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101.
Studies of collaborative watershed groups show that effective leadership is an important factor for success. This research uses data from in-depth interviews and meeting observation to qualitatively examine leadership in a Midwestern collaborative watershed group operating with government funding. One major finding was a lack of role definition for volunteer steering-committee members. Lack of role clarity and decision-making processes led to confusion regarding project management authority among the group, paid project staff members, and agency personnel. Given the important role of government grants for funding projects to protect water quality, this study offers insight into leadership issues that groups with Clean Water Act Section 319 (h) funds may face and suggestions on how to resolve them.  相似文献   
102.
Antler asymmetry and immunity in reindeer   总被引:3,自引:0,他引:3  
Fluctuating asymmetry (FA) measures an individual's ability to undergo identical development in bilaterally symmetrical characters and may indicate sensitivity to environmental stress. FA in ornamental characters is often positively related to parasite intensities, which are important environmental stressors. Parasites affect and are affected by several parts of the immune system, and the ability to resist parasites may be signalled via FA in ornaments. In this study we examined reindeer antlers, which show FA, demonstrated to be caused by parasite infections. We measured antler FA, immune parameters (i.e. densities of different classes of leukocytes, IgG levels and abomasal lymph node numbers) and intensity of abomasal nematodes in free-ranging 1.5-year-old male reindeer slaughtered in the early part of their rutting period. We found a relationship between parasite intensity and immune parameters suggesting that our measures of immune activity reflect density of current parasite infections. More important, these immune parameters were associated with FA in both the main beam length and numbers of antler tines. The immune parameters were, however, only weakly correlated to antler size. This indicates that FA, but not size, of antlers grown during exposure to a multitude of environmental stressors may reveal information about individual immunity that can be important for host-parasite interactions. Antler FA may therefore communicate an individual's quality during the rut in reindeer. Received: 30 March 1998 / Accepted after revision: 15 August 1998  相似文献   
103.
Transport affects climate directly and indirectly through mechanisms that operate on very different timescales and cause both warming and cooling. We calculate contributions to the historical development in global mean temperature for the main transport sectors (road transport, aviation, shipping and rail) based on estimates of historical emissions and by applying knowledge about the various forcing mechanisms from detailed studies. We also calculate the development in future global mean temperature for four transport scenarios consistent with the IPCC SRES scenarios, one mitigation scenario and one sensitivity test scenario. There are large differences between the transport sectors in terms of sign and magnitude of temperature effects and with respect to the contributions from the long- and short-lived components. Since pre-industrial times, we calculate that transport in total has contributed 9% of total net man-made warming in the year 2000. The dominating contributor to warming is CO2, followed by tropospheric O3. By sector, road transport is the largest contributor; 11% of the warming in 2000 is due to this sector. Likewise, aviation has contributed 4% and rail ~1%. Shipping, on the other hand, has caused a net cooling up to year 2000, with a contribution of ?7%, due to the effects of SO2 and NOx emissions. The total net contribution from the transport sectors to total man-made warming is ~15% in 2050, and reaches 20% in 2100 in the A1 and B1 scenarios. For all scenarios and throughout the century, road transport is the dominating contributor to warming. Due to the anticipated reduction in sulphur content of fuels, the net effect of shipping changes from cooling to warming by the end of the century. Significant uncertainties are related to the estimates of historical and future net warming mainly due to cirrus, contrails and aerosol effects, as well as uncertainty in climate sensitivity.  相似文献   
104.
There is increasing interest among scholars in producing information that is useful and usable to land and natural resource managers in a changing climate. This interest has prompted transitions from scientist- to stakeholder-driven or collaborative approaches to climate science. A common indicator of successful collaboration is whether stakeholders use the information resulting from the projects in which they are engaged. However, detailed examples of how stakeholders use climate information are relatively scarce in the literature, leading to a challenge in understanding what researchers can and should expect and plan for in terms of stakeholder use of research findings. Drawing on theoretical, typological, and evaluation insights from the field of information use, we examine stakeholder use of climate information emerging from 13 collaborative climate science projects conducted in the western United States between 2012 and 2016. Three primary types of use emerge from our findings—conceptual, instrumental, and justification—reflecting common typologization of information use. Conceptual use was the most predominant. We suggest that researcher awareness of this typology can enable more systematic understanding of what project outputs stakeholders use and impacts of those outputs, giving way to new areas of inquiry and aiding in the conceptualization and design of climate information products for land and natural resource managers.  相似文献   
105.
此文以霸县凹陷文安斜坡和饶阳凹陷留楚构造为研究对象,对比了斜坡区和隆起区断裂密集带的特征及其对不同构造部位油气分布的控制作用。在三维地震资料、钻井资料和已发现油气藏特征的基础上,利用断裂密集带识别方法和分类方案,识别出文安斜坡和留楚构造的断裂密集带,并对其进行了分类。对比两种构造部位断裂密集带发育的差异性及对油气分布的控制作用,认为隆起区(留楚构造)相对于斜坡区(文安斜坡)断裂密集带发育数量较少,规模大,斜坡区断裂密集带主要以顺向背形断裂密集带为主,而隆起区主要以屋脊背形断裂密集带为主,隆起区油气主要分布在顺向背形断裂密集带内,斜坡区主要分布在屋脊背形断裂密集带内部及靠近生烃中心的边部。  相似文献   
106.

