全文获取类型
收费全文 | 22858篇 |
免费 | 804篇 |
国内免费 | 83篇 |
专业分类
电工技术 | 293篇 |
综合类 | 44篇 |
化学工业 | 5146篇 |
金属工艺 | 478篇 |
机械仪表 | 460篇 |
建筑科学 | 1719篇 |
矿业工程 | 160篇 |
能源动力 | 686篇 |
轻工业 | 2135篇 |
水利工程 | 182篇 |
石油天然气 | 56篇 |
武器工业 | 1篇 |
无线电 | 1483篇 |
一般工业技术 | 4161篇 |
冶金工业 | 2769篇 |
原子能技术 | 137篇 |
自动化技术 | 3835篇 |
出版年
2023年 | 152篇 |
2022年 | 308篇 |
2021年 | 533篇 |
2020年 | 312篇 |
2019年 | 327篇 |
2018年 | 493篇 |
2017年 | 426篇 |
2016年 | 530篇 |
2015年 | 479篇 |
2014年 | 689篇 |
2013年 | 1506篇 |
2012年 | 1081篇 |
2011年 | 1518篇 |
2010年 | 1092篇 |
2009年 | 1043篇 |
2008年 | 1265篇 |
2007年 | 1098篇 |
2006年 | 939篇 |
2005年 | 865篇 |
2004年 | 774篇 |
2003年 | 688篇 |
2002年 | 660篇 |
2001年 | 392篇 |
2000年 | 377篇 |
1999年 | 412篇 |
1998年 | 409篇 |
1997年 | 371篇 |
1996年 | 340篇 |
1995年 | 294篇 |
1994年 | 301篇 |
1993年 | 297篇 |
1992年 | 250篇 |
1991年 | 214篇 |
1990年 | 201篇 |
1989年 | 230篇 |
1988年 | 186篇 |
1987年 | 177篇 |
1986年 | 174篇 |
1985年 | 239篇 |
1984年 | 214篇 |
1983年 | 184篇 |
1982年 | 168篇 |
1981年 | 195篇 |
1980年 | 130篇 |
1979年 | 147篇 |
1978年 | 143篇 |
1977年 | 127篇 |
1976年 | 138篇 |
1975年 | 120篇 |
1974年 | 105篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The awareness of value management (VM) and the nature and extent of its practice by professional civil, electrical and mechanical engineers in the South African construction industry are investigated using a web-based, online questionnaire survey as the first part of a more extensive investigation. A primary objective of the early study is to test the UK-based assertion of Kelly et al. [Kelly, J., Male, S., Graham, D., 2004. Value Management of Construction Projects. Blackwell, Oxford] that VM is an established service with commonly understood tools, techniques and styles. The survey findings suggest that, while awareness of VM is reasonably prevalent among South African engineers, its practice is considerably less extensive. Where VM is undertaken, almost no attempt is made to benchmark VM activities against international standards nor does its use appear to conform to any standard methodology. Engineers prefer other ways of delivering value to projects, and do not generally employ VM to facilitate the client briefing process. The findings are important given the increasing globalization of construction services, especially given the international ties between designers, project managers and other professionals. Professional engineering associations in South Africa should adopt a proactive role in promoting the use of VM by engineers, possibly through continuing professional development programmes. 相似文献
992.
993.
Resource allocation in decentralised computational systems: an evolutionary market-based approach 总被引:1,自引:0,他引:1
We present a novel market-based method, inspired by retail markets, for resource allocation in fully decentralised systems
where agents are self-interested. Our market mechanism requires no coordinating node or complex negotiation. The stability
of outcome allocations, those at equilibrium, is analysed and compared for three buyer behaviour models. In order to capture
the interaction between self-interested agents, we propose the use of competitive coevolution. Our approach is both highly
scalable and may be tuned to achieve specified outcome resource allocations. We demonstrate the behaviour of our approach
in simulation, where evolutionary market agents act on behalf of service providing nodes to adaptively price their resources over time, in response to market conditions.
We show that this leads the system to the predicted outcome resource allocation. Furthermore, the system remains stable in
the presence of small changes in price, when buyers’ decision functions degrade gracefully. 相似文献
994.
995.
996.
Peter Jones 《Landscape Research》2013,38(2):50-58
The Groundwork trusts have now been in operation for well over a decade and have implemented a wide range of projects across England and Wales. The origins and purposes of Groundwork are traced, and an overview of the types of project undertaken is presented. The relationship of the trusts to public and private sector funding, and the kinds of partnership involved, are examined. Many successes have been achieved in landscape renewal, although there have been some frictions with local authorities, and it is still difficult to make objective assessments of value for money or performance across a wide range of criteria. Nevertheless, the network of Groundwork trusts looks set to continue to offer a broad and flexible approach to environmental management. 相似文献
997.
998.
Dijk Corine; Koenig Bryan; Ketelaar Tim; de Jong Peter J. 《Canadian Metallurgical Quarterly》2011,11(2):313
This study examined whether blushing after a sociomoral transgression remediates trustworthiness in an interdependent context. Participants (N = 196) played a computerized prisoner's dilemma game with a virtual opponent who defected in the second round of the game. After the defection, a photograph of the opponent was shown, displaying a blushing or a nonblushing face. In a subsequent Trust Task, the blushing opponent was entrusted with more money than the nonblushing opponent. In further support of the alleged remedial properties of the blush, participants also indicated that they trusted the blushing opponent more, expected a lower probability that she would defect again, and judged the blushing opponent more positively. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
999.
1000.