全文获取类型
收费全文 | 3778篇 |
免费 | 520篇 |
国内免费 | 265篇 |
专业分类
电工技术 | 332篇 |
技术理论 | 2篇 |
综合类 | 440篇 |
化学工业 | 110篇 |
金属工艺 | 24篇 |
机械仪表 | 36篇 |
建筑科学 | 900篇 |
矿业工程 | 586篇 |
能源动力 | 239篇 |
轻工业 | 69篇 |
水利工程 | 701篇 |
石油天然气 | 35篇 |
武器工业 | 9篇 |
无线电 | 249篇 |
一般工业技术 | 180篇 |
冶金工业 | 117篇 |
原子能技术 | 44篇 |
自动化技术 | 490篇 |
出版年
2024年 | 12篇 |
2023年 | 84篇 |
2022年 | 139篇 |
2021年 | 166篇 |
2020年 | 211篇 |
2019年 | 124篇 |
2018年 | 135篇 |
2017年 | 138篇 |
2016年 | 155篇 |
2015年 | 169篇 |
2014年 | 304篇 |
2013年 | 284篇 |
2012年 | 315篇 |
2011年 | 359篇 |
2010年 | 255篇 |
2009年 | 310篇 |
2008年 | 259篇 |
2007年 | 214篇 |
2006年 | 190篇 |
2005年 | 131篇 |
2004年 | 127篇 |
2003年 | 107篇 |
2002年 | 77篇 |
2001年 | 62篇 |
2000年 | 65篇 |
1999年 | 45篇 |
1998年 | 23篇 |
1997年 | 29篇 |
1996年 | 13篇 |
1995年 | 15篇 |
1994年 | 15篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有4563条查询结果,搜索用时 15 毫秒
1.
The importance of data processing and storage to colleges and universities is increasing day by day. However, many colleg-
es and universities are still at a low level in the process of data recovery and application reduction, and its RPO and RTO indicators
need to be improved by adopting the dual active technology architecture. Taking the Guizhou Vocational Technology Institute as an
example, this paper focuses on the analysis of the architecture of the double active data center, aiming at the actual situation of the
college, and gradually realizes multiple disaster recovery level of data level, application level and business level. 相似文献
2.
Olga Filippova Yu Xiao Michael Rehm Jason Ingham 《Building Research & Information》2018,46(7):711-724
The marked increase in the awareness of earthquake risk following the Canterbury earthquakes in New Zealand offered a unique opportunity to investigate the economic effect of disaster-mitigation regulations on the commercial building stock. A difference-in-differences (DD) framework was used to determine whether earthquake risk has been capitalized into the property prices of buildings constructed prior to 1976, as a response to the national policy requiring assessment and strengthening (or demolition) of the existing earthquake-prone building stock. A negative externality is found in the policy announcement on affected (pre-1970s) office and retail buildings which caused office buildings to suffer a 12.5% stigma discount. However, retail properties were less impacted suffering a 2.3% stigma loss. The value of the commercial building stock has been affected by the policy. These findings provide policy-makers with timely evidence as to the economic effects of New Zealand’s earthquake-prone buildings policy. Facing losses in property value and financial responsibility for retrofitting their assets, building owners will be looking for a workable set of regulatory and non-regulatory incentives to encourage disaster risk management and protect the built environment. 相似文献
3.
AbstractIn recent years, to prevent accidents and disaster are desired by implementing maintenance and management of facilities, such as conducting periodic inspections with appropriate frequency at plants. However, because the dangerous materials such as flammable gas and explosives is used in a plant, and there are many dangerous places in a plant such as high-temperature environment and high places and narrow spaces, it is desirable to use a remote-controlled robot for safety work and short inspections. Against this background, the Disaster Robotics Category-Plant Disaster Prevention Challenge was held in Japan at the World Robot Summit 2018. Our team was ranked 3rd in this competition, because our strategy of ‘inspection and investigation in cooperation with UGV and UAV’ was effective. In this paper, the competition contents of World Robot Summit 2018 and the robot inspection system that we are studying are explained. And what kind of strategy was challenged and result for these given competition tasks by using our robot system are introduced. And the lessons learned such as advantages and issues in UGV and UAV collaboration work at this competition are described for evaluate a robot investigation system for disaster response and inspection work at plants. 相似文献
4.
