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   399篇
  免费   1篇
  国内免费   7篇
安全科学   14篇
废物处理   23篇
环保管理   34篇
综合类   74篇
基础理论   52篇
污染及防治   139篇
评价与监测   48篇
社会与环境   22篇
灾害及防治   1篇
  2023年   7篇
  2022年   7篇
  2021年   16篇
  2020年   9篇
  2019年   10篇
  2018年   16篇
  2017年   7篇
  2016年   19篇
  2015年   12篇
  2014年   20篇
  2013年   32篇
  2012年   19篇
  2011年   36篇
  2010年   27篇
  2009年   26篇
  2008年   29篇
  2007年   17篇
  2006年   15篇
  2005年   12篇
  2004年   19篇
  2003年   13篇
  2002年   7篇
  2001年   1篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   1篇
  1994年   4篇
  1993年   3篇
  1992年   2篇
  1991年   1篇
  1990年   2篇
  1988年   1篇
  1986年   3篇
  1985年   3篇
  1983年   2篇
  1982年   1篇
  1970年   1篇
  1964年   1篇
排序方式: 共有407条查询结果,搜索用时 109 毫秒
261.

Chemiluminescence appearing during oxidation of isoproterenol using chemical system involving superoxide anion radical has been studied. Chemiluminescence and fluorescence spectra were measured. The chemiluminescence spectrum was measured with cut‐off filters and revealed bands with maximum at 440, 480, 550, 640 and 700 nm. The bands at 480, 640 and 700 nm were similar to those observed for singlet oxygen. The fluorescence spectrum exhibited maximum at 560 nm.

The inhibitory effect of several biologically important compounds known as O2 ?‐ HO? and 1O2 scavengers on the light emission was studied.

