全文获取类型
收费全文 | 1814篇 |
免费 | 82篇 |
国内免费 | 78篇 |
专业分类
电工技术 | 61篇 |
技术理论 | 1篇 |
综合类 | 433篇 |
化学工业 | 48篇 |
金属工艺 | 32篇 |
机械仪表 | 66篇 |
建筑科学 | 426篇 |
矿业工程 | 47篇 |
能源动力 | 43篇 |
轻工业 | 46篇 |
水利工程 | 50篇 |
石油天然气 | 28篇 |
无线电 | 110篇 |
一般工业技术 | 66篇 |
冶金工业 | 106篇 |
原子能技术 | 3篇 |
自动化技术 | 408篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 20篇 |
2021年 | 29篇 |
2020年 | 37篇 |
2019年 | 19篇 |
2018年 | 28篇 |
2017年 | 34篇 |
2016年 | 45篇 |
2015年 | 33篇 |
2014年 | 193篇 |
2013年 | 121篇 |
2012年 | 146篇 |
2011年 | 159篇 |
2010年 | 114篇 |
2009年 | 138篇 |
2008年 | 112篇 |
2007年 | 148篇 |
2006年 | 115篇 |
2005年 | 103篇 |
2004年 | 92篇 |
2003年 | 73篇 |
2002年 | 51篇 |
2001年 | 36篇 |
2000年 | 26篇 |
1999年 | 19篇 |
1998年 | 19篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1978年 | 1篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1965年 | 1篇 |
1960年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有1974条查询结果,搜索用时 15 毫秒
1.
Geraint Johnes Swati Virmani 《International Transactions in Operational Research》2020,27(4):1869-1885
Data from the Young Lives study are used to evaluate the efficiency of education systems in four low and middle income countries: Ethiopia, India, Peru and Vietnam. A meta‐frontier variant of data envelopment analysis is used to assess the relative performance of each country's system, and, within each country, to evaluate the impact of public and private schooling, and of urban and rural location. Comparisons are drawn between the four countries; the results indicate that in no country does the educational system perform uniformly badly or well. Conditioning on the inputs available, rural areas are often indicative of higher levels of efficiency, thus suggesting a number of implications for policy. 相似文献
2.
AbstractRecently, a literature has emerged using empirical techniques to study the evolution of international cities over many centuries; however, few studies examine long-run change within cities. Conventional models and concepts are not always appropriate and data issues make long-run neighbourhood analysis particularly problematic. This paper addresses some of these points. First, it discusses why the analysis of long-run urban change is important for modern urban policy and considers the most important concepts. Second, it constructs a novel data set at the micro level, which allows consistent comparisons of London neighbourhoods in 1881 and 2001. Third, the paper models some of the key factors that affected long-run change, including the role of housing. There is evidence that the relative social positions of local urban areas persist over time but, nevertheless, at fine spatial scales, local areas still exhibit change, arising from aggregate population dynamics, from advances in technology, and also from the effects of shocks, such as wars. In general, where small areas are considered, long-run changes are likely to be greater, because individuals are more mobile over short than long distances. Finally, the paper considers the implications for policy. 相似文献
3.
ABSTRACTGiven that online platforms disrupt established industries and challenge existing institutions, they can only be successful if their innovation becomes both legal and legitimate. This requires ‘institutional work’ that changes perceptions and regulations within society. Rather than only focussing on the online platform as the sole agent engaging in institutional work, our study analyses institutional work as a collective process. We investigate the case of home-sharing platform Airbnb and the process of institutional change its introduction prompted regarding short-term rental in Amsterdam, London and New York. We find, contrary to the popular view of online platforms as disruptive entrepreneurs, that the platform mainly focusses on creating new institutions rather than disrupting existing ones, and that users and non-users undertake most of the institutional work activities. We also show that different types of actors carry out different types of institutional work suggesting that the process of institutional work is highly distributed. 相似文献
4.
5.
论文比较详细地阐述了涉密网主机系统所面临的安全隐患,提出了涉密网主机安全防护所要解决的几个技术问题,并就可能实现的技术方法进行了探讨和比较。 相似文献
6.
Georgios D. Styliaras Georgios K. Tsolis Chris M. Papaterpos 《International Journal on Digital Libraries》2007,8(1):61-78
In this paper, AssetCollector is presented, which is a system for managing collections of cultural assets. AssetCollector
covers the needs of collection curators towards defining, populating and searching a collection in a flexible way, while supporting
them in generating reports based on the collection’s assets and reusing them in order to build web sites and CD-ROMs. In order
to support the above functionality, the system provides the content structuring subsystem, the content input subsystem, the
search subsystem and the report subsystem. The use of the subsystems is straightforward and requires no technical skills from
the curators. AssetCollector has been successfully applied for organizing various collections of cultural assets in Greece,
such as archaeological sites, museums and published books. In the future, an evaluation procedure is planned in order to further
refine the use of the system according to the targeted users’ needs. Furthermore, more import and export facilities will be
provided, which will make the system compliant with widely accepted standards. 相似文献
7.
大型电信运营业务支撑系统(BOSS)有其独特的复杂性,集中化改造后,对BOSS系统的信息安全保障能力也提出了更高的要求,安全评估方面的考虑也越来越多,从管理和技术两个方面探计了大型电信运营业务支撑系统的安全评估方法。 相似文献
8.
9.
指出了高职计算机文化课程教学面临的诸多问题,这些问题的存在严重制约了课程教学效果的提高.为此,在深入企业调研和对教学对象调查的基础上,结合各专业类别特点及其对计算机基本操作技能的不同需求,选取不同专业的班级作为研究对象,采用“横向分专业,纵向分层次”的教学方法进行了实践教学.实践结果表明,分专业分层次教学方法能有效解决高职“计算机文化”课程教学中存在的主要问题. 相似文献
10.
进一步扩大高校办学自主权深化学科专业管理体制改革 总被引:3,自引:0,他引:3
学科专业结构合理化程度直接关系到高等教育办学质量和办学效益,以往人们在研究学科专业结构时,过多强调了学科专业的布局,各学科专业招生规模比例和资源配置等问题,但对制度层面上如何保证学科专业主动适应经济社会发展需要及高等教育自身发展逻辑要求重视不够。本文着重探讨了建立学科专业自主调节的体制和机制。 相似文献