全文获取类型
收费全文 | 1925篇 |
免费 | 177篇 |
国内免费 | 129篇 |
专业分类
安全科学 | 122篇 |
废物处理 | 13篇 |
环保管理 | 582篇 |
综合类 | 572篇 |
基础理论 | 309篇 |
环境理论 | 58篇 |
污染及防治 | 26篇 |
评价与监测 | 100篇 |
社会与环境 | 318篇 |
灾害及防治 | 131篇 |
出版年
2024年 | 3篇 |
2023年 | 60篇 |
2022年 | 43篇 |
2021年 | 55篇 |
2020年 | 74篇 |
2019年 | 116篇 |
2018年 | 114篇 |
2017年 | 122篇 |
2016年 | 114篇 |
2015年 | 129篇 |
2014年 | 69篇 |
2013年 | 202篇 |
2012年 | 120篇 |
2011年 | 124篇 |
2010年 | 95篇 |
2009年 | 77篇 |
2008年 | 68篇 |
2007年 | 70篇 |
2006年 | 75篇 |
2005年 | 55篇 |
2004年 | 65篇 |
2003年 | 49篇 |
2002年 | 49篇 |
2001年 | 39篇 |
2000年 | 63篇 |
1999年 | 58篇 |
1998年 | 18篇 |
1997年 | 24篇 |
1996年 | 11篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 20篇 |
1992年 | 4篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有2231条查询结果,搜索用时 78 毫秒
61.
1961-2012 年西藏极端降水事件的变化 总被引:2,自引:0,他引:2
利用18 个气象站点1961-2012 年逐日降水量资料,计算了10 个极端降水指数,采用滑动平均、线性回归、Mann-Kendall 非参数检验和Morlet 小波分析等方法,分析了西藏极端降水事件的变化规律。结果表明:西藏近52 a 连续干旱日数(CDD)呈显著减少趋势,最大5 d 降水量也趋于减少但不显著,大雨日数和强降水量的线性趋势不明显,其他6 个极端降水指数都表现为增加趋势且不显著。与全球、青藏高原及其周边地区比较,西藏CDD和连续湿日的变幅明显偏大,最大1 日降水量、强降水量和极强降水量的变幅明显偏小。除CDD外,极端降水指数的变化趋势与海拔高度呈显著的二次曲线关系,仅有中雨日数的变化趋势与经度呈显著的正相关。在近52 a 的时间尺度上各项极端降水指数都存在3~4 a 显著周期,多数指数也存在12a、15 a 和16 a 的周期。在时间转折上,CDD的突变点时间较早,从1974 年开始;中雨日数、连续湿日和年总降水量的突变点发生在20 世纪80 年代末。从空间分布来看,那曲地区西部是极端降水指数变化最为显著的区域,雅鲁藏布江中游大部的多数极端降水指标趋于下降,而山南地区南部、林芝地区东南部的降水极值和降水强度都在增加。 相似文献
62.
3种生物滞留设计对城市地表径流溶解性氮的去除作用 总被引:4,自引:2,他引:2
城市地表径流溶解性氮(N)的有效控制具有挑战性.2015构建了3种不同设计的生物滞留设施:壤砂种植紫穗狼尾草(CB)、壤砂种植紫穗狼尾草设置饱和带(MB1)、壤砂种植紫穗狼尾草设置饱和带并添加10%木块(MB2).在模拟城市地表径流水文、水质变化条件下,研究3种生物滞留种植植物、设置饱和带以及添加碳源对城市地表径流溶解性N(NH_4~+-N、NO_3~--N)的去除作用.通过为期1年试验监测表明,在进水NH_4~+-N浓度平均值为(5.45±2.21)mg·L-1情况下,3种生物滞留对NH_4~+-N均具有显著的去除作用(去除率95%).基质吸附、硝化与植物吸收是生物滞留有效去除城市地表径流NH_4~+-N的主要途径.在进水NO_3~--N平均值为(5.88±2.32)mg·L-1情况下,CB、MB1和MB2出水NO_3~--N浓度的平均值分别为(4.04±2.64)、(0.84±1.18)和(0.26±0.48)mg·L-1,相应去除率分别为31.3%、85.7%和95.6%.生物滞留种植紫穗狼尾草、设置饱和带以及添加碳源均可显著降低出水NO_3~--N浓度,减少NO_3~--N淋溶输出,提高NO_3~--N去除率.植物吸收和微生物反硝化是生物滞留去除NO_3~--N的主要途径.进水NO_3~--N浓度、水量、间隔天数是影响生物滞留出水NO_3~--N浓度的主要因素.生物滞留种植紫穗狼尾草、设置饱和带并添加碳源,在水文、水质变化情况下,仍可有效去除城市地表径流溶解性N. 相似文献
63.
