全文获取类型
收费全文 | 678篇 |
免费 | 11篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 690篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 13篇 |
2020年 | 11篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 22篇 |
2015年 | 11篇 |
2014年 | 57篇 |
2013年 | 32篇 |
2012年 | 59篇 |
2011年 | 78篇 |
2010年 | 54篇 |
2009年 | 33篇 |
2008年 | 31篇 |
2007年 | 32篇 |
2006年 | 44篇 |
2005年 | 31篇 |
2004年 | 31篇 |
2003年 | 35篇 |
2002年 | 25篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 14篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 1篇 |
排序方式: 共有690条查询结果,搜索用时 31 毫秒
1.
2.
研究2017年冬季季节性供气紧张形成过程,对于认识我国天然气行业的市场化现状,促进行业平稳发展具有重要意义。为此,基于大量数据分析了2017年我国冬季季节性供气紧张的演变过程和严重程度,进而在前人研究成果的基础上,依据天然气供求框架系统分析了供气紧张的形成原因,并提出了应对策略。结果表明:①2017年季节性供气紧张从9月初见端倪,10月开始出现,11月集中爆发,12月持续发酵,并演变为全国性供气紧张,其严重性体现在供气缺口巨大、波及区域广以及LNG价格大幅度上涨等方面;②经济回暖与“煤改气”导致天然气需求量的增长超过国内外气源的生产与储运能力约束下的供给增长,从而形成季节性供气紧张。最后,提出了针对性的应对策略:①以中游为突破口,上下游配合,有序推进天然气行业的市场化改革是解决季节性供气紧张的根本途径;②统筹推进旧管网的开放与新管网建设,有序建设联络线、核心管网、区域管网等新管网;③减缓经济波动与煤改气的冲击,增强供给的保障能力;④实行季节差价、峰谷差价等手段调节用气高峰需求,取消交叉补贴,推动气价并轨,出台区域性的应急调峰预案与建立区域性市场等。结论认为:2018年天然气供求形势预计有所好转,但形势依然不容乐观。 相似文献
3.
Babloo Chaudhary Hemanta Hazarika Akira Murakami Kazunori Fujisawa 《Geotextiles and Geomembranes》2018,46(5):597-610
Earthquake and tsunami impose great threats on the stability of a breakwater. Foundation of the breakwater is weakened by these forces, and it may result in collapse of the breakwater. Lateral flow of seabed soils take place beneath the breakwater, and excess pore water pressure is generated in the foundation by an earthquake that precedes tsunami. These factors may lead to excessive settlement and horizontal displacement of the breakwater. Tsunami introduces additional instability to the deformed breakwater. Due to water level difference between seaside and harborside of the breakwater during a tsunami, seepage occurs through its foundation, and it may cause pipping of seabed soils. Tsunami induced scouring of mound is also a big problem for the stability of the breakwater foundation. Finally, these result in failure of the breakwater foundation. Due to failure of its foundation, the breakwater may collapse and cannot block the tsunami. It results in entering of the tsunami in coastal areas. In order to make a breakwater resilient against earthquake and tsunami induced damage, reinforcing countermeasures were developed for foundation of a breakwater. Geogrid, gabions and sheet piles were used for reinforcing a foundation model. The effectiveness of the model is evaluated through physical modeling for mitigating the earthquake and tsunami induced damage. Shaking table tests were performed to determine the effectiveness of the reinforced model under different earthquake loadings. Tsunami overflow test was conducted on the same deformed model in order to see the effects of tsunami on the model. Comparisons were made between the unreinforced and reinforced foundations, and it was observed during the tests that the reinforced foundation performed well in reducing the damage of the breakwater brought by the earthquake and tsunami. Overall, this study is useful for practice engineering, and the reinforced foundation model can be adopted for designing a breakwater foundation to reduce damage triggered by an earthquake and tsunami in the future. 相似文献
4.
上海城市居住社区变迁及其规划对策 总被引:3,自引:2,他引:3
20世纪90年代后,上海的城市居住面貌和空间格局发生极大的变化,在这样一个强烈急遽的变迁过程中,也暴露出不少问题,凸显出我国当前城市规划中的诸多不足之处,急待我们的进一步完善。 相似文献
5.
6.
随着经济和社会的发展,人们的流动性越来越强,运营商的用户、移动终端也在同步漫游迁移。在3G时代,由于智能终端的大量普及和用户使用习惯的改变,这种大规模的用户迁移对网络产生了较大的冲击。深入分析了候鸟用户的组成和使用习惯,聚焦于农民工和学生2个候鸟用户群体,并通过中国联通2个地(市)春节前后网络数据的对比,得出了候鸟用户对人口流出城市和人口流入城市移动通信网络的不同影响,并提出了运营商的应对策略,即网络建设中充分考虑漫游用户数量,修正用户预测模型,在人口流入地区与人口流出地区采用灵活的资源共享机制。 相似文献
7.
Against the backdrop of global climate change and in regards of urban sustainable development, enhancing climate resilience has become a critical strategy in adapting climate change for urban areas, where blue-green infrastructure is considered an important means. Although existing studies mention that blue-green infrastructure (BGI) can promote urban resilience by increasing its own diversity, flexibility, redundancy, modularization, and decentralization, questions like where to promote, by what specific means to promote and to what extent it could promote to are still lack of scientific exploration, leading insufficient support for applying resilience theory into planning and design practice. This research recognizes the role of BGI in building climate resilience in the key fields of functioning–urban floods, sea level rise, and high temperature and heat waves–and summarizes that the common functioning mechanisms include the biophysical properties of BGI, forming modular units with other infrastructures of similar functions, and the reliance on networked structures to help the system restore its physical functions and social connections as quickly as possible after disturbances and attacks. This paper also analyzes possible obstacles that hinder the promotion of BGI solutions–the lack of data support to BGI functioning mechanism, the lack of comprehensive assessment on ecological-social-economic benefits, and the difficulty in gaining confidence from decision-makers and the public. Finally, this paper proposes countermeasures from aspects of theoretical development, planning practice, and implementation and management, in order to offer insights for building urban climate resilience. 相似文献
8.
近年来,电动自行车成为广大居民出行的重要交通工具,但是电动自行车引发的火灾也呈不断上升趋势,给人民的生命财产安全造成了重大损失.电动自行车消防安全问题也引起了社会的广泛关注,做好电动自行车的消防安全工作能有效减少和遏制电动自行车火灾的发生.文章通过对电动自行车存在的消防安全问题进行分析,提出了一些相应的火灾防范对策. 相似文献
9.
10.
Jennifer Oxley Judith Charlton Jim Scully Sjaanie Koppel 《Accident; analysis and prevention》2010,42(2):515-522
This paper describes an investigation of safety, mobility and travel patterns in a sample of older women drivers and former drivers aged 60 years and over. Participants provided information on general health and functional abilities, travel and driving patterns, driving experiences and confidence, difficulty with and avoidance of driving situations, self-assessment of driving ability, crash and infringement history, the process and experiences leading up to stopping driving, and satisfaction with current mobility. The sample was a fairly active group, travelling frequently and substantial distances, and generally satisfied with their level of mobility. Current drivers were strongly interested in keeping driving for as long as possible, expressed strong concerns about the prospect of stopping driving and reported little evidence of self-regulation. In contrast, former drivers were less negative about driving cessation and mostly reported successful retirement from driving with few negative mobility consequences. Further, a number of relationships between crash involvement and driving experience, confidence of being a safe driver, and problems in driving situations were found. These findings have added to our understanding of the issues concerning the safety and mobility of older women. Implications for the promotion of safe driving practices are discussed. 相似文献