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   308篇
  免费   5篇
安全科学   24篇
废物处理   5篇
环保管理   44篇
综合类   57篇
基础理论   82篇
污染及防治   67篇
评价与监测   20篇
社会与环境   9篇
灾害及防治   5篇
  2023年   6篇
  2022年   4篇
  2021年   14篇
  2020年   2篇
  2019年   6篇
  2018年   6篇
  2017年   11篇
  2016年   24篇
  2015年   10篇
  2014年   4篇
  2013年   27篇
  2012年   17篇
  2011年   16篇
  2010年   10篇
  2009年   9篇
  2008年   18篇
  2007年   17篇
  2006年   17篇
  2005年   2篇
  2004年   10篇
  2003年   11篇
  2002年   10篇
  2001年   4篇
  2000年   3篇
  1999年   4篇
  1998年   2篇
  1996年   4篇
  1994年   5篇
  1993年   1篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1987年   1篇
  1986年   3篇
  1985年   2篇
  1984年   2篇
  1983年   3篇
  1982年   3篇
  1981年   3篇
  1980年   1篇
  1979年   1篇
  1977年   2篇
  1976年   1篇
  1973年   1篇
  1964年   1篇
  1962年   1篇
  1955年   1篇
  1927年   1篇
  1921年   2篇
排序方式: 共有313条查询结果,搜索用时 178 毫秒
281.
Sustainable provision of seafood from wild-capture fisheries and mariculture is a fundamental component of healthy marine ecosystems and a major component of the Ocean Health Index. Here we critically review the food provision model of the Ocean Health Index, and explore the implications of knowledge gaps, scale of analysis, choice of reference points, measures of sustainability, and quality of input data. Global patterns for fisheries are positively related to human development and latitude, whereas patterns for mariculture are most closely associated with economic importance of seafood. Sensitivity analyses show that scores are robust to several model assumptions, but highly sensitive to choice of reference points and, for fisheries, extent of time series available to estimate landings. We show how results for sustainable seafood may be interpreted and used, and we evaluate which modifications show the greatest potential for improvements.  相似文献   
282.
Large quantities of nahcolite ore, a naturally occurring mineral containing between 70 and 90% sodium bicarbonate are known to occur in the Green River Formation of the Piceance Creek Basin of northwestern Colorado.1 Deposits occur in two major forms, as either bedded or disseminated ore. In the latter case, the host rock is oil shale, a dolomitic marlstone containing kerogen material. Bench and pilot scale studies have shown finely divided nahcolite ore to be an effective SO2 sorbent in baghouse filters.2 These studies form the basis of the nahcolite ore injection process as a means for controlling SO2 emissions to the environment.3 Although there have been published investigations of reactions of SO2 with Na2CO3and NaHCO3, 4 no reference could be found to a systematic study of nahcolite ore reacting with SO2.  相似文献   
283.
There has been widespread interest in using compost to improve the hydrologic functions of degraded soils at construction sites for reducing runoff and increasing infiltration. The objective of this study was to determine the effects of compost amendment rate on saturated hydraulic conductivity (Ks) and water retention in order to identify target compost rates for enhancing soil hydrologic functions. Samples were prepared with three soil textures (sandy loam, silt loam, and sandy clay loam), amended with compost at 0%, 10%, 20%, 30%, 40%, and 50%. All soils were tested at a porosity of 0.5 m3/m3, and the sandy loam was further tested at high (0.55 m3/m3) and low (0.4 m3/m3) porosities. The Ks and water retention data were then used to model infiltration with HYDRUS-1D. With increasing compost amendment rate, Ks and water retention of the mixtures generally increased at the medium porosity level, with more compost needed in heavier soils. As porosity decreased in the sandy loam soil, the amount of compost needed to improve Ks rose from 20% to 50%. Water distribution in pore fractions (gravitational, plant-available, and unavailable water) depended on texture, with only the highest compost rates increasing plant-available water in one soil. Results suggest soil texture should be taken into consideration when choosing a compost rate in order to achieve soil improvement goals. Hydrologic benefits may be limited even at a high rate of compost amendment if soil is compacted.  相似文献   
284.
285.
This paper presents the design, development and implementation of an integrated GIS-controlled knowledge-based system for environmental monitoring applications, utilizing indigenous flora for assessing quality. The system gathers and combines geographical, ecological, and physicochemical data of organisms' response to pollution within an intelligent computer program that (a) recognises groups of indigenous species suitable for long-term monitoring of a specific pollutant or a combination of pollutants, (b) estimates the ambient concentration of pollutant(s) from the population of the species comprising the bioindicator group and (c) provides biomonitoring capacity indices at national and international/transboundary levels. Significantly, a novel system in the form of a rational framework at the conceptual design level has been developed, that actually contributes towards achieving a cost-effective long-term biomonitoring program, with the flexibility to counter on-course any (anticipated or not) variations/modifications of the surveillance environment: the scheme assumes a robust dynamic cooperation between instrumental and biomonitoring systems, with a view to minimise uncertainty and monitoring costs and increase reliability of pollution control and abatement, aiming eventually at the shifting, partially or totally, from instrumental to natural monitoring. The proposed approach is presently implemented at pilot-scale for establishing a biomonitoring network at a large industrial area in Greece. The results obtained indicate that a cost-effective program can be only attained and maintained under a suitable financial/organizational scheme at the macro level, whereas the micro level viability strongly depends upon careful management of human resources and fixed assets.  相似文献   
286.
