全文获取类型
收费全文 | 562篇 |
免费 | 67篇 |
国内免费 | 202篇 |
专业分类
安全科学 | 2篇 |
废物处理 | 6篇 |
环保管理 | 73篇 |
综合类 | 547篇 |
基础理论 | 89篇 |
污染及防治 | 24篇 |
评价与监测 | 56篇 |
社会与环境 | 25篇 |
灾害及防治 | 9篇 |
出版年
2024年 | 3篇 |
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 12篇 |
2019年 | 23篇 |
2018年 | 21篇 |
2017年 | 16篇 |
2016年 | 21篇 |
2015年 | 28篇 |
2014年 | 29篇 |
2013年 | 57篇 |
2012年 | 64篇 |
2011年 | 65篇 |
2010年 | 47篇 |
2009年 | 45篇 |
2008年 | 36篇 |
2007年 | 53篇 |
2006年 | 50篇 |
2005年 | 29篇 |
2004年 | 35篇 |
2003年 | 28篇 |
2002年 | 19篇 |
2001年 | 17篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 14篇 |
1997年 | 10篇 |
1996年 | 14篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有831条查询结果,搜索用时 31 毫秒
151.
Coastal waters have been significantly influenced by increased inputs of nutrients that have accompanied population growth
in adjacent drainage basins. In Tampa Bay, Florida, USA, the population has quadrupled since 1950. By the late 1970s, eutrophic
conditions including phytoplankton and macroalgal blooms and seagrass losses were evident. The focus of improving Tampa Bay
is centered on obtaining sufficient water quality necessary for restoring seagrass habitat, estimated to have been 16,400
ha in 1950 but reduced to 8800 ha by 1982. To address these problems, targets for nutrient load reductions along with seagrass
restoration goals were developed and actions were implemented to reach adopted targets. Empirical regression models were developed
to determine relationships between chlorophyll a concentrations and light attenuation adequate for sustainable seagrass growth. Additional empirical relationships between
nitrogen loading and chlorophyll a concentrations were developed to determine how Tampa Bay responds to changes in loads. Data show that when nitrogen load
reduction and chlorophyll a targets are met, seagrass cover increases. After nitrogen load reductions and maintenance of chlorophyll a at target levels, seagrass acreage has increased 25% since 1982, although more than 5000 ha of seagrass still require recovery.
The cooperation of scientists, managers, and decision makers participating in the Tampa Bay Estuary Program’s Nitrogen Management
Strategy allows the Tampa Bay estuary to continue to show progress towards reversing many of the problems that once plagued
its waters. These results also highlight the importance of a multi-entity watershed management process in maintaining progress
towards science-based natural resource goals. 相似文献
152.
确定自然海岸特征是海岸修复中的重要内容,但是在开发后弃管的无居民海岛却面临缺少历史资料参考的困难。在大连普兰店湾中部前大连岛的研究证明,依据历史影像和现存海岸地质地貌情况可以分析确定原自然海岸位置及性质。1972年KH 卫星影像表明当时的前大连岛仍然保持自然海岸形态,海岸位置在2020年海岸后
方的岛屿陆域内部。结合2020年海岸地质考察结果可以进一步确定1972年的前大连岛东部、西部分布海蚀崖形式的基岩海岸,南部、北部则分布砾石质海岸。1972—2020年,前大连岛自然海岸全部变化为人工海岸,海岸长度也从约2.38 km 增加至约3.12 km。 相似文献
153.
González-Macías C Schifter I Lluch-Cota DB Méndez-Rodríguez L Hernández-Vázquez S 《Environmental monitoring and assessment》2007,133(1-3):187-207
Concentrations of total aromatic hydrocarbons and extractable organic matter in the water column and sediment were determined
in samples collected in the course of the last 20 years from the Salina Cruz Harbor, México, to assess the degree of organic
contamination. In sediments, organic compounds accumulate in shallow areas mostly associated with extractable organic matter
and fine fractions. Calculated geocumulation index and enrichment factors suggest that contamination could be derived from
anthropogenic activities attributed to harbor and ship scrapping activities, as well as transboundary source. Concentration
of total aromatic hydrocarbons (as chrysene equivalents) ranged from 0.01 to 534 μg l−1 in water, and from 0.10 to 2,160 μg g−1 in sediments. Total aromatic concentration of 5 μg g−1 is proposed as background concentration. 相似文献
154.
