首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   416篇
  免费   2篇
  国内免费   6篇
安全科学   12篇
废物处理   33篇
环保管理   39篇
综合类   43篇
基础理论   77篇
环境理论   3篇
污染及防治   167篇
评价与监测   25篇
社会与环境   23篇
灾害及防治   2篇
  2023年   5篇
  2022年   18篇
  2021年   16篇
  2020年   3篇
  2019年   10篇
  2018年   16篇
  2017年   20篇
  2016年   20篇
  2015年   10篇
  2014年   23篇
  2013年   34篇
  2012年   24篇
  2011年   38篇
  2010年   22篇
  2009年   12篇
  2008年   25篇
  2007年   24篇
  2006年   20篇
  2005年   15篇
  2004年   10篇
  2003年   14篇
  2002年   11篇
  2001年   2篇
  2000年   3篇
  1999年   5篇
  1998年   2篇
  1997年   1篇
  1996年   4篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1992年   2篇
  1991年   3篇
  1990年   1篇
  1986年   1篇
  1982年   2篇
  1981年   1篇
  1958年   1篇
  1956年   1篇
排序方式: 共有424条查询结果,搜索用时 171 毫秒
351.
Selective predation can be an important force driving the evolution of organisms. In particular, sex-biased predation is expected to have implications for sexual selection, sex allocation and population dynamics. In this study, we analysed sex differences in the predation of the western green lizard (Lacerta bilineata) by the Eurasian kestrel (Falco tinnunculus) during the reproductive season. In addition, we investigated whether the rate of predation differed during the 8-year study period and among the three habitats studied. We collected lizard remains from nest boxes of kestrels. Freshly killed lizards were sexed by visual inspection, whilst the sex of head remains was assigned by analysing the cephalic scale morphology using geometric morphometrics. Our results show that the risk of being predated by a kestrel in our population was overall about 3.55 times higher for males than for females. To our knowledge this is the first study showing a male-biased predation in a lizard species. The selective predation of males was consistent between years over the 8-year study period (1999-2006) and also consistent between the three types of kestrel hunting habitat. Overall predation rates on lizards differed between habitats, depending on the year. We propose that the observed sex-biased predation is mainly due to sex differences in lizard behaviour.  相似文献   
352.
Sublethal toxicity of the Prestige oil spill on yellow-legged gulls   总被引:1,自引:0,他引:1  
The Prestige oil spill in November 2002 is considered the biggest large-scale catastrophe of its type in Europe, thousands of seabirds dying in the subsequent months. Here, the total concentration of 16 polycyclic aromatic hydrocarbons (TPAH) was measured in the blood cell fraction of adult and chick yellow-legged gulls (Larus michahellis) from unoiled and oiled coastal areas in North Western Spain. In addition, hematocrit, plasma metabolites, electrolytes and enzymes, as well as body mass were determined in the same individuals. Our results strongly suggest the presence of health damages of sublethal nature in adult gulls breeding in oiled colonies 17 months after the Prestige oil spill. This is supported by the following evidences: (1) gulls sampled in unoiled and oiled colonies differed in blood TPAH levels, (2) gulls sampled in unoiled and oiled colonies differed in several blood parameters indicative of physiological disorders, and (3) TPAH in blood was significantly related to several of these parameters. Differences in the level of asparatate aminotransferase (AST), gamma-glutamyl transferase (GGT), total protein, glucose and inorganic phosphorus suggest damages on some vital organs (i.e. liver and kidney) in adult birds from oiled areas. Meanwhile, chicks presented weaker effects than adults, showing only between-area differences in hematocrit. Since TPAH levels in blood did not differ between both age-groups, the stronger effects on adults should be due to their longer exposure to these pollutants and/or to severe exposure in the months following the spill. The presence of PAHs in chicks indicates that these pollutants were incorporated into the food chain because nestlings would have been only exposed to contaminated organisms in the diet (e.g. fishes and crustaceans). Our findings support the view that PAHs may deeply alter the physiology of seabirds, and emphasize the necessity of quantifying the circulating levels of these compounds in order to evaluate the sublethal effects associated to large oil spills.  相似文献   
353.
354.
We investigate the spatial and temporal features of variable-density contaminant plumes migration in porous materials. Our analysis is supported by novel experimental results concerning concentration profiles inside a vertical column setup that has been conceived at CEA to this aim. The experimental method relies on X-ray spectrometry, which allows determining solute profiles as a function of time at several positions along the column. The salient outcomes of the measurements are elucidated, with focus on miscible fluids in homogeneous saturated media. The role of the injected solution molarity is evidenced. As molarity increases, the solutes plume transport progressively deviates from the usual Fickian behavior, and pollutants distribution becomes skewed in the direction dictated by gravity. By resorting to a finite elements approach, we numerically solve the nonlinear equations that rule the pollutants migration: a good agreement is found between the simulated profiles and the experimental data. At high molarity, a strong dependence on initial conditions is found. Finally, we qualitatively explore the (unstable) interfacial dynamics between the dense contaminant plume and the lighter resident fluid that saturates the column, and detail its evolution for finite-duration contaminant injections.  相似文献   
355.
