全文获取类型
收费全文 | 246521篇 |
免费 | 28774篇 |
国内免费 | 19409篇 |
专业分类
电工技术 | 22671篇 |
技术理论 | 3篇 |
综合类 | 24228篇 |
化学工业 | 31873篇 |
金属工艺 | 16713篇 |
机械仪表 | 17419篇 |
建筑科学 | 19345篇 |
矿业工程 | 8988篇 |
能源动力 | 7167篇 |
轻工业 | 24370篇 |
水利工程 | 8152篇 |
石油天然气 | 9151篇 |
武器工业 | 3645篇 |
无线电 | 27426篇 |
一般工业技术 | 22827篇 |
冶金工业 | 9105篇 |
原子能技术 | 3897篇 |
自动化技术 | 37724篇 |
出版年
2024年 | 1368篇 |
2023年 | 3735篇 |
2022年 | 8554篇 |
2021年 | 11178篇 |
2020年 | 8152篇 |
2019年 | 6151篇 |
2018年 | 6551篇 |
2017年 | 7628篇 |
2016年 | 7121篇 |
2015年 | 10749篇 |
2014年 | 13738篇 |
2013年 | 15788篇 |
2012年 | 19870篇 |
2011年 | 20966篇 |
2010年 | 19696篇 |
2009年 | 19278篇 |
2008年 | 19694篇 |
2007年 | 19283篇 |
2006年 | 17195篇 |
2005年 | 13807篇 |
2004年 | 10190篇 |
2003年 | 7379篇 |
2002年 | 7017篇 |
2001年 | 6184篇 |
2000年 | 4876篇 |
1999年 | 2510篇 |
1998年 | 1177篇 |
1997年 | 941篇 |
1996年 | 752篇 |
1995年 | 643篇 |
1994年 | 480篇 |
1993年 | 404篇 |
1992年 | 300篇 |
1991年 | 221篇 |
1990年 | 204篇 |
1989年 | 203篇 |
1988年 | 124篇 |
1987年 | 98篇 |
1986年 | 100篇 |
1985年 | 38篇 |
1984年 | 43篇 |
1983年 | 46篇 |
1982年 | 31篇 |
1981年 | 32篇 |
1980年 | 51篇 |
1979年 | 40篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1959年 | 43篇 |
1951年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
BDI模型能够很好地解决在特定环境下的Agent的推理和决策问题,但在动态和不确定环境下缺少决策和学习的能力。强化学习解决了Agent在未知环境下的决策问题,却缺少BDI模型中的规则描述和逻辑推理。针对BDI在未知和动态环境下的策略规划问题,提出基于强化学习Q-learning算法来实现BDI Agent学习和规划的方法,并针对BDI的实现模型ASL的决策机制做出了改进,最后在ASL的仿真平台Jason上建立了迷宫的仿真,仿真实验表明,在加入Q-learning学习机制后的新的ASL系统中,Agent在不确定环境下依然可以完成任务。 相似文献
92.
结构的安全性是结构防止破坏倒塌的能力,是结构工程重要的质量指标.老工业基地中的厂房主体结构安全性评价,对于厂房加固改造起到了关键性作用.文中通过对某工业厂房主体结构大量现场勘验、隐患排查及检测数据,结合结构验算,从承载能力、损伤等几方面对该老旧工业厂房的安全性进行了评价与分析,并详细介绍了检测鉴定的流程,为以后类似的老旧工业厂房的检测鉴定提供参考. 相似文献
94.
95.
96.
文中对曲沃县水资源开发利用现状进行了认真分析,并从思想观念、管理体制、管理模式上提出了问题,为解决问题提出了相应对策。 相似文献
97.
