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991.
Modern science is global. This is particularly true of environmental science, which has been guided to a considerable extent by international environmental policy. Accordingly, one might expect the standards of scientific research around the globe to have unified over the last 30 years. Yet environmental scientists from different nations and scientific schools have demonstrably dissimilar views on key environmental issues. This is the conclusion we reached after a series of in-depth interviews with prominent American and Russian environmental scientists. The greatest difference was found in the perception of two global issues—stratospheric ozone depletion and climate change.  相似文献   
992.
The major problem associated with gravity dam was siltation of reservoir which reduced its effective water storage capacity. In order to maintain effective storage capacity of reservoir, dredging of deposits was required and dredged material was disposed of haphazardly causing damage to the sensitive environment. A better alternative could be the possibility of utilization of dredged deposits in construction works involving large quantities of material. The dredged material consisted of very fine sandy silt possessing poor geotechnical characteristics and was required to be stabilized with suitable additives before use as construction material. This laboratory investigation evaluated geotechnical properties of dredged reservoir material stabilized with cement, fly ash and fiber for its probable use as subbase in lightly trafficked roads. Compaction, unconfined compressive strength and tensile strength tests were performed on appropriate combinations of the constituent materials. The results of study revealed significant improvement in unconfined compressive strength and split tensile strength after stabilization with cement and fly ash. The unconfined compressive strength and split tensile strength of cement–fly ash-stabilized dredged reservoir material improved further upon addition of polypropylene fiber. The composite possessed the potential to be utilized as sustainable material in subbase of roads subject to further validation before application in the field. The dredging of sediments improved effective storage capacity of reservoir and increased its sustainable life period. The utilization of fly ash could diminish the environmental and economic concerns arising out of its haphazard disposal.  相似文献   
993.
Land reform is identified as a key tool in fostering development in South Africa. Twenty years after the advent of democracy in South Africa, the land question remains a critical issue for policy makers. Several frameworks have been put in place by the government to identify land that is strategically located for land reform. However, many of these frameworks are not well aligned and not objective in defining strategically located land for land reform and often lead to unsustainable land use management practices. This has hampered the government’s land reform initiative in promoting agricultural land reform and food security. Accordingly, there is a need to develop a decision support tool that facilitates the identification of strategically located land for land reform. This study proposes the use of geographic information systems (GIS) and multi-criteria decision analysis (MCDA) to develop a strategically located land index (SLLI) to identify land suitable for agricultural land reform. Participatory workshops and the group analytical hierarchy process were utilised to identify and weigh criteria used in computing the SLLI. The results indicate that land that is suitable for agricultural land reform is scarce, and there are also competing needs on the highly suitable land for agriculture. The study demonstrates that GIS and MCDA are invaluable tools in facilitating evidence-based decision-making for land reform and sustainable land use management practices. The SLLI is not the panacea to land identification; there is also need to appreciate the contested nature of land in South Africa.  相似文献   
994.
The aim of this paper is to evaluate and analyze the impact of adoption of soil conservation practices (SCPs) on the technical efficiency of smallholder rice producers in Central China. We address self-selection bias and unobserved heterogeneity problems by estimating a switching regression model for the adoption decision function and separate stochastic production frontiers for SCP and Conventional farms while allowing for production inefficiency. SCP farms exhibit statistically higher average technical efficiency than Conventional farms. Education, extension services, membership in cooperatives, access to credit, and alternative income sources are positively and significantly associated with technical efficiency for both groups. Conventional farms display higher partial output elasticity for land, while only SCP farms show significant elasticity for capital.  相似文献   
995.
In Libya, municipal solid waste management is one of the services provided by the authorities to keep the county clean. This study was conducted in the City of Al-Bayda, located in the eastern part of Libya, as there have been several major problems facing the city in dealing with solid waste management. One of these problems is the generation, collection, handling, transportation, recycling, and disposal of municipal solid waste (MSW). This study has identified that the ongoing disposal of MSW to poorly engineered “dump sites” on the outskirts of the city is unsustainable and will not meet the demands of the growing population and increasing urbanization currently experienced within Al-Bayda. Factors impacting the decision-making and operational processes of MSW include lack of resources and services that significantly affect the disposal of waste, an inadequate number of waste collection containers making the distance to these containers for many households excessive, and thus leading to an increasing likelihood of dumping solid waste in open areas and roadsides. The study recommends that the city government of Al-Bayda should identify synergies and increase partnership-working arrangements with the private sector to ensure efficient management of MSW within the city area.  相似文献   
996.
Market-based instruments (MBIs) have emerged as a popular approach to balance development and conservation objectives. However, their ability to accomplish this is often beset by poor implementation in practice. This is testament to a widening gap between the rate of policy development and implementation of MBIs and the maturity of research and evaluation on their design, and impact on affected stakeholders. Within this context, this paper examines multi-stakeholder perspectives to the adoption of Biodiversity Offsetting in England, an instrument designed to enable biodiversity losses in one place to be compensated through conservation improvements elsewhere. Analysis reveals issues associated with social and ecological compensation of biodiversity loss. Findings suggest that there is a need for a broader consideration of issues surrounding distributive justice, access to nature and the status of ownership over sites of common heritage when accounting for biodiversity loss and its compensation. This message is salient to both the study context as well as the burgeoning international practice of Biodiversity Offsetting.  相似文献   
997.
