全文获取类型
收费全文 | 791篇 |
免费 | 80篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 7篇 |
综合类 | 131篇 |
化学工业 | 47篇 |
金属工艺 | 22篇 |
机械仪表 | 12篇 |
建筑科学 | 287篇 |
矿业工程 | 20篇 |
能源动力 | 30篇 |
轻工业 | 6篇 |
水利工程 | 37篇 |
石油天然气 | 1篇 |
无线电 | 15篇 |
一般工业技术 | 201篇 |
冶金工业 | 25篇 |
原子能技术 | 7篇 |
自动化技术 | 46篇 |
出版年
2024年 | 3篇 |
2023年 | 13篇 |
2022年 | 28篇 |
2021年 | 48篇 |
2020年 | 34篇 |
2019年 | 36篇 |
2018年 | 36篇 |
2017年 | 36篇 |
2016年 | 38篇 |
2015年 | 34篇 |
2014年 | 45篇 |
2013年 | 71篇 |
2012年 | 74篇 |
2011年 | 70篇 |
2010年 | 51篇 |
2009年 | 66篇 |
2008年 | 30篇 |
2007年 | 28篇 |
2006年 | 23篇 |
2005年 | 20篇 |
2004年 | 7篇 |
2003年 | 15篇 |
2002年 | 5篇 |
2001年 | 14篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有894条查询结果,搜索用时 296 毫秒
1.
2.
《Journal of power sources》2006,160(1):716-732
Energy storage technologies provide an alternative solution to the problem of balancing power generation and power consumption. Redox flow cells are designed to convert and store electrical energy into chemical energy and release it in a controlled fashion when required. Many redox couples and cell designs have being evaluated. In this paper, redox flow systems are compared in the light of characteristics such as open circuit potential, power density, energy efficiency and charge-discharge behaviour. The key advantages and disadvantages of redox flow cells are considered while areas for further research are highlighted. 相似文献
3.
《Construction and Building Materials》2005,19(1):75-79
This paper reports results of a study conducted to investigate the causes of cracks noted on concrete beams in a student facility on a university campus. Cracks were noted on the beams within 6 months of construction. They increased in size within a month. Field and laboratory investigations were conducted to assess the causes of cracking of the beams. The compressive strength of the concrete cores taken from the beams was found to be less than the specified strength. The cracks were repaired by epoxy injection and the structural integrity of the repaired beams was assessed by conducting load tests. The deflection of the repaired beams, under the imposed test loads, was less than that specified by ACI 318 indicating the efficiency of the repair procedure utilized. 相似文献
4.
5.
A new approach using the Fiber Bragg Grating(FBG)sensor and viscoelastic model to monitor and analyze the internal strain and temperature of asphalt pavement is proposed.Some parameters including peak strain,temperature and loading time were calculated with the application of multi-dimensional sensors group.These parameters were incorporated with viscoelastic model of five units to evaluate the permanent deformation of pavement.An application example was conducted,and the results show that it is feasible to analyze and calculate the permanent deformation of pavement structures with FBG sensors. 相似文献
6.
为获取桥梁断面涡激共振过程中的气动效应特性,提出一种基于风洞试验的气动效应特性识别方法,首先提出涡振系统总体阻尼及刚度瞬时特性识别方法,在此基础上提出从涡振系统总体阻尼及刚度中分离气动阻尼及气动刚度的方法.以一个开口断面风洞试验数据为例对该方法的准确性进行了验证,并对该断面涡振气动效应特性进行研究.结果表明:识别得到的系统总体阻尼比为零的等高线与结构涡振响应曲线能很好吻合,从而验证了该方法的准确性.在此基础上对涡振过程中作用于结构的气动阻尼及气动刚度特性进行了研究,获得了气动阻尼及刚度随结构振幅和约化风速的变化规律,可为后续理论模型研究提供参考. 相似文献
7.
研究了大跨轻柔斜拉人行桥多维脉动风荷载模拟问题。首先基于多变量随机过程理论建立了桥梁结构风荷载模型的互谱和自谱表达式,进一步地基于相干函数考虑了塔-索-桥的风荷载相关效应。通过引入Fourier变换减小了随机过程模拟的计算量。在此基础上,以某实际的大跨度轻柔斜拉人行桥为工程背景,研究了其考虑塔-索-桥相关性的多维脉动风荷载特点和规律,并对模拟结果进行了验证和对比研究。 相似文献
8.
9.
《International journal of human-computer studies》2008,66(2):51-66
Web directories organize voluminous information into hierarchical structures, helping users to quickly locate relevant information and to support decision-making. The development of existing ontologies and Web directories either relies on expert participation that may not be available or uses automatic approaches that lack precision. As more users access the Web in their native languages, better approaches to organizing and developing non-English Web directories are needed. In this paper, we have proposed a semi-automatic framework, which consists of anchor directory boosting, meta-searching, and heuristic filtering, to construct domain-specific Web directories. Using the framework, we have built a Web directory in the Spanish business (SBiz) domain. Experimental results show that the SBiz Web directory achieved significantly better recall, F-value, efficiency, and satisfaction rating than the benchmark directory. Subjects provided favorable comments on the SBiz Web directory. This research thus contributes to developing a useful framework for organizing domain-specific information on the Web and to providing empirical findings and useful insights for end-users, system developers, and researchers of Web information seeking and knowledge management. 相似文献
10.