全文获取类型
收费全文 | 20787篇 |
免费 | 1503篇 |
国内免费 | 2882篇 |
专业分类
安全科学 | 2961篇 |
废物处理 | 381篇 |
环保管理 | 3312篇 |
综合类 | 11237篇 |
基础理论 | 1743篇 |
环境理论 | 9篇 |
污染及防治 | 1261篇 |
评价与监测 | 2168篇 |
社会与环境 | 1161篇 |
灾害及防治 | 939篇 |
出版年
2024年 | 74篇 |
2023年 | 323篇 |
2022年 | 563篇 |
2021年 | 737篇 |
2020年 | 794篇 |
2019年 | 578篇 |
2018年 | 497篇 |
2017年 | 682篇 |
2016年 | 814篇 |
2015年 | 882篇 |
2014年 | 1008篇 |
2013年 | 1266篇 |
2012年 | 1438篇 |
2011年 | 1549篇 |
2010年 | 1085篇 |
2009年 | 1170篇 |
2008年 | 854篇 |
2007年 | 1357篇 |
2006年 | 1335篇 |
2005年 | 1196篇 |
2004年 | 1023篇 |
2003年 | 1018篇 |
2002年 | 847篇 |
2001年 | 723篇 |
2000年 | 649篇 |
1999年 | 609篇 |
1998年 | 411篇 |
1997年 | 362篇 |
1996年 | 242篇 |
1995年 | 216篇 |
1994年 | 190篇 |
1993年 | 184篇 |
1992年 | 106篇 |
1991年 | 71篇 |
1990年 | 50篇 |
1989年 | 29篇 |
1988年 | 36篇 |
1987年 | 24篇 |
1986年 | 16篇 |
1985年 | 16篇 |
1984年 | 23篇 |
1983年 | 18篇 |
1982年 | 15篇 |
1981年 | 10篇 |
1980年 | 21篇 |
1979年 | 17篇 |
1978年 | 6篇 |
1973年 | 8篇 |
1972年 | 5篇 |
1971年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 656 毫秒
771.
本文分析了利用产业信托投资城市环境基础设施的可行性和现实性,并做出一个环境基础设施信托投资方案的结构设计。 相似文献
772.
Ramsis B. Salama 《Water, Air, & Soil Pollution: Focus》2005,5(1-2):27-44
Perth groundwater resources are obtained from three major aquifers that occur beneath the Perth metropolitan area: the Superficial
aquifer, Leederville aquifer and Yarragadee aquifer. Each aquifer has a unique seasonal water level pattern controlled by
soils, geomorphology and geology. Landuse is mainly responsible for variations in recharge; however, the hydraulic properties
control aquifer response and water level pattern to a greater degree. Groundwater in the three aquifers is generally of very
good quality except in localised areas. Salinity increases with depth and in direction of groundwater flow in the three aquifers.
The best water quality is in the Superficial aquifer in the Wanneroo well field area. The geochemistry and stable isotope
signatures from the three major aquifers revealed distinct water types that suggest very little hydraulic connection or mixing
of waters between these aquifers at the present abstraction and recharge regimes. The results also show that the Leederville
and Yarragadee aquifers were recharged during earlier cooler times while the Superficial aquifer is being recharged at present. 相似文献
773.
Kazuo Kamura Yu Hara Bulent Inanc Masato Yamada Yuzo Inoue Yusaku Ono 《Journal of Material Cycles and Waste Management》2005,7(2):66-70
It is always possible for impermeable layers to exist in landfills. When they do, the properties of the solution at the exit of the leachate-collection system might not accurately reflect the overall properties of the landfill. This study examines whether resistivity monitoring is effective for determining the influence of impermeable layers on the leachate. The test cell used in this study was filled with waste made up mainly of incinerator ash and shredded incombustible material. Three lines of resistivity sensors were laid in the uppermost layer of the fill. A resistivity profile was recorded periodically from each of these lines. The water-table level and leachate properties were measured concurrently. Leachate conductivity was mainly controlled by concentrations of the main ions, and it correlated inversely to variations in resistivity. Temporal changes in the resistivity of the fills are an excellent means of assessing the leaching in fills. Monitoring the properties of leachate, combined with resistivity profiling, is extremely useful for interpreting the temporal changes of properties in landfills containing impermeable layers. 相似文献
774.
马建华 《中国环境管理干部学院学报》2005,15(1):38-41
采用顶空气相色谱法测定食品中甜蜜素含量,探讨了气液相平衡条件及色谱条件的选择,实验结果表明甜蜜素的标准溶液在0.1-0.4μg/l范围内具有良好的线性关系,回收率为87.5%-101.8%,相对标准偏差为2.6%. 相似文献
775.
对实验室污染问题的思考和建议 总被引:10,自引:0,他引:10
余华 《中国环境管理干部学院学报》2005,15(1):58-60
分析了目前实验室存在的污染种类及危害,阐明实验室是一种不容忽视的污染源,且污染种类复杂,毒害较大.提出实验室污染防治措施. 相似文献
776.
浅谈高职高专院校中的语文素质教育 总被引:2,自引:0,他引:2
一方面阐释语文素质教育在高职高专教育中的重要性及其作用;另一方面阐释了作为一名大学语文教师应如何在教学中体现"素质教育",培养出具有较高综合素质的职业技术人才. 相似文献
777.