Few studies have been conducted on the impact of carbon emissions disclosure on firms’ financial performance in emerging economies. Furthermore, comparison between accounting-based measures and market-based ones remains limited. This article examines the effect of carbon emissions reporting on the financial value of South African companies for the period 2010–2015. Using panel regression approaches, the findings show that, in most cases, carbon emission disclosure generates a positive relationship with ROA (an accounting-based indicator) but a negative association with MVA (a market-based indicator). The article concludes that accounting-based indicators offer more explanatory power for corporate greening initiatives.  相似文献   
998.
Doroth&#;e Ehrich  Niels M. Schmidt  Gilles Gauthier  Ray Alisauskas  Anders Angerbj&#;rn  Karin Clark  Frauke Ecke  Nina E. Eide  Erik Framstad  Jay Frandsen  Alastair Franke  Olivier Gilg  Marie-Andr&#;e Giroux  Heikki Henttonen  Birger H&#;rnfeldt  Rolf A. Ims  Gennadiy D. Kataev  Sergey P. Kharitonov  Siw T. Killengreen  Charles J. Krebs  Richard B. Lanctot  Nicolas Lecomte  Irina E. Menyushina  Douglas W. Morris  Guy Morrisson  Lauri Oksanen  Tarja Oksanen  Johan Olofsson  Ivan G. Pokrovsky  Igor Yu. Popov  Donald Reid  James D. Roth  Sarah T. Saalfeld  Gustaf Samelius  Benoit Sittler  Sergey M. Sleptsov  Paul A. Smith  Aleksandr A. Sokolov  Natalya A. Sokolova  Mikhail Y. Soloviev  Diana V. Solovyeva 《Ambio》2020,49(3):786-800
Lemmings are a key component of tundra food webs and changes in their dynamics can affect the whole ecosystem. We present a comprehensive overview of lemming monitoring and research activities, and assess recent trends in lemming abundance across the circumpolar Arctic. Since 2000, lemmings have been monitored at 49 sites of which 38 are still active. The sites were not evenly distributed with notably Russia and high Arctic Canada underrepresented. Abundance was monitored at all sites, but methods and levels of precision varied greatly. Other important attributes such as health, genetic diversity and potential drivers of population change, were often not monitored. There was no evidence that lemming populations were decreasing in general, although a negative trend was detected for low arctic populations sympatric with voles. To keep the pace of arctic change, we recommend maintaining long-term programmes while harmonizing methods, improving spatial coverage and integrating an ecosystem perspective.  相似文献   
999.
Subalpine meadows in the Dongling Mountains (located at E115o26′-115o40′, N40o00′-40o05′) of Beijing, China are important for tourism and the provision of ecosystem services. However, because of poor management serious degradation has occurred on these subalpine meadows. The aim of this paper is to present a quantitative analysis of effects of tourism disturbance and topography on the status and diversity of montane meadow communities and to provide direction for improved management. Sixty quadrats of 2 × 2 m2 along 10 transects were set up to collect data on site characteristics and vegetation status. The relationships between community composition and structure, species diversity, and tourism disturbance and topographic variables were analyzed by multivariate methods (TWINSPAN and CCA). The results showed that eight meadow communities were identified by TWINSPAN. Most of them were seriously degraded. The first CCA axis identified an elevation and tourism disturbance intensity gradient, which illustrated that tourism disturbance and elevation were most important factors influencing meadow types, composition and structure. Some resistant species and response species to tourism disturbance were identified and can be used as indicator species of tourism disturbance. Species richness, heterogeneity and evenness were closely related to tourism disturbance and elevation. It is concluded that tourism disturbance must be controlled to enable grassland rehabilitation to occur in the meadows. Measures of effective management of the meadows were discussed.  相似文献   
1000.
The history of the establishment and management philosophies of the mainland Portuguese Protected Areas was reconstructed through the use of written records and oral history interviews. The objectives were to review the main philosophies in the creation and management of these areas, to assess the influence of international PA models, to compare the Portuguese case with other European and international literature concerning PAs and to discuss the value of the oral history in this research. As main results, it was found that the initial management model of “Wilderness (or Yellowstone)” was replaced by the “new paradigm” of PAs when the democracy was re-established. Changes in the management philosophies within this “new paradigm” were also identified, which resulted in the transition of a “Landscape” to a “Nature conservation” model. After the establishment of the Natura 2000 network, the “Biodiversity conservation” model prevailed. It was also found that the initiative for the establishment of most PAs came from the government, although there were few cases of creation due to the action of NGOs and municipalities. Finally, oral history interviews enabled the addition of information to the literature review, but also provided more insight and detail to this history.  相似文献   
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