全文获取类型
收费全文 | 1850篇 |
免费 | 51篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 22篇 |
综合类 | 6篇 |
化学工业 | 312篇 |
金属工艺 | 37篇 |
机械仪表 | 30篇 |
建筑科学 | 183篇 |
矿业工程 | 12篇 |
能源动力 | 41篇 |
轻工业 | 152篇 |
水利工程 | 16篇 |
石油天然气 | 7篇 |
武器工业 | 1篇 |
无线电 | 226篇 |
一般工业技术 | 279篇 |
冶金工业 | 151篇 |
原子能技术 | 16篇 |
自动化技术 | 412篇 |
出版年
2023年 | 7篇 |
2022年 | 18篇 |
2021年 | 34篇 |
2020年 | 25篇 |
2019年 | 33篇 |
2018年 | 30篇 |
2017年 | 47篇 |
2016年 | 45篇 |
2015年 | 25篇 |
2014年 | 71篇 |
2013年 | 158篇 |
2012年 | 91篇 |
2011年 | 104篇 |
2010年 | 97篇 |
2009年 | 107篇 |
2008年 | 117篇 |
2007年 | 114篇 |
2006年 | 122篇 |
2005年 | 100篇 |
2004年 | 95篇 |
2003年 | 77篇 |
2002年 | 56篇 |
2001年 | 39篇 |
2000年 | 34篇 |
1999年 | 36篇 |
1998年 | 26篇 |
1997年 | 32篇 |
1996年 | 31篇 |
1995年 | 13篇 |
1994年 | 19篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 9篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 1篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1974年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有1903条查询结果,搜索用时 15 毫秒
61.
Sam Fletcher Mike J. S. Lowe Madis Ratassepp Colin Brett 《Journal of Nondestructive Evaluation》2012,31(1):56-64
The implementation of synthetic guided wave focusing to locate axially aligned defects in pipes has been investigated. Results
from both finite element computer models and experiments on real pipes are presented and the data show good agreement. Focusing
is necessary to improve the reflection coefficient from axially aligned defects, as the signals are very weak. The Common
Source Method (CSM) of synthetic focusing has been applied which makes it possible to apply focusing via post processing to
previously collected data. The dependence of reflection coefficient on crack length was measured for both through thickness
and part depth axially aligned defects, at a range of frequencies, using the torsional guided wave family. The results show
that the reflection coefficient is approximately doubled when focusing is employed, compared to the sensitivity for unfocused
fundamental torsional waves. However the sensitivity is still very low, so in practise this approach could only be used to
find severe defects. 相似文献
62.
Mike Thelwall 《Scientometrics》2012,92(2):429-441
In theory, the web has the potential to provide information about the wider impact of academic research, beyond traditional scholarly impact. This is because the web can reflect non-scholarly uses of research, such as in online government documents, press coverage or public discussions. Nevertheless, there are practical problems with creating metrics for journals based on web data: principally that most such metrics should be easy for journal editors or publishers to manipulate. Nevertheless, two alternatives seem to have both promise and value: citations derived from digitised books and download counts for journals within specific delivery platforms. 相似文献
63.
Béatrice Fuster Deborah Houssin-Agbomson Simon Jallais Elena Vyazmina Guy Dang-Nhu Gilles Bernard-Michel Mike Kuznetsov Vladimir Molkov Boris Chernyavskiy Volodymyr Shentsov Dmitry Makarov Randy Dey Philip Hooker Daniele Baraldi Evelyn Weidner Daniele Melideo Valerio Palmisano Alexandros Venetsanos Jan Der Kinderen 《International Journal of Hydrogen Energy》2017,42(11):7600-7607
Hydrogen energy applications often require that systems are used indoors (e.g., industrial trucks for materials handling in a warehouse facility, fuel cells located in a room, or hydrogen stored and distributed from a gas cabinet). It may also be necessary or desirable to locate some hydrogen system components/equipment inside indoor or outdoor enclosures for security or safety reasons, to isolate them from the end-user and the public, or from weather conditions.Using of hydrogen in confined environments requires detailed assessments of hazards and associated risks, including potential risk prevention and mitigation features. The release of hydrogen can potentially lead to the accumulation of hydrogen and the formation of a flammable hydrogen-air mixture, or can result in jet-fires. Within Hyindoor European Project, carried out for the EU Fuel Cells and Hydrogen Joint Undertaking safety design guidelines and engineering tools have been developed to prevent and mitigate hazardous consequences of hydrogen release in confined environments. Three main areas are considered: Hydrogen release conditions and accumulation, vented deflagrations, jet fires and including under-ventilated flame regimes (e.g., extinguishment or oscillating flames and steady burns). Potential RCS recommendations are also identified. 相似文献
64.
