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排序方式: 共有289条查询结果,搜索用时 15 毫秒
71.
在依据出口能力不同对中国工业行业进行分类的基础上,利用灰色关联分析,定量比较了出口能力不同工业行业对环境污染的影响差异;通过构造环境影响系数,分析了依出口能力差异划分的工业结构变动对环境污染的影响趋势。研究表明,中国出口能力强的工业行业对环境污染影响较大,目前的工业行业出口能力结构变动趋势对环境污染有减轻迹象,适度降低工业行业结构中出口能力强行业的比重,有助于减轻中国环境污染压力。 相似文献
72.
Dry deposition velocities and fluxes of PM10during Asian dust events over the Yellow Sea from 2001 to 2007 were investigated using observation data in Qingdao, China and Jeju, Korea. The dry deposition velocities of PM10 during dust events over the Yellow Sea ranged from 0.19 to 8.17 cm/sec, with an average of 3.38 cm/sec. Dry deposition fluxes of PM10during dust events over the Yellow Sea were in the range of 68.5–2647.1 mg/(m2·day), with an average of 545.4 mg/(m2·day), which is 2–10 times higher than those reported by other studies for both dust and non-dust periods. It was estimated that 2.6 × 1011–48.7 × 1011g dust particles deposit to the Yellow Sea during dust events through dry deposition every year. Compared with the results in previous studies, it was found that the dry deposition of PM10over the Yellow Sea during dust events in the years with high frequency of dust could account for a large or overwhelming fraction of the annual total dry deposition. Backward air mass trajectory analysis showed that dust events influenced Jeju mainly originated from the desert regions located in Mongolia and Inner Mongolia, China. There were 119 backward trajectories influenced both Qingdao and Jeju during 15 dust events from 2001 to 2007, accounting for 61.3% of the total trajectories of 194, indicating that Qingdao and Jeju were usually on the same pathway of dust transport downwind from source areas. 相似文献
73.
Emission characteristics of carbon dioxide in the semiarid Stipa grandis steppe in Inner Mongolia, China 总被引:3,自引:1,他引:2
DONG Yun-she QI Yu-chun LIU Ji-yuan Manfred Domroes LIU Li-xin GENG Yuan-bo LIU Xing-ren YANG Xiao-hong LI Ming-feng 《环境科学学报(英文版)》2006,18(3):488-494
Introduction The emission and absorption of greenhouse gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) etc. by soil is one of the hot topics on global change research, more and more attention has been paid to the flux measurement… 相似文献
74.
75.
Tao Liang Hao Wang Hsiang‐te Rung Chao‐sheng Zhang 《Journal of the American Water Resources Association》2004,40(6):1499-1510
ABSTRACT: Five types of land use/land covers in the West Tiaoxi watershed of China were studied for nutrient losses in artificial rainstorm runoff. A self‐designed rainfall simulator was used. In situ rainfall simulations were used to: (1) compare the concentrations of nitrogen and phosphorous in different land use/land covers and (2) evaluate the flux of nitrogen and phosphorous export from runoff and sediment in various types of land use/land covers. Three duplicated experiments were carried out under rain intensity of 2 mm/min, each lasting 32 minutes on a 3 m2 plot. Characteristics of various species of nitrogen and phosphorous in runoff and sediment were investigated. The results showed that the concentrations of total nitrogen (TN) and total phosphorous (TP) were greatest in runoff from mulberry trees and smallest from pine forest. The TN and TP export was mainly from suspended particulate in runoff. TN and TP exports from the top 10 cm layer of five types of land use/land covers were estimated as high as 4.66 to 9.40 g/m2 and 2.57 to 4.89 g/m2, respectively, of which exports through sediment of runoff accounted for more than 90 percent and 97 percent. The rate of TN and TP exports ranged from 2.68 to approximately 14.48 and 0.45 to approximately 4.11 mg/m2/min in runoff; these rates were much lower than those of 100.01 to approximately 172.67 and 72.82 to approximately 135.96 mg/m2/min in the runoff sediment. 相似文献
76.
颗粒态重金属通过河流与大气向海洋输送 总被引:8,自引:2,他引:8
本文综述了河流与大气向海洋输送颗态重金属的过程、特点及输送通量、参考文献83篇。 相似文献
77.
