全文获取类型
收费全文 | 476篇 |
免费 | 27篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 10篇 |
综合类 | 33篇 |
化学工业 | 34篇 |
金属工艺 | 1篇 |
机械仪表 | 8篇 |
建筑科学 | 120篇 |
矿业工程 | 18篇 |
能源动力 | 54篇 |
轻工业 | 33篇 |
水利工程 | 37篇 |
石油天然气 | 74篇 |
无线电 | 18篇 |
一般工业技术 | 16篇 |
冶金工业 | 23篇 |
原子能技术 | 2篇 |
自动化技术 | 29篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 12篇 |
2021年 | 16篇 |
2020年 | 23篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 16篇 |
2016年 | 29篇 |
2015年 | 15篇 |
2014年 | 30篇 |
2013年 | 34篇 |
2012年 | 29篇 |
2011年 | 39篇 |
2010年 | 24篇 |
2009年 | 31篇 |
2008年 | 20篇 |
2007年 | 23篇 |
2006年 | 23篇 |
2005年 | 17篇 |
2004年 | 8篇 |
2003年 | 25篇 |
2002年 | 12篇 |
2001年 | 7篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 3篇 |
1986年 | 1篇 |
排序方式: 共有510条查询结果,搜索用时 859 毫秒
371.
This study contributes to the literature by analyzing the effects of information and communication technology (ICT) on economic performance and energy consumption of selected South Asian economies i.e. Bangladesh, India, Pakistan and Sri Lanka for the period of 1990–2018. For empirical analysis, we employed the bounds testing approach of cointegration and error correction modelling. The findings of the study confirm that, in the long-run, ICT significantly and positively contributed to the economic growth of India only. Similarly, India is the only country in South Asia that has achieved energy efficiency as a result of increased use of ICT. However, energy consumption proved to be an important determinant of GDP per capita in India and Pakistan. Also, GDP per capita has a positive and significant impact on energy consumption in both India and Pakistan. These results imply that South Asian economies try to follow their regional partner, India, in increasing the role of ICT in their economies, which on one side will boost their economic growth and on the other side will help them in achieving energy efficiency. Moreover, the energy conservation policy could prove detrimental to South Asian economies. 相似文献
372.
Joyotee Smith Gloria Umali Mark W. Rosegrant A. M. Mandac 《Nutrient Cycling in Agroecosystems》1989,21(2):113-123
Year to year variability in nitrogen response is widely believed to be responsible for low levels of fertilizer application by risk averse farmers. Certain authors have claimed that production risk is not responsible for sub-optimal applications of fertilizer. Since these studies estimated fertilizer response in irrigated areas or in simulated rainfed areas in experiment stations they may have underestimated the degree of risk faced by the majority of farmers.This study seeks to address this issue of risk under farmers' conditions by using data from rainfed farmers fields in a risky rice growing area of the Philippines.Long term distributions of factors responsible for temporal variability in N-response, such as moisture stress and typhoons, are derived by using a rainfall simulator and a water balance model. These distributions are combined with a hetereoscedastic nitrogen response function to simulate long term yield distributions at different N-rates. The application of risk averse and risk neutral decision making models shows that risk aversion reduces fertilizer application by only 7–9%. These results occur because as N-rates increase, the benefits from increased average profits outweigh the disadvantages of increased variability in profits. These findings provide additional evidence to support the emerging consensus that the impact of risk aversion on fertilizer use is much smaller than previously believed. 相似文献
373.
The principal sources of organic carbon (OC) and elemental carbon (EC) are anthropogenic or biogenic, whereas secondary sources are atmospheric oxidation processes of specific precursor gases. These compounds are considered atmospheric contaminants and adversely affect human health. Numerous studies have monitored atmospheric particulates and gaseous phases of OC and EC in Asia over the last decade. This work compares and analyzes different sample collection, pretreatment and analytical approaches. The principal carbonaceous sources are traffic exhaust and industrial emissions. The OC and EC concentrations are highest in high traffic areas, followed by urban sites, and lowest in suburban sites. Many characteristics of these sites, such a dense population, are important to research. The major OC to EC ratios in Asia cities were 1.0-3.0. This work elucidates the characteristics, sources, distributions, and characteristics of atmospheric carbonaceous species in Asia. 相似文献
374.
