全文获取类型
收费全文 | 765篇 |
免费 | 60篇 |
国内免费 | 97篇 |
专业分类
安全科学 | 56篇 |
废物处理 | 16篇 |
环保管理 | 147篇 |
综合类 | 424篇 |
基础理论 | 54篇 |
污染及防治 | 36篇 |
评价与监测 | 67篇 |
社会与环境 | 73篇 |
灾害及防治 | 49篇 |
出版年
2024年 | 6篇 |
2023年 | 13篇 |
2022年 | 27篇 |
2021年 | 26篇 |
2020年 | 25篇 |
2019年 | 18篇 |
2018年 | 16篇 |
2017年 | 23篇 |
2016年 | 29篇 |
2015年 | 38篇 |
2014年 | 35篇 |
2013年 | 37篇 |
2012年 | 71篇 |
2011年 | 67篇 |
2010年 | 48篇 |
2009年 | 27篇 |
2008年 | 35篇 |
2007年 | 56篇 |
2006年 | 44篇 |
2005年 | 38篇 |
2004年 | 38篇 |
2003年 | 39篇 |
2002年 | 34篇 |
2001年 | 25篇 |
2000年 | 21篇 |
1999年 | 13篇 |
1998年 | 9篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1972年 | 2篇 |
排序方式: 共有922条查询结果,搜索用时 46 毫秒
761.
汶川地震对四川及周边省区旅游业的影响 总被引:1,自引:0,他引:1
依据本底趋势线理论和1997-2008年统计数据,从更高的时空分辨率上,完成了汶川地震对四川及其周边省区旅游业影响的分析,结果显示:①2008年5-12月地震共使四川入境旅游损失112.1万人,国内旅游损失4 410.7万人,损失率分别为61.4%和22.4%;②四川北部主要旅游景点旅游业损失惨重,各景点游客损失率均达到了67.0%以上,其中,九寨沟、都江堰游客损失量较大,分别为212.2万人和194.7万人;③四川周边省区入境旅游遭受了不同程度的冲击,其中,湖北、甘肃损失量最大,分别为35.1万人和26.9万人;各省区受地震影响时间存在较大差异,地震影响期以甘肃最长,其影响期将超过8个月;④2008年汶川地震对四川及其周边省区旅游业的影响,其游客损失量与客流量基数(本底值)成正比;游客损失率与2008年本底值(基数)成反比;损失量和损失率两者均与汶川地震烈度分布存在一定的正比关系,以汶川为中心大致成同心圆状分布。 相似文献
762.
为加强对秸秆焚烧的管理,通过对国家环境保护总局公布的夏冬收获季节卫星遥感探测的火点情况的统计分析,2004年-2009年夏冬收获季节南通市空气质量日变化趋势分析及典型秸秆焚烧日环境空气中污染物的小时变化趋势分析,得出秸秆焚烧对南通市环境空气质量影响的程度,掌握了南通市秸秆焚烧地域分布情况. 相似文献
763.
Agriculture is the largest source of nutrients into surface waters in Finland, and yet relatively little is known about the
actual impact of the agricultural load on the state of lakes. We analysed the water quality data of 20 Finnish agricultural
lakes and found that they had higher levels of nutrients, chlorophyll a and turbidity than did the other types of lakes (e.g. those receiving point-source load) in the national monitoring network
(the Finnish Eurowaternet). Currently, six of the agricultural lakes can be classified as eutrophic and 14 as hypertrophic.
Trend analysis (based on Kendall's tau-b) indicated that during 1976–2002 the water quality of the lakes either remained constant or showed signs of increasing
eutrophication and elevated turbidity. Decreasing nutrient concentrations were found only in one intensively restored lake.
In none of the lakes had the chlorophyll a concentration decreased. The results of the trend analysis are compatible with the recent finding that, despite vigorous
efforts, the nutrient load from agriculture has not declined in Finland. Recovery of the most eutrophied agricultural lakes
would call for a drastic reduction in the external nutrient load, possibly supplemented with in-lake restoration. 相似文献
764.
The purpose of this article is to identify the effect of land-use pattern on rainfall-runoff and runoff-sediment relations in Zichang Watershed of the Loess Plateau. From 1986 to 1997, many farmlands changed into grassland or woodland, especially the farmland in steep slope positions or far away from the river. The change of land-use pattern altered the rainfall-runoff and runoff-sediment relationships, and led to higher slope of trend curves(STCs) of annual rainfall-runoff mass curve and runoff-sediment mass curve in 1990s than that in 1980s. It is implied that more soil and water loss yielded in 1990s. In order to reduce soil loss, more attentions should be paid to land-use pattern and some grass or other herbaceous filter strips should be built along rivers. 相似文献
765.