5.
This paper reviews the fire problem in critical transportation infrastructures such as bridges and tunnels. The magnitude of the fire problem is illustrated, and the recent increase in fire problems in bridges and tunnels is highlighted. Recent research undertaken to address fire problems in transportation structures is reviewed, as well as critical factors governing the performance of those structures. Furthermore, key strategies recommended for mitigating fire hazards in bridges and tunnels are presented, and their applicability to practical situations is demonstrated through a practical case study. Furthermore, research needs and emerging trends for enhancing the “state-of-the-art” in this area are discussed. 相似文献
6.
7.
优质电力园区以最低成本满足用户对电能质量的特殊需求,成为解决电压暂降问题的新途径,已在国内外开展了广泛的试点应用。针对中国优质电力园区规划缺少经济高效的优化配置方法的实际情况,提出了一种基于过程免疫力的动态电压恢复器优化配置方法。基于工业过程电压暂降免疫力,以满足用户用电需求为目标,以治理设备购置费用最低为约束,采用遗传算法对园区供电质量分级制定动态电压恢复器的优化配置方案,实现工业园区电压暂降治理的经济性。对大型精密温控系统的电压暂降治理装置的优化配置方法进行仿真计算,验证了所提方法的有效性与经济性。 相似文献
8.
系统总结中国自然灾害风险主要特点和综合防灾减灾工作的现状特征,全面梳理综合防灾减灾工作的发展趋势,分析综合防灾减灾面临的三大挑战,提出有针对性和可实施性的五大战略对策。一方面,未来100年中国的气候变暖趋势将进一步加剧,极端天气事件发生的频率将增大,荒漠化、海平面上升、冰川退缩趋势将进一步加重,全球气候变化所引发的各类巨灾和由此触发的各类自然灾害的突发性、并发性、群发性、异常性日益凸显。另一方面,中国能源结构以煤为主,同时是世界上进口石油资源的大国,随着中国经济的发展,未来能源消费和二氧化碳排放量还将持续增长,经济社会发展对能源安全、粮食安全、生态安全提出了更高要求。为适应气候变化背景下的各类灾害带来的不利影响,中国应全面提高监测预警水平,建立综合防灾减灾体系,全面提高应对突发灾害和巨灾的应急能力;推动建立区域综合防灾减灾范式,系统实施绿色经济战略,大力推进节能减排,转变经济发展方式。 相似文献
9.
Natural disasters greatly impact the environment of affected societies with often unknown consequences. In this study we examine the impact that the Canterbury Earthquakes of 2010–2011 had on the distribution of alcohol outlets in Christchurch, New Zealand. Specifically, we compare the distribution of both on-site and off-site alcohol outlets pre- (December 2009) and post-earthquake (December 2014) and use spatial regression models to identify whether any neighbourhood-level factors predict the observed redistributions. Overall, the number of alcohol outlets decreased by almost 13% after the Canterbury Earthquakes. However, we found a moderate increase in the clustering of both outlet types of outlets in the post-quake period. Increases in rates of both on-site and off-site alcohol outlets in neighbourhoods were positively associated with the percentage of residents who resided in their neighbourhood < 5 years and with neighbourhood crime rate change, while negative associations were found with percentage population aged between 15 and 29 years. The results suggest that the changing spatial distribution of alcohol outlets in Christchurch was not random but driven, in part, by the emergent demographic composition of neighbourhoods. The significant practical and policy implications of a redistribution of alcohol outlets are outlined providing a tangible link between empirical research and practice in an urban environment plagued with post-disaster spatial and social uncertainties. 相似文献
10.
Hospital emergency departments (HEDs) are the most critical units since they undertake a vital health care mission. It is required for these departments to find out rational solution methods in case of issues occurred in normal and disaster times. Simulation is an effective method to improve policies on operational, tactical and strategic decisions about EDs. The main reasons prompting us to do this study are to reveal the importance of simulation for disaster preparedness of EDs and the innovative aspects of recent ED simulation applications unlike the available literature surveys. This systematic and comprehensive review study can provide an insight for researchers on ED simulation modeling in terms of showing current state and gaps to be focused in the future. 相似文献