Rawiwan Oranratmanee 《Vernacular Architecture》2018,49(1):99-120
This paper explores the vernacular architecture of the Shan ethnic group in Myanmar within the context of South-east Asian architecture. The purpose is to understand the relationship between the settlement system, village and houses that together form the cultural landscape and architecture of the river valleys of mainland South-east Asia. The fieldwork is comprised of an architectural enquiry through geographic surveys of settlements and measurements of houses, and a social enquiry, including observations and interviews about the social dimensions of architecture. The detailed spatial analysis embraces three tiers, namely settlements, villages and houses, together identifying the characteristics and underlying concepts of Shan architecture, meanwhile deepening the understanding of the holistic relationships between people, ethnicity, geography, social system and the production of dwellings and cultural geographies of South-east Asia. 相似文献
375.
文章主要介绍了第二届Holcim全球可持续建筑大奖赛信息发布会的概况,同时附加了第二届大奖赛的参赛信息,意在鼓励参与本次大赛,通过设计超越传统,积极应对未来可持续发展的挑战。 相似文献
376.
377.
《Food Control》2017
This paper considers the current status, the changes, and the challenges of food authentication and traceability with specific reference to the Asian and Australian perspective. Building on the experience of the author (who has presented at seven International Atomic Energy Agency Regional Training Courses in Pakistan, Malaysia, Indonesia, Vietnam and The Philippines), and some relevant case studies, the use of chemical analysis for identification of the origin and potential adulteration of foods and beverages will be discussed. Examples of applications of these techniques include: 1) detecting passing off produce from country A as coming from other countries or conversely passing off non-country A produce as if they originated from country A, and 2) detecting, and prosecuting, people who were taking seafood from a protected marine area and claiming it came from another area. Some reasons why countries in the Asian and Australian region are interested in using these techniques to investigate food authentication and traceability include: desire to have confidence in what we are eating, desire to pay a correct price for the product, health and food safety issues, prevention of criminal activities, and safeguarding environments by preventing the spread of disease and invasion of non-indigenous species. Food and food security is a growing global concern and having a reliable, confirmable, diet is a daily concern for inhabitants of the Asian and Australian region. 相似文献
378.
赵苏文 《探矿工程(岩土钻掘工程)》2016,43(11):26-31
针对琼东南盆地深水钻井过程中存在的地层孔隙压力预测精度低、井身结构设计要求高、低温异常压力和较窄的钻井液密度安全窗口等难题,通过对区域地层压力预测方法、井身结构优化设计、钻井液技术优化、表层套管固井技术优化、环空圈闭压力控制技术等关键技术的研究和实践,形成了一套适用于该地区的深水钻井关键技术体系,已在该盆地近几年深水井的钻井作业中成功应用,实现了钻井作业时效高、事故率低、费用控制合理的目标。对该盆地后续的深水井钻井作业及类似地区深水井的钻井作业具有借鉴意义。 相似文献
379.
中亚与中国西北盆地构造演化及含油气性 总被引:12,自引:4,他引:8
中亚及中国西北地区中生代以来就一直处于欧亚大陆的南缘。侏罗纪以来两地区经历了相似的构造演化,即侏罗纪-老第三纪的伸展构造阶段和新第三纪-第四纪的挤压构造阶段。始新世以来由于受印度板块和古欧亚板块陆陆碰撞挤压并持续向北推移的影响,形成了现今中亚及中国西北地区的盆山构造格局。中亚及中国西北地区贫地油气资源丰富,成藏条件优越。各盆地受后期改造程度不同,前陆冲断带是这些盆地山前带共有的构造特征,盆地内部构造差异大,新构造对油气的储集具有重要影响。 相似文献
380.
根据北乌斯丘尔特盆地主要地质特征及已发现油气田的分布特点,总结了油气富集规律及其主控因素,并分析了勘探潜力。受油气来源及烃源岩沉积环境差异的影响,北乌斯丘尔特盆地的油气分布具有“西油东气”的特点,而且优质储层的发育决定了石油和天然气分别富集于中侏罗统和始新统储层中,良好的运移通道则是北布扎奇隆起油田形成的重要条件。北布扎奇隆起中生界的勘探目标主要是发育于隆起北坡及顶部的拉长型断背斜构造,古生界巴什基尔阶和阿赛尔阶碳酸盐岩储层的勘探潜力也不容忽视。盆地中部和东部地区的侏罗系和始新统储层潜力较有限,但东北部的下白垩统可能是一个新的勘探层系,东南部石炭系维宪阶碳酸盐岩储层在局部地区也具有一定潜力。 相似文献