针对传统的污染排放数据指标计算方法存在的问题,提出污染物排放指标应根据排污强度和经济指标确定的新思路,同时提出污染物排放指标数据的快速测算模型设计.建议通过环境监测数据或物料衡算数据确定每个排污单位的平均排污强度,作为计算机处理的参数,再由该排污单位申报每月的经济指标(产量或产值),输入计算机计算其产污量、排污量和去除量.实施计算机管理的关键是选取适当的数据计算模型.新思路应该能够规范计算程序,建立污染源动态数据库,对排污数据实行有效的统计分析. 相似文献
778.
A data analysis of three major Korean cities was conducted to assess roadside inhalable particulate matter 10 μm or smaller
in aerodynamic diameter (PM10), including temporal and meteorological variations, over a recent period of 4 to 6 years. The yearly roadside PM10 concentrations presented a well-defined increasing trend or no trend depending on the roadside monitoring station. Most mean
values exceeded or approximated the Korean standard of 70 μg/m3 per year for PM10. A representative roadside diurnal trend was characterized by a distinct morning maximum. In most cases, the Sunday roadside
concentrations were similar to or somewhat lower than the weekday concentrations, and the PM10 concentrations presented a well-defined seasonal variation, with the maximum concentration in March. The monthly maximum
concentrations observed in March were most likely attributable to Asian dust storms. In two metropolitan cities (Seoul and
Busan), the frequency of days with roadside PM10 concentrations exceeding the standard of 150μg/m3 per 24 h was much lower for the roadside monitoring stations than for the residential monitoring station, whereas in the
third city (Daegu), this result was reversed. Interestingly, the average maximum concentrations observed for the roadside
sites in Seoul and Busan during March were higher than those for the residential sites, suggesting that the roadside concentrations
responded more to the dust storms than the residential areas. The relationship between the pollutant concentrations and five
important meteorological parameters (solar radiation, wind speed, air temperature, relative humidity, and precipitation) showed
that the number and type of meteorological variables included in the equations varied according to the monitoring station
or season. Finally, the current results confirmed that attention should be given to the PM10 exposure of residents living near roadways. 相似文献
779.
The Water Fluxes of the Yellow River to the Sea in the Past 50 Years, in Response to Climate Change and Human Activities 总被引:12,自引:1,他引:12
Jiongxin X 《Environmental management》2005,35(5):620-631
Since the 1970s, the water fluxes to the sea of the Yellow River have declined significantly. Based on data of precipitation, air temperature, the measured and “natural” river flow, the water diversion and consumption, and the areas of erosion and sediment control measures over the drainage basin, water fluxes to the sea of the Yellow River are studied in relation with the influences of changing climate and human activities. The Yellow River basin can be divided into different water source areas; multiple regression indicates that the variation in precipitation over different water source areas has different effect on water fluxes to the sea. In the period between 1970 and 1997, averaged air temperature over the whole Yellow River increased by about 1.0°C, from 16.5°C to 17.5°C, a factor that is negatively correlated with the water yield of the Yellow River. Water diversion and consumption has sharply increased and resulted in a significant decline in the water fluxes to the sea. Since the 1960s, erosion and sediment control measures have been practiced over the drainage basin. This factor, to a lesser degree, is also responsible for the decrease in water fluxes to the sea. A multiple regression equation has been established to estimate the change in water fluxes to the sea caused by the changes in precipitation, air temperature, water diversion and consumption, erosion, and sediment control measures, indicating that the contribution of water diversion and consumption to the variation in annual water flux to the sea is 41.3%, that of precipitation is 40.8%, that of temperature is 11.4%, and that of erosion and sediment control measures is 6.5%. 相似文献
780.
Summary The balance of evidence suggests a perceptible human influence on global ecosystems. Human activities are affecting the global
ecosystem, some directly and some indirectly. If researchers could clarify the extent to which specific human activities affect
global ecosystems, they would be in a much better position to suggest strategies for mitigating against the worst disturbances.
Sophisticated statistical analysis can help in interpreting the influence of specific human activities on global ecosystems
more carefully. This study aims at identifying significant or influential human activities (i.e. factors) on CO2 emissions using statistical analyses. The study was conducted for two cases: (i) developed countries and (ii) developing
countries. In developed countries, this study identified three influential human activities for CO2 emissions: (i) combustion of fossil fuels, (ii) population pressure on natural and terrestrial ecosystems, and (iii) land
use change. In developing countries, the significant human activities causing an upsurge of CO2 emissions are: (i) combustion of fossil fuels, (ii) terrestrial ecosystem strength and (iii) land use change. Among these
factors, combustion of fossil fuels is the most influential human activity for CO2 emissions both in developed and developing countries. Regression analysis based on the factor scores indicated that combustion
of fossil fuels has significant positive influence on CO2 emissions in both developed and developing countries. Terrestrial ecosystem strength has a significant negative influence
on CO2 emissions. Land use change and CO2 emissions are positively related, although regression analysis showed that the influence of land use change on CO2 emissions was still insignificant. It is anticipated, from the findings of this study, that CO2 emissions can be reduced by reducing fossil-fuel consumption and switching to alternative energy sources, preserving exiting
forests, planting trees on abandoned and degraded forest lands, or by planting trees by social/agroforestry on agricultural
lands. 相似文献