全文获取类型
收费全文 | 493篇 |
免费 | 78篇 |
国内免费 | 235篇 |
专业分类
安全科学 | 48篇 |
废物处理 | 8篇 |
环保管理 | 68篇 |
综合类 | 437篇 |
基础理论 | 88篇 |
环境理论 | 1篇 |
污染及防治 | 21篇 |
评价与监测 | 56篇 |
社会与环境 | 59篇 |
灾害及防治 | 20篇 |
出版年
2024年 | 6篇 |
2023年 | 23篇 |
2022年 | 33篇 |
2021年 | 55篇 |
2020年 | 52篇 |
2019年 | 38篇 |
2018年 | 28篇 |
2017年 | 31篇 |
2016年 | 30篇 |
2015年 | 33篇 |
2014年 | 33篇 |
2013年 | 61篇 |
2012年 | 56篇 |
2011年 | 45篇 |
2010年 | 38篇 |
2009年 | 24篇 |
2008年 | 31篇 |
2007年 | 36篇 |
2006年 | 16篇 |
2005年 | 18篇 |
2004年 | 14篇 |
2003年 | 22篇 |
2002年 | 7篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 8篇 |
1998年 | 3篇 |
1997年 | 9篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有806条查询结果,搜索用时 15 毫秒
781.
基于2022年1—12月青岛市沿海区域臭氧(O3)自动监测数据和气象观测资料,对O3污染变化特征及影响因素进行了分析,结合后向轨迹聚类与潜在源区分析等方法,对O3外来输送通道及潜在源分布情况进行分析研究。结果表明:青岛市沿海区域O3污染主要集中在4—10月份,日变化特征呈单峰单谷趋势,峰值出现在15:00—16:00;气象因素中,地面短波辐射对O3浓度变化的相对贡献最大,偏南风易导致O3污染;受二氧化氮(NO2)滴定作用以及海陆风转换影响,沿海区域O3峰值与谷值均滞后青岛城区1 h左右;O3生成整体处于VOCs控制区,1-丁烯、正丁烷与异戊烷是O3污染期间导致O3浓度上升的关键组分;O3污染的主要潜在源区为长三角北部和黄海近岸海域,以及山东中南部地区。 相似文献
782.
Robert J. Luxmoore William W. Hargrove M. Lynn Tharp Wilfred M. Post Michael W. Berry Karen S. Minser Wendell P. Cropper Jr. Dale W. Johnson Boris Zeide Ralph L. Amateis Harold E. Burkhart V. Clark Baldwin Jr. Kelly D. Peterson 《Environmental Modeling and Assessment》2000,5(2):125-137
Stochastic transfer of information in a hierarchy of simulators is offered as a conceptual approach for assessing forest responses
to changing climate and air quality across 13 southeastern states of the USA. This assessment approach combines geographic
information system and Monte Carlo capabilities with several scales of computer modeling for southern pine species and eastern
deciduous forests. Outputs, such as forest production, evapotranspiration and carbon pools, may be compared statistically
for alternative equilibrium or transient scenarios providing a statistical basis for decision making in regional assessments.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
783.
Simulation and evaluation on the eco-industrial system of Changchun economic and technological development zone, China 总被引:2,自引:0,他引:2
Reasonable structure, adaptive patterns and effective regulation of society, economy and environment subsystems should be
taken into account in order to obtain harmonious development of urban eco-industrial system. We simulated and evaluated a
redesigned eco-industrial system in Changchun Economic and Technological Development Zone (CCETDZ) in the present work using
system dynamics and grey cluster methods. Four typical development strategies were simulated during 2005–2020 via standard
system dynamic models. Furthermore, analytic hierarchy process and grey cluster allowed for the eco-industrial system evaluation
and scenarios optimizing. Our dynamic simulation and statistical analysis revealed that: (1) CCETDZ would have different development
scenarios under different strategies. The total population in scenario 2 grew most rapidly and reached 3.28 × 105 in 2020, exceeding its long-term planning expected population. And the GDP differences among these four scenarios would amount
to 6.41 × 1010 RMB. On the other hand, environmental pollution would become serious along with economy increasing. As a restriction factor,
positive or negative increment of water resource will occur according to the selected strategy. (2) The fourth strategy would
have the best efficiency, which means that the most efficiently development of CCETDZ required to take science, technology,
environment progress and economy increase into account at the same time. (3) Positive environment protection measures, such
as cleaner production, green manufacture, production life cycle management and environment friendly industries, should be
attached great importance the same as economy development during 2005–2020 in CCETDZ. 相似文献
784.