The aim of this paper was to investigate the effect of recycled polypropylene (PP) on the rheological, mechanical and thermal properties of wood flour polypropylene composites. Beforehand, the influence of wood flour treated with a coupling agent on the rheological behaviour had been looked at. By analysing moduli and viscosity curves and studying the thermal and mechanical properties of samples with 10% filler it was possible to see that the recycled PP that was added change in either its physical properties or its rheology. In the other wood plastic composites (WPC) studied, slight changes in the rheology behaviour were observed. However, the same processing parameters may be used with and without recycled PP. Recycled PP is appropriate for these kinds of composites to maintain the optimal rheological properties that make it easier to process the material by extrusion. Furthermore, it is also possible to maintain the thermal and mechanical properties in comparison with the behaviour of virgin PP/wood flour composites.  相似文献   
356.
Chemical-Looping Combustion (CLC) is an emerging technology for CO2 capture because separation of this gas from the other flue gas components is inherent to the process and thus no energy is expended for the separation. Natural or refinery gas can be used as gaseous fuels and they may contain different amounts of light hydrocarbons. This paper presents the combustion results obtained with a Cu-based oxygen carrier using mixtures of CH4 and light hydrocarbons (LHC) (C2H6 and C3H8) as fuel. The effect on combustion efficiency of the fuel reactor temperature, solid circulation flow rate and gas composition was studied in a continuous CLC plant (500 Wth). Full combustions were reached at 1073 and 1153 K working at oxygen to fuel ratios, ? higher than 1.5 and 1.2 respectively. Unburnt hydrocarbons were never detected at any experimental conditions at the fuel reactor outlet. Carbon formation can be avoided working at 1153 K or at ? values higher than 1.5 at 1073 K. After 30 h of continuous operation, the oxygen carrier exhibited an adequate behavior regarding attrition and agglomeration. It can be concluded that no special measures should be taken in a CLC process with Cu-based OC with respect to the presence of LHC in the fuel gas.  相似文献   
357.
The Coordinating Research Council held its 16th workshop in March 2006, with 83 presentations describing the most recent mobile source-related emissions research. In this paper, we summarize the presentations from researchers who are engaged in improving our understanding of the contribution of mobile sources to air quality. Participants in the workshop discussed evaluation of in-use emissions control programs, effects of fuels on emissions, emission models and emission inventories, results from gas- and particle-phase emissions studies from spark-ignition and diesel-powered vehicles, and efforts to improve our capabilities in performing on-board emissions measurements, as well as topics for future research.  相似文献   
358.
Sediment cores from four Chilean lakes along the Andes Chain (Chungará, Laja, Castor and Venus) were analysed in order to investigate PCB concentrations and distributions in sediment samples. Sediment cores were analysed for PCBs using gas chromatography (GC-ECD/MS) and radioisotopically dated using 210Pb. Organic carbon content (OC) and 210Pb fluxes were also measured. Results showed that sediment PCB concentrations (ngg(-1) d.w.) at Lake Chungará (1.2 +/- 1) in northern Chile, Laja (5 +/- 4) in central, and in Lake Castor (3.5 +/- 4) in southern Chile (the eastern side of the Andes Mountain) were lower than sediments collected from Lake Venus (64 +/- 30) located in southern Chile (the western side) which contained 15-fold higher concentrations of PCBs. The percentage (%) of organic carbon was variable and showed a high range of values in the sediment fluctuating from 2% (Lake Laja) to 22% (Lake Chungará). Analysis of 210Pb fluxes, presented a decrease trend following Lake Laja>Castor>Chungará with a positive correlation with rainfall at each site. Sedimentation rates in Lake Castor (1846 gm(-2)yr(-1)) were higher than at Chungará (748 gm(-2)yr(-1)) and Lake Laja (508 gm(-2)yr(-1)). Focusing factor (FF) is used as a tool to elucidate PCB input in the aquatic ecosystem. FF were lower (<1) for the shallower lakes (Lakes Chungará and Castor). This study provides background levels of PCBs at remote lakes in Chile. Differences in geographical characteristics (orographic effect) might play an important role in the arrival of PCBs, particularly into the southern lakes. PCB fluxes indicated deposition of PCBs in recent sediments is higher than in previous years with peaks of PCB between 1991 and 1998. The continuing increase of PCB inputs in remote Chilean lakes, could be associated with long range atmospheric transport (LRAT).  相似文献   
359.
This paper reports the results of a pesticide monitoring survey on wine grapes from the 2008–2010 vintage from vineyards grown according to integrated pest management strategies. A multi-residue gas chromatography-mass spectrometry method in electron ionization and chemical ionization mode has been used for the determination of 30 pesticides in wine samples. The analytical method showed good recoveries and allowed a good separation of the selected pesticides. Repeatability and intermediate precision showed good results with CV?<?20 %. The instrumental method limits of determination (LOD) and of quantification (LOQ) were below the maximum residue levels set in wine. The analysis of the wines showed that pesticide residues were below the instrumental LOQ, and most of them were undetectable (<LOD). Only the 38 % of the pesticide applied has been detected in at least one cultivar. Metalaxil, myclobutanil, and penconazole were the pesticides most frequently found, while carignano and vermentino were the cultivars with the higher number of residues.  相似文献   
360.
Environment, Development and Sustainability - An energy transition is currently underway around the world, in response to the objectives laid out by international agreements. Since the Kyoto...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号