献