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   124篇
  免费   2篇
  国内免费   1篇
安全科学   1篇
废物处理   6篇
环保管理   4篇
综合类   20篇
基础理论   24篇
污染及防治   43篇
评价与监测   17篇
社会与环境   11篇
灾害及防治   1篇
  2023年   3篇
  2022年   5篇
  2021年   5篇
  2020年   6篇
  2019年   3篇
  2018年   11篇
  2017年   9篇
  2016年   4篇
  2015年   4篇
  2014年   6篇
  2013年   7篇
  2012年   5篇
  2011年   12篇
  2010年   5篇
  2009年   1篇
  2008年   6篇
  2007年   6篇
  2006年   10篇
  2005年   6篇
  2004年   1篇
  2003年   1篇
  2002年   8篇
  1994年   1篇
  1990年   1篇
  1986年   1篇
排序方式: 共有127条查询结果,搜索用时 15 毫秒
81.
Environmental Geochemistry and Health - Renewable natural resources are strategic for reducing greenhouse gas emissions and the human footprint. The renewability of these resources is a crucial...  相似文献   
82.
83.
Sacrococcygeal teratoma (SCT) is one of the most common tumors in newborns with a birth prevalence of up to 1 in 21 700 births. Routine fetal anomaly screening programs allow for prenatal diagnosis in many cases. Fetal ultrasound with Doppler evaluation and more recently magnetic resonance imaging may be used to document the extent of the tumor as well as identifying the population at risk for serious fetal complications. Rapidly growing SCT and highly vascularized tumors are more likely to have hemodynamic repercussions. Fetal hydrops is usually considered as a poor prognostic marker and a potential indicator for fetal intervention. Newborns with SCT require stabilization prior to early surgical resection. In case of malignancy additional chemotherapy may be required. SCT may result in significant morbidity, either directly or as a consequence of surgical therapy. Careful postnatal follow-up is required for timely identification and treatment of complications as well as recurrence. This paper aims to review the perinatal management of this condition. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
84.
Sustainability science is at an early stage of development. Among many other obstacles, there are two prominent issues hindering its advance. There is both a lack of a set of principles for knowledge construction, and a need to implement research to solve real problems. This paper proposes a typology of scientific reflections for meeting these two challenges and contributing to sustainability science development. This typology is made up of four kinds of reflection: practical, instrumental-methodological, theoretical-conceptual, and onto-epistemological. Each kind of reflection is based on a different type of question and gives shape to its respective type of research.  相似文献   
85.
Most hypotheses explaining the general gradient of higher diversity toward the equator are implicit or explicit about greater species packing in the tropics. However, global patterns of diversity within guilds, including trophic guilds (i.e., groups of organisms that use similar food resources), are poorly known. We explored global diversity patterns of a key trophic guild in stream ecosystems, the detritivore shredders. This was motivated by the fundamental ecological role of shredders as decomposers of leaf litter and by some records pointing to low shredder diversity and abundance in the tropics, which contrasts with diversity patterns of most major taxa for which broad-scale latitudinal patterns haven been examined. Given this evidence, we hypothesized that shredders are more abundant and diverse in temperate than in tropical streams, and that this pattern is related to the higher temperatures and lower availability of high-quality leaf litter in the tropics. Our comprehensive global survey (129 stream sites from 14 regions on six continents) corroborated the expected latitudinal pattern and showed that shredder distribution (abundance, diversity and assemblage composition) was explained by a combination of factors, including water temperature (some taxa were restricted to cool waters) and biogeography (some taxa were more diverse in particular biogeographic realms). In contrast to our hypothesis, shredder diversity was unrelated to leaf toughness, but it was inversely related to litter diversity. Our findings markedly contrast with global trends of diversity for most taxa, and with the general rule of higher consumer diversity at higher levels of resource diversity. Moreover, they highlight the emerging role of temperature in understanding global patterns of diversity, which is of great relevance in the face of projected global warming.  相似文献   
86.
87.
Mitigation and Adaptation Strategies for Global Change - Climate adaptation is seen by many as increasingly important and as deeply political, leading some to argue for its democratization. Social...  相似文献   
88.
The aim of this research is to determine the lethal concentration (LC(50-96 h)) of fungicide tebuconazole for common carp (Cyprinus carpio) and to investigate the occurrence of oxidative stress and metabolic changes after acute exposure to different concentrations of tebuconazole. For this purpose, several parameters were assessed as whole-body levels of thiobarbituric acid-reactive substance (TBARS), protein carbonyl, catalase, superoxide dismutase, glutathione S-transferase, nonprotein thiols, ascorbic acid, glycogen, glucose, lactate, protein, amino acids and ammonia in tebuconazole-exposed fish. The calculated LC(50-96 h) was 2.37 mg L(-1). Fish exhibited significant increase in TBARS levels in all concentrations used while the enzymatic and nonenzymatic antioxidants were decreased. Among the metabolic parameters, glycogen and glucose increased at 1.19 mg L(-1) and protein levels decreased at 1.78 and 2.37 mg L(-1). In conclusion, the fish health was adversely affected by exposure to tebuconazole, and those changes can compromise animal survival in the natural environment. The results indicate that the some of the parameters measured like a possible biomarkers of exposure to tebuconazole for this species of fish.  相似文献   
89.
An analytical procedure for the determination of Hg in otter (Lontra longicaudis) feces was developed, to separate fish scales for the identification of the animal diet. Samples were washed with ultra-pure water and the suspension was sampled and transferred for digestion. The solubilization was performed with nitric-perchloric acid mixture, and detection carried out by the atomic fluorescence spectrometry (AFS). The quality of the analytical procedure was assessed by analyzing in-house standard solutions and certified reference materials. Total Hg concentrations were in the range of 7.6-156 ng g(-1) (July 2004), 25.6-277 ng g(-1) (January 2005) and 14.6-744 ng g(-1) (May 2005) that is approximately the same order of magnitude for all samples collected in two reservoirs at the Tiete River, Brazil. Although Hg concentrations varied with sampling periods and diet, high levels were correlated to the percentage of carnivorous fish scales present in the otter feces.  相似文献   
90.
The aim of this work was to elucidate the role of nitrate as a terminal electron acceptor on the biodegradation of NPEO. We have characterized the products of NPEO degradation by mixed microbial communities in anaerobic batch tests by means of HPLC, 1H NMR and GC–MS. Anaerobic degradation of NPEO was strictly dependent on the presence of nitrate. Within seven days of anoxic incubation, NP2EO appeared as the major degradation product. After 21 days, NP was the main species detected, and was not degraded further even after 35 days. Nitrate concentration decreased in parallel with NPEO de-ethoxylation. A transient accumulation of nitrite was observed within the time period in which NP formation reached its maximum production. The observed generation of nonylphenol coupled to nitrate reduction suggests that the microbial consortium possessed an alternate pathway for the degradation of NPEO, which was not accessible under aerobic conditions.  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