Newton M Cole EC Tinsley IJ 《Environmental science and pollution research international》2008,15(7):573-583
Background, aim, and scope Large-scale deforestation is occurring in subarctic North America following clearing by salvage logging or insect attack.
Numerous shrubs, herbs, and deciduous tree species tend to dominate areas on which stands of white spruce have grown. In the
absence of economically advantageous mechanical methods, several herbicides have value in efforts to reforest by planting
white spruce. Glyphosate, imazapyr, triclopyr, and hexazinone are all capable of selectively removing many competing species,
but there is concern about whether they would degrade naturally or persist owing to the frigid climate.
Materials and methods We established test plots with all four herbicides in upland and river bottom sites at 65°N and 58°N latitudes. The northern
site has extremely cold winters, with soils that freeze to a depth of 1–2 m, and precipitation of 275 mm/year. The southern
site has heavy rain and snowfall, amounting to 2,250 mm/year evenly distributed. Soil seldom freezes deeply. On each test
plot, one of the four herbicides was applied at twice the normal operational use rate to facilitate detection. They were applied
at the normal timing, with hexazinone, imazapyr, and triclopyr applied in June and glyphosate applied in fall. Soils were
sampled immediately after treatment and those samples used as references for dissipation data gathered over the next 11–14 months
from soil 0- to 15- and 15- to 45-cm depths.
Results Dissipation rates did not follow first-order rates because freezing conditions slowed most microbial activity. All products
dissipated to close to or below detection limits within the time of the study. Dissipation from vegetation was substantially
more rapid and depended on the nature of the plants treated as well as the product used. While soil residues dissipated more
slowly than in temperate regions, they did display consistent dissipation patterns during above-freezing conditions and also
the influence of microbial activity. Mobility was very limited with all products but hexazinone.
Discussion These products dissipate during summer in high latitudes much as they would in temperate climates. Winter changes are small,
but are not unlike some changes reported elsewhere under freezing conditions. Unlike many other studies, soil water did not
influence dissipation heavily, but the high latitude and semi-arid climate also did not create severely droughty soils. Residues
in plants were much higher than those in soils, but denatured the vegetation quickly, leading to unsuitability for forage
in any case.
Conclusions Low toxicity of these products and their metabolites combined with consistent dissipation and low mobility suggest that toxic
hazard of their use at high latitudes need not be a matter of serious concern to humans, terrestrial wildlife, or aquatic
systems. They are safe for use in management and rehabilitation of boreal forests when used properly.
Recommendations and perspectives Dissipation at rates approaching those in warmer climates offer a hypothesis that microflora native to high latitudes may
be adapted to destruction of such molecules at lower temperatures than may be indicated by experiments with microflora adapted
to warmer climates. Residues pose no observable risk to wildlife or humans in the area of use when products are applied properly.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available for authorized users. 相似文献
64.
65.
影响上海地区热带气旋频数的预测水平评估 总被引:2,自引:0,他引:2
在文献「1」研究的基础上,探讨了热带气旋频数预测水平的评估方法,定义了三个更适合于评估每年热带气旋预测性能的参数,对影响上海地区热带气旋频数的预测水平进行了评估,并与“九五”攻关前的业务预测性进行了比较。 相似文献
66.
