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   489篇
  免费   10篇
  国内免费   4篇
安全科学   11篇
废物处理   35篇
环保管理   55篇
综合类   62篇
基础理论   90篇
污染及防治   169篇
评价与监测   52篇
社会与环境   26篇
灾害及防治   3篇
  2023年   9篇
  2022年   28篇
  2021年   25篇
  2020年   17篇
  2019年   11篇
  2018年   25篇
  2017年   24篇
  2016年   20篇
  2015年   18篇
  2014年   18篇
  2013年   41篇
  2012年   24篇
  2011年   45篇
  2010年   29篇
  2009年   30篇
  2008年   30篇
  2007年   29篇
  2006年   22篇
  2005年   13篇
  2004年   16篇
  2003年   8篇
  2002年   4篇
  2001年   4篇
  2000年   4篇
  1998年   2篇
  1994年   3篇
  1993年   2篇
  1991年   1篇
  1983年   1篇
排序方式: 共有503条查询结果,搜索用时 15 毫秒
361.
LC-MS/MS was used for determination of selected tetracyclines, sulfonamides, trimethoprim, and fluoroquinolones in manure samples of pig, chicken and turkey, as well as arable soils fertilized with manure. Recoveries from spiked samples ranged from 61 to 105%. Method quantification limits were set to 100 microg/kg for all substances. Analysis of 30 pig manure, 20 chicken and turkey dung, and 30 lyophilized soil samples taken in Austria revealed that in pig manure up to 46 mg/kg chlortetracycline, 29 mg/kg oxytetracycline and 23 mg/kg tetracycline could be detected. As representatives of the group of sulfonamides, sulfadimidine in pig manure and sulfadiazine in chicken and turkey dung were detected in significant amounts (maximum concentration, 20 and 91 mg/kg, respectively). Enrofloxacin was particularly observed in chicken and turkey samples. Positive detection of chlortetracycline, enrofloxacin, and ciprofloxacin, in soil samples should be outlined as most important results of this study.  相似文献   
362.
Sediments in the National Park of the Atlantic Islands (Galicia, Spain) were affected by the spill of the tanker Prestige (November, 2002) and still present high levels of Polycyclic aromatic hydrocarbons. The adverse effects associated with the contaminants in sediments were tested using a chronic bioassay, exposing juveniles of the fish Sparus aurata (seabream). A toxicokinetic approach is proposed to evaluate sediment quality by linking chemical and ecotoxicological data along the time. Sediment samples were physicochemically characterized and the concentration of contaminants (Polycyclic aromatic hydrocarbons – PAHs – and metals) was measured. Fishes were exposed to contaminated sediments, and samples from different tissues were collected every 15 days throughout the 60 days that lasted the experiment. A biomarker of exposure (ethoxyresorufin O-deethylase activity – EROD activity) and a biomarker of effect (histopathology) were analyzed during the exposure period. Results show a relationship between the biomarkers and the concentrations in sediments of polycyclic aromatic hydrocarbons—PAHs. Besides, the toxicokinetic approach links biomarkers response providing information about the relationship between the detoxification process and the damages observed in the different tissues. The frequency of the histological damage is highest when the EROD activity slightly decreases in accordance with the mechanism of detoxification of this enzymatic system against PAHs and other organic contaminants.  相似文献   
363.
Summary. The earwig Doru taeniatum (Dermaptera, Forficulidae) has a pair of defensive glands, opening on the 4th abdominal tergite, from which it discharges a spray when disturbed. It aims the discharges by revolving the abdomen, a maneuver that enables it simultaneously to use its pincers in defense. The secretion contains two quinones (methyl-1,4-benzoquinone and 2,3-dimethyl-1,4-benzoquinone) present in the glands as a crystalline mass, together with pentadecane and a (presumably) aqueous phase. The gland openings are minute, with the result that virtually no quinone crystals are expelled with the spray. Only the two liquid phases are discharged, together with the ca. 1% quinone they carry in solution. Such a solute-economizing discharge mechanism appears to be without parallel among insect defensive glands. Received 14 February 2000; accepted 21 February 2000  相似文献   
364.
The conservation of long-distance migratory birds requires coordination between the multiple countries connected by the movements of these species. The recent expansion of tracking studies is shedding new light on these movements, but much of this information is fragmented and inaccessible to conservation practitioners and policy makers. We synthesized current knowledge on the connectivity established between countries by landbirds and raptors migrating along the African–Eurasian flyway. We reviewed tracking studies to compile migration records for 1229 individual birds, from which we derived 544 migratory links, each link corresponding to a species’ connection between a breeding country in Europe and a nonbreeding country in sub-Saharan Africa. We used these migratory links to analyze trends in knowledge over time and spatial patterns of connectivity per country (across species), per species (across countries), and at the flyway scale (across all countries and all species). The number of tracking studies available increased steadily since 2010 (particularly for landbirds), but the coverage of existing tracking data was highly incomplete. An average of 7.5% of migratory landbird species and 14.6% of raptor species were tracked per country. More data existed from central and western European countries, and it was biased toward larger bodied species. We provide species- and country-level syntheses of the migratory links we identified from the reviewed studies, involving 123 populations of 43 species, migrating between 28 European and 43 African countries. Several countries (e.g., Spain, Poland, Ethiopia, Democratic Republic of Congo) are strategic priorities for future tracking studies to complement existing data, particularly on landbirds. Despite the limitations in existing tracking data, our data and results can inform discussions under 2 key policy instruments at the flyway scale: the African–Eurasian Migratory Landbirds Action Plan and the Memorandum of Understanding on the Conservation of Migratory Birds of Prey in Africa and Eurasia.  相似文献   
365.
