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   159篇
  免费   0篇
  国内免费   5篇
安全科学   1篇
废物处理   23篇
环保管理   5篇
综合类   11篇
基础理论   28篇
污染及防治   46篇
评价与监测   30篇
社会与环境   19篇
灾害及防治   1篇
  2023年   5篇
  2022年   20篇
  2021年   18篇
  2020年   2篇
  2019年   2篇
  2018年   12篇
  2017年   10篇
  2016年   11篇
  2015年   5篇
  2014年   9篇
  2013年   9篇
  2012年   11篇
  2011年   7篇
  2010年   8篇
  2009年   2篇
  2008年   11篇
  2007年   8篇
  2006年   3篇
  2005年   3篇
  2004年   1篇
  2003年   2篇
  2002年   1篇
  2001年   2篇
  1999年   1篇
  1995年   1篇
排序方式: 共有164条查询结果,搜索用时 515 毫秒
111.
Given the importance of markets and fairs for the commerce of medicinal plants, an ethnobotanical study was undertaken at the Caruaru Fair (Pernambuco, northeastern Brazil) to compare the richness of species sold and their values of relative importance (RI) using two datasets collected with a 4-year interval. The seasonality of these plants?? supplies was also analyzed. The Caruaru Fair is located in the 18 de Maio Park. It covers an area 40,000?m2 and is used by merchants who sell several types of products, such as supplies, handicrafts, clay and aluminum utensils, shoes, clothes and medicinal plants. Semistructured interviews were carried out with the vendors who agreed to take part in the study in order to record which plants were sold and their respective indications. The plants were collected, and the species were determined. The information was analyzed with quantitative tools. A total of 169 plants were identified from both surveys, which were significantly different with regard to species richness (p?<?0.05) but did not vary in relation to species?? Relative Importance (p?>?0.05). In relation to the seasonality of the plant supply, habit may explain the lack of some species during certain periods of the year, as most of the absent plants are herbaceous. In terms of the species most sold locally, it was found that spontaneous tree species are well known and extensively commercialized.  相似文献   
112.
The coastal zone of the Brazilian state of Maranhão is an area characterized by a large variety of human activities and services, in particular in the Itaqui-Bacanga port complex (IBC). The IBC is an area prone to oil spills resulting from the processes of transportation, storage, and tank cleaning. The present study aimed to map the different physical environments adjacent to this complex and the socioeconomic profile of the local population that would be most vulnerable to this type of disaster. Vulnerability studies are essential as one of the first step in the development of an integrated coastal zone management. The variables analyzed in this study included geomorphological units, and the income, education, and dependence on fishing of the local population. The estimate of the vulnerability index was based on the relationships between these variables, which were used to generate a vulnerability map using GIS and the interpretation of high-resolution remote sensing, showing the areas of highest priority for intervention in the case of oil spills. The analysis of the natural and socioeconomic environments indicated that the areas of highest vulnerability correspond to the mangroves and the Vila Nova and Alto da Esperança neighborhoods, respectively. These neighborhoods have a direct relationship with fishing, and low levels of both income and education. By contrast, the lowest vulnerability was attributed to the coastal plateau and the central Anjo da Guarda neighborhood, which is occupied by residents with relatively high income and education, who do not depend on fishing.  相似文献   
113.
Sugarcane today plays a major role in the worldwide economy, and Brazil is the leading producer of sugar and alcohol, which are important international commodities. The production process generates bagasse as a waste, which is used as fuel to stoke boilers that produce steam for electricity cogeneration. The final product of this burning is residual sugarcane bagasse ash (SBA), which is normally used as fertilizer in sugarcane plantations. Ash stands out among agroindustrial wastes because it results from energy generating processes. Many types of ash do not have hydraulic or pozzolanic reactivity, but can be used in civil construction as inert materials. The present study used ash collected from four sugar mills in the region of São Carlos, SP, Brazil, which is one of the world’s largest producers of sugarcane. The ash samples were subjected to chemical characterization, sieve analysis, determination of specific gravity, X-ray diffraction, scanning electron microscopy, and solubilization and leaching tests. Mortars and concretes with SBA as sand replacement were produced and tests were carried out: compressive strength, tensile strength and elastic modulus. The results indicated that the SBA samples presented physical properties similar to those of natural sand. Several heavy metals were found in the SBA samples, indicating the need to restrict its use as a fertilizer. The mortars produced with SBA in place of sand showed better mechanical results than the reference samples. SBA can be used as a partial substitute of sand in concretes made with cement slag-modified Portland cement.  相似文献   
114.
Virgin plastic pellets and plastic fragments are reported as ubiquitous beach contaminants in the peer-reviewed literature. A surface density of 0.3 virgin plastic pellets and plastic fragments per square centimeter of the strandline area was registered on an urban beach of the northeast of Brazil. This beach is presently not affected by petrochemical facilities or pellet processing plants. The main source of fragments (96.7%) was attributed to the breaking down of larger plastic items deposited on the beach. In the case of virgin plastic pellets (3.3%), the main sources were the marine environment and possibly nearby port facilities. This category of plastic pollutant offers particular threats to the marine environment and to beach users.  相似文献   
115.
