全文获取类型
收费全文 | 7661篇 |
免费 | 874篇 |
国内免费 | 603篇 |
专业分类
电工技术 | 1217篇 |
综合类 | 585篇 |
化学工业 | 432篇 |
金属工艺 | 209篇 |
机械仪表 | 695篇 |
建筑科学 | 418篇 |
矿业工程 | 135篇 |
能源动力 | 117篇 |
轻工业 | 262篇 |
水利工程 | 75篇 |
石油天然气 | 147篇 |
武器工业 | 259篇 |
无线电 | 1186篇 |
一般工业技术 | 657篇 |
冶金工业 | 161篇 |
原子能技术 | 146篇 |
自动化技术 | 2437篇 |
出版年
2024年 | 44篇 |
2023年 | 135篇 |
2022年 | 225篇 |
2021年 | 272篇 |
2020年 | 296篇 |
2019年 | 213篇 |
2018年 | 197篇 |
2017年 | 291篇 |
2016年 | 320篇 |
2015年 | 361篇 |
2014年 | 661篇 |
2013年 | 605篇 |
2012年 | 693篇 |
2011年 | 662篇 |
2010年 | 448篇 |
2009年 | 435篇 |
2008年 | 418篇 |
2007年 | 455篇 |
2006年 | 408篇 |
2005年 | 345篇 |
2004年 | 285篇 |
2003年 | 248篇 |
2002年 | 203篇 |
2001年 | 172篇 |
2000年 | 137篇 |
1999年 | 98篇 |
1998年 | 73篇 |
1997年 | 91篇 |
1996年 | 60篇 |
1995年 | 57篇 |
1994年 | 32篇 |
1993年 | 32篇 |
1992年 | 34篇 |
1991年 | 18篇 |
1990年 | 14篇 |
1989年 | 16篇 |
1988年 | 14篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1974年 | 2篇 |
1959年 | 2篇 |
1955年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有9138条查询结果,搜索用时 15 毫秒
1.
Transportation demand of shipping container fluctuates due to the seasonality of international trade, thus, every 3–6 months, the liner company has to alter its current liner shipping service network, redeploy ships and design cargo routes with the objective of minimizing the total cost. To solve the problem, the paper presents a mixed integer linear program model. The proposed model incorporates several relevant constraints, such as weekly frequency, the transshipment of cargo between two or more service routes, and transport time. Extensive numerical experiments based on realistic date of Asia–Europe–Oceania shipping operations show that the proposed model can solve real-case problems efficiently by CPLEX. The results demonstrate that the model can reduce ship’s capacity consumption and raise ships’ capacity utilization. 相似文献
2.
针对空空宽带高速通信的需求,设计了小型化机载激光通信系统。仿真分析了300 km、2.5 Gb/s无线激光链路性能,并通过运动仿真台模拟机动环境测试了系统的跟踪与通信性能,其中粗跟踪误差为533.2 μrad(1σ),精跟踪误差为3.6 μrad(1σ),测试数据传输240 s,通信误码率为2.82×10-9。仿真与实验验证了该系统用于远距离空空无线激光通信的可行性。 相似文献
3.
某雷达数据处理有关问题分析 总被引:1,自引:0,他引:1
对某雷达数据处理应用中存在的一些特殊问题进行讨论分析,并就具体问题提出了解决的方法. 相似文献
4.
5.
6.
本文概述INMARSAT 21世纪工程的规划及为实现这一规划,INMARSAT组织在本世纪末正在进行和即将进行的一系列卫星通信技术工作。着重阐述INMARSAT 21世纪工程的业务性能以及对三种卫星布局方案进行抉择的新动向。 相似文献
7.
本文首先讨论了中国电信开展固网短信业务的必要性,然后分析了开展固网短信业务存在的问题,最后介绍了固网短信系统的构成。 相似文献
8.
Generation of Technology-Independent Retargetable Analog Blocks 总被引:1,自引:0,他引:1
R. Castro-López F. V. Fernández F. Medeiro A. Rodríguez-Vázquez 《Analog Integrated Circuits and Signal Processing》2002,33(2):157-170
This paper introduces a complete methodology for retargeting of analog cells to different sets of specifications. This methodology is technology-independent, thus allowing the migration, from one technology to another, of the circuit under retargeting. Careful integration of the device sizing and layout generation tasks via the incorporation of layout constraints during the sizing process allows to generate fully functional designs in a few minutes. The methodology is illustrated via the retargeting of a fully-differential Miller-compensated two-stage operational amplifier for a new set of specifications and two different technological processes.An erratum to this article can be found at 相似文献
9.
Many approaches have been proposed to enhance software productivity and reliability. These approaches typically fall into three categories: the engineering approach, the formal approach and the knowledge-based approach. But the optimal gain in software productivity cannot be obtained if one relies on only one of these approaches. This paper describes the work in knowledge-based software engineering conducted by the authors for the past 10 years. The final goal of the research is to develop a paradigm for software engineering which integrates the three approaches mentioned above. A knowledge-based tool which can support the whole process of software development is provided in this paper. 相似文献
10.
Self-control is demonstrated when a less desirable immediate outcome is chosen to ensure a substantially better future. In a novel animal analogue of this situation, primary reinforcement was delivered in both the initial and terminal links of a concurrent chain schedule. Rats made initial link choices between equal amounts of ethanol-free or ethanol-containing milk. Choosing the ethanol-free reinforcer resulted in delivery of the larger terminal link reinforcer and was thus analogous to self-control. Self-control decreased as the delay between initial and terminal links increased. The results have implications for human choice situations where decisions are made between two immediately available reinforcement alternatives each associated with a different delayed outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献