Guiling?L.?ZhangEmail author Jing?Zhang Jie?Xu Jingling?L.?Ren Sumei?M.?Liu 《Water, Air, & Soil Pollution: Focus》2007,7(6):645-654
CH4 concentrations in both the surface and bottom waters of Jiaozhou Bay were determined during four surveys in 2003, which showed
variability with both seasons and tidal cycles. Atmospheric fluxes of CH4 in Jiaozhou Bay showed obvious seasonal and spatial variations, with the highest values occurring in summer and the lowest
in winter. The annual emission of CH4 from Jiaozhou Bay was estimated to be . CH4 in the water column of Jiaozhou Bay was found to come from several land-sources including riverine water input, sewage water
input and groundwater input. The spatial and temporal variation in distributions and atmospheric fluxes of CH4 in Jiaozhou Bay was influenced mainly by the input of polluted river waters and the sewage effluents along the eastern coast,
which highlights the effects of human impacts on CH4 emission rates. 相似文献
155.
Hosny K. Khordagui 《Environmental management》1992,16(3):309-316
It is estimated that some 17 metric tons of residual oxidants (chlorine) are discharged into the enclosed coastal seawater
of Kuwait on a daily basis from power-desalination plants alone. Alarmed by the unlimited number of reported cases of damage
to marine aquatic systems due to chlorine discharge around the world, several alternatives were proposed to control such a
massive discharge of residual oxidant into seawaters. Most of the proposed alternatives lacked the basic criteria necessary
for their evaluation, justification, and then selection.
The objective of this article is to provide a conceptual approach that can be used to select a control measure for residual
oxidant discharge in Kuwait coastal seawaters. This approach is based on state-of-the-art knowledge and the unique operational
and environmental factors involved. A matrix system was designed whereby the cost of residual chlorine control alternative,
its effectiveness, and environmental and public health impact, performance, and reliability in Kuwait can be compared and
evaluated. The selection approach considered currently operating power plants in terms of their engineering design and material
(cast iron or steel condensers), current operational conditions, operator's perception, acceptability, and projected problems
associated with the environmental management of proposed modifications.
The proposed approach revealed that in Kuwait, conventinal chlorination was marginally superseded only by chlorination/dechlorination
using SO2 and operation alteration using process optimization. The overall cost-effective assessment matrix classified other alternatives
as worse than chlorination by various degrees.
Ozone and UV were found to be the worst and the least desirable alternatives for biofouling control of seawater in Kuwait.
In light of the available information on the consequences of the Gulf War on the marine environment, and the potential formation
of additional halogenated organic compounds through the reaction of residual chlorine with the released petroleum hydrocarbons,
it is essential to control residual chlorine discharged into the nearshore environment of Kuwait. 相似文献
156.
157.
海湾扇贝苗运输环境条件的研究 总被引:4,自引:0,他引:4
在实验室条件下,研究了温度和湿度对海湾扇贝苗存活的影响;双结合生产性运输,研究了温度,溶解氧,运输季节和贝苗规格对运输贝苗存活的影响。担子同运输包装贝苗方法:12h以内的运输,用干贮法;12-18h以内,用淋贮法,18-21h以内,用水贮帆布桶法。21-34h内,用水贮保温箱法。运输贝苗的主要条件是;低温,高湿度或足够的溶解适宜季节,适宜贝苗规格。 相似文献
158.
Concentration level of heavy metals in the Great Wall Bay, Antarctica in austral summer 总被引:1,自引:0,他引:1
ConcentrationlevelofheavymetalsintheGreatWallBay,Antarcticainaustralsummer¥PuJiabin;FuYunna;LiZhongping(InstituteofMarineEnvi... 相似文献
159.
实验研究了海泊河废水及其河口区水体的光学性质以及溶解有机碳(DOC)浓度,分析了光吸收系数(aCDOM)、最大荧光强度与DOC的关系.结果表明,海水中aCDOM在1.81~3.51 m-1内,平均值为2.39 m-1;而废水样品的aCDOM在0.59~16.23 m-1内,平均值为3.35 m-1.海水中aCDOM、光吸收指数斜率系数(S)、最大荧光强度以及DOC浓度都小于废水中相应的参数.水体中aCDOM、最大荧光强度以及DOC浓度三者之间均存在较好的线性关系.胶州湾东部海区海水中CDOM主要来源于海泊河排放的废水,由于水动力和潮汐作用较强而很快扩散,它们的浓度很快降低,在海泊河附近海区没有明显的积累. 相似文献
160.
根据青岛市胶州湾周边的水文地质条件及地下水位、水质动态特征,运用断面法计算了2001~2003年该区地下水及其N、P、Si无机营养盐向海湾的输送量.研究表明近年该区地下水向海湾的输送量分别为(1.87~2.41)×106m3,其中白沙河平原输送量占95%以上.地下水向海湾的NO 2、NH 4、PO3-4输送量较少,而NO 3和可溶性SiO2的输送量较大,分别达(4.3~6.6)×106 mol/a、(0.6~1.1)×106 mol/a,分别占河流输送量的20%和1.3%,白沙河平原地下水NO 3输送量占研究区地下水总输送量的99%. 相似文献