全文获取类型
收费全文 | 15532篇 |
免费 | 1905篇 |
国内免费 | 1604篇 |
专业分类
电工技术 | 1183篇 |
综合类 | 1505篇 |
化学工业 | 428篇 |
金属工艺 | 148篇 |
机械仪表 | 794篇 |
建筑科学 | 259篇 |
矿业工程 | 136篇 |
能源动力 | 73篇 |
轻工业 | 171篇 |
水利工程 | 64篇 |
石油天然气 | 239篇 |
武器工业 | 125篇 |
无线电 | 3430篇 |
一般工业技术 | 381篇 |
冶金工业 | 146篇 |
原子能技术 | 45篇 |
自动化技术 | 9914篇 |
出版年
2024年 | 28篇 |
2023年 | 125篇 |
2022年 | 210篇 |
2021年 | 243篇 |
2020年 | 268篇 |
2019年 | 191篇 |
2018年 | 231篇 |
2017年 | 310篇 |
2016年 | 355篇 |
2015年 | 492篇 |
2014年 | 851篇 |
2013年 | 886篇 |
2012年 | 1146篇 |
2011年 | 1266篇 |
2010年 | 1126篇 |
2009年 | 1165篇 |
2008年 | 1304篇 |
2007年 | 1596篇 |
2006年 | 1368篇 |
2005年 | 1240篇 |
2004年 | 1042篇 |
2003年 | 999篇 |
2002年 | 699篇 |
2001年 | 501篇 |
2000年 | 396篇 |
1999年 | 259篇 |
1998年 | 164篇 |
1997年 | 117篇 |
1996年 | 95篇 |
1995年 | 108篇 |
1994年 | 72篇 |
1993年 | 65篇 |
1992年 | 45篇 |
1991年 | 21篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1967年 | 1篇 |
1957年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 25 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(56):23762-23771
Limiting current density at different temperatures, backpressures, and balance gases can be used to separate molecular diffusion resistance, Knudsen diffusion resistance and local transport resistance of membrane electrode assembly (MEA). However, the measurement of limiting current density has no unified protocol. The diverse choices in the literature, either in the control of current or voltage or in the atmosphere like relative humidity and O2 concentrations, make it difficult to compare the results and identify the true bottleneck hindering the mass transport. In this work, the current-voltage curves obtained by current scanning/stepping and voltage scanning/stepping methods under dilute O2 of different concentrations and a wide range of relative humidity were measured and analyzed systematically. It is found that the voltage stepping method is superior to the other three ways of control for the reliable determination of the limiting current density. Aided with simultaneous electrochemical impedance spectroscopy measurement, the limiting current density can be determined with pinpoint accuracy. When the limiting current density is just used to qualitatively evaluate different MEA, the voltage scanning method can be used instead for its high time efficiency. The selection of the atmosphere also plays an important role in suppressing the distortion from excessive water and reducing the spurious contribution from proton conduction resistance. It is found that O2 concentrations at 0.5 vol% and relative humidity at 90% can give the best estimation of O2 transport resistance in membrane electrode assembly. 相似文献
2.
At present, the development and implementation of digital transformation are the keys to promoting high-quality industry development. The new digital fabrication method of robotic 3D printing is a research area being studied by many to tackle the issue of the declining productivity of traditional construction methods. Although many studies have been done, most of the current 3D printing projects are facing limitations in terms of scale. In order to bridge the gap, this article proposed a mass customization 3D printing framework system for large-scale projects. This article discusses how mass customization is made possible through the joint operation of the FUROBOT software and 3D printing hardware. By taking the east gate of Nanjing Happy Valley Plaza as a case study, the article demonstrates and studies the feasibility of the large-scale mass customization 3D printing framework system. 相似文献
3.
Yude Ji Yanping Guo Yuejuan Liu Yun Tian 《International Journal of Adaptive Control and Signal Processing》2020,34(3):283-297
This article focuses on the consensus problem of leader-following fractional-order multi-agent systems (MASs) with general linear and Lipschitz nonlinear dynamics. First, the distributed adaptive protocols for linear and nonlinear fractional-order MASs are constructed, respectively. We allow the control coupling gains to be time varying for each agent. Moreover, the adaptive modification schemes for the control gain are designed, which renders smaller control gains and thus requires smaller amplitude on the control input without sacrificing consensus convergence. Second, based on fractional-order Lyapunov stability theorem and Barbalat's lemma, two novel sufficient conditions in terms of linear matrix inequalities are provided to ensure that the leader-following consensus can be obtained in the case for any undirected connected communication graph. Furthermore, we show that the proposed algorithm also works for consensus of agents with intrinsic Lipschitz nonlinear dynamics. As a result, the proposed framework requires no global information and thus can be implemented in a fully distributed manner. Finally, the numerical simulations are given to demonstrate the effectiveness of obtained the theoretical results. 相似文献
4.
This article presents a new method for pairing devices securely. The commitment-based authentication uses a fuzzy secret that the devices only know approximately. Its novel feature is time-based opening of commitments in a single round. We also introduce a new source for the fuzzy secret: synchronized drawing with two fingers of the same hand on two touch screens or surfaces. The drawings are encoded as strings and compared with an edit-distance metric. A prototype implementation of this surprisingly simple and natural pairing mechanism shows that it accurately differentiates between true positives and man-in-the-middle attackers. 相似文献
5.
AbstractMulti-agent systems need to communicate to coordinate a shared task. We show that a recurrent neural network (RNN) can learn a communication protocol for coordination, even if the actions to coordinate are performed steps after the communication phase. We show that a separation of tasks with different temporal scale is necessary for successful learning. We contribute a hierarchical deep reinforcement learning model for multi-agent systems that separates the communication and coordination task from the action picking through a hierarchical policy. We further on show, that a separation of concerns in communication is beneficial but not necessary. As a testbed, we propose the Dungeon Lever Game and we extend the Differentiable Inter-Agent Learning (DIAL) framework. We present and compare results from different model variations on the Dungeon Lever Game. 相似文献
6.
7.
嵌入式RTOS中任务优先级反转问题研究 总被引:1,自引:0,他引:1
针对嵌入式实时系统任务调度策略的特点,任务在运行的时候可能被更高优先级的任务中断。分析了嵌入式RTOS中的最高就绪任务的查找算法,指出该调度算法存在的不同优先级的反转问题,并且针对这一问题进行研究,给出了相应的优先级继承方案。较好地解决了RTOS中任务调度中的优先级的反转问题。 相似文献
8.
异构数据集成方法研究与实现 总被引:4,自引:4,他引:0
王行荣 《微电子学与计算机》2006,23(4):172-173,176
为解决异构数据集成的复杂性问题,文章提出了一种异构数据同步的新方法——半集成式中间件法。该方法成功地应用在重庆市社会保障综合信息系统中,具有易于实现、可扩展性、跨平台性和效率高等特点。 相似文献
9.
10.
首先介绍了HART通信协议及他的优点,然后介绍了HART通信协议在汽油机测速方面的软件实现。该软件主要采用目前流行的VB编程语言。可设计出界面友好、功能强大的测量和监控软件。 相似文献