全文获取类型
收费全文 | 4056篇 |
免费 | 69篇 |
国内免费 | 41篇 |
专业分类
安全科学 | 187篇 |
废物处理 | 155篇 |
环保管理 | 706篇 |
综合类 | 688篇 |
基础理论 | 932篇 |
环境理论 | 3篇 |
污染及防治 | 1020篇 |
评价与监测 | 240篇 |
社会与环境 | 189篇 |
灾害及防治 | 46篇 |
出版年
2023年 | 33篇 |
2022年 | 41篇 |
2021年 | 51篇 |
2020年 | 50篇 |
2019年 | 50篇 |
2018年 | 98篇 |
2017年 | 118篇 |
2016年 | 133篇 |
2015年 | 136篇 |
2014年 | 142篇 |
2013年 | 226篇 |
2012年 | 175篇 |
2011年 | 296篇 |
2010年 | 221篇 |
2009年 | 228篇 |
2008年 | 235篇 |
2007年 | 243篇 |
2006年 | 209篇 |
2005年 | 137篇 |
2004年 | 164篇 |
2003年 | 133篇 |
2002年 | 134篇 |
2001年 | 113篇 |
2000年 | 68篇 |
1999年 | 48篇 |
1998年 | 49篇 |
1997年 | 43篇 |
1996年 | 48篇 |
1995年 | 50篇 |
1994年 | 45篇 |
1993年 | 25篇 |
1992年 | 36篇 |
1991年 | 36篇 |
1990年 | 25篇 |
1989年 | 24篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 12篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1982年 | 23篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1970年 | 11篇 |
1969年 | 7篇 |
1967年 | 7篇 |
1965年 | 9篇 |
1960年 | 6篇 |
排序方式: 共有4166条查询结果,搜索用时 797 毫秒
751.
The engagement of UK local authorities is vital if national government is to meet its climate change commitments. However, with no mandatory targets at local government level, other drivers must explain engagement. Using a Geographic Information System, this study compares the spatial distribution of action on climate change based on past actions and stated intentions to a suite of relevant independent variables. The Action Index created is among the first to quantify climate change engagement beyond a simple binary measure and provides a useful comparative study to recent work in the USA. The Index enables investigation of both mitigation and adaptation, which show different trends in relation to some variables. The study shows that action is strongest where the voting habits of the local population suggest environmental concern and where neighbouring local authorities are also engaging in action on climate change. Physical vulnerability to the effects of climate change is a motivator for action only where the dangers are obvious. Action is less likely where other resource-intensive issues such as crime and housing exist within a local authority area. 相似文献
752.
Jeroen van der Heijden Ernst ten Heuvelhof Bertien Broekhans Sonja van der Arend Ellen van Bueren Casper Harteveld 《Local Environment》2013,18(3):318-333
The European Union Water Framework Directive (WFD) has provided the European Member States with a range of interacting governance challenges. This article studies three of these (the need for new administrative arrangements, public participation, and the enforced strict time frame). It questions how these interacting governance challenges were addressed in implementing the WFD in the Netherlands – a particularly interesting country since the European Commission assesses its implementation process in relatively positive terms, while an in-depth study reported on in this article tells a contrasting story. Based on this study, the article concludes that especially the interaction effects between the governance challenges may help us to better understand the outcome of the WFD-implementation process, and to provide more suitable advice as to how to improve the implementation process in future rounds. 相似文献
753.