Background, aim, and scope

Current knowledge on environmental impacts of industrial activities in Romania, particularly persistent organic pollutants (POPs), indicates that environmental standards of the European Union are not systematically met. In our study area, additional sources of POPs are agriculture and domestic wastes. Very scarce information is available upon environmental contaminations and effects. In the present study, we investigated the chemical pollution and their eventual impact on the ecosystem by measuring POPs and by using biological indicators of pollution.

Materials and methods

The survey was carried out at six main sample sites along the Bahlui River. Sediments were chemically analysed for their content in polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs)—hexachlorocyclohexanes (HCHs) isomers and the dichlorodiphenyl trichloroethane (DDT) family. River water was biologically monitored at the level of phytoplankton and benthic invertebrates’ communities. Water samples from six locations have been analyzed for algal species composition and correspondence to various water quality indices. Biological samples have been taken from the same locations so as to calculate the macroinvertebrate indices. In the most polluted areas, as revealed by previous methods, toxicity was tested by exposing the green alga Pseudokirchneriella subcapitata and the cladoceran Daphnia magna to various dilutions of water sample.

Results

Important concentrations of POPs were identified only in sediments at river mouths (sites S5 and S6). Along the year, the sum of PCB concentrations ranged between 3 and 10 ng/g dw (S5), and between 4 and 26 ng/g dw (S6). Concentration of HCHs ranged between 0.4 and 3 ng/g dw (both S5 and S6) with a higher contribution of the gamma-HCH (30–70%), followed by beta-HCH (20–50%). The beta-HCH isomer was found at lower concentrations or even not detected in outer city sites. DDTs were found at higher concentrations than HCHs and ranged between 0.18 and 4 ng/g dw (S5) and between 0.56 and 18 ng/g dw (S6). The parent compound, p,p′-DDT, could be detected only in low concentrations (up to 5 ng/g dw) and contributed with less than 30% to the sum of DDTs in sediment. The principal contributors of the ΣDDTs in sediment were p,p′-DDE, and p,p′-DDD. The o,p′-DDD and DDT isomers were minor contributors to the sum of DDT. PAHs were found at higher concentrations than DDTs and ranged between 6 and 36 ng/g dw (S5) and between 36 and 155 ng/g dw (S6). Fluoranthene was predominant (up to 40%), followed by phenantrene (up to 30%), naphthalene (up to 35%), and benzo-(g,h,i)-perylene (up to 23%). The saprobity index and the diatom index increased from springs to river mouth, indicating a decrease in the water quality, but within the limits of moderate pollution. The saprobity index varied between 1.99 at spring to 2.70 at mouth. The diatom index varied from 3.48 to 3.14. The species’ richness in phytoplankton has a less clear pattern along the river, but in general, it appears to be negatively influenced by pollution. At the level of biological consumer species, the analyses of the macroinvertebrates confirm the situation and the tendency shown with algae. In addition, the Shannon–Wiener index, the Pielou evenness index, and the McNaughton dominance index indicate a peculiar pattern: invertebrate communities appear to a have a more stable structure along the river, with visible shifts at springs and at river mouths. Water toxicity testing indicates low toxicity of river waters around the city of Iasi, with two notable exceptions: the point pollution at the domestic wastewater treatment discharge and at the old open-air deposit of domestic solid wastes. Another important result was that tested algae appeared to be more readily affected than tested cladoceran: EC50 (percent effluent) was 16 in algae and 28 in cladocerans. The slope of toxic effect was also much steeper in cladocerans (6) than in algae (1.8), which means that the toxic effect is more sudden on the tested invertebrates than on the tested algae.

Discussion

Pollutant concentrations reported herein are lower or similar than those reported for the sediments by earlier studies (RIZA 2000; Dragan et al., Int J Environ Anal Chem 86:833–842, 2006). Ratios of individual PAH compounds indicate important pyrolytic inputs and suggest that PAHs in the area are derived from the combustion of fossil fuels. Biologically, the waters appear to be beta-mesosaprobic towards alpha-mesosaprobic according to the saprobic index classification and undergo moderate pollution according to the diatom index classification. Water quality decreases from springs to river mouths. Algal species richness index has a less clear pattern along the river. Water toxicity is low, but certain sources of point pollution require increased attention.