Atmospheric surface aerosol radiative forcing (SARF) ΔF, forcing efficiency ΔFe and fractional forcing efficiency ΔFFe evaluated from cloud-screened narrowband spectral and thermal-offset-corrected radiometric observations during the Asia dust
outbreak episodes in Gwangju, Republic of Korea are reported in this study. Columnar aerosol optical properties (aerosol optical
depth (AOD), τ
aλ, Angstrom exponent α, mass concentration of fine and coarse mode particles) were also reported for the station between January
2000 and May 2001 consisting of 211cloud-free days. Results indicate that majority of the AOD were within the range 0.25–0.45
while some high aerosol events in which AODs ≥ 0.6 were observed during the severe dust episodes. For example, AOD increases
from annual average value of 0.34 ± 0.13 at 501 nm to values >0.60 during the major dust events of March 27–30 and April 7–9,
2000, respectively. The α
501–870 nm which is often used as a qualitative indicator of aerosol particle size had values ranging from 0.01 to 1.77. The diurnal
forcing efficiency ΔDFe at Gwangju was estimated to be −81.10 ± 5.14 W m −2/τ
501 nm and −47.09 ± 2.20 W m −2/τ
501 nm for the total solar broadband and visible band pass, respectively while the fractional diurnal forcing efficiency ΔFDFe were −15.8 ± 0.64%/τ
501 nm and −22.87 ± 1.13%/τ
501 nm for the same band passes. Analyses of the 5-day air-mass back trajectories were further developed for Gwangju in order to
classify the air-mass and types of aerosol reaching the site during the Asia dust episodes. 相似文献
785.
Inverse geochemical modeling from PHREEQC, and multivariate statistical methods were jointly used to define the genetic origin of chemical parameters of groundwater from the Voltaian aquifers in the Afram Plains area. The study finds, from hierarchical cluster analysis that there are two main hydrochemical facies namely the calcium-sodium-chloride-bicarbonate waters and the magnesium-potassium-sulfate-nitrate waters in the northern and southern sections, respectively, of the Afram Plains area. This facies differentiation is confirmed by the distribution of the SO(4)(2-)/Cl(-) ratio, which associates groundwater from the northern and southern sections to areas influenced by contact with evaporites and seawater, respectively. Principal component analysis (PCA) with varimax rotation using the Kaiser criterion identifies four principal sources of variation in the hydrochemistry. Mineral saturation indices calculated from both major ions and trace elements, indicate saturation-supersaturation with respect to calcite, aragonite, k-mica, chlorite, rhodochrosite, kaolinite, sepiolite, and talc, and undersaturation with respect to albite, anorthite, and gypsum in the area. Inverse geochemical modeling along groundwater flowpaths indicates the dissolution of albite, anorthite and gypsum and the precipitation of kaolinite, k-mica, talc, and quartz. Both the PCA and inverse geochemical modeling identify the incongruent weathering of feldspars as the principal factors controlling the hydrochemistry in the Afram Plains area. General phase transfer equations have been developed to characterize the geochemical evolution of groundwater in the area. A very good relationship has been established between calcite and aragonite saturation indices in the Afram Plains area, with R(2)=1.00. 相似文献
786.
787.
788.
用后向空气轨迹方法对胶州湾主要大气污染物分布的分析 总被引:3,自引:2,他引:1
采用青岛崂山点位2005-2009年的大气监测数据,利用HYSPLIT4.8模式和象限分析方法,计算出污染物的方位贡献情况,判断出胶州湾大气污染物的传输路径主要为北、西北和西部路径,S02、N02和PM10在北部和西北部象限的5年平均贡献率分别为25.32%和28.21%、21.16%和21.53%以及20.25%和22.83%,这与胶州湾东方和东南方为海洋、北方和西北方为工业城市有关.通过个例分析得出的传输路径与象限分析的结果一致.另一方面,胶州湾地区的主要污染物在过去5年中的年均值浓度变化显示,SD2浓度呈下降趋势,NO2浓度呈上升趋势,PM10浓度变化趋势不明显.为调查青岛市和周边5个省污染物排放水平对胶州湾污染物分布的影响,分析了2005-2009年的相关环境统计数据,SO,的排放量下降,燃料煤消耗量、氮氧化物排放量以及机动车数量逐年升高可能是导致胶州湾地区污染物浓度变化的原因. 相似文献
789.
丹江口水库湖北库区水质分区及长期变化趋势 总被引:1,自引:0,他引:1
丹江口水库是南水北调中线工程水源地,准确地掌握丹江口水库水环境质量状况变化情况,对保障调水工程顺利进行有着极其重要的意义。基于水质理化指标将丹江口水库湖北库区水域划分为4个区,各分区的主要物理指标存在显著差异,化学指标较为均一;近10年水质历史监测数据显示,湖北库区除总氮指标外,其余监测指标水质类别均达到或优于Ⅱ类,总体水质保持优良;氨氮、总磷、总氮3项指标年均浓度从2007年起呈增加趋势,在2011年后均有所降低并趋于稳定。农业面源污染对丹江口水库水质影响较大。目前采取的各项环保措施对丹江口水库的水质产生了积极的影响,需继续加大各项治理措施的实施力度,完善水质监测系统,保障丹江口水库水质安全。 相似文献
790.
为解决城市群综合承灾度评价过程中的模糊性与随机性问题,合理评估城市群的综合承灾度。从防灾、抗灾、救灾和恢复4个维度构建城市综合承灾度评价指标体系,提出基于云模型的城市群综合承灾度评价模型。以西北地区3个城市群为例,运用云模型对城市群的综合承灾度进行评价,通过熵权法进行赋权,最终确定算例城市群的综合承灾状况。结果表明:西北地区3个城市群承灾度等级均为Ⅱ级,承灾能力中等;该方法利用能综合反映多因素之间复杂关系的特征指标得出相应的评价等级,同时为地区内城市的承灾度大小判断提供参考,对提升城市群综合承灾度具有积极意义。 相似文献