氯甲烷在镁修饰的ZSM-5分子筛催化剂上催化转化研究 总被引:1,自引:1,他引:0
在镁修饰的ZSM-5分子筛催化剂上,氯甲烷可以被催化转化为烃类产品。分别采用了离子交换和浸渍的方法来修饰ZSM-5分子筛。离子交换的Mg-ZSM-5催化剂和浸渍的Mg/ZSM-5催化剂都可以提高反应产物中的低碳烯烃的选择性,降低烷烃的选择性,并且保持较高的反应活性,但高的浸渍量对反应活性有一定的影响。NH3-TPD的结果表明,浸渍镁的ZSM-5催化剂的强酸中心数目明显减少。镁的修饰对催化剂酸性的影响导致了产物中低碳烯烃的增加。浸渍Mg的ZSM-5催化剂是潜在氯甲烷转化生成低碳烯烃的催化剂。 相似文献
98.
Frequency Insertion Strategy for Channel Assignment Problem 总被引:1,自引:0,他引:1
This paper presents a new heuristic method for quickly finding a good feasible solution to the channel assignment problem
(CAP). Like many other greedy-type heuristics for CAP, the proposed method also assigns a frequency to a call, one at a time.
Hence, the method requires computational time that increases only linear to the number of calls. However, what distinguishes
the method from others is that it starts with a narrow enough frequency band so as to provoke violations of constraints that
we need to comply with in order to avoid radio interference. Each violation is then resolved by inserting frequencies at the
most appropriate positions so that the band of frequencies expands minimally. An extensive computational experiment using
a set of randomly generated problems as well as the Philadelphia benchmark instances shows that the proposed method perform
statistically better than existing methods of its kind and even yields optimum solutions to most of Philadelphia benchmark
instances among which two cases are reported for the first time ever, in this paper.
Won-Young Shin was born in Busan, Korea in 1978. He received B.S. in industrial engineering from Pohang University of Science and Technology
(POSTECH) in 2001 and M.S in operation research and applied statistics from POSTECH in 2003. Since 2003 he has been a researcher
of Agency for Defense Development (ADD) in Korea. He is interested in optimization of communication system and applied statistics.
Soo Y. Chang is an associate professor in the Department of Industrial Engineering at Pohang University of Science and Technology (POSTECH),
Pohang, Korea. He teaches linear programming, discrete optimization, network flows and operations research courses. His research
interests include mathematical programming and scheduling. He has published in several journals including Discrete Applied
Mathematics, Computers and Mathematics with Application, IIE Transactions, International Journal of Production Research, and
so on. He is a member of Korean IIE, and ORMSS.
Jaewook Lee is an assistant professor in the Department of Industrial Engineering at Pohang University of Science and Technology (POSTECH),
Pohang, Korea. He received the B.S. degree in mathematics with honors from Seoul National University, and the Ph.D. degree
from Cornell University in applied mathematics in 1993 and 1999, respectively. He is currently an assistant professor in the
department of industrial engineering at the Pohang University of Science and Technology (POSTECH). His research interests
include nonlinear systems, neural networks, nonlinear optimization, and their applications to data mining and financial engineering.
Chi-Hyuck Jun was born in Seoul, Korea in 1954. He received B.S. in mineral and petroleum engineering from Seoul National University in
1977, M.S. in industrial engineering from Korea Advanced Institute of Science and Technology in 1979 and Ph.D. in operations
research from University of California, Berkeley, in 1986. Since 1987 he has been with the department of industrial engineering,
Pohang University of Science and Technology (POSTECH) and he is now a professor and the department head. He is interested
in performance analysis of communication and production systems. He has published in several journals including IIE Transactions,
IEEE Transactions, Queueing Systems and Chemometrics and Intelligent Laboratory Systems. He is a member of IEEE, INFORMS and
ASQ. 相似文献
99.
100.
以目前电力系统广泛应用的六氟化硫断路器和真空断路器作为分析对象,从介质特性、结构特性和灭弧特性等几个方面详细介绍了各自的特点。结合运行经验,总结了六氟化硫断路器和真空断路器的优点和缺点。充分了解它们的特性以及优缺点,有助于更合理地选择高压断路器,在实际生产中进行更有效地运行和检修维护。 相似文献