Conclusions

The water quality is better than expected, probably because of the drop in pollution intensity following the collapse of local agricultural and industrial activity following the fall of communism in 1989. Nevertheless, further studies will be needed to confirm and refine our results. While this study draws no strident alarm, it appeals for high attention, particularly because the economic activity in the area is expected to increase.

Recommendations and perspectives

Future close monitoring will be necessary for insuring compliance with the Water Framework Directive, and for refining standards and understanding of the local situation, but with relevance for the wider international community. On the basis of the situation described in the present study, we recommend that future studies dedicate specific efforts to point pollution and effluent toxicity, particularly around the city of Iasi. For a better understanding of pollution and its effects, we recommend pursuing the type of multidisciplinary investigations proposed by the present study: chemical, ecotoxicological, and ecological. We also recommend that new methods should be developed and/or refined, like the empirical determination of partitioning coefficients in water and soils, process-based toxicity methods in ecotoxicological assessments, searching for interactions between pollution, producers, and consumers in aquatic ecosystems. We also recommend preference for cheaper survey methods, as these will be more applicable locally.
  相似文献   
107.
108.
Acquired immunodeficiency syndrome (AIDS) was first described in 1981, and continues to be one of the worst global health pandemics in recorded history. Concerted international efforts have helped to increase awareness of human immunodeficiency (HIV) status, improve access to treatment and continuation of therapy to achieve viral suppression with a goal of ending the AIDS epidemic by 2030. The clinical outcomes for patients living with HIV on combined antiretroviral therapy are considerably improved with prolonged life expectancy and superior quality of life. Further, perinatal transmission rates have dramatically decreased with elimination of mother to child transmission of HIV in a growing number of countries worldwide. However, there have been significant reductions in the pace of progress in treatment expansion for pregnant women with failure to meet global targets in 2018. In this review, we will highlight recent advances and challenges ahead in 2020 for three areas of perinatal care for women with HIV in developed countries: (a) pregnancy planning considerations, (b) impact of antiviral medications on perinatal outcomes, and (c) infant feeding practices. The promise of a HIV-free generation is on the horizon and continued international efforts in preventing perinatal transmission are an important component of this achievement.  相似文献   
109.
In the Kullu District, Himachal Pradesh, India, economic and urban growth, and diversification have increased pressure on forests and forest-based social-ecological systems. As in many Himalayan regions, livelihood sustainability is linked to forest resources, products and services. Recent development in the region, to which these systems may be vulnerable, brings into question environmental and livelihood sustainability. This paper examines the resilience of integrated systems of people and nature, or social-ecological systems, in the face of development pressures by evaluating a number of local and state-level institutional responses. Resilience, which describes the ability of the social-ecological systems to adapt to change by buffering shocks, improving self-organization and increasing capacity for learning, is an essential quality for sustainable development. Institutional responses which positively contribute to resilience and sustainability include the work of mahila mandals in forest management, adoption of Joint Forest Management (JFM) policies and practices, upholding rules, strengthening local institutions, establishing firewood depots and adopting alternative energy sources. Institutional failures brought about by the lack of rule enforcement and corruption erode resilience. The analysis of institutional responses helps to identify areas where capacity exists and areas in which capacity building is needed to produce resilient social-ecological systems and therefore, sustainable development.  相似文献   
110.
Several types of fuels, including coal, fuel wood, and biogas, are commonly used for cooking and heating in Chinese rural households, resulting in indoor air pollution and causing severe health impacts. In this paper, we report a study monitoring multiple pollutants including PM10, PM2.5, CO, CO2, and volatile organic compounds (VOCs) from fuel combustion at households in Guizhou province of China. The results showed that most pollutants exhibited large variability for different type of fuels except for CO2. Among these fuels, wood combustion caused the most serious indoor air pollution, with the highest concentrations of particulate matters (218~417 μg m?3 for PM10 and 201~304 μg m?3 for PM2.5), and higher concentrations of CO (10.8 ± 0.8 mg m?3) and TVOC (about 466.7 ± 337.9 μg m?3). Coal combustion also resulted in higher concentrations of particulate matters (220~250 μg m?3 for PM10 and 170~200 μg m?3 for PM2.5), but different levels for CO (respectively 14.5 ± 3.7 mg m?3 for combustion in brick stove and 5.5 ± 0.7 mg m?3 for combustion in metal stove) and TVOC (170 mg m?3 for combustion in brick stove and 700 mg m?3 for combustion in metal stove). Biogas was the cleanest fuel, which brought about the similar levels of various pollutants with the indoor case of non-combustion, and worth being promoted in more areas. Analysis of the chemical profiles of PM2.5 indicated that OC and EC were dominant components for all fuels, with the proportions of 30~48%. A high fraction of SO42? (31~34%) was detected for coal combustion. The cumulative percentages of these chemical species were within the range of 0.7~1.3, which was acceptable for the assessment of mass balance.  相似文献   
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