The Swedish Navy has operated submarines equipped with air independent propulsion for two decades. This type of submarine can stay submerged for periods far longer than other non-nuclear submarines are capable of. The air quality during longer periods of submersion has so far not been thoroughly investigated. This study presents results for a number of air quality parameters obtained during more than one week of continuous submerged operation. The measured parameters are pressure, temperature, relative humidity, oxygen, carbon dioxide, hydrogen, formaldehyde and other volatile organic compounds, ozone, nitrogen dioxide, particulate matter and microbiological contaminants. The measurements of airborne particles demonstrate that air pollutants typically occur at a low baseline level due to high air exchange rates and efficient air-cleaning devices. However, short-lived peaks with comparatively high concentrations occur, several of the sources for these have been identified. The concentrations of the pollutants measured in this study do not indicate a build-up of hazardous compounds during eight days of submersion. It is reasonable to assume that a substantial build-up of the investigated contaminants is not likely if the submersion period is prolonged several times, which is the case for modern submarines equipped with air independent propulsion.  相似文献   
287.
Employee creativity is critical for an organization's innovativeness and survival in today's competitive business environment. As such, scholars have devoted significant attention to the predictors of employee creativity, seeking to understand how to best increase employees' creative output. However, employee creativity may not always translate into organizational innovation and performance. In fact, employee creativity may result in various outcomes for creative individuals, their coworkers, teams, and organizations. While there have been several integrative reviews on the antecedents of creativity, an in-depth review of the outcomes of creativity is still needed to gain a holistic understanding of the benefits and costs of employee creativity and identify fruitful areas for future research. Thus, we aim to provide a comprehensive multilevel examination of the theories, methods, and creativity-related constructs used to examine the outcomes of creativity. We also provide several theoretical and empirical opportunities for future research. This review may provide managers with knowledge of the pros and cons of employee creativity, enabling them to make informed decisions on how to better manage employee creativity.  相似文献   
288.
The estuary Byfjord (Sweden) is characterized by high primary production, a well developed meiofauna compared to the macrofauna, high epifaunal biomass, a low number of herbivorous copepods and a small fish stock. A simplified energy flow model of the ecosystem of the fjord is given. The energy transfer is approximated to 15%. About one-fourth-300 (metric) tons of carbon — of the annual primary production is suggested to be directly consumed and to produce 5 tons of zooplankton carbon and 40 tons of epifaunal (mainly Mytilus edulis) carbon. About 500 tons of carbon from the detritus pool are probably utilized in animal production. This amount will produce 5 tons of zooplankton carbon, 6 tons of meiofaunal carbon, and 3 tons of carbon from the benthic macrofauna. Production of fish is estimated at 0.3 ton carbon per year. M. edulis seems to be the only food resource in the fjord worth harvesting by man.  相似文献   
289.
This paper explores the conceptualisation and application of 'protection' by the United Nations High Commissioner (UNHCR), Ugandan government, and Congolese refugees in Kyaka II refugee settlement, Uganda. Analysing the origins and consequences of a demonstration against school fees, and drawing on other ethnographic data, it explores how different interpretations of this incident reflect different conceptions of, and approaches to, protection. Ugandan government officials viewed the demonstration as a security incident; Congolese and Ugandan adults responded with increased monitoring and 'sheltering' of children and young people; students justified the demonstration as a legitimate manifestation of their rights; while UNHCR promoted assistance and resettlement. The paper argues that prevailing protection responses, including 'sensitisation', sheltering, and resettlement, are de-contextualised from daily realities and fail to address the underlying power relations that undermine protection. It concludes with recommendations on how international refugee agencies can reorient assistance to address protection concerns in refugee contexts.  相似文献   
290.
Importance of insects in environmental impact assessment   总被引:9,自引:0,他引:9  
Insects are particularly suited for use in environmental impact assessment (e.i.a.) because of their high species diversity, ubiquitous occurrence, and importance in the functioning of natural ecosystems. Examples are given of the use of insects in the predictive phase of e.i.a., in the monitoring and assessment phase, and in the much rarer instance of an e.i.a. that includes both of these phases. The importance of working at the species level to understanding the results of e.i.a. is emphasized.  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