全文获取类型
收费全文 | 1143篇 |
免费 | 92篇 |
国内免费 | 285篇 |
专业分类
安全科学 | 11篇 |
废物处理 | 7篇 |
环保管理 | 99篇 |
综合类 | 758篇 |
基础理论 | 291篇 |
污染及防治 | 147篇 |
评价与监测 | 68篇 |
社会与环境 | 68篇 |
灾害及防治 | 71篇 |
出版年
2024年 | 8篇 |
2023年 | 21篇 |
2022年 | 53篇 |
2021年 | 60篇 |
2020年 | 31篇 |
2019年 | 41篇 |
2018年 | 32篇 |
2017年 | 25篇 |
2016年 | 45篇 |
2015年 | 38篇 |
2014年 | 55篇 |
2013年 | 128篇 |
2012年 | 88篇 |
2011年 | 96篇 |
2010年 | 61篇 |
2009年 | 81篇 |
2008年 | 68篇 |
2007年 | 86篇 |
2006年 | 71篇 |
2005年 | 68篇 |
2004年 | 56篇 |
2003年 | 56篇 |
2002年 | 47篇 |
2001年 | 45篇 |
2000年 | 32篇 |
1999年 | 24篇 |
1998年 | 20篇 |
1997年 | 17篇 |
1996年 | 14篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
排序方式: 共有1520条查询结果,搜索用时 234 毫秒
911.
Zhijun Ma Ying Chen David S. Melville Jun Fan Jianguo Liu Jinwei Dong Kun Tan Xuefei Cheng Richard A. Fuller Xiangming Xiao Bo Li 《Conservation biology》2019,33(5):1066-1075
Nature reserves (NR) are the cornerstone of biodiversity conservation. Over the past 60 years, the rapid expansion of NRs in China, one of the world's megadiverse countries, has played a critical role in slowing biodiversity loss. We examined the changes in the number and area of China's NRs from 1956 to 2014 and analyzed the effect of economic development on the expansion of China's NRs from 2005 to 2014 with linear models. Despite a continuing increase in the number of NRs, the total area of China's NRs decreased by 3% from 2007 to 2014. This loss resulted from downsizing and degazettement of existing NRs and a slowdown in the establishment of new ones. Nature reserves in regions with rapid economic development exhibited a greater decrease in area, suggesting that downsizing and degazettement of NRs are closely related to the intensifying competition between economic growth and conservation. For example, boundary adjustments to national NRs, the most strictly protected NRs, along the coast of China's Yellow Sea, a global biodiversity hotspot with a fast-growing economy, resulted in the loss of one-third of the total area. One of the most important ecosystems in these NRs, tidal wetlands, decreased by 27.8% because of boundary adjustments and by 25.2% because of land reclamation. Our results suggest conservation achievement, in terms of both area and quality, are declining at least in some regions in the Chinese NR estate. Although the designation of protected areas that are primarily managed for sustainable use has increased rapidly in recent years in China, we propose that NRs with biodiversity conservation as their main function should not be replaced or weakened. 相似文献
912.
Interactions with sea turtles have occurred at an alarming rate in swordfish longlining in Hawaii in recent years and various regulations have been put forward to protect sea turtles. In order to understand the cost of reducing sea turtle interactions, methods have been developed to derive the shadow price of sea turtle bycatch based on fisher's welfare loss from a specific regulation. This paper illustrates an alternative method of calculating temporal and trip-specific cost of sea turtle bycatch reduction. The advantages of this method lie in the computation of shadow price without assuming specific regulation implementation and its relatively modest data requirement. A parametric output distance function is used to simultaneously model desirable and undesirable catches. Using the duality argument, the revenue-related shadow price of sea turtle bycatch can be derived from the estimated distance function. Average shadow price of sea turtle bycatch for the period 1991-1999 is estimated to be US $30873 in 1991 dollars. Average shadow prices of sea turtle bycatch by trip characteristics, such as fishing year, trip type and location are also estimated. Such information can be useful for policy makers to analyze tradeoffs and make appropriate policy decisions. 相似文献
913.
Fossi MC Casini S Marsili L 《Environmental science and pollution research international》2006,13(3):204-207
- DOI: http://dx.doi.org/10.1065/espr2006.01.018
Background, Aims and Scope
Man-made Endocrine Disruptors (EDs) range across all continents and oceans. Some geographic areas are potentially more threatened
than others: one of these is the Mediterranean Sea. Levels of some xenobiotics are much higher here than in other seas and
oceans. In this paper we review the final results of a project in which the hypothesis that Mediterranean top predator species
(such as large pelagic fish and marine mammals) are potentially at risk due to EDs was investigated.
Methods In a four-year survey on the Mediterranean population of swordfish (Xiphias gladius), the potential toxicological effects
of organochlorine compounds (OCs) on specimens of swordfish and tuna fish (Thunnus thynnus thynnus), caught in the spawning
seasons from 1999 to 2002 in the Straits of Messina, Sicily (Italy), were investigated using vitellogenin (Vtg), Zona radiata
proteins (Zrp), and cytochrome P4501A (CYP1A) activities (EROD, BPMO). Tissues (skin and blubber) were obtained from Stenella
coeruleoalba, Tursiops truncatus, Delphinus delphis and Balaenoptera physalus from the western Ligurian Sea, between Corsica
and the French-Italian coast, and Ionic Sea using biopsy darts launched with a crossbow. Benzo(á)pyrene monoxigenase (BPMO)
activity was mesured in biopsies and cholrinated hydrocarbon levels were detected.