为探索周围邻域对交通运输业碳排放效率演变的影响,分析了交通运输业碳排放效率的时空演变特征,并对其长期演变趋势进行预测.首先,采用超效率SBM模型测度我国30个省份的交通运输业碳排放效率,利用核密度估计方法分析其随时间演变的特征;其次,构建传统与空间马尔可夫概率转移矩阵进一步分析了交通运输业碳排放效率的时空演变特征;最后,针对不同类型的省份提出相关建议.结果表明:(1)交通运输业碳排放效率的平均水平低于0.6,但呈逐年递增的趋势,且区域差异逐渐缩小.(2)各省份交通运输业碳排放效率至少有71%的概率维持原有状态,且短期内难以实现跨阶段转移.(3)地理空间格局影响交通运输业碳排放效率的演变过程,当某省份与碳排放效率高的省份相邻时,转移到高效率的概率增加,而与碳排放效率低的省份相邻时则相反.此外,在空间溢出效应的影响下,交通运输业碳排放效率的演变逐渐呈现“俱乐部收敛”的趋势.(4)从长期演变趋势来看,各省份交通运输业碳排放效率向高水平转移的可能性增大,呈现出由低到高递增的态势,同时“俱乐部收敛”现象逐渐消失. 相似文献
766.
Despite the demonstrated importance of time perspective on key outcomes, its growing popularity, and its wide reach in terms of samples and disciplines, the construct has been plagued with definitional and measurement problems since its inception. Given the historical and current confusion regarding both conceptualization and operationalization, the purpose of this article is to provide an overview of methodological and measurement issues related to time perspective. Clearly, definitional and measurement clarity are critical for the success of future research. Through integrating the fragmented and eclectic time perspective literature fraught with ambiguity, we help to clarify measurement options and their psychometric evidence for future researchers. Specifically, we provide an in-depth comparison of four (and their offshoots) commonly used, scale-based measures of time perspective with respect to their dimensional content, psychometric properties, and validation evidence. We end with recommendations for time perspective research. 相似文献
767.
长株潭城市群核心区大气环境承载力初探 总被引:2,自引:0,他引:2
对长株潭城市群核心区大气环境质量现状进行了分析,评价了长株潭城市群核心区大气环境承载力,分析了长株潭核心区大气环境承载力发展趋势,提出了提高长株潭核心区大气环境承载力利用水平的建议。 相似文献
768.
769.
The data collected from the five air quality monitoring stations established by the Taiwan Environmental Protection Administration
(TEPA) in Taipei City were analyzed to assess the changes in air quality. The analyses reveal that the air quality in Taipei
City improved over the last decade from 1994 to 2003, as evidenced by the significant downward trends of the various primary
air pollutant concentrations, such as CO, NOX, SO2, and PM10. An air pollution fee was collected by TEPA in 1995, and several air pollution control measures were likewise taken to improve
the air quality in Taiwan. However, although the extreme daily maximum O3 concentrations occurred more frequently in earlier years and showed a downward trend, its moderately high concentrations
increased annually in recent years. It implied that after the reduction of various primary pollutant concentrations, the effective
reduction of O3 pollution still remains an important issue. 相似文献
770.
Eugenia V. Bragina A. R. Ives A. M. Pidgeon T. Kuemmerle L. M. Baskin Y. P. Gubar M. Piquer‐Rodríguez N. S. Keuler V. G. Petrosyan V. C. Radeloff 《Conservation biology》2015,29(3):844-853
Anecdotal evidence suggests that socioeconomic shocks strongly affect wildlife populations, but quantitative evidence is sparse. The collapse of socialism in Russia in 1991 caused a major socioeconomic shock, including a sharp increase in poverty. We analyzed population trends of 8 large mammals in Russia from 1981 to 2010 (i.e., before and after the collapse). We hypothesized that the collapse would first cause population declines, primarily due to overexploitation, and then population increases due to adaptation of wildlife to new environments following the collapse. The long‐term Database of the Russian Federal Agency of Game Mammal Monitoring, consisting of up to 50,000 transects that are monitored annually, provided an exceptional data set for investigating these population trends. Three species showed strong declines in population growth rates in the decade following the collapse, while grey wolf (Canis lupus) increased by more than 150%. After 2000 some trends reversed. For example, roe deer (Capreolus spp.) abundance in 2010 was the highest of any period in our study. Likely reasons for the population declines in the 1990s include poaching and the erosion of wildlife protection enforcement. The rapid increase of the grey wolf populations is likely due to the cessation of governmental population control. In general, the widespread declines in wildlife populations after the collapse of the Soviet Union highlight the magnitude of the effects that socioeconomic shocks can have on wildlife populations and the possible need for special conservation efforts during such times. Declinación Rápida de las Poblaciones de Mamíferos Mayores después del Colapso de la Unión Soviética 相似文献