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   76篇
  免费   3篇
安全科学   7篇
废物处理   1篇
环保管理   10篇
综合类   9篇
基础理论   24篇
污染及防治   21篇
评价与监测   5篇
社会与环境   1篇
灾害及防治   1篇
  2023年   1篇
  2022年   1篇
  2021年   4篇
  2020年   1篇
  2018年   4篇
  2017年   3篇
  2016年   3篇
  2014年   1篇
  2013年   6篇
  2012年   3篇
  2011年   6篇
  2010年   4篇
  2009年   2篇
  2008年   2篇
  2006年   5篇
  2005年   2篇
  2004年   7篇
  2003年   5篇
  2002年   2篇
  2001年   4篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1995年   1篇
  1994年   2篇
  1993年   3篇
  1991年   1篇
  1985年   1篇
排序方式: 共有79条查询结果,搜索用时 15 毫秒
61.
Biomarkers in the earthworm Aporrectodea tuberculata (Eisen) were measured to find out their possible induction under Cu and Zn exposure and differences in the responses between two populations with different exposure history. The biomarkers applied were concentration of metallothioneins (MT), and cytochrome P4501A (CYP1A) monooxygenase and glutathione-S-transferase (GST) activities. These were measured from earthworms sampled at three distances from a steel smelter in Finland and from the individuals from two populations, one with and another without earlier metal exposure, exposed to three combined Cu/Zn concentrations in the laboratory. In the field, MT concentration, and cytochrome CYP1A and GST activities decreased with increasing distance from the smelter. In the laboratory, biomarker responses varied in relation to the duration and level of exposure, and they were also dependent on the population. The endpoints appeared to be analytically reproducible and sensitive parameters in A. tuberculata, and thus, they can be used in ecotoxicological field monitoring and in experimental research in the laboratory.  相似文献   
62.
A new potential toxaphene congener 3-endo,5-endo-dichloro-7,7-bis-chloromethyl-4-dichloromethyl-tricyclo[2.2.1.0(2,6)]heptane 2 has been isolated from reaction mixture obtained by the chlorination of 2-exo, 10,10-trichlorobornane 1. The X-ray structural analysis of 2 revealed an unusual tricyclic structure, where the two chlorine atoms occupying endo-positions are in close spatial proximity with each other and near to the neighbouring CHCl2 group. Further, it revealed that the symmetry of the molecule is distorted. The 1H and 13C NMR spectra of 2 have been assigned by means of 1H, 1H double-quantum filtered correlation spectroscopy (DQF COSY), PFG 1H, 13C HMQC (pulsed field gradient heteronuclear multiple-quantum coherence), 1H, 13C heteronuclear multiple bond correlation (HMBC) experiments, and computer aided 1H NMR spectral analysis. The asymmetry of 2 is also discernible on the 1H NMR parameters. In addition, gas chromatographic (GC) properties and electron impact (EI) mass spectrum of 2 has been studied. Ab initio Hartree-Fock (HF) method with the basis set 6-31G(d) has been used for the optimization of the equilibrium geometry and calculation of total energy for 2. The optimized geometry is in good agreement with the crystal structure. According to the rotation energy profile calculated at the HF/6-31G(d) level, rotation of the chloromethyl and dichloromethyl groups are highly unlikely at the room temperature.  相似文献   
63.
