全文获取类型
收费全文 | 15322篇 |
免费 | 515篇 |
国内免费 | 1969篇 |
专业分类
安全科学 | 564篇 |
废物处理 | 703篇 |
环保管理 | 1640篇 |
综合类 | 5201篇 |
基础理论 | 3793篇 |
环境理论 | 4篇 |
污染及防治 | 2995篇 |
评价与监测 | 1063篇 |
社会与环境 | 1639篇 |
灾害及防治 | 204篇 |
出版年
2024年 | 27篇 |
2023年 | 151篇 |
2022年 | 409篇 |
2021年 | 421篇 |
2020年 | 387篇 |
2019年 | 320篇 |
2018年 | 906篇 |
2017年 | 930篇 |
2016年 | 873篇 |
2015年 | 485篇 |
2014年 | 586篇 |
2013年 | 867篇 |
2012年 | 829篇 |
2011年 | 1398篇 |
2010年 | 924篇 |
2009年 | 992篇 |
2008年 | 1175篇 |
2007年 | 1304篇 |
2006年 | 465篇 |
2005年 | 416篇 |
2004年 | 325篇 |
2003年 | 434篇 |
2002年 | 443篇 |
2001年 | 302篇 |
2000年 | 270篇 |
1999年 | 173篇 |
1998年 | 163篇 |
1997年 | 121篇 |
1996年 | 96篇 |
1995年 | 103篇 |
1994年 | 84篇 |
1993年 | 82篇 |
1992年 | 75篇 |
1991年 | 57篇 |
1990年 | 67篇 |
1989年 | 52篇 |
1988年 | 41篇 |
1987年 | 31篇 |
1986年 | 31篇 |
1985年 | 32篇 |
1984年 | 42篇 |
1983年 | 43篇 |
1982年 | 34篇 |
1981年 | 43篇 |
1980年 | 30篇 |
1979年 | 31篇 |
1978年 | 28篇 |
1976年 | 28篇 |
1975年 | 26篇 |
1972年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
为研究于桥水库浮游植物群落结构及其与环境因子的关系,于2014年春夏季进行采样分析。两季共鉴定出浮游植物6门99种,其中绿藻门(Chlorophyta)62种,硅藻门(Diatoms)21种,蓝藻门(Cyanophyta)7种,裸藻门(Euglenophyta)4种,甲藻门(Pyrrophyta)2种,隐藻门(Cryptophyta)2种。春季浮游植物6门86种,第一优势种为绿藻门的四尾栅藻(Scenedesmus quadricauda);夏季浮游植物5门62种,第一优势种为蓝藻门的铜绿微囊藻(Microcystis aeruginosa)。春季浮游植物密度低于夏季,于桥水库浮游植物群落结构具有明显的季节变化规律。RDA分析结果表明,春季采样点的相似性高于夏季,透明度、水温、溶解氧和营养盐是影响于桥水库浮游植物群落组成的关键环境因子。 相似文献
993.
994.
995.
An Approach to Reaeration Coefficient Modeling in Local Surface Water Quality Monitoring 总被引:1,自引:0,他引:1
Reaeration coefficient (k 2) for River Atuwara, Ogun State, Nigeria was calculated from dissolved oxygen and biochemical oxygen demand data collected over period of 3 months covering the two prevailing climatic seasons in the country. Both the Akaike and Bayesian information criteria were used in the selection and analysis of ten models to identify the most suitable reaeration coefficient (k 2) model for Atuwara River. Models that passed the confidence limit were subjected to model evaluation using measures of agreement between observed and predicted data such as percent bias, Nash–Sutcliffe efficiency, and root mean square observation standard deviation ratio. The used approach yield better results than empirical models developed for local conditions while it is also useful in conserving scarce resources. 相似文献
996.
The dynamics of toxic and nontoxic Microcystis during bloom in the large shallow lake,Lake Taihu,China 总被引:1,自引:0,他引:1
Daming Li Yang Yu Zhen Yang Fanxiang Kong Tongqing Zhang Shengkai Tang 《Environmental monitoring and assessment》2014,186(5):3053-3062
Lake Taihu is a large shallow freshwater lake (surface area 2,338 km2, mean depth 1.9 m) in China, which has experienced toxic cyanobacterial bloom dominated by Microcystis annually during the last few decades. In the present study, the dynamics of toxic and nontoxic Microcystis in three sampling stations (Meiliang Bay (site N2), Gonghu Bay (site N4), and the lake center area (site S4)) were quantified using quantitative real-time PCR (qPCR) during bloom periods from April to September, 2010. Our data showed that the abundance of toxic Microcystis and the toxic proportion gradually increased from April to August in water samples and reached the peak in August. During the study period, toxic Microcystis genotypes comprised between 26.2 and 64.3, between 4.4 and 22.1, and between 10.4 and 20.6 % of the total Microcystis populations in the three sampling sites, respectively. Correlation analysis suggested that there was a strong positive relationship between total Microcystis, toxic Microcystis and the toxic proportion. Chlorophyll a, total phosphorus, and water temperature were positively correlated with the abundances of total Microcystis and toxic Microcystis. Furthermore, the toxic proportion was positively correlated with total phosphorus (P?<?0.05) and water temperature (P?<?0.01), showing that global warming together with eutrophication could promote more frequent toxic blooms. 相似文献
997.
