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 406 毫秒
161.
CHENG Song 《环境科学学报(英文版)》2007,19(4):502-507
To demonstrate the existence of light thresholds in plant growth and to examine the effects of elevated CO2 on the shade tolerance of a tree species, an experiment consisting of a completely randomized design for a total of 96 yellow birch (Betula alleghaniensis Britton) seedlings was conducted with 3 light levels (2.9%, 7.7%, 26.1% of full sunlight)×2 CO2 levels (350 and 700±10 ppm) with 4 replications in a phytotron. The study proved that thresholds exist and they vary in different plant organs. In ambient CO2, the thresholds were 13.3%, 18.7%, 15.0%, 15.2%, and 15.6% of full sunlight for stem, leaf, root, total plant biomass, and the averaged value, respectively. In 700 ppm CO2, the corresponding thresholds were 16.7%, 21.3%, 18.1%, 21.7% and 19.5% for stem, leaf, root, total plant biomass, and the averaged value, respectively. The lowest threshold in the stem is an indicator of the minimal light intensity for regular growth for seedlings of this species. Below this threshold, light-stressful growth occurs. The result of a paired t-test indicated that the thresholds in elevated CO2 were significantly higher than in ambient CO2. This suggests that yellow birch will lose its moderate shade tolerance, evolutionally becoming a shade-intolerant species, and that it may become more difficult to naturally regenerate in the future. 相似文献
162.
163.
164.
165.
Spatial variability of organochlorine pesticides (DDTs and HCHs) in surface soils from the alluvial region of Beijing, China 总被引:1,自引:0,他引:1
ZHANG Hong-yan GAO Ru-tai HUANG Yuan-fang JIA Xiao-hong JIANG Shu-ren 《环境科学学报(英文版)》2007,19(2):194-199
The spatial variability in the concentrations of 1,2,3,4,5,6-hexachlorocyclohexane (HCH) and 1,1,1-trichloro-2,2-bis-(p-chlorophenyl) ethane (DDT) in surface soils was studied on the basis of the analysis of 131 soil samples collected from the surface layer (0-20 cm depth) of the alluvial region of Beijing, China. The concentrations of total HCHs (including α-, β-, γ-, and δ-isomers) and total DDTs (i ncluding p,p'-DDT, p,p'-DDD, p,p'-DDE, and o,p'-DDT) in the surface soils tested were in the range from nondetectable to 31.72 μg/kg dry soil, with a mean value of 0.91, and from nondetectable to 5910.83 μg/kg dry soil, with a mean value of 32.13,respectively. It was observed that concentrations of HCHs in all soil samples and concentrations of DDTs in 112 soil samples were much lower than the first grade (50 μg/kg) permitted in "Environment quality standard for soils in China (GB15618-1995)". This suggests that the pollution due to organochlorine pesticides was generally not significant in the farmland soils in the Beijing alluvial region. In this study, the spatial distribution and trend of HCHs and DDTs were analyzed using Geostatistical Analyst and GS (513).Spatial distribution indicated how these pesticides had been applied in the past. Trend analysis showed that the concentrations of HCHs,DDTs, and their related metabolites followed an obvious distribution trend in the surface soils from the alluvial region of Beijing. 相似文献
166.
我国经济已经从高速增长转向中高速增长的新常态阶段,经济发展方式从规模速度型粗放增长转向质量效率型集约增长,产业结构从劳动密集型向资金密集型和知识密集型转换,经济发展动力从要素驱动、投资驱动转向创新驱动。经济新常态下,环境保护将迎来难得的历史机遇,同时也面临严峻的挑战。为了深入理解和准确把握经济新常态下我国"环境态"的发展特征,本文基于中长期环境经济预测模型定量测算了2020年我国社会经济、能源和水资源以及主要污染物排放趋势和特征。结果表明,"十三五"期间,我国能源和水资源消耗总量增长将趋缓,新增消耗量进入涨幅收窄期;产业转型升级加速将从源头上减轻新增污染减排的压力,主要大气和水污染物排放将进入高位平台期,排放强度将呈现高位回落。 相似文献
167.
Spatio‐Temporal Patterns of Open Surface Water in the Central Valley of California 2000‐2011: Drought,Land Cover,and Waterbirds
下载免费PDF全文
![点击此处可从《Journal of the American Water Resources Association》网站下载免费的PDF全文](/ch/ext_images/free.gif)
168.
本文从中国环境立法,特别是再次修改《大气污染防治法》等展望中国大气污染防治的重要战略方向。 相似文献
169.
长江入海口北支沿海滩涂养殖区底泥重金属污染特征及趋势评价 总被引:3,自引:0,他引:3
对长江入海口北支沿海滩涂养殖区底泥重金属污染的总体水平进行调查,结果表明,滩涂养殖区底泥重金属含量满足海洋沉积物质量一类标准要求,污染程度属于安全Ⅰ级水平,重金属潜在生态危害属轻微级别,6种重金属潜在生态危害由大到小排序依次为Cd﹥Hg﹥Cu﹥Cr﹥Pb﹥As,2005年~2011年,底泥重金属污染程度均处于安全的Ⅰ级水平。 相似文献
170.
K. Srogi 《Environmental Chemistry Letters》2007,5(4):169-195
Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds with two or more fused aromatic rings. They
have a relatively low solubility in water, but are highly lipophilic. Most of the PAHs with low vapour pressure in the air
are adsorbed on particles. When dissolved in water or adsorbed on particulate matter, PAHs can undergo photodecomposition
when exposed to ultraviolet light from solar radiation. In the atmosphere, PAHs can react with pollutants such as ozone, nitrogen
oxides and sulfur dioxide, yielding diones, nitro- and dinitro-PAHs, and sulfonic acids, respectively. PAHs may also be degraded
by some microorganisms in the soil. PAHs are widespread environmental contaminants resulting from incomplete combustion of
organic materials. The occurrence is largely a result of anthropogenic emissions such as fossil fuel-burning, motor vehicle,
waste incinerator, oil refining, coke and asphalt production, and aluminum production, etc. PAHs have received increased attention
in recent years in air pollution studies because some of these compounds are highly carcinogenic or mutagenic. Eight PAHs
(Car-PAHs) typically considered as possible carcinogens are: benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene,
benzo(a)pyrene (B(a)P), dibenzo(a,h)anthracene, indeno(1,2,3-cd)pyrene and benzo(g,h,i)perylene. In particular, benzo(a)pyrene
has been identified as being highly carcinogenic. The US Environmental Protection Agency (EPA) has promulgated 16 unsubstituted
PAHs (EPA-PAH) as priority pollutants. Thus, exposure assessments of PAHs in the developing world are important. The scope
of this review will be to give an overview of PAH concentrations in various environmental samples and to discuss the advantages
and limitations of applying these parameters in the assessment of environmental risks in ecosystems and human health. As it
well known, there is an increasing trend to use the behavior of pollutants (i.e. bioaccumulation) as well as pollution-induced
biological and biochemical effects on human organisms to evaluate or predict the impact of chemicals on ecosystems. Emphasis
in this review will, therefore, be placed on the use of bioaccumulation and biomarker responses in air, soil, water and food,
as monitoring tools for the assessment of the risks and hazards of PAH concentrations for the ecosystem, as well as on its
limitations. 相似文献