全文获取类型
收费全文 | 491篇 |
免费 | 41篇 |
国内免费 | 16篇 |
专业分类
电工技术 | 5篇 |
综合类 | 16篇 |
化学工业 | 3篇 |
金属工艺 | 11篇 |
机械仪表 | 58篇 |
建筑科学 | 15篇 |
矿业工程 | 2篇 |
能源动力 | 8篇 |
轻工业 | 19篇 |
石油天然气 | 15篇 |
武器工业 | 50篇 |
无线电 | 39篇 |
一般工业技术 | 32篇 |
冶金工业 | 9篇 |
原子能技术 | 2篇 |
自动化技术 | 264篇 |
出版年
2024年 | 3篇 |
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 14篇 |
2020年 | 15篇 |
2019年 | 22篇 |
2018年 | 17篇 |
2017年 | 23篇 |
2016年 | 31篇 |
2015年 | 32篇 |
2014年 | 34篇 |
2013年 | 27篇 |
2012年 | 36篇 |
2011年 | 14篇 |
2010年 | 33篇 |
2009年 | 23篇 |
2008年 | 24篇 |
2007年 | 31篇 |
2006年 | 30篇 |
2005年 | 12篇 |
2004年 | 15篇 |
2003年 | 17篇 |
2002年 | 17篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1961年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有548条查询结果,搜索用时 0 毫秒
1.
Surveying instructor and learner attitudes toward e-learning 总被引:2,自引:2,他引:0
The trend of using e-learning as a learning and/or teaching tool is now rapidly expanding into education. Although e-learning environments are popular, there is minimal research on instructors’ and learners’ attitudes toward these kinds of learning environments. The purpose of this study is to explore instructors’ and learners’ attitudes toward e-learning usage. Accordingly, 30 instructors and 168 college students are asked to answer two different questionnaires for investigating their perceptions. After statistical analysis, the results demonstrate that instructors have very positive perceptions toward using e-learning as a teaching assisted tool. Furthermore, behavioral intention to use e-learning is influenced by perceived usefulness and self-efficacy. Regarding to learners’ attitudes, self-paced, teacher-led, and multimedia instruction are major factors to affect learners’ attitudes toward e-learning as an effective learning tool. Based on the findings, this research proposes guidelines for developing e-learning environments. 相似文献
2.
A楼·B楼·C楼--同济校园新建筑评述 总被引:3,自引:1,他引:2
同济大学校园在几十年发展过程中出现了各种形式的个性建筑。从20世纪50年代的文远楼到80年代的建筑城规学院明成楼再到21世纪的建筑城规学院新楼,代表了三个历里时期的建筑特色,并共同坚持着同一种精神,那就是勇于创新,紧跟潮流的时代精神。 相似文献
3.
康鑫 《数码设计:surface》2012,(7):130-132
在当代,艺术创作已不再局限于传统绘画的方式,而是用更多元的语言来表述。借助数字技术和新材料应用,通过纪实或观念影像、装置雕塑、大地艺术、行为艺术等表达观点与情感。艺术家吕胜中作品——"众"的创作灵感根植于对中国民间美术的深刻认识和西方当代艺术的体悟,包涵了辩证统一的哲学思想。他的艺术态度是为实现以国际当代多元文化为背景和中国深厚传统文化为土壤,开辟具有中国式、国际化当代艺术所坚持的实验艺术精神。 相似文献
4.
J. Thunberg 《控制理论与应用(英文版)》2014,12(1):48-55
We consider the problem of attitude synchronization for systems of rigid body agents with directed topologies. Two different scenarios for the rotation matrices of the agents are considered. In the first scenario, the rotations are contained in a convex subset of SO(3), which is a ball of radius less than π/2, whereas in the second scenario the agents are contained in a subset of SO(3), which is a ball of radius less than π. Using a control law based on backstepping and sliding mode control, we provide distributed, semi-global, torque control laws for the agents so that the rotations asymptotically synchronize. The control laws for the agents in the first scenario only depend on the relative rotations between neighboring agents, whereas the control laws in the second scenario depend on rotations defined in a global coordinate frame. Illustrative examples are provided where the synchronization is shown for both scenarios. 相似文献
5.
6.
In this paper, an adaptive fuzzy PD+ controller is proposed for the attitude maneuver of rigid spacecraft. The novel controller adjusts the gains of the PD+ attitude controller online according to attitude errors and angular velocity errors during the maneuver procedure. Therefore, quick response and avoidance of actuator saturation can be achieved simultaneously. Furthermore, the adaptation mechanism is designed, based on Lyapunov theory, to guarantee the stability of the closed‐loop system. To achieve good performance of the closed‐loop system under the constraint of actuator saturation, controller parameter optimization is developed on the basis of a genetic algorithm. Simulation results show that the transient performance and robustness against parametric uncertainty and environmental disturbance of the adaptive fuzzy PD+ controller are better than those of a constant PD+ controller. 相似文献
7.
在爬管机器人的运动稳定性问题的研究中,设计了一种应用关节式机器人运动原理的爬管机器人.为提高机器人运动的稳定性,提出以关节翻转力矩和手爪夹持力来评判运动姿态的稳定性,以躯干质心位移和速度的变化规律来评判运动轨迹的稳定性.利用ADAMS软件建立了在一个运动周期内,各关节驱动电机的输出转矩、手爪与管道之间的接触力,以及躯干质心的位移、速度等随时间的变化规律模型.结果表明所设计的爬管机器人的关节翻转力矩和手爪夹持力能满足运动姿态稳定性的要求,且能够以约1.11 m/min的速度沿着垂直管道平稳地爬行,不偏离爬行方向,保证了机器人运动轨迹的稳定性.仿真结果为下一步研制关节式爬管机器人的物理样机提供了理论指导,也为其它类型的爬管机器人研究提供了参考. 相似文献
8.
Confirmation Bias in Online Searches: Impacts of Selective Exposure Before an Election on Political Attitude Strength and Shifts
下载免费PDF全文
![点击此处可从《Journal of Computer-Mediated Communication》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Silvia Knobloch‐Westerwick Benjamin K. Johnson Axel Westerwick 《Journal of Computer-Mediated Communication》2015,20(2):171-187
Impacts of Internet use on political information seeking and subsequent processes have been subject to much debate. A 2‐session online field study presented online search results on political topics to examine selective exposure and its attitudinal impacts. Session 1 captured attitudes, including their accessibility. Session 2 tracked what online search results participants selected and how long they read them; participants then reported attitudes again. The study represented a 4x8x2x2 within‐subjects design: 4 topics, 8 browsing intervals each, with articles presenting opposing stances, with low versus high source credibility. Attitude‐consistent messages and messages from high‐credibility sources were preferred. Exposure to attitude‐consistent search results increased attitude accessibility and reinforced attitudes, whereas exposure to attitude‐discrepant content had opposite effects, regardless of messages' source credibility. 相似文献
9.
10.
针对防空导弹垂直发射姿态调转时的快速性要求,研究了快速姿态调转的控制问题.首先基于一类多输入多输出高阶非线性系统的Teminal(终态)滑模变结构控制方法,对垂直发射防空导弹的滚动和俯仰、偏航通道所呈现的非线性、强耦合性进行了分析,并设计了一种新型滑模控制器.控制器设计方案消除了滑模控制的到达阶段,系统的初始状态始终保持在滑模面上,确保了系统的全局鲁棒性和稳定性,且能在有限且可控时间内使跟踪误差趋近于零.最后通过数字仿真验证了系统在不确定因素情况下具有强鲁棒性和适应性,可用于防空导弹短时间姿态调转控制. 相似文献