全文获取类型
收费全文 | 1597篇 |
免费 | 25篇 |
国内免费 | 24篇 |
专业分类
安全科学 | 69篇 |
废物处理 | 19篇 |
环保管理 | 496篇 |
综合类 | 614篇 |
基础理论 | 100篇 |
污染及防治 | 111篇 |
评价与监测 | 63篇 |
社会与环境 | 133篇 |
灾害及防治 | 41篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 8篇 |
2021年 | 27篇 |
2020年 | 31篇 |
2019年 | 18篇 |
2018年 | 21篇 |
2017年 | 35篇 |
2016年 | 37篇 |
2015年 | 29篇 |
2014年 | 51篇 |
2013年 | 93篇 |
2012年 | 41篇 |
2011年 | 89篇 |
2010年 | 43篇 |
2009年 | 97篇 |
2008年 | 113篇 |
2007年 | 88篇 |
2006年 | 75篇 |
2005年 | 58篇 |
2004年 | 61篇 |
2003年 | 80篇 |
2002年 | 65篇 |
2001年 | 63篇 |
2000年 | 85篇 |
1999年 | 68篇 |
1998年 | 64篇 |
1997年 | 42篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 17篇 |
1993年 | 19篇 |
1992年 | 17篇 |
1991年 | 11篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1974年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有1646条查询结果,搜索用时 125 毫秒
251.
While factors influencing perceptions of drinking water have been well studied, those of aquatic ecosystems have been to lesser extent. We conducted a review to improve awareness of these factors. Environmental factors found to influence public perceptions of aquatic ecosystems were presence/absence of water plants and algae, presence/absence of floating debris, the odor, movement (for flowing waters) and clarity/turbidity of the water, and the type, condition, setting, naturalness, and overall aesthetic appeal of the ecosystem. Sociocultural factors found to influence public perceptions of aquatic ecosystems included age, education, gender, and place-based knowledge. We provide perspectives of how managers can better meet the diverse social demands placed on aquatic ecosystems. The importance and benefits of considering these perspectives may be especially beneficial where significant multi-generational and culturally relevant place-based knowledge exist. 相似文献
252.
Reductions in global bee populations are threatening the pollination benefits to both the planet and people. Whilst the contribution of bee pollination in promoting sustainable development goals through food security and biodiversity is widely acknowledged, a range of other benefits provided by bees has yet to be fully recognised. We explore the contributions of bees towards achieving the United Nation’s Sustainable Development Goals (SDGs). Our insights suggest that bees potentially contribute towards 15 of the 17 SDGs and a minimum of 30 SDG targets. We identify common themes in which bees play an essential role, and suggest that improved understanding of bee contributions to sustainable development is crucial for ensuring viable bee systems. 相似文献
253.
Péter Batáry Lynn V. Dicks David Kleijn William J. Sutherland 《Conservation biology》2015,29(4):1006-1016
Over half of the European landscape is under agricultural management and has been for millennia. Many species and ecosystems of conservation concern in Europe depend on agricultural management and are showing ongoing declines. Agri‐environment schemes (AES) are designed partly to address this. They are a major source of nature conservation funding within the European Union (EU) and the highest conservation expenditure in Europe. We reviewed the structure of current AES across Europe. Since a 2003 review questioned the overall effectiveness of AES for biodiversity, there has been a plethora of case studies and meta‐analyses examining their effectiveness. Most syntheses demonstrate general increases in farmland biodiversity in response to AES, with the size of the effect depending on the structure and management of the surrounding landscape. This is important in the light of successive EU enlargement and ongoing reforms of AES. We examined the change in effect size over time by merging the data sets of 3 recent meta‐analyses and found that schemes implemented after revision of the EU's agri‐environmental programs in 2007 were not more effective than schemes implemented before revision. Furthermore, schemes aimed at areas out of production (such as field margins and hedgerows) are more effective at enhancing species richness than those aimed at productive areas (such as arable crops or grasslands). Outstanding research questions include whether AES enhance ecosystem services, whether they are more effective in agriculturally marginal areas than in intensively farmed areas, whether they are more or less cost‐effective for farmland biodiversity than protected areas, and how much their effectiveness is influenced by farmer training and advice? The general lesson from the European experience is that AES can be effective for conserving wildlife on farmland, but they are expensive and need to be carefully designed and targeted. 相似文献
254.
Selim Baradan Ozge Akboga Kale 《International journal of occupational safety and ergonomics》2019,25(1):40-50
The International Labour Organization (ILO) reports that the risk of fatal occupational injuries in developing countries is almost twice as high as in developed countries, indicating a potential relationship between the fatality rates and the development level. The human development index (HDI), based on life expectancy, knowledge level and purchasing power parity, endorsed by the United Nations Development Programme, is a widely accepted measure of the development level. This study investigates the relationship between the HDI and the fatality rates reported by the ILO. A 23-country data set is used to demonstrate the general trend of the relationship followed by country-specific analyses for Australia, Spain, Hungary and Turkey. The study conducted is limited to fatal occupational injuries in construction, where the accidents are notoriously high. The results demonstrate a statistically significant inverse relationship between the fatality rates and the HDI. 相似文献
255.