Hydrologic modelling for Lake Basaka: development and application of a conceptual water budget model
Megersa O. Dinka Willibald Loiskandl Julius M. Ndambuki 《Environmental monitoring and assessment》2014,186(9):5363-5379
Quantification of fluxes of water into and out of terminal lakes like Basaka has fundamental challenges. This is due to the fact that accurate measurement and quantification of most of the parameters of a lake’s hydrologic cycle are difficult. Furthermore, quantitative understanding of the hydrologic systems and hence, the data-intensive modelling is difficult in developing countries like Ethiopia due to limitation of sufficient recorded data. Therefore, formulation of a conceptual water balance model is extremely important as it presents a convenient analytical tool with simplified assumptions to simulate the magnitude of unknown fluxes. In the current study, a conceptual lake water balance model was systematically formulated, solved, calibrated, and validated successfully. Then, the surface water and groundwater interaction was quantified, and a mathematical relationship developed. The overall agreement between the observed and simulated lake stage at monthly time step was confirmed based on the standard performance parameters (R 2, MAE, RMSE, E f). The result showed that hydrological water balance of the lake is dominated by the groundwater (GW) component. The net GW flux in recent period (post-2000s) accounts about 56 % of the total water inflow. Hence, GW plays a leading role in the hydrodynamics and existence of Lake Basaka and is mostly responsible for the expansion of the lake. Thus, identification of the potential sources/causes for the GW flux plays a leading role in order to limit the further expansion of the lake. Measurement of GW movement and exchange in the area is a high priority for future research. 相似文献
998.
M. Ausejo M. Recuero C. Asensio I. Pavón J. M. López 《Environmental Modeling and Assessment》2010,15(2):125-135
This article aims to discuss the influence of input data on the simulation model when designing Strategic Noise Maps. The
studied noise map was made in the Macrocenter of the Independent City of Buenos Aires (Argentina), which has an approximated
extension of 20 km2 and about 500,000 inhabitants. The several input data for the model are analyzed, for their quality and the lack of some
of them could affect the final result. Also, the evolution and validity of experimental measurements are analyzed when validating
a simulated map. Finally, a study of the uncertainty of the map based on the input data is made, comparing it with the recommendations
internationally adopted. 相似文献
999.
Evangelia Strogyloudi Michael O. Angelidis Anastassios Christides Evangelos Papathanassiou 《Environmental monitoring and assessment》2012,184(12):7189-7205
Spatial and temporal variability of Cd, Cu, Cr, Ni, Zn, Fe and Mn and metallothionein (MT) concentrations were determined in mussels Mytilus galloprovincialis from Elefsis bay (Saronikos gulf, Greece). Higher concentrations of both metal concentrations and MTs were recorded in mussels inhabiting industrial locations (steelworks and shipyard), indicating a markedly higher metal bioavailability. However at these sites, located at the eastern part of the bay, mussel metal concentrations were not always correlated with both seawater metal concentrations and MTs possibly due to different time scales of integration of the metal sources into mussels and/or the participation of other metal regulatory mechanisms except MT induction. The pattern of the temporal variation of mussel metal concentrations and the MT levels was similar among stations with higher values during the winter–spring season and lower during the summer–autumn period. The inverse relationship of flesh condition index with mussel metal concentrations was attributed to the influence of mussel annual reproductive cycle. 相似文献
1000.
This study applied a method of the rotated empirical orthogonal functions to directly decompose the space-time groundwater level variations and determine the potential recharge zones by investigating the correlation between the identified groundwater signals and the observed local rainfall records. The approach is used to analyze the spatiotemporal process of piezometric heads estimated by Bayesian maximum entropy method from monthly observations of 45 wells in 1999-2007 located in the Pingtung Plain of Taiwan. From the results, the primary potential recharge area is located at the proximal fan areas where the recharge process accounts for 88% of the spatiotemporal variations of piezometric heads in the study area. The decomposition of groundwater levels associated with rainfall can provide information on the recharge process since rainfall is an important contributor to groundwater recharge in semi-arid regions. Correlation analysis shows that the identified recharge closely associates with the temporal variation of the local precipitation with a delay of 1-2 months in the study area. 相似文献