Janneke de Jonge Hans C. M. van Trijp 《Journal of Agricultural and Environmental Ethics》2013,26(3):629-661
The legitimacy of the dominant intensive meat production system with respect to the issue of animal welfare is increasingly being questioned by stakeholders across the meat supply chain. The current meat supply is highly undifferentiated, catering only for the extremes of morality concerns (i.e., conventional vs. organic meat products). However, a latent need for compromise products has been identified. That is, consumer differences exist regarding the trade-offs they make between different aspects associated with meat consumption. The heterogeneity in consumer demand could function as a starting point for market segmentation, targeting and positioning regarding animal welfare concepts that are differentiated in terms of animal welfare and price levels. Despite this, stakeholders in the meat supply chain seem to be trapped in the dominant business model focused on low cost prices. This paper aims to identify conflicting interests that stakeholders in the meat supply chain experience in order to increase understanding of why heterogeneous consumer preferences are not met by a more differentiated supply of meat products produced at different levels of animal welfare standards. In addition, characteristics of the supply chain that contribute to the existence of high exit barriers and difficulty to shift to more animal-friendly production systems are identified. Following the analysis of conflicting interests among stakeholders and factors that contribute to difficulty to transform the existing dominant regime, different routes are discussed that may help and motivate stakeholders to overcome these barriers and stimulate the creation of new markets. 相似文献
754.
755.
The REAcct (for Regional Economic Accounting) tool was developed for estimating order-of-magnitude economic impacts within DHS scenario analysis. REAcct uses input–output modeling, geo-spatial data computational tools, and publically available economic data and allows for detailed specification of sectors, regions, and disruption intervals. Direct impacts are estimated as changes in output and employment; total (direct plus indirect) impacts are calculated using regional total and final demand multipliers. In total, the REAcct framework and software allow for scenario analysts to understand and assess the interdependent relationships between critical infrastructures, economic industries, and consumers that are essential to broader homeland security scenario analysis. 相似文献
756.
Globally, invasions by alien plants are rapidly increasing in extent and severity, leading to large-scale ecosystem degradation. Weed biological control offers opportunities to arrest or even reverse these trends and, although it is not always effective or appropriate as a management strategy, this practice has an excellent record of safety and many notable successes over two centuries. In recent years, growing concerns about the potential for unintended, non-target damage by biological control agents, and fears about other unpredictable effects on ecosystems, have created an increasingly demanding risk-averse regulatory environment. This development may be counter-productive because it tends to overemphasize potential problems and ignores or underestimates the benefits of weed biological control; it offers no viable alternatives; and it overlooks the inherent risks of a decision not to use biological control. The restoration of badly degraded ecosystems to a former pristine condition is not a realistic objective, but the protection of un-invaded or partial restoration of invaded ecosystems can be achieved safely, at low cost and sustainably through the informed and responsible application of biological control. This practice should therefore be given due consideration when management of invasive alien plants is being planned. This discussion paper provides a perspective on the risks and benefits of classical weed biological control, and it is aimed at assisting environmental managers in their deliberations on whether or not to use this strategy in preference, or as a supplement to other alien invasive plant control practices. 相似文献
757.
A.M. Fermont P.J.A. van Asten K.E. Giller 《Agriculture, ecosystems & environment》2008,128(4):239-250
Increasing land pressure during the past three to four decades has transformed farming systems in the mid-altitude zone of East Africa. Traditional millet-, cotton-, sugarcane- and/or banana-based farming systems with an important fallow and/or grazing component have evolved into continuously cultivated cassava or cassava/maize-based systems. Within three to four decades, cassava cultivation increased from 1–11 to 16–55% of cropped fields in our six study sites. Declining soil fertility, and not labour or food shortage, was apparently the primary trigger for this transformation. The land use changes have increased nutrient offtakes and reduced nutrient recycling rates. Cassava and maize now account for 50–90% of nutrient removal. Whereas single-season fallows were the most important source of nutrient recycling on cropped fields in the past, currently cassava litterfall and maize stover contribute roughly 70% of nutrient recycling, with 50–70% of N, P and K recycled in cassava litterfall. This may explain why many farmers reason that cassava ‘rests’ the soil. With increasing land use pressure farmers progressively use cassava as an ‘imitation fallow’ throughout their farm. Farmers increasingly target cassava to poor fertility fields characterized by low pH and available P. High cassava intensities are nonetheless maintained on more fertile fields, probably to guarantee regeneration of soil fertility on all fields. Once cassava is targeted to poor fertility soils, farmers have run out of low-input management options and need to intensify management to maintain system productivity. As cassava is now used by more farmers and on a larger acreage than fallowing in the studied farming systems, cassava cropping could perhaps serve as an excellent entry point to strengthen system sustainability. 相似文献
758.