Structural change and sustainable development 总被引:3,自引:0,他引:3
Ramn E. Lpez Gustavo Anríquez Sumeet Gulati 《Journal of Environmental Economics and Management》2007,53(3):307-322
In this paper, we show that the commonly observed decline in primary (natural resource using) sector output and employment shares, often termed structural change, can be explained as an endogenous response to the presence of nature's constraint. Structural change takes place even if consumer preferences are homothetic, and technological progress does not discriminate against the primary sector. Under certain conditions, structural change allows an open economy to grow with natural resource sustainability. Sustained and environmentally sustainable economic growth is possible even if the natural resource is exploited under open access. Well-defined property rights are neither necessary, nor sufficient for sustainable growth. We show that there is no unique relationship between natural resource endowment and the rate of economic growth over the long run. Resource-rich economies may grow faster or slower than resource-poor ones. 相似文献
256.
Irena Rot-Nikcevic Christopher N. Taylor Richard J. Wassersug 《Behavioral ecology and sociobiology》2006,60(1):116-25
Tadpoles can alter their behavior, morphology, and life history in response to habitat change. Although chemical signals from
conspecifics or predators play an important role in tadpole habitat assessment, little is known about the role of visual cues
and the extent to which tadpoles rely on their vision for intraspecific social assessment. The aim of our experiments was
to determine whether larval anurans use visual images of other tadpoles as indicators of density and to analyze how, and to
what extent, images of conspecifics alone affect tadpole development, growth, and behavior. To assess this, we raised both
Rana sylvatica and Bufo americanus tadpoles in aquaria with either quarter- or half-mirrored walls. Both physically increased density and increased density
simulated with mirrors decreased tadpole growth and developmental rates, and increased activity in Rana tadpoles. Bufo tadpoles did not significantly alter their growth and development in response to visually increased density. Only true, i.e.,
physically, increased density had an effect on growth and activity in Bufo tadpoles. Our data show that images of conspecifics are used as visual cues by Rana tadpoles and can induce phenotypically plastic changes in several traits. This response to visual cues is taxon-specific.
An erratum to this article can be found at 相似文献
257.
We studied sampling behaviour and mate choice in the fiddler crab Uca mjoebergi. Once a female selects a mate, she copulates in his burrow and remains there until releasing her aquatic larvae. U. mjoebergi occurs in habitats that are inundated only by the highest amplitude spring tides. Females can only release their larvae during
these tides, and release before or after will result in complete failure of reproductive effort. Matings occur over a 5-day
period near the end of neap tides. Our results suggest that within the mating period, females adjust their larval developmental
rates by selecting specific burrows in which to incubate their clutches. We found that at the start of the mating period,
females chose larger males as mates. Since male size was positively correlated to burrow width, females were selecting wide
burrows and effectively incubating at lower temperatures. This would slow down the developmental rates of larvae. In contrast,
females that mated late in the mating period selectively chose small males. By incubating in narrower, warmer burrows, these
females may increase the developmental rates of larvae. We propose that females are selecting burrows to influence incubation
rate and ensure timely release of their larvae. Female U. mjoebergi appear to adjust their preference for the direct benefits of mate choice to increase their reproductive success. 相似文献
258.
Peggy?Gunkel Estelle?Roth Bernard?FabreEmail author 《Environmental Chemistry Letters》2003,1(1):92-97
Agricultural practices can lead to copper accumulation in soils and at high concentration it can become toxic for plants.
One common toxic effect of copper on plants is a decrease of crop yield. Here, we studied 1) the crop yield of maize grown
on plots of a soil intentionally enriched with copper sulphate and 2) the possible relationship between the copper concentration
in chemical soil fractions and the maize crop yield. Anthropogenic copper is mainly bound to manganese oxides, to iron oxides
and to the organic matter. Maize (Zea maize L.) was grown on outdoor experimental plots. The crop yield was evaluated for three development stages: the 6–10 leaf stage,
the female flowering stage and the maturity stage, 2, 4 and 6 years after the soil copper enrichment. Strong crop yield reductions,
proving a toxic effect of copper on maize growth were noted 2 years after the copper input at the maturity stage and 4 years
after the copper input at the 6–10 leaf stage. Variations in maize crop yield are described with linear multiple regression
equations including the variable copper content in soil, and other variables when needed such as soil pH, soil organic carbon
level and the climatic variables, the precipitation rate and the ambient temperature. The crop yield study at the 6–10 leaf
stage and at the female flowering stage does not provide significant regression equations, while the crop yield study at the
maturity stage does. Request variables for the models are the total copper content or the copper bound to the organic matter
and the meteorological data.
Electronic Publication 相似文献
259.
260.
ABSTRACT Farmland size is a key factor in debates over agricultural land use, food security, agrochemical pollution, and the future of smallholder systems. This paper examines relationships between farmland size, chemical fertilizers and irrigation management, and maize and wheat yield in Mexico. We used agricultural census data to estimate the mean farmland areas and crop yields of 5.5 million farms and nine million agricultural plots in 2,455 Mexican municipalities. We also derived indices of socio-environmental and management factors to examine relationships with yield. Using multiple regression models, we found that although mean farmland area positively relates to maize and wheat yield, the relationships depend critically on the management contexts of chemical fertilizers and irrigation, which vary widely across farm size gradients. Smallholder yield gaps were associated with deficits in irrigation, rather than chemical inputs. Findings highlight the growing need for expanded irrigation access and/or water management assistance for smaller farms. 相似文献