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121.
土地利用变化是影响陆地生态系统碳储量变化的重要因素,研究土地利用变化与碳储量之间关系对优化区域土地利用结构,维持区域碳平衡可提供可靠的数据支撑.以江西省为例,分析1990~2020年土地利用变化,基于PLUS模型,结合自然发展情景、生态优先情景和经济发展情景设置,对2030年江西省土地利用格局进行模拟分析,运用InVEST模型测算1990~2020年及未来不同情景下江西省碳储量变化,利用空间自相关分析探索江西省不同情景下陆地生态系统碳储量时空变化特征,并提出相应的政策建议.结果表明:①1990~2020年江西省碳储量整体呈下降趋势,共减少4.58×107 t.其中,水域和建设用地的面积增加,耕地、林地、草地及未利用地面积减少是导致碳储量减少的主要原因.②2030年江西省陆地生态系统碳储量在自然发展情景、生态优先情景和经济发展情景下分别为2.20×109、2.24×109和2.19×109 t.③3种情景下的碳储量值在空间分布上具有相似性,碳储量高值区域在江西省北部、西北部及西部区域出现集聚,低值区域则在中部区域聚集.研究结果可为江西省未来国土空间规划,提升陆地生态系统碳储量提供数据支撑.  相似文献   
122.
根据江西省2013年采集的16582个农田耕层(0~20 cm)土壤样点数据,运用实地调查、经典统计学与地统计学等相结合方法,研究了江西省耕地土壤碳氮磷生态化学计量特征的空间变异性及不同农田利用方式对其的影响.研究结果表明:江西省耕地土壤有机碳(SOC)、全氮(TN)和全磷(TP)平均含量分别为17.90、1.58和0.52 g·kg~(-1),土壤碳氮比(C∶N)、碳磷比(C∶P)和氮磷比(N∶P)平均值分别为11.72、38.29和3.38,土壤C∶N∶P比平均值为34.44∶3.03∶1,说明P是江西省耕地土壤主要的限制因素.此外,由于碳、氮、磷三者之间并不存在显著的两两相关性,表明江西省耕地土壤中不存在稳定的"Redfield ratio";半方差函数表明,江西省土壤碳、氮、磷生态化学计量特征具有中等程度的空间变异性,其空间变异特征主要受到随机性因素的影响;经ANOVA检验显示,不同农田利用方式对土壤碳氮磷生态化学计量特征影响显著(p0.05),土壤SOC和TN平均含量依次表现为:两季水田水旱轮作一季水田一季旱地两季旱地,土壤TP平均含量依次表现为:两季旱地两季水田一季水田一季旱地水旱轮作,土壤C∶N依次表现为:两季水田两季旱地一季水田水旱轮作一季旱地,土壤C∶P平均值依次表现为:水旱轮作两季水田一季水田一季旱地两季旱地,土壤N∶P平均值依次表现为:水旱轮作一季旱地两季水田一季水田两季旱地.总体而言,土壤碳、氮、磷生态化学计量比的变化特征是农田利用方式和环境因子综合作用的结果,土壤C∶N∶P比对土壤碳、氮、磷储量及养分的限制性具有重要的指示作用.  相似文献   
123.
Investigators monitoring air quality at the World Trade Center, after the September 11th attacks, found extremely high levels of volatile organic chemicals as well as unusual species that had never been seen before in structure fires. Data collected by the U.S. Environmental Protection Agency indicate striking spikes in levels of benzene, styrene, and several other products of combustion. These spikes occurred on specific dates in October and November 2001, and February 2002. Additionally, data collected by researchers at the University of California Davis showed similar spikes in the levels of sulfur and silicon compounds, and certain metals, in aerosols. To better explain these data, as well as the unusual detection of 1,3-diphenylpropane, the presence of energetic nanocomposites in the pile at Ground Zero is hypothesized.  相似文献   
124.
Landscape change alters the visual scale of agricultural landscapes, as production units get larger and strips of taller vegetation are removed between smaller units. Visual scale, defined as the perceptual units reflecting the experience of landscape rooms, visibility and openness, is considered a key factor shaping landscape preference. The visual expression of landscapes affects people in many ways; aesthetic appreciation, health and well being. In order to understand how landscape changes alter the visual scale of landscapes, and hence its effect on human beings, it is important to establish efficient and practical ways of measuring visual scale and its relation to landscape preferences. This paper presents an empirical test of the ability to predict landscape preference of two photo-based indicators of visual scale; percentage open land in the view and size of landscape rooms. A preference survey was conducted with two groups of respondents; a student group from the Norwegian University of Life Sciences (UMB) and a public group. The student group was chosen to represent future landscape professionals. Photos of landscapes varying in the expression of visual scale were shown to survey respondents, who were asked to give scores according to how much they liked the landscapes. Both indicators were found to be predictors of preference for the student group, but not for the public group. The results demonstrate that student preferences do not reflect the landscape preferences of the wider public. The different appreciation of visual scale in the landscape of future landscape professionals and the public implies that experts wanting to reflect preferences of the wider public should be cautious when evaluating the visual impact of landscape change.  相似文献   
125.
近40年气候变化对江西自然植被净第一性生产力的影响   总被引:1,自引:0,他引:1  
根据全球气候变化的趋势,采用植被净第一性生产力模型,对江西省南昌、吉安、赣州3地近40年气候变化对自然植被净第一性生产力(NPP)的影响进行研究,并模拟了3地自然植被NPP在未来气候3种水热条件下的变化趋势。此外还以1980年江西全省自然植被NPP为例分析了自然植被NPP的区域分布特征,结果表明:3地近40年自然植被NPP平均值分别为1319 、1311和1320 t/hm2〖DK1〗·a,总体上都呈上升的趋势。 当年均气温增加2℃且降水量增加20%时,NPP值增加了149%~1585%;随着年均气温增加2℃且降水量减少20%,NPP减少了477%~516%;当年均气温增加2℃且降水量不变时,NPP增加了530%~569%。江西自然植被NPP区域分布特征由东、南、西3个方向向北呈放射状分布,随着地形由高山向丘陵、平原的方向变化而减小。  相似文献   
126.