Results and Discussion We illustrate the need to develop and apply sensitive methodological tools, such as biomarkers (Vitellogenin, Zona Radiata
proteins and CYP1A activities) for evaluation of toxicological risk in Xiphias gladius and Thunnus thynnus thynnus), and nondestructive
biomarkers (CYP1A activities and fibroblast cell culture in skin biopsy), for the hazard assessment of threatened marine mammals
species (Stenella coeruleoalba, Tursiops truncatus, Delphinus delphis and Balaenoptera physalus) exposed to EDs.
Conclusion The present research shows that: a) Vtg and Zrp can be used as diagnostic tools for fish stocks hazard assessment in the
Mediterranean Sea; b) that CYP1A1 (BPMO) induction in cetaceans skin biopsy may be an early sign of exposure to EDs such as
OCs and a potential alert for transgenerational effects.
Recommendation and Outlook This research represents a warning signal of the potential reproductive alterations in marine top predators and suggest the
need for continuous monitoring to avoid reductions in population and biodiversity in the Mediterranean Sea. 相似文献
914.
915.
916.
917.
Mikołaj Piniewski Ignacy Kardel Marek Giełczewski Paweł Marcinkowski Tomasz Okruszko 《Ambio》2014,43(5):644-660
Currently, there is a major concern about the future of nutrient loads discharged into the Baltic Sea from Polish rivers because they are main contributors to its eutrophication. To date, no watershed-scale studies have properly addressed this issue. This paper fills this gap by using a scenario-modeling framework applied in the Reda watershed, a small (482 km2) agricultural coastal area in northern Poland. We used the SWAT model to quantify the effects of future climate, land cover, and management changes under multiple scenarios up to the 2050s. The combined effect of climate and land use change on N-NO3 and P-PO4 loads is an increase by 20–60 and 24–31 %, respectively, depending on the intensity of future agricultural usage. Using a scenario that assumes a major shift toward a more intensive agriculture following the Danish model would bring significantly higher crop yields but cause a great deterioration of water quality. Using vegetative cover in winter and spring (VC) would be a very efficient way to reduce future P-PO4 loads so that they are lower than levels observed at present. However, even the best combination of measures (VC, buffer zones, reduced fertilization, and constructed wetlands) would not help to remediate heavily increased N-NO3 loads due to climate change and agricultural intensification. 相似文献
918.
Ulrike Löptien 《Ecological modelling》2011,222(8):1376-1386
Pelagic, coupled ocean circulation-ecosystem models, are widely used in climate research. These tools aim to quantify fluxes of nutrients and carbon in the ocean and are, increasingly, the base of future projections. For this purpose it is crucial to quantify and identify the sources of uncertainties. In contrast to physical models, the underlying equations for ecosystem models are derived from empirical relationships rather than based on first principles. This resulted in the development of a multitude of different ecosystem models - different in respect to both, underlying principles and complexity. Clearly, the question arises, to what extent the sensitivities of these models are comparable.This study focuses on the intrinsic dynamics of some widely used, simple (containing 2-3 prognostic variables) ecosystem models in a 0-D framework (i.e., comprising only the well-mixed oceanic surface layer). A suite of differing model approaches is tuned such that their behavior is similar. The setup resembles the well-mixed oceanic surface layer in the Baltic proper. It is illustrated that strong differences between the model approaches appear due to exemplary, anticipated changes in the external nutrient and light conditions. Herewith, we demonstrate the well-known, but rarely demonstrated fact that, apparent consistency between modeled prognostic variables with today's data bases is not necessarily a good measure of forecast skill. The causes which lead to the different sensitivities are illustrated by considering the steady state solutions. It is pointed out, that apparently small changes in the model formulations can result in very different dynamical behavior and an enormous spread between the model approaches, despite the feasibility to tune a common behavior in a limited range of light and nutrient supply. In our examples, the sensitivity is mainly a function of the formulation of the loss rate of phytoplankton. It is thus, in particular, the formulation of highly unknown heteorotrophic processes that determines the model sensitivity. 相似文献
919.
Maria J. Espinosa-Romero Edward J. GregrCarl Walters Villy ChristensenKai M.A. Chan 《Ecological modelling》2011,222(9):1569-1579
Ecosystem models play an important role in supporting ecosystem approaches to management. To improve the representation of how ecosystems work, ecosystem models should be able to represent mediating effects (e.g., habitat provision) that species provide to each other as well as species (re)introductions, both common situations that can strongly influence ecosystem dynamics. We examine how such processes can be incorporated into Ecopath with Ecosim (EwE), a widely used tool for represent aquatic ecosystems with the potential to support ecosystem-based management. We used the reintroduction of sea otters (Enhydralutris) to the west coast of Vancouver Island, British Columbia, Canada as a case study. The model demonstrates how to account for benefits provided by kelp forests by contributing to primary production, increased feeding areas and food availability through prey retention. It also demonstrates how the reintroduction and range expansion of sea otters can be represented in Ecospace, and the implications of these options. 相似文献
920.
Alexander G. Murray 《Ecological modelling》2011,222(11):1854-1862
Sea lice are damaging marine copepod parasites that infest wild and farmed salmon. Lice are controlled largely by the application of medicines; however resistance has evolved to several such treatments. A simple model is used to explore situations under which treatment-resistant lice are likely to emerge. The model consists of farmed and wild populations of hosts that are infected with lice that exist in treatment-sensitive and treatment-resistant morphs. Resistance is assumed to impose costs on lice fitness, so the sensitive morphs have a selective advantage in the absence of treatment. Larval lice are exchanged between treated farmed hosts and untreated wild hosts by variable water currents. The model finds that resistance is most strongly selected under moderate levels of treatment on farms. High levels of treatment remove both sensitive and resistant lice from farms and, leave the wild untreated fish as a source of lice. The treatment per fish required to eradicate the resistant morphs increases as hydrodynamic mixing rates increase and so controlling emergence of resistance becomes less cost effective when mixing rates are high. 相似文献