Qiu H Huang J Keyzer M van Veen W Rozelle S Fisher G Ermolieva T 《Journal of environmental quality》2011,40(4):1058-1067
With concerns of energy shortages, China, like the United States, European Union, and other countries, is promoting the development of biofuels. However, China also faces high future demand for food and feed, and so its bioenergy program must try to strike a balance between food and fuel. The goals of this paper are to provide an overview of China's current bioethanol program, identify the potential for using marginal lands for feedstock production, and measure the likely impacts of China's bioethanol development on the nation's future food self-sufficiency. Our results indicate that the potential to use marginal land for bioethanol feedstock production is limited. Applying a modeling approach based on highly disaggregated data by region, our analysis shows that the target of 10 million t of bioethanol by 2020 seems to be a prudent target, causing no major disturbances in China's food security. But the expansion of bioethanol may increase environmental pressures due to the higher levels of fertilizer use. This study shows also that if China were able to cultivate 45% of its required bioethanol feedstock on new marginal land, it would further limit negative effects of the bioethanol program on the domestic and international economy, but at the expense of having to apply another 750 thousand t of fertilizer. 相似文献
759.
Water governance has emerged as perhaps the most important topic of the international water community in the 21st century, and achieving “good” water governance is now a focus of both policy discourse and innumerable development projects. Somewhat surprisingly in light of this attention, there is widespread confusion about the meaning of the term “water governance”. This paper reviews the history of the term's use and misuse to reveal how the concept is frequently inflated to include issues that go well beyond governance. Further, it highlights how calls to improve water governance often espouse predetermined goals that should instead be the very function of water governance to define. To help overcome this confusion, the paper suggests a more refined definition of water governance and related qualities of good water governance that are consistent with broader notions of the concepts. In light of the substantial resources allocated in its name, this paper's findings show there is significant potential to strengthen efforts at improving water governance. 相似文献
760.
He J Dougherty M Shaw J Fulton J Arriaga F 《Journal of environmental management》2011,92(10):2479-2485
Rural areas represent approximately 95% of the 14000 km(2) Alabama Black Belt, an area of widespread Vertisols dominated by clayey, smectitic, shrink-swell soils. These soils are unsuitable for conventional onsite wastewater treatment systems (OWTS) which are nevertheless widely used in this region. In order to provide an alternative wastewater dosing system, an experimental field moisture controlled subsurface drip irrigation (SDI) system was designed and installed as a field trial. The experimental system that integrates a seasonal cropping system was evaluated for two years on a 500-m(2) Houston clay site in west central Alabama from August 2006 to June 2008. The SDI system was designed to start hydraulic dosing only when field moisture was below field capacity. Hydraulic dosing rates fluctuated as expected with higher dosing rates during warm seasons with near zero or zero dosing rates during cold seasons. Lower hydraulic dosing in winter creates the need for at least a two-month waste storage structure which is an insurmountable challenge for rural homeowners. An estimated 30% of dosed water percolated below 45-cm depth during the first summer which included a 30-year historic drought. This massive volume of percolation was presumably the result of preferential flow stimulated by dry weather clay soil cracking. Although water percolation is necessary for OWTS, this massive water percolation loss indicated that this experimental system is not able to effective control soil moisture within its monitoring zone as designed. Overall findings of this study indicated that soil moisture controlled SDI wastewater dosing is not suitable as a standalone system in these Vertisols. However, the experimental soil moisture control system functioned as designed, demonstrating that soil moisture controlled SDI wastewater dosing may find application as a supplement to other wastewater disposal methods that can function during cold seasons. 相似文献