Scales and sludge generated during oil extraction and production can contain uranium, thorium, radium and other natural radionuclides, which can cause exposure of maintenance personnel. This work shows how the oil content can influence the results of measurements of radionuclide concentration in scale and sludge. Samples were taken from a PETROBRAS unit in Northeast Brazil. They were collected directly from the inner surface of water pipes or from barrels stored in the waste storage area of the E&P unit. The oil was separated from the solids with a Soxhlet extractor by using aguarras at 90+/-5 degrees C as solvent. Concentrations of 226Ra and 228Ra in the samples were determined before and after oil extraction by using an HPGe gamma spectrometric system. The results showed an increase in the radionuclide concentration in the solid (dry) phase, indicating that the above radionuclides concentrate mostly in the solid material.  相似文献   
116.
The adsorption of metals from aqueous solutions of Pb2+, Zn2+ and Mg2+ on naturally occurring pyrolusite have been studied. The chemical stability of the pyrolusite has been determined in NaOH, H2SO4, HNO3, HCl, NaCl and NK4Cl solutions of various concentrations. Adsorption of the metal ions followed the order Pb2+>Zn2+>Cd2+.The maximum adsorption of Pb2+ (100%) occurred at pH 7. the relation between the amount of Pb2+ adsorbed per unit weight of pyrolusite and the concentration of Pb2+ at equilibrium follows the Freundlich adsorption isotherm.The efficiency of pyrolusite has been demonstrated by removing lead from synthetic waste water. 100% and 96% removal of lead have been achieved from synthetic waste water containing 5 mg l–1 and 120 mg l–1 of Pb2+ respectively at pH 7. The results of these studies suggest that pyrolusite might provide an economical method for the removal of lead from industrial waste water.  相似文献   
117.
Microbial Removal of Arsenic   总被引:1,自引:0,他引:1  
Bangladesh is currently the subject of the world's largest mass arsenic poisoning in history. Groundwater throughout Bangladesh and West Bengal is contaminated with naturally occurring arsenic from the alluvial and deltaic sediments that form the region's aquifers. It has been estimated that 75 million people are at risk of developing health effects associated with the ingestion of arsenic. This project focuses on the use of microorganisms such as bacteria and algae to remove arsenic from water. Arsenic in the arsenite form was used in the studies. Experiments were conducted with a common alga and wastewater bacteria. A common green algae Scenedesmus abundans was used for determining arsenic uptake in batch experiments. Results of the experiments indicated that the algae biosorption could be modeled by the conventional Langmuir isotherm model. Algae morphology studies indicated that the algae cells were impacted due to the presence of arsenic as evidenced by clumping or loss of cell clusters. The wastewater bacteria also were capable of high percent of arsenic removal. Results indicate that microbial uptake of arsenic may be a viable method of pretreatment of arsenic contaminated water. However algae and sludge disposal would pose a problem and will have to be dealt with accordingly.  相似文献   
118.
Environmental Geochemistry and Health - As the largest organ of the human body, the skin is the major exposure route of NO2. However, the evidence for a relationship between NO2 exposure and...  相似文献   
119.
Optimal foraging theory predicts that individuals should become more opportunistic when intraspecific competition is high and preferred resources are scarce. This density-dependent diet shift should result in increased diet breadth for individuals as they add previously unused prey to their repertoire. As a result, the niche breadth of the population as a whole should increase. In a recent study, R. Svanb?ck and D. I. Bolnick confirmed that intraspecific competition led to increased population diet breadth in threespine stickleback (Gasterosteus aculeatus). However, individual diet breadth did not expand as resource levels declined. Here, we present a new method based on complex network theory that moves beyond a simple measure of diet breadth, and we use the method to reexamine the stickleback experiment. This method reveals that the population as a whole added new types of prey as stickleback density was increased. However, whereas foraging theory predicts that niche expansion is achieved by individuals accepting new prey in addition to previously preferred prey, we found that a subset of individuals ceased to use their previously preferred prey, even though other members of their population continued to specialize on the original prey types. As a result, populations were subdivided into groups of ecologically similar individuals, with diet variation among groups reflecting phenotype-dependent changes in foraging behavior as prey density declined. These results are consistent with foraging theory if we assume that quantitative trait variation among consumers affects prey preferences, and if cognitive constraints prevent individuals from continuing to use their formerly preferred prey while adding new prey.  相似文献   
120.
We evaluated 41 rural workers occupationally exposed to pesticides and 32 subjects as a control group, using the micronucleus (MN) and the comet assay. For the comet assay, we evaluated the peripheral blood, and for the MN, we sampled cells from the oral epithelium. Damage to DNA was measured by tail length, % DNA in tail (% tail), olive tail moment (OTM), and tail moment (TM). The exposed group presented an 8× increase in MN frequency, when compared to the control group (p <0.05). When we contrasted the MN frequencies between the individuals that use and do not use personal protective equipment, we found a mean of 7.5 MN (57 % variance) and 12.1 MN (130 % variance), respectively. The binucleated cells were 0.04 and 0.005, in the exposed and control groups, respectively, indicating 8× increase in the number of binucleated cells, when comparing the groups (p <0.05). In the comet assay, we demonstrated statistically significant differences in three parameters (% DNA, OTM, and TM) indicating that the rural workers presented high levels of genomic damages. Our results indicate that occupational exposure to pesticides could cause genome damage in somatic cells, representing a potential health risk to Brazilian rural workers that deal constantly with agrochemicals without adequate personal protection equipment.  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