Many webometric studies have used hyperlinks to investigate links to or between specific collections of websites to estimate their impact or identify connectivity patterns. Whilst major commercial search engines have previously been used to identify hyperlinks for these purposes, their hyperlink search facilities have now been shut down. In response, a range of alternative sources of link data have been suggested, but all have limitations. This article introduces a new type of link that can be identified from commercial search engines, linked title mentions. These can be found by querying title mentions in a search engine and then removing those not associated with a relevant hyperlink. Results of a proof of concept test on 51 U.S. library and information science schools and four other sets of schools suggest that linked title mentions may tend to give better results than title mentions in some cases when used for site inlinks but may not always be an improvement on URL citations. For links between or co-inlinks to specified pairs of academic websites, linked title mentions do not generally provide an improvement over title mentions, but they do over URL citations in some cases. Linked title mentions may also be useful for sets of non-academic websites when the alternatives give too few or misleading results. 相似文献
65.
The built environment is a key target of decarbonization policies. However, such policies often have a narrow objective and narrow focus, resulting in ‘policy-resistance’ and unintended consequences. The literature attributes these unintended consequences to a narrow financial focus, adverse incentives, and inadequate handling of knowledge, skills, communication and feedback gaps, but it provides little advice on how these complex interactions can be captured. This paper illustrates the development and application of an integrated approach to address these complex interactions with regard to housing performance, energy, communal spaces and wellbeing. In particular, it explores the dynamics created by these relationships with simulation modelling in participatory settings, and with a diverse group of stakeholders. The simulation results suggest that monitoring is key to improve the performance of the housing stock besides energy efficiency; and investments in communal spaces positively affect the adoption of energy-efficiency measures and the wellbeing of residents. The evaluation results for participatory workshops show this approach was found useful by the stakeholders for supporting more integrated decision-making about housing. In future research, this approach can be implemented for policy problems in specific contexts. 相似文献
66.
Michaela Fox Mike Mitchell Moira Dean Christopher Elliott Katrina Campbell 《Food Security》2018,10(4):939-963
Food fraud is an intentional act for economic gain. It poses a risk to food integrity, the economy, public health and consumers’ ethics. Seafood is one commodity which has endured extensive fraudulent activity owing to its increasing consumer demand, resource limitations, high value and complex supply chains. It is essential that these fraudulent opportunities are revealed, the risk is evaluated and countermeasures for mitigation are assigned. This can be achieved through mapping of the seafood supply chains and identifying the vulnerability analysis critical control points (VACCP), which can be exposed, infiltrated and exploited for fraudulent activity. This research systematically maps the seafood supply chain for three key commodities: finfish, shellfish and crustaceans in the United Kingdom. Each chain is comprised of multiple stakeholders across numerous countries producing a diverse range of products distributed globally. For each supply chain the prospect of fraud, with reference to species substitution, fishery substitution, illegal, unreported and unregulated substitution, species adulteration, chain of custody abuse, catch method fraud, undeclared product extension, modern day slavery and animal welfare, has been identified and evaluated. This mapping of the fraudulent opportunities within the supply chains provides a foundation to rank known and emerging risks and to develop a proactive mitigation plan which assigns control measures and responsibility where vulnerabilities exist. Further intelligence gathering and management of VACCPs of the seafood supply chains may deter currently unknown or unexposed fraudulent opportunities. 相似文献
67.
68.
69.
70.
International development policies inevitably encounter a conflict in their implementation, representing the gap between universal goals and grass-roots practice. The aim of this study was to explore and understand the significance of this gap, and to apply knowledge management principles as a lens to suggest bridging solutions. The research focuses on non-governmental organisations, which are a sub-section of the civil society. The study was unique as it took a Southern perspective—the views and experiences of policy-makers, practitioners and beneficiaries in Kenya form the basis of the empirical research. Consequently, the research and its findings provide some answers as to how systems of knowledge can be aligned with the core values of organisational and societal culture in order to positively influence international stability. 相似文献