Elani UA 《Environmental monitoring and assessment》2007,124(1-3):235-241
The ultraviolet UV solar radiation flux is monitored over a fixed time interval to study the daily, monthly and annual variations
for a nearly one decade in Riyadh. Mathematical expressions will be presented based on a comparison between theoretical and
experimental values. It is believed that the present analysis of UV radiation suggest that the environmental effects led to
a better understanding of UV scattering, UV reflection, ozone and clouds layers in Riyadh and other selected areas in the
mid-east region. 相似文献
78.
Georgios K. Sylaios Vassilios A. Tsihrintzis 《Environmental Modeling and Assessment》2009,14(1):59-72
The nutrient dynamics of the Strymonikos and Ierissos Gulfs, two semienclosed coastal water bodies, are studied using a simple
steady-state budget model, according to the Land–Ocean Interaction in the Coastal Zone modeling guidelines. Strymon river
plume dynamics prevailed in the area of the Inner and Outer Srymonikos Gulfs, comprising two layers, while the Ierissos Gulf
was defined as a one-box system. Seasonal and mean annual model input data for river discharge, precipitation, evaporation,
and concentrations of salt, phosphorus, and nitrogen were obtained during four field campaigns. Results from the nitrogen
and phosphorus cycling revealed the importance of river discharge in the horizontal and vertical transport of these substances
within the system. Furthermore, it occurred that the major biogeochemical transformation of nitrogen and phosphorus takes
place in the immediate nearshore zone (Inner Strymonikos Gulf), while the outer system sustains its nutrient dependence on
oceanic exchanges. Therefore, under the summer low flow conditions, the river-influenced inner system acts as a net source
of nitrogen and phosphorus, while under increased Strymon River discharge, phosphorus is transferred to the biological material
(and the sediments), and the system moves to an autotrophic state. The outer system showed an opposite behavior being autotrophic
throughout the year and heterotrophic in February. The Ierissos Gulf, a system not directly influenced by significant river
discharge, experienced a seasonally independent behavior with net heterotrophic and denitrification processes prevailing.
Model scenarios demonstrated that phosphate concentration increases, even under low river flow conditions and stimulates primary
production in excess of respiration, resulting in nitrogen fixation prevalence in the Inner Strymonikos Gulf. 相似文献
79.
潘辉 《中国人口.资源与环境》2012,22(2):41-46
碳关税是美国提出的针对国际贸易中高能耗进口产品征税的一种新型绿色贸易壁垒。从表面上看,碳关税的提出是为了缓解全球气候变暖的现实,促进全球贸易的公平竞争。实质上,碳关税的提出是美国国内政治经济博弈的结果,其目的是为了夺取世界经济新的话语权,同时也是为了制衡中国在内的发展中国家。碳关税对我国出口的影响机制有二:第一,碳关税产生的价格效应促使出口商品成本上升,出口量下降,造成出口国净福利损失。第二,长期来看,碳关税的环境规制效应会促使出口企业实施创新、改进效率,企业竞争力增强。但是,就短期来说,由于我国尚不具备"波特假说"成立的前提条件,碳关税会促使成本上升,出口产品竞争力下降。本文系统分析了我国出口商品结构和地理方向,指出碳关税的推出将对我国当前出口贸易形成严峻的挑战,长期看将有利于我国市场结构、产业结构和出口结构的改善。基于以上的分析,文章提出了政府"环境外交"、逐步开征国内碳税、构建绿色制造体系等政策建议。 相似文献
80.
Marek MV Janouš D Taufarová K Havránková K Pavelka M Kaplan V Marková I 《Environmental pollution (Barking, Essex : 1987)》2011,159(5):1035-1039
By comparing five ecosystem types in the Czech Republic over several years, we recorded the highest carbon sequestration potential in an evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). Because of a massive ecosystem respiration, the final carbon gain of the grassland was negative. Climate was shown to be an important factor of carbon uptake by ecosystems: by varying the growing season length (a 22-d longer season in 2005 than in 2007 increased carbon sink by 13%) or by the effect of short- term synoptic situations (e.g. summer hot and dry days reduced net carbon storage by 58% relative to hot and wet days). Carbon uptake is strongly affected by the ontogeny and a production strategy which is demonstrated by the comparison of seasonal course of carbon uptake between coniferous (Norway spruce) and deciduous (European beech) stands. 相似文献