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   282篇
  免费   6篇
安全科学   14篇
废物处理   16篇
环保管理   59篇
综合类   37篇
基础理论   72篇
污染及防治   51篇
评价与监测   27篇
社会与环境   8篇
灾害及防治   4篇
  2024年   1篇
  2023年   3篇
  2022年   7篇
  2021年   2篇
  2020年   3篇
  2019年   3篇
  2018年   4篇
  2017年   8篇
  2016年   8篇
  2015年   10篇
  2014年   14篇
  2013年   20篇
  2012年   10篇
  2011年   22篇
  2010年   6篇
  2009年   10篇
  2008年   17篇
  2007年   13篇
  2006年   9篇
  2005年   10篇
  2004年   4篇
  2003年   8篇
  2002年   11篇
  2001年   5篇
  2000年   6篇
  1999年   8篇
  1997年   5篇
  1996年   4篇
  1995年   4篇
  1994年   4篇
  1993年   4篇
  1992年   4篇
  1990年   2篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1986年   3篇
  1985年   6篇
  1984年   4篇
  1983年   3篇
  1982年   6篇
  1981年   3篇
  1980年   4篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1970年   1篇
  1959年   1篇
排序方式: 共有288条查询结果,搜索用时 15 毫秒
101.
Depleted uranium (DU) weapons testing programmes have been conducted at two locations within the UK. An investigation was therefore carried out to assess the extent of any environmental contamination arising from these test programmes using both alpha spectrometry and mass spectrometry techniques. Uranium isotopic signatures indicative of DU contamination were observed in soil, plant and earthworm samples collected in the immediate vicinity of test firing points and targets, but contamination was found to be localised to these areas. This paper demonstrates the superiority of the (235)U : (238)U ratio over the (234)U : (238)U ratio for identifying and quantifying DU contamination in environmental samples, and also describes the respective circumstances under which alpha spectrometry or mass spectrometry may be the more appropriate analytical tool.  相似文献   
102.
Since 1987, the Alaska Marine Mammal Tissue Archival Project (AMMTAP) has collected tissues from 18 marine mammal species. Specimens are archived in the National Institute of Standards and Technology's National Biomonitoring Specimen Bank (NIST-NBSB). AMMTAP has collected blubber, liver and/or kidney specimens from a number of ringed seals (Phoca hispida) from the areas near Nome and Barrow, Alaska and walruses (Odobenus rosmarus) from several locations in the Bering Sea. Thirty-three ringed seal and 15 walrus blubber samples from the NIST-NBSB were analyzed for persistent organic pollutants (POPs). The compounds determined included PCBs (28 congeners or congener groups), DDT and related compounds, hexachlorobenzene (HCB), hexachlorocyclohexane isomers (HCHs), chlordanes, dieldrin, and mirex. POP concentrations in ringed seal blubber were significantly higher in Barrow than in Nome when statistically accounting for the interaction of age and gender; HCB, however, was not statistically different between the two locations. Unlike males, POP concentrations and age were not significantly correlated in females probably as a result of lactational loss. POP concentrations in walrus blubber were lower than in ringed seal blubber for SigmaPCBs, chlordanes, and HCHs, but higher for dieldrin and mirex. POP concentrations in ringed seals and walrus from Alaska provide further evidence that the western Arctic tends to have lower or similar POP concentrations compared to the eastern Canadian Arctic.  相似文献   
103.
Two regions of the mitochondrial genome (cytochrome oxidase I and ATPase 8–ATPase 6) were used to examine the population genetic structure of New Zealand’s endemic abalone (Haliotis iris). Samples were collected from 28 locations around New Zealand between January 2005 and February 2008. At least four phylogeographic breaks were present and occurred across the Chatham rise, in the western Cook Strait region, along the southeast coast of the South Island, and at East Cape in the North Island. Gene flow across the Chatham rise is probably limited due to infrequent dispersal across large geographic distances (~850 km), while factors limiting gene flow around the North and South Islands are less clear, and understanding these may require intense temporal and spatial sampling in complex hydrographic regions. High genetic diversity and weak genetic structure may be a general feature of abalone potentially reflecting large and/or ancient populations.  相似文献   
104.
Housedusts and garden soils were sampled in 14 houses in the vicinity of a secondary Pb smelter and analysed for concentrations of Pb, Zn, Cu, Cd, As, and Hg. Sixty-one topsoil samples were also taken from a 2 km2 grid covering the smelter grounds and surrounding residential areas and analysed for concentrations of Pb, Zn, Cd and Cu. Contour maps generated from the grid data indicate significant contamination in the area (maximum Pb concentration 58 500 g g-1), particularly down-wind of the smelter grounds. A geometric mean Pb concentration of 2225 g g-1 was recorded in garden soil and similarly elevated levels were recorded for Zn, Cd, As and Sb. In housedusts, a geometric mean Pb concentration of 1668 g g-1 was observed. Whilst housedust metal concentrations were generally elevated, compared to other urban or residential areas, there appears to be a large degree of attenuation of the metals between the exterior and interior environments of the homes studied. A significant correlation was not recorded between metal concentrations of garden soils and housedusts. There were significant correlations for: distance from the smelter against garden soil metal concentrations; garden soil metal concentrations against each other; housedust metal concentrations against each other; and house age against garden soil metal concentrations.  相似文献   
105.