Graham Dixon Olivia Bullock Dinah Adams 《Environmental Communication: A Journal of Nature and Culture》2019,13(2):135-143
In 2017, the United States experienced a series of natural hazards (hurricanes, wildfires, and blizzards) that resulted in significant loss of life and property. Emphasizing the role of climate change in these events might offer an important tool for engagement, particularly with skeptical audiences. However, in a survey experiment (N?=?1504) involving three different natural hazards – hurricanes, wildfires, and blizzards – we find that emphasizing the role of climate change in these hazards produced unintended effects for climate change skeptics. In particular, skeptics experienced resistance to the news article, which associated with reduced perceived hazard severity. These backfiring effects likely serve as a defensive mechanism used by skeptics to maintain their prior views of climate change, illustrating the challenges faced in communicating climate change to skeptical audiences. These findings offer additional insight for those attempting to communicate climate-related risk information to skeptical audiences. 相似文献
67.
Samantha Stea 《Environmental Communication: A Journal of Nature and Culture》2019,13(5):633-648
Red meat production has a range of negative environmental impacts. We sought to characterize the motivations, environmental attitudes and demographics of red meat-eaters, and examine the effect of message framing in reducing future meat consumption. Canadian adult meat-eaters (593) completed a survey and were randomly assigned to one of six message treatments that presented information on the environmental impacts of meat production using frames representing social norms and/or place identity constructs. Taste and quality were the most important motivators for eating meat, while moral/ethical factors were the least. Forty-nine percent of respondents indicated they would reduce red meat intake after exposure to an information only message, while the social norms frame was more effective than others (χ2). Awareness of the environmental effects increased significantly after messaging for all 13 impacts. These findings should assist communicators with designing more effective messaging aimed at encouraging pro-environmental behaviours associated with meat consumption. 相似文献
68.
Vera Ferreira André Samora-Arvela 《Journal of Environmental Planning and Management》2016,59(7):1238-1256
Climate and land-use/cover changes (LUCC) influence soil erosion vulnerability in the semi-arid region of Alqueva, threatening the reservoir storage capacity and sustainability of the landscape. Considering the effect of these changes in the future, the purpose of this study was to investigate soil erosion scenarios using the Revised Universal Soil Loss Equation (RUSLE) model. A multi-agent system combining Markov cellular automata with multi-criteria evaluation was used to investigate LUCC scenarios according to delineated regional strategies. Forecasting scenarios indicated that the intensive agricultural area as well as the sparse and xerophytic vegetation and rainfall-runoff erosivity would increase, consequently causing the soil erosion to rise from 1.78 Mg ha?1 to 3.65 Mg ha?1 by 2100. A backcasting scenario was investigated by considering the application of soil conservation practices that would decrease the soil erosion considerably to an average of 2.27 Mg ha?1. A decision support system can assist stakeholders in defining restrictive practices and developing conservation plans, contributing to control the reservoir's siltation. 相似文献
69.
John Rice 《Journal of Environmental Planning and Management》2016,59(1):44-61
Recent climate change projections and a push towards a universal agreement on carbon emission reductions suggest that firms will need to respond to future regulatory changes. This paper employs an influencing strategies lens to examine how large-scale firms might respond to future climate change regulations. The study uses a structured qualitative methodology to explore and explicate the strategic responses from 21 international firms to the proposed emissions trading scheme outlined in Australia's Garnaut Climate Change Review. The results of the analysis show that firms can use pre-emptive influencing strategies in attempts to shape and mould regulatory design parameters, secure high levels of transitional economic support, and shift the balance of public policies and expenditure. Complementary defensive strategies may also target policy makers and regulators with some of the potential negative consequences of the new regulations. 相似文献
70.
How do choices among information sources reinforce political differences on topics such as climate change? Environmental sociologists have observed large-scale and long-term impacts from news media and think-tank reports, while experimental science-communication studies detect more immediate effects from variations in supplied information. Applying generalized structural equation modeling to recent survey data, previous work is extended to show that political ideology, education and their interaction predict news media information choices in much the same way they predict opinions about climate change itself. Consequently, media information sources serve as intervening variables that can reinforce and, through their own independent effects, amplify existing beliefs about climate change. Results provide empirical support for selective exposure and biased assimilation as mechanisms widening political divisions on climate change in the United States. The findings fit with the reinforcing spirals framework suggesting partisan media strengthens climate change beliefs which then influences subsequent use of media. 相似文献