首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   132篇
  免费   4篇
安全科学   6篇
废物处理   2篇
环保管理   46篇
综合类   6篇
基础理论   32篇
污染及防治   32篇
评价与监测   5篇
社会与环境   2篇
灾害及防治   5篇
  2024年   1篇
  2023年   1篇
  2020年   1篇
  2019年   1篇
  2018年   3篇
  2017年   1篇
  2016年   2篇
  2015年   2篇
  2013年   21篇
  2011年   5篇
  2010年   5篇
  2009年   8篇
  2008年   6篇
  2007年   8篇
  2006年   5篇
  2005年   5篇
  2004年   2篇
  2003年   3篇
  2002年   3篇
  2001年   3篇
  1998年   2篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1992年   1篇
  1990年   1篇
  1989年   4篇
  1988年   2篇
  1987年   3篇
  1986年   5篇
  1985年   4篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
  1979年   4篇
  1978年   2篇
  1977年   2篇
  1976年   1篇
  1975年   2篇
  1974年   2篇
  1972年   1篇
  1971年   1篇
  1970年   2篇
排序方式: 共有136条查询结果,搜索用时 0 毫秒
51.
52.
53.
The rapid growth of Latin American urban centres beginning in the 1970s placed a heavy strain upon urban transport service providers. Facing high population growth from a citizenry dependent upon public transport and having limited financial resources to develop car‐based infrastructure, Latin American municipal planners were challenged to create a new transport paradigm. One ingenious response to this dilemma was the busway, a surface metro system that utilizes exclusive right‐of‐way bus lanes. The developers of the Latin American busways astutely observed that the ultimate objective was to swiftly, efficiently and cost‐effectively move people rather than cars. Examples of innovative busway systems are presented from Curitiba, Bogota, Porto Alegre, Quito and Sao Paulo. The low cost, flexibility and speed of the exclusive busways all contribute to extremely high levels of customer satisfaction. Innovative approaches to the design of busway loading stations and simplified ticketing have also helped to reduce operating costs and improve customer flows. Additionally, clear system maps, colour‐coded routing, system safety and cleanliness and superior customer service have helped direct consumer preference towards the busway. The success of busways has also proved that costly subway systems or uncontrolled sprawl are not the only options available to municipal planners. The Latin American busway corridors provide high peak capacities that permit busway corridors to serve the transit requirements of most medium‐ to large‐sized cities. When integrated with progressive land‐use policies, busways can also form the basis of more sustainable urban design by encouraging development corridors with high‐density, mixed‐use land use. The environmental benefits and calming influences afforded cities by busway systems have translated into dramatically improved levels of quality of life indicators, including improvements in health, crime reduction and poverty alleviation. The user‐friendliness and cost‐effectiveness of busway systems have convinced municipal leaders in North America, Europe and Australia to develop similar systems of their own. Latin American busways thus provide a unique example of South to North technology transfer.  相似文献   
54.
The results of an investigation characterizing the nutrients and suspended solids contained in stormwater from Kranji Catchment in Singapore are reported in this paper. Stormwater samples were collected from 4 locations and analyzed for the following eleven analytes: TOC, DOC, TN, TDN, NH4+, NO2 + NO3 (NOx), TP, TDP, OP, SiO2 and TSS. Stormwater was sampled from catchments with various proportions of rural and urban land use, including forested areas, grassed areas, agricultural and residential and commercial areas. The event mean concentrations (EMCs) of nutrients and TSS from sampling stations which have agricultural land use activities upstream were found to be higher. Comparison of site EMCs (SMCs) with published data showed that the SMCs of the nutrients and TSS are generally higher than SMCs reported for forested areas but lower than published SMCs for urban areas. Positive correlations (p < 5%) were found between loading and peak flow at locations most impacted by ubanisation or agricultural activities. Correlation between loading and rainfall variables was less distinct. EMC was found to correlate less with rainfall and flow variables compared to pollutant loading. Unlike loading, no consistent pattern exists linking EMC to any particular storm or flow variable in any of the catchments. Lastly, positive correlations were obtained between the particulate forms of nitrogen and phosphorus and TSS.  相似文献   
55.
Traditional conservation measures may not be, and usually are not, all that is needed to assure a quality environment. They are, however, fundamental. A national course of action involving land and water management is determined (1) at the market place, (2) at the ballot box, and (3) in the hearts and minds of individuals. To inform people about environmental management and conservation and appropriate uses of land, water and related resources is an exceedingly difficult problem. Research, action and educational programs dealing with environmental problems must have greater attention and support.  相似文献   
56.
Conservation tillage can reduce soil loss; however, the residual herbicides normally used to control weeds are often detected in surface runoff at high levels, particularly if runoff-producing storms occur shortly after application. Therefore, we measured losses of alachlor, atrazine, linuron, and metribuzin from seven small (0.45-0.79-ha) watersheds for 9 yr (1993-2001) to investigate whether a reduced-input system for corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] production with light disking, cultivation, and half-rate herbicide applications could reduce losses compared with chisel and no-till. As a percentage of application, annual losses were highest for all herbicides for no-till and similar for chisel and reduced-input. Atrazine was the most frequently detected herbicide and yearly flow-weighted concentrations exceeded the drinking water standard of 3 microg L(-1) in 20 out of 27 watershed years that it was applied. Averaged for 9 corn yr, yearly flow-weighted atrazine concentrations were 26.3, 9.6, and 8.3 microg L(-1) for no-till, chisel, and reduced-input, respectively. Similarly, flow-weighted concentrations of alachlor exceeded the drinking water standard of 2 microg L(-1) in 23 out of 54 application years and in all treatments. Thus, while banding and half-rate applications as part of a reduced-input management practice reduced herbicide loss, concentrations of some herbicides may still be a concern. For all watersheds, 60 to 99% of herbicide loss was due to the five largest transport events during the 9-yr period. Thus, regardless of tillage practice, a small number of runoff events, usually shortly after herbicide application, dominated herbicide transport.  相似文献   
57.
58.
59.
Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association.   相似文献   
60.
This paper discusses the present position and future prospects of mineral exploration and exploitation in Indonesia. It places the industry within the economic and political context of the country as a whole and considers the development of government policy towards the sector. Although the mineral resources of Indonesia are believed to be vast, the performance of the industry in the past has been erratic. The relative political stability of the last few years, combined with rising prices, has encouraged the opening up of new mines, and has also emphasised the need for more local processing of those minerals that are produced. At present, income from oil provides most of the government revenue and consequently the prospects of this sector are critically important for the nation's future. Increased diversification can, however, be expected in the next few years as the resources of tin, bauxite, nickel, copper, coal and many other products are developed. Given a favourable political and economic climate, Indonesia could be one of the world's major mineral producers by the end of the century.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号