The ultimate aim of toxicological studies is to determine the effects of pollutants on the health and welfare of human beings. To get this it is essential to conduct animal studies to evaluate the potential toxicity of different pollutants. Toxicological appraisal of the photochemical oxidant type of air pollution shows: (1) The effects are primarily on the lungs and the senses. (2) There is impairment of pulmonary function in humans at concentrations found in polluted air. (3) Both ozone and nitrogen dioxide tend to oxidize in animals the lung tissue for a time. This process creates agents which have the potential for cross-linking structural proteins, and this process initiates inflammation which accelerates cell turnover rates. Both crosslinking and cell turnover rates are factors in aging, which may thus be accelerated by years of repeated exposure to oxidants. (4) Long-term exposure to low levels of nitrogen dioxide can produce pre-emphasematous lesions in the lungs of rats and mice. Studies with other species are needed. (5) Ozone, nitrogen dioxide, and dilute irradiated car exhausts increase susceptibility to respiratory infection.

The constant search for more sophisticated and sensitive techniques to detect subtle changes indicative of pre-disease conditions should not be relaxed. Such techniques will provide chronic disease predictors of great relevance as air quality criteria.  相似文献   
106.
The application of a phosphorus monitoring device based on microsystems technology (MST) to the analysis of river water is presented. An alternative to the standard molybdenum blue method known as the yellow vanadomolybdophosphoric acid method has been very effectively implemented. The method is simple, a reagent and sample are mixed in a 1:1 ratio forming a yellow complex that absorbs strongly below 400 nm in the UV spectrum. The kinetics of the reaction are rapid and sample turnaround is typically 3 min at room temperature. Therefore a very uncomplicated microfluidic design can be adopted. The working wavelength was chosen as 380 nm to coincide with the peak output of a UV-LED narrow bandwidth light source recently developed by Nichia. The limit of detection for the yellow method in the microfluidic system is 0.2 ppm with a dynamic linear range from 0-50 ppm. The method was applied to a measurement of phosphorus in a local river at specific sampling points along its course.  相似文献   
107.
Sustainability standards and certification serve to differentiate and provide market recognition to goods produced in accordance with social and environmental good practices, typically including practices to protect biodiversity. Such standards have seen rapid growth, including in tropical agricultural commodities such as cocoa, coffee, palm oil, soybeans, and tea. Given the role of sustainability standards in influencing land use in hotspots of biodiversity, deforestation, and agricultural intensification, much could be gained from efforts to evaluate and increase the conservation payoff of these schemes. To this end, we devised a systematic approach for monitoring and evaluating the conservation impacts of agricultural sustainability standards and for using the resulting evidence to improve the effectiveness of such standards over time. The approach is oriented around a set of hypotheses and corresponding research questions about how sustainability standards are predicted to deliver conservation benefits. These questions are addressed through data from multiple sources, including basic common information from certification audits; field monitoring of environmental outcomes at a sample of certified sites; and rigorous impact assessment research based on experimental or quasi‐experimental methods. Integration of these sources can generate time‐series data that are comparable across sites and regions and provide detailed portraits of the effects of sustainability standards. To implement this approach, we propose new collaborations between the conservation research community and the sustainability standards community to develop common indicators and monitoring protocols, foster data sharing and synthesis, and link research and practice more effectively. As the role of sustainability standards in tropical land‐use governance continues to evolve, robust evidence on the factors contributing to effectiveness can help to ensure that such standards are designed and implemented to maximize benefits for biodiversity conservation.  相似文献   
108.
The changing status of the global environment, in both developed and developing countries, and our perception of these changes since the convening of the United Nations Conference on the Human Environment in Stockholm in 1972 are reviewed. The present as well as potential future environmental issues facing mankind are discussed under three interrelated broad categories: interrelationship between people, resources, environment and development, rational use of natural resources and new patterns of development and lifestyle.  相似文献   
109.
110.
Clean Development Mechanism (CDM) forestry project development requires highly multi-disciplinary and multiple-source information that can be complex, cumbersome and costly to acquire. Yet developing countries in which CDM projects are created and implemented are often data poor environments and unable to meet such complex information requirements. Using Cameroon as an example, the present paper explores the structure of an enabling host country data support infrastructure for CDM forestry implementation, and also assesses the supply potential of current forestry information. Results include a conceptual data model of CDM project data needs; the list of meso- and macro-level data and information requirements (Demand analysis); and an inventory of relevant data available in Cameroon (Supply analysis). From a comparison of demand and supply, we confirm that data availability and the relevant infrastructure for data or information generation is inadequate for supporting carbon forestry at the micro, meso and macro-levels in Cameroon. The results suggest that current CDM afforestation and reforestation information demands are almost impenetrable for local communities in host countries and pose a number of cross-scale barriers to project adoption. More importantly, we identify proactive regulatory, institutional and capacity building policy strategies for forest data management improvements that could enhance biosphere carbon management uptake in poor countries. CDM forestry information research needs are also highlighted.  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