全文获取类型
收费全文 | 2807篇 |
免费 | 21篇 |
国内免费 | 8篇 |
专业分类
安全科学 | 59篇 |
废物处理 | 117篇 |
环保管理 | 174篇 |
综合类 | 829篇 |
基础理论 | 487篇 |
环境理论 | 7篇 |
污染及防治 | 841篇 |
评价与监测 | 184篇 |
社会与环境 | 128篇 |
灾害及防治 | 10篇 |
出版年
2023年 | 16篇 |
2022年 | 36篇 |
2021年 | 52篇 |
2020年 | 29篇 |
2019年 | 33篇 |
2018年 | 81篇 |
2017年 | 67篇 |
2016年 | 94篇 |
2015年 | 80篇 |
2014年 | 98篇 |
2013年 | 168篇 |
2012年 | 81篇 |
2011年 | 139篇 |
2010年 | 104篇 |
2009年 | 103篇 |
2008年 | 151篇 |
2007年 | 136篇 |
2006年 | 110篇 |
2005年 | 93篇 |
2004年 | 68篇 |
2003年 | 78篇 |
2002年 | 67篇 |
2001年 | 75篇 |
2000年 | 52篇 |
1999年 | 30篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 21篇 |
1995年 | 22篇 |
1994年 | 38篇 |
1993年 | 19篇 |
1992年 | 16篇 |
1991年 | 15篇 |
1984年 | 16篇 |
1981年 | 18篇 |
1969年 | 14篇 |
1968年 | 13篇 |
1967年 | 15篇 |
1966年 | 23篇 |
1965年 | 29篇 |
1964年 | 17篇 |
1963年 | 25篇 |
1962年 | 23篇 |
1961年 | 30篇 |
1960年 | 20篇 |
1959年 | 21篇 |
1958年 | 13篇 |
1957年 | 24篇 |
1956年 | 16篇 |
1955年 | 16篇 |
排序方式: 共有2836条查询结果,搜索用时 93 毫秒
81.
82.
The significant processes controlling the fate of particulates are convection an dispersion on one hand, and sedimentation on the other hand. Due to inteparticulated reactions, larger aggregates can be formed from smaller units thus changing the sedimentation characteristics. These phenomena are summarized in a mathematical model whereby hydrodynamic effects as well as the control mechanisms of the dissolved phase are included. A relationship was derived on the basis of energy considerations leading to the formulation of a critical sedimentation velocity of the suspensa, which determines the transport capacity of the flowing system. The sedimentation term is calculated from the above discussed transport capacity, hydro-dynamic parameters and suspending media properties. Aggregation effects are taken into account as an increase of sedimentation velocities of the particles. The equations are solved in a particular computational routine such that the horizontal distribution of suspended solids in a natural system can be describe as function of the above discussed phenomena. The model was tested with in situ-measurements. It was found that the observed processes are described satisfactorily by this model. 相似文献
83.
A pedagogic problem in forestry and landscape management is to visualize future landscape effects of forest growth and current management activities in the forest. This paper presents a method for forecasting digital image projections of forest landscape dynamics. Static nonlinear regression functions estimate the digital numbers in a Landsat Thematic Mapper image. Regressors used are forest stand variables. By estimating the future forest stand data, based on intermediate treatment and growth, future satellite digital images are created. In a case study example, the future landscape of a forest block in the province of Västernorrland, Sweden, is projected to demonstrate the application of this visualization technique. 相似文献
84.
Aaron I. Packman Andrea Marion Mattia Zaramella Cheng Chen Jean-François Gaillard Denis T. Keane 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):433-442
Hyporheic exchange is known to provide an important control on nutrient and contaminant fluxes across the stream-subsurface
interface. Similar processes also mediate interfacial transport in other permeable sediments. Recent research has focused
on understanding the mechanics of these exchange processes and improving estimation of exchange rates in natural systems.
While the structure of sediment beds obviously influences pore water flow rates and patterns, little is known about the interplay
of typical sedimentary structures, hyporheic exchange, and other transport processes in fluvial/alluvial sediments. Here we
discuss several processes that contribute to local-scale sediment heterogeneity and present results that illustrate the interaction
of overlying flow conditions, the development of sediment structure, pore water transport, and stream-subsurface exchange.
Layered structures are shown to develop at several scales within sediment beds. Surface sampling is used to analyze the development
of an armor layer in a sand-and-gravel bed, while innovative synchrotron-based X-ray microtomography is used to observe patterns
of grain sorting within sand bedforms. We show that layered bed structures involving coarsening of the bed surface increase
interfacial solute flux but produce an effective anisotropy that favors horizontal pore water transport while limiting vertical
penetration. 相似文献
85.