The obtained results indicate that oxidation of isoproterenol by O2 ?‐ involves products in the electronically excited states. The data also seem to indicate the protective effect of isoproterenol on the deoxyribose degradation.  相似文献   
262.
Environmental psychology with a Latin American taste   总被引:1,自引:1,他引:0  
This paper describes and analyzes the actual and potential contributions of Latin American environmental psychology (EP) to the study of environment–behaviour interactions. Latin America is a richly socoi- and bio-diverse region; the multitude of problems caused by threats to its diversity requires especial conceptual and methodological approaches for studying and solving those problems. Latin American environmental psychologists have contributed ideas and studies according to the specificities (indigenous psychologies) of their nations. These specificities include Latin American traditions of collective participation, holistic worldviews, emotional attachment to places and other individuals, biospheric attitudes and preference for diversity, among others, in addition to the cultural traditions inherited from Europe. These traditions are considered in EP studies conducted by Latin American authors, which are described and commented upon. The importance of formative programs for a professionalizing environmental psychology in the area is discussed. Finally, this paper envisions the future of EP in Latin America. Such a forecast includes our vision of how environmental psychologists in the region could contribute to the general development of a universal environmental psychology.  相似文献   
263.
At urban areas in south Europe atmospheric aerosol levels are frequently above legislation limits as a result of road traffic and favourable climatic conditions for photochemical formation and dust suspension. Strategies for urban particulate pollution control have to take into account specific regional characteristics and need correct information concerning the sources of the aerosol.With these objectives, the ionic and elemental composition of the fine (PM2.5) and coarse (PM2.5–10) aerosol was measured at two contrasting sites in the centre of the city of Oporto, roadside (R) and urban background (UB), during two campaigns, in winter and summer.Application of Spatial Variability Factors, in association with Principal Component/Multilinear Regression/Inter-site Mass Balance Analysis, to aerosol data permitted to identify and quantify 5 main groups of sources, namely direct car emissions, industry, photochemical production, dust suspension and sea salt transport. Traffic strongly influenced PM mass and composition. Direct car emissions and road dust resuspension contributed with 44–66% to the fine aerosol and with 12 to 55% to the coarse particles mass at both sites, showing typically highest loads at roadside. In fine particles secondary origin was also quite important in aerosol loading, principally during summer, with 28–48% mass contribution, at R and UB sites respectively. Sea spray has an important contribution of 18–28% to coarse aerosol mass in the studied area, with a highest relative contribution at UB site.Application of Spatial Variability/Mass Balance Analysis permitted the estimation of traffic contribution to soil dust in both size ranges, across sites and seasons, demonstrating that as much as 80% of present dust can result from road traffic resuspension.  相似文献   
264.
Nowadays, there is a trend in many countries towards more environmentally benign products and processes. Life-Cycle Assessment (LCA) is a quantitative analysis tool developed and utilized for the evaluation of environmental impacts occurring throughout the entire life-cycle of a product, process or activity. LCA requires a large amount of data in its different phases and can also generate large amounts of results which may be hard to interpret. In order to uncover and visualize the structure of large multidimensional data sets, Multivariate Analysis techniques can help. Hence, in this paper, a methodology using Principal Component Analysis and Multi-Dimensional Scaling is proposed and illustrated by means of two case studies. The first case study evaluates the operation of several wastewater treatment plants. The second case study deals with the environmental evaluation of the cultivation, processing and consumption of mussels. In both case studies, the redundancy present in the data allowed a dimensionality reduction from seven and ten to two dimensions, with a small loss of information. Plotting the environmental impact data in these two dimensions can help visualize, interpret and communicate them.  相似文献   
265.
The São Francisco River is the largest river located entirely within Brazil, and water scarcity problems have been a major concern of Brazilian society and government. Water quality issues are also a concern and have worsened with the recent intensification of urbanization and industrialization. In this study, violations to water quality standards established by local legislation were calculated as a percentage for 26 selected parameters over a monitoring period of 14 years. The violation percentages were analyzed spatially using the Kruskal-Wallis test, followed by multiple comparison analysis. Temporal analysis was performed using the Mann-Kendall test and Spearman correlation. Some parameters could be identified as cause for concern due to high violation levels, such as the fecal coliform indicator (FCI) and phosphorus—both related to domestic and effluent disposal without treatment or with insufficient treatment—and color, turbidity, manganese, and total suspended solids—which can be affected by erosive processes of natural and anthropogenic causes. The study found that these violations are concentrated in the most urbanized and industrialized areas of the basin. Some metallic parameters, such as iron and arsenic violations, may be related to mining activities in the rich soil of the Iron Quadrangle area located within the Minas Gerais State. Trend analysis results indicated that most monitoring stations did not have significant modification (elevation or reduction) trends over time, which, together with the high violation percentages, might indicate the maintenance of a scenario of constant pressure upon water resources, in particular in those more urbanized areas.  相似文献   
266.
Ultrafine particles represent a growing concern in the public health community but their precise role in many illnesses is still unknown. This lack of knowledge is related to the experimental difficulty in linking their biological effects to their multiple properties, which are important determinants of toxicity. Our aim is to propose an interdisciplinary approach to study fine(FP) and ultrafine(UFP) particles, generated in a controlled manner using a mini CAST(Combustion Aerosol Standard) soot ...  相似文献   
267.
Nurses are often obliged to work in a 12-hr shift work system. We have decided to check whether such a working system constitutes an excessive load for nurses. On the basis of a questionnaire survey among nurses working in an 8-hr daytime shift system (169 nurses) and in a 12-hr shift (536 nurses), the amount of physical workload, work stress, and after-work activities were compared. Data analysis has shown that a 12-hr shift system is characterized by less significant physical workload but greater mental load. The nurses working in a 2-shift system were more tired after work, but they could spend more time on leisure activities and do housework. The data suggest that there are no significant contraindications for nurses to work in a 2-shift system.  相似文献   
268.
Sonographic prenatal diagnosis and management of a pregnancy complicated by dys-segmental dysplasia of the Silverman-Handmaker type are presented. This is a documented case of this type of short-limbed dwarfism presenting in a family of Hispanic-American ancestry.  相似文献   
269.
Introduction: With a growing interest in increasing parental involvement in teen driving, it is important to find out what parents are already doing. Method This study assessed the content, delivery, rigidity, and consequences of 143 driving rules reported by 24 parent-teen dyads. Results: Strengths included that driving rules covered the full range of concerns, especially night driving limits and passenger limits, and most parents and teens reported that violations would be followed by consequences, especially talk/warn or no driving. Weaknesses included that many rules were not very strict and only half showed parent-teen agreement on content. Conclusions: These findings suggest that teen driving rules are not clearly defined.  相似文献   
270.
A model for the biodegradation of non-ionic surfactants in an activated sludge system during acclimatisation was developed, based on respirometric and titrimetric experimental data. The data were obtained in a sequencing batch reactor (SBR) using a non-ionic surfactant as sole carbon source and sludge previously acclimatised to a different surfactant. The model was successfully applied to successive SBR-cycles of sludge acclimatisation processes subjected to two ethoxylated surfactants. The model was validated using the corresponding total organic carbon data. The evolution of the model parameters along the acclimatisation process was examined. An acclimatisation model was developed using the evolution of two of these parameters (affinity constant and inhibition constant), supported by two independently calculated acclimatisation indicators. This acclimatisation model was then applied to determine an optimal surfactant concentration sequence to feed non-acclimatised sludge during a period of 41 days, in order to induce pre-acclimatisation to this surfactant before it replaces another one in the wastewater. The model was also useful in the economical assessment of this and alternative procedures to cope with frequent changes in activated sludge feed composition.  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