The number of species and individuals, and the total biomass of earthworms decreased with decreasing distance from a lead smelter in southern Finland, as the Pb load of the soil increased. In soils highly polluted with Pb significant interspecific differences were found in the Pb concentration and the Pb concentration factor of lumbricids, whereas in slightly Pb polluted 'control' soils there were no significant interspecific differences. Near the smelter, the Pb concentration of the endogeic Aporrectodea caliginosa was higher than in the epigeic Lumbricus rubellus and L. casteneus. Pb concentration factors of these three species were lower in the highly polluted soil than in the 'control' soil, indicating that they were able to regulate their Pb accumulation. Contradicting these field observations, of the worms from the 'control' soil but reared in highly Pb polluted soil for up to 70 days, the epigeic L. castaneus, L. rubellus and Dendrodrilus rubidus took up more Pb than did the endogeic A. caliginosa and A. rosea. They also accumulated more Pb during the rearing periods than their counterparts permanently living in the highly Pb polluted soil, indicating that besides interspecific differences in Pb accumulation there seem to be intraspecific differences as well. Acclimatization and/or genotype differences can underlie earthworms' adaptation to Pb polluted soil, where they may have dissimilar physiological pathways to cope with high soil Pb concentrations. The amount of Pb rendered available to a local food chain by a population of earthworms will depend on the ability of the worms to accumulate Pb in their tissues, which in turn, is a function of the population's history of Pb exposure. Species such as A. caligonosa, which accumulate and continuously withstand high Pb concentrations in their tissues, are most appropriate for biomonitoring.  相似文献   
64.
Ecosystems at high latitudes are highly dynamic, influenced by a multitude of large-scale disturbances. Due to global change processes these systems may be expected to be particularly vulnerable, affecting the sustained production of renewable wood resources and abundance of plants and animals on which local cultures depend. In this paper, we assess the implications of new understandings of high northern latitude ecosystems and what must be done to manage systems for resilience. We suggest that the focus of land management should shift from recovery from local disturbance to sustaining ecosystem functions in the face of change and disruption. The role of biodiversity as insurance for allowing a system to reorganize and develop during the disturbance and reorganization phases needs to be addressed in management and policy. We emphasize that the current concepts of ecological reserves and protected areas need to be reconsidered to developp dynamic tools for sustainable management of ecosystems in face of change. Characteristics of what may be considered as customary reserves at high latitudes are often consistent with a more dynamic view of reserves. We suggest new directions for addressing biodiversity management in dynamic landscapes at high latitudes, and provide empirical examples of insights from unconventional perspectives that may help improve the potential for sustainable management of biodiversity and the generation of ecosystem services.  相似文献   
65.
This paper presents the results of life cycle inventory (LCI) analyses that were carried out to determine the environmental impacts (emissions, resource extractions and land use) of different newspaper waste management options for the Helsinki Metropolitan Area (HMA). LCI analyses were performed for five product systems, in which discarded newspapers were divided into two streams: separately collected newspapers and newspapers in mixed waste. In all the options, the manufacturing and printing processes of newspaper were kept unchanged. The waste management alternatives included combinations of material recycling, energy recovery and landfilling. These product systems were modelled using the current collection rate of newspaper and four additional collection rates. The LCIs of the product systems showed that the life cycle phase causing the most environmental impacts was the paper mill. When comparing the different waste management systems, the energy recovery options were in general superior to landfilling. The ecological implications of the increased energy recovery and decreased material recycling of newspaper were, however, not yet considered in the study. These aspects were assessed in the life cycle impact assessment (LCIA), which was performed after the LCI phase.  相似文献   
66.
The Tens Rule, as well as the last stage described therein, i.e., the proportion of established species that becomes pests, is frequently perceived by the scientific community to indicate that introduced established species have little impact on communities. This belief is dangerous because it strengthens the perspective of the general public and decision makers that the risks of species introductions are largely overestimated. It is often difficult to detect the actual negative impact of an introduced established species. It might be less apparent or indirect; it might be delayed or masked by the “noise” caused by other anthropogenic disturbances. It is also likely that numerous ecological interactions are still not detected or properly understood. Therefore, the ten-percent rule might be more of an indicator of our lack of understanding of the impacts that established introduced species produce than the actual ratio of such species that produces negative impacts. In such a state of affairs, adopting the precautionary principle is crucial. The scientific community must be much more cautious and responsible regarding the message it delivers to the general public and management authorities.  相似文献   
67.
Indicators are commonly used as tools to identify and highlight socio‐economic and ecological trends and to assess progress towards sustainability. Different quality criteria can be considered for indicators. This paper focuses on the timeliness of indicators used in the evaluation of sustainable development strategies. The analysis is based on indicators included in four assessment reports of the sustainable development strategy of the European Union and three assessment reports of the national strategy of Finland. Furthermore, a web‐based national level indicator portal is analysed. The results show that the timeliness of indicators has generally not improved during the past decade and that indicators used in strategy evaluations have a time lag of approximately two years. It is suggested that more attention should be given to efforts to improve the timeliness of indicators in order to increase the effectiveness of the evaluations. More generally, it is suggested that greater emphasis should be put on the empirical research on actual use of indicators.  相似文献   
68.