This study aimed to make a review and forecast on fertilizers consumption worldwide in order to provide basal data for the decision-making of fertilizers production and for the environmental impact assessment of fertilizers application. It was found that fertilizers consumption was dependent on human population and the increase of fertilizers consumption was mainly resulted from expansion of human population. The univariate linear model, y=a+rx(t), where y is the fertilizers consumption, x(t) is the total human population at year t, r is the annual fertilizers consumption per capita, was used to fit historical data of fertilizers consumption, and the forecasts during 2010 to 2030 were given in detail. Model analysis showed that world’s per capita annual consumption of total fertilizers, nitrogenous fertilizers, phosphate fertilizers, and potash fertilizers, were 34.6, 24.4, 6.6, and 3.7 kg, respectively. Per capita annual consumption of total fertilizers for Asia, Africa, Caribbean, Oceania, North & Central America, Europe, and South America were 38.8, 5.9, 6.8, 114.0, 62.9, −0.9, and 43.6 kg, respectively. Compared to the current level, the world’s total fertilizers consumption would reach 226,150,381 Mt by 2030, an increase of 32.1% against current level. Worldwide consumption of nitrogenous fertilizers, phosphate fertilizers, and potash fertilizers would reach 141,800,601, 50,961,129, and 33,388,650 Mt by 2030, increasing 37.5, 25.8, and 21.2% based on current levels. Consumption of total, nitrogenous, phosphate, and potash fertilizers in Asia and Africa would increase 54 to 55% and 40 to 60% by 2030, respectively. Total fertilizers consumption in North & Central America would see an increase of 39.4% by 2030, and in South America and Oceania it would increase by 30.9 and 64.7%, respectively. By 2030, Caribbean’s consumption for total fertilizers would increase 2.8%. Europe’s total fertilizers consumption was forecast to continuously decline and would have a decrease of 2.4% by 2030. Annual relative growths of consumption of total fertilizers, nitrogenous fertilizers, phosphate fertilizers, and potash fertilizers for the world, Africa, Asia, and South America were forecast to decrease in the forecast period. For North & Central America, annual relative growths of consumption of total fertilizers and nitrogenous fertilizers would decrease and the others would increase annually by 2030. Annual relative growths of consumption of total fertilizers, phosphate fertilizers, and potash fertilizers for Oceania were forecast to rise annually by 2030. Europe’s annual relative growths of consumption of total fertilizers and potash fertilizers would decrease in the future.  相似文献   
127.
Our world is largely dependent upon the forestry productions. Through the exploitation of forest reserves, we manufacture various industrial products, furniture, and obtain fuel and energy. Forestry productions should be conducted without large-scale deforestation and environmental degradation. In present study we perform a review and forecast analysis on forestry productions worldwide, with the objectives of providing an insight into the trend for several types of forestry productions in the future, and providing referential data for sustainable forestry productions and environmental management. Polynomial functions are used to fit trajectories of forestry productions since 1961 and forecasts during the coming 20 years are given in detail. If the past pattern continues, world fibreboard production would dramatically grow and reach 224,300,000 ± 44,400,000 m3 by the year 2020, an increase up to 240.7 to 408.9% as compared to the present level. Roundwood production of the world would change by −55.5 to 70.4% and reach 3,526,600,000 ± 2,066,800,000 m3 by 2020. In 2020 world production of sawlogs and veneer logs would change by −100 to 164.6% and reach 1,212,900,000 ± 1,242,600,000 m3. Global wood fuel production would change by −68.9 to 1.4% and reach 1,130,900,000 ± 600,800,000 m3 by 2020. Forestry productions in developed countries would largely surpass productions in developing countries in the near future. World forestry production grew since 1961 excluding wood fuel. Roundwood and wood fuel account for the critical proportions in the forestry productions. Wood fuel production has being declined and rapid growing of roundwood production has slowed in recent years. Widespread use of regenerative wood substitutes and worldwide afforestation against deforestation will be among the most effective ways to reduce deforestation and environment degradation associated with forestry productions.  相似文献   
128.
Healthy watersheds provide valuable services to society, including the supply and purification of fresh water. Because these natural ecosystem services lie outside the traditional domain of commercial markets, they are undervalued and underprotected. With population and development pressures leading to the rapid modification of watershed lands, valuable hydrological services are being lost, which poses risks to the quality and cost of drinking water and the reliability of water supplies. Increasing the scale and scope of programmes to protect hydrological services requires policies that harmonize land uses in watersheds with the provision of these important natural services. This article summarizes key attributes of hydrological services and their economic benefits; presents a spectrum of institutional mechanisms for safeguarding those services; discusses programmes in Quito (Ecuador), Costa Rica and New York City; and offers some lessons learned and recommendations for achieving higher levels of watershed protection.  相似文献   
129.
130.
世界遗产地和国家级风景名胜区是一种保护性资源而不是开发性资源,其经营目标应该是增进社会福利。这种性质决定了它的经营目标和主体,而门票价格的高低最能体现出该类产品是否具有公益性特征。本文根据世界遗产和国家级风景区的性质。应用资源经济学与旅游经济学的原理,构建理论模型,结合具体案例进行实证研究来说明门票价格定位的依据、条件和目标。并希望通过合理的价格定位来实现消费者剩余最大化和提高社会整体经济福利。  相似文献   
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