Maie Bachmann Maksim Säkki Jaan Kalda Jaanus Lass Viiu Tuulik Hiie Hinrikus 《The Environmentalist》2005,25(2-4):165-171
Summary This study focuses on discrimination of changes, produced by low-level microwave exposure in intensity and time variability
of the human EEG at rest. The power spectral density (PSD) method and nonlinear scaling analysis of the length distribution
of low variability periods (LDLVP) were selected for analysis of the EEG signal. During the study, 19 healthy volunteers were
exposed to a microwave (450 MHz) of 217 Hz frequency on-off modulation. The field power density at the scalp was 0.16 mW/cm2. The experimental protocol consisted of ten cycles of repetitive microwave exposure. Signals from frontal, temporal, parietal
and occipital EEG channels on EEG theta, alpha and beta rhythms were analysed. Exposure to microwave causes average increase
of EEG activity. LDLVP analysis discriminated significant effect in time variability for 2 subjects (11%). PSD method detected
significant changes in intensity for 4 subjects (21%). The effect of low-level microwave exposure is stronger on EEG beta
rhythm in temporal and parietal regions of the human brain. 相似文献
86.
Tüzün I Bayramoğlu G Yalçin E Başaran G Celik G Arica MY 《Journal of environmental management》2005,77(2):85-92
The microalgae Chlamydomonas reinhardtii was used for the biosorption of Hg(II), Cd(II) and Pb(II) ions. The maximum adsorption of Hg(II) and Cd(II) ions on Chlamydomonas reinhardtii biomass was observed at pH 6.0 and the corresponding value for Pb(II) ions was 5.0. The biosorption of Hg(II), Cd(II) and Pb(II) ions by microalgae biomass increased as the initial concentration of Hg(II), Cd(II) and Pb(II) ions increased in the biosorption medium. The maximum biosorption capacities of microalgae for Hg(II), Cd(II) and Pb(II) ions were 72.2+/-0.67, 42.6+/-0.54 and 96.3+/-0.86 mg/g dry biomass, respectively. The affinity order for algal biomass was Pb(II)>Hg(II)>Cd(II). FT-IR analysis of algal biomass revealed the presence of amino, carboxyl, hydroxyl and carbonyl groups, which were responsible for biosorption of metal ions. Biosorption equilibrium was established in about 60 min and the equilibrium was well described by the Freundlich biosorption isotherms. Temperature change in the range of 5-35 degrees C did not affect the biosorption capacity. The microalgae could be regenerated using 0.1 M HCl, with up to 98% recovery, which allowed the reuse of the biomass in six biosorption-desorption cycles without any considerable loss of biosorption capacity. 相似文献
87.
Toxic metals removal from wastewater sewage sludge can be achieved through microbial processes involving Acidithiobacillus ferrooxidans. The oxidation of ferrous ions by A. ferrooxidans, cultured in sewage sludge filtrate, was studied in both batch and continuous flow stirred tank reactors. Sewage sludge filtrate containing natural nutrients (phosphorus and nitrogen) was recovered as effluent following the dehydration of a primary and secondary sludge mixture. Batch and continuous flow stirred tank reactor tests demonstrated that A. ferrooxidans were able to grow and completely oxidize ferrous iron in a culture medium containing more than 80% (v v(-1)) sewage sludge filtrate with 10 g Fe(II) L(-1) added. Toxic levels were reached when total organic carbon in the sewage sludge filtrate exceeded 250 mg L(-1). The ferric iron solution produced in the sludge filtrate by A. ferrooxidans was used to solubilize heavy metals in primary and secondary sludge. The solubilization of Cu, Cr, and Zn yielded 71, 49, and 80%, respectively. This is comparable with the yield percentages obtained using a FeCl(3) solution. The cost of treating wastewater sewage sludge by bioproducing a ferric ion solution from sewage sludge is three times less expensive than the conventional method requiring a commercial ferric chloride solution. 相似文献
88.
Christian Mougin Agnès Bouchez Laurence Denaix Isabelle Lamy François Laurent Fabrice Martin-Laurent Michel Mench 《Environmental science and pollution research international》2016,23(4):2974-2976
The fifth meeting of INRA’s national network of ecotoxicologists took place on 25 to 27 November 2014 in Biarritz, France. The main aim of the meeting was to bring together ecotoxicologists from INRA and associated partners, providing them ample opportunity to share and discuss their latest scientific results as well as the national policy of research in ecotoxicology and to precise perspectives for the network. 相似文献
89.
90.
Niinemets Ülo Kahru Anne Nõges Peeter Tuvikene Arvo Vasemägi Anti Mander Ülo Nõges Tiina 《Regional Environmental Change》2017,17(7):2079-2096
Regional Environmental Change - Globally increasing temperature and modifications in precipitation patterns induce major environmental alterations in aquatic ecosystems. Particularly profound... 相似文献