Metal concentrations (Cu, Ni, Zn, Cd, Cr, Hg, Pb and Mo) were analysed from the liver and kidneys of moles, Talpa europaea L. (Insectivora), trapped in southern Finland on both contaminated and rural areas. In rural areas the concentrations of Cd, Cu, Zn, Pb and Mo were lower in juveniles (individuals in their first summer), except for Zn in the liver, which was lower in adults. When the animals were divided into annual classes (0-6 years), Cd and Mo concentrations in the liver increased significantly with age, while concentrations of Cu, Zn and Cr tended to decrease. Female moles had higher Pb concentrations than males, especially adult females, which also had lower levels of Cu in the liver than adult males. Moles in the metropolitan area of Helsinki clearly differed from those in rural areas in that the concentrations of heavy metals in these moles were higher (especially for the most toxic metals: Cd, Pb and Hg), and their body weight was lower. The renal concentrations of Cd in most of the moles in Helsinki exceeded the threshold that has been shown to have a nephrotoxic effect in mammals. In one subsample from Helsinki, Pb and Zn concentrations in the mole liver decreased as the distance from the highway increased. Concentrations of Pb in earthworms and several heavy metals in soil also decreased similarly in the same area. Our data indicate that Pb accumulates in moles through their diet of earthworms.  相似文献   
69.
The significance of engineered nanomaterials (ENM) and nanotechnologies grows rapidly. Nanotechnology applications may have a positive marked impact on many aspects of on human every day life, for example by providing means for the production of clean energy and pure drinking water. Hundreds of consumer nano-based products are already on the market. However, very little is known of the risks of ENM to occupational safety and health (OSH), even though workers are likely to be at extra risk, as compared with other potentially exposed groups of people, because the levels of exposure are usually higher at workplaces than in other environments. However, knowledge of the exposure to, or effects of, ENM on human health and safety in occupational environments is limited and does not allow reliable assessment of risks of ENM on workers’ health. Several issues related to ENM in the workplaces require marked attention. The most topical issues include: (1) improved understanding of ENM metrics associated with ENM toxicity; (2) development of monitoring devices for ENM exposure assessment; (3) understanding the changes of ENM structure and state of agglomeration at different concentrations in aerosols; (4) understanding translocation of ENM in the human body; (5) identifying the key health effects of ENM including pulmonary toxicity, genotoxicity, carcinogenic effects, and effects on circulation; (6) development of tiered approaches for testing of safety of ENM; and (7) utilizing these data for health risk assessment, with a special emphasis on occupational environment. Available data on several ENM – ability to enter the body and reach almost any organ, to cause pulmonary inflammation and fibrosis, and even to cause increased risk of mesotheliomas in animal models, call for immediate action. It is crucial to identify those ENM that may cause occupational health and safety risks from those ENM which are innocent, hence allowing prioritization of regulatory and preventive actions at workplaces at national, regional and global levels.  相似文献   
70.
Ellagitannins are widely distributed plant polyphenols showing potent anti-herbivore activities, but rather complex chemical structures. Here we show how ellagitannins with different structures can be efficiently characterized from plant extracts by utilizing the information obtained from four universal methods used for ellagitannin analysis: Sephadex LH-20 gel chromatography, high-performance liquid chromatography, ultraviolet spectroscopy, and mass spectrometry. We show that by combining the information obtained from the ellagitannins’ chromatographic elution order, specific shapes of the ultraviolet spectra, molecular masses and characteristic mass spectral fragmentations, it is possible to classify these polyphenols into different ellagitannin sub-groups, and even characterize the structures within the sub-groups. These findings aid in the fast screening of complex plant samples for their ellagitannin composition without having to isolate compounds for individual characterization.  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