Journal of Material Cycles and Waste Management - Leakage modeling can be crucial for environmental management and control of waste landfills. However, defining boundary conditions for these models...  相似文献   
366.
367.
Dispersal and migratory behaviours are often important determinants of gene flow in wild species, and we have studied their role using ringing-recapture data in the Portuguese population of Miniopterus schreibersii, a cave-dwelling bat that forms large maternity colonies. Juvenile dispersal, usually a major agent of gene flow, appears to be negligible, as young females never settled to give birth in foreign colonies. Likewise, there was virtually no dispersal of adult females to foreign maternity colonies. This strong philopatry virtually eliminated female-mediated gene flow, but we found a great potential for male-mediated gene flow among colonies, as regional migrations temporarily joined both sexes from different colonies in the same roosts, during the mating season. In fact, females from some colonies were more likely to mate with males from foreign colonies than from their own, thus potentially bringing home genes of foreign males. In spite of this abundant gene flow, we found a pattern of isolation by distance and even strong barriers to gene flow, which is explained by the fact that migrations were usually too short to allow direct flow among distant colonies. We concluded that potential gene flow is influenced by the distance between colonies and the availability of mating roosts between them. In addition, we found this flow to be asymmetrical, with a dominant direction from the largest to the smallest colonies. Our ringing-recapture estimates of potential gene flow based on dispersal and migratory behaviour are compatible with the genetic structure of the population for both nuclear and mitochondrial DNA. Our conclusions have implications for the conservation of bats with a spatial behaviour similar to that of M. schreibersii. Colonies should be managed individually because strict female philopatry not only promotes their isolation but also minimises the contribution of immigration in rescuing declining colonies. Furthermore, the results underline the importance of preserving mating roosts to maintain gene flow among colonies.  相似文献   
368.
Abstract: Returning confiscated animals to their native habitats is desirable when it makes a positive contribution to the conservation of the species. Release of captive individuals is complex and controversial, however, particularly when risks are potentially high, as in the case of orphaned apes. We describe the decision-making process that led to the successive release of 20 wild-born orphan chimpanzees (    Pan troglodytes troglodytes ) into the Conkouati Reserve in the Republic of Congo. Recommendations of the Reintroduction Specialist Group of the World Conservation Union's Species Survival Commission were followed closely. The conservation status, ecology, and behavior of wild chimpanzees; the biological, social, economic and political context of the release site; and the health and genetic status of the candidates for release were all taken into account in the planning and execution of the project. Rigorous post-release monitoring of behavior and health allowed documentation of the outcome. The project was of benefit to the chimpanzees that were released but also brought broad benefits to the site through effective protection from poaching and deforestation, and direct and indirect benefits to local people. The genetic and behavioral diversity of chimpanzees require a variety of conservation strategies to reduce threats and maintain as many viable wild populations as possible.  相似文献   
369.
Degradation of total phenol (TPh) and organic matter, (expressed as total organic carbon TOC), of a simulated olive mill wastewater was evaluated by the Fenton oxidation process under batch and continuous mode conditions. A mixture of six phenolic acids usually found in these agro-industrial wastewaters was used for this purpose. The study focused on the optimization of key operational parameters of the Fenton process in a batch reactor, namely Fe2+ dosage, hydrogen peroxide concentration, pH, and reaction temperature. On the assessment of the process efficiency, > 99% of TPh and > 56% of TOC removal were attained when [Fe2+] = 100 ppm, [H2O2] = 2.0 g/L, T = 30 °C, and initial pH = 5.0, after 300 min of reaction. Under those operational conditions, experiments on a continuous stirred-tank reactor (CSTR) were performed for different space-time values (τ). TOC and TPh removals of 47.5 and 96.9%, respectively, were reached at steady-state (for τ = 120 min). High removal of COD (> 75%) and BOD5 (> 70%) was achieved for both batch and CSTR optimum conditions; analysis of the BOD5/COD ratio also revealed an increase in the effluent’s biodegradability. Despite the high removal of lumped parameters, the treated effluent did not met the Portuguese legal limits for direct discharge of wastewaters into water bodies, which indicates that coupled chemical-biological process may be the best solution for real olive mill wastewater treatment.  相似文献   
370.
The aim of this study was to assess the degradation and mineralization of hydroquinone (HQ) by the Fenton’s process in a bubble column reactor (BCR). The effect of the main operating variables, namely, air flow rate, effluent volume, hydrogen peroxide (H2O2) concentration, catalyst (Fe2+) dose, initial pH, and temperature, were assessed. For all air flow rates tested, no concentration gradients along the column were noticed, evidencing that a good mixing was reached in the BCR. For the best conditions tested ([H2O2] = 500 mg/L, [Fe2+] = 45 mg/L, T = 24 °C, Q air = 2.5 mL/min, pH = 3.0, and V = 5 L), complete HQ degradation was reached, with ~ 39% of total organic carbon (TOC) removal, and an efficiency of the oxidant use—η H2O2—of 0.39 (ratio between TOC removed per H2O2 consumed normalized by the theoretical stoichiometric value); moreover, a non-toxic effluent was generated. Under these conditions, the intermediates and final oxidation compounds identified and quantified were a few carboxylic acids, namely, maleic, pyruvic, and oxalic. As a strategy to improve the TOC removal, a gradual dosage of the optimal H2O2 concentration was implemented, being obtained ~ 55% of mineralization (with complete HQ degradation). Finally, the matrix effect was evaluated, for which a real wastewater was spiked with 100 mg/L of HQ; no reduction in terms of HQ degradation and mineralization was observed compared to the solution in distilled water.  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