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   168篇
  免费   2篇
  国内免费   1篇
安全科学   2篇
废物处理   11篇
环保管理   10篇
综合类   22篇
基础理论   50篇
污染及防治   52篇
评价与监测   9篇
社会与环境   14篇
灾害及防治   1篇
  2023年   2篇
  2022年   4篇
  2021年   7篇
  2020年   5篇
  2019年   4篇
  2018年   3篇
  2017年   5篇
  2016年   4篇
  2015年   4篇
  2014年   5篇
  2013年   17篇
  2012年   11篇
  2011年   11篇
  2010年   9篇
  2009年   4篇
  2008年   11篇
  2007年   12篇
  2006年   4篇
  2005年   6篇
  2004年   6篇
  2003年   3篇
  2002年   7篇
  2001年   2篇
  2000年   4篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1995年   2篇
  1993年   1篇
  1990年   3篇
  1989年   2篇
  1988年   2篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
排序方式: 共有171条查询结果,搜索用时 593 毫秒
61.
The experimental site was a Mediterranean type forest located in Viols-en-Laval near Montpellier (France). The principal species studied were Quercus ilex and Quercus pubescens. The determination of biogenic emissions was carried out by the enclosure method, which consists in enclosing an intact branch in a Teflon cuvet. The evolution of global terpenic emissions were recorded on June 1995.For Quercus ilex it appears that most terpenic emissions take place during the diurnal period. The evolution of terpenic emission rates versus light (PAR), internal temperature within the cuvet, CO2 exchange and transpiration (H2O) were carried out. A close relation between terpene emission and light-triggered physiological activities, was always found. It is obvious that there was no simple correlation between the leaf temperature and the terpenic emission. The temperature of the leaves does not seem to play a significant role in the regulation of the monoterpenic emission. This behaviour allows us to conclude that light with its effect on assimilation and stomatal behaviour is the most important factor for monoterpenic emission by Quercus ilex like for Quercus pubescens which is an isoprene emitter.  相似文献   
62.
Journal of Material Cycles and Waste Management - The use of food waste (FW) for the production of biofuels and value-added compounds is growing worldwide. However, the significant chemical...  相似文献   
63.
The picloram (PCM) adsorption on nontronite, illite and kaolinite was studied at pH 3, 5 and 7. The adsorption isotherms had well-fitted to Langmuir and Freundlich models equations. The interactions of PCM with the clay mineral surfaces exhibited an anionic profile adsorption, with a decrease in adsorption when the pH increases. The PCM adsorption capacity increases in the following order: kaolinite?<?illite?<?nontronite. The X-ray diffraction (XRD) analysis of PCM-clay samples revealed that the picloram molecule does not enter into the clays basal space. The interaction of PCM with clays surface sites through nitrogen of the pyridine ring was confirmed by X-ray photoelectron spectroscopy (XPS). Due to the anionic form of PCM, the adsorption onto the external and edges surface sites of the clay minerals was proposed.  相似文献   
64.
Metal contamination is a recurring problem in Peru, caused mainly by mine tailings from a past active mining activity. The Ancash region has the largest number of environmental liabilities, which mobilizes high levels of metals and acid drainages into soils and freshwater sources, posing a standing risk on human and environmental health. Native plant species spontaneously growing on naturally acidified soils and acid mine tailings show a unique tolerance to high metal concentrations and are thus potential candidates for soil phytoremediation. However, little is known about their propagation capacity and metal accumulation under controlled conditions. In this study, we aimed at characterizing nine native plant species, previously identified as potential hyperaccumulators, from areas impacted by mine tailings in the Ancash region. Plants were grown on mine soils under greenhouse conditions during 5 months, after which the concentration of Cd, Cu, Ni, Pb, and Zn was analyzed in roots, shoots, and soils. The bioaccumulation (BAF) and translocation factor (TF) were calculated to determine the amount of each metal accumulated in the roots and shoots and to identify which species could be better suited for phytoremediation purposes. Soil samples contained high Cd (6.50–49.80 mg/kg), Cu (159.50–1187.00 mg/kg), Ni (3.50–8.70 mg/kg), Pb (1707.00–4243.00 mg/kg), and Zn (909.00–7100.00 mg/kg) concentrations exceeding national environmental quality standards. After exposure to mine tailings, concentrations of metals in shoots were highest in Werneria nubigena (Cd, 16.68 mg/kg; Cu, 41.36 mg/kg; Ni, 26.85 mg/kg; Zn, 1691.03 mg/kg), Pennisetum clandestinum (Pb, 236.86 mg/kg), and Medicago lupulina (Zn, 1078.10 mg/kg). Metal concentrations in the roots were highest in Juncus bufonius (Cd, 34.34 mg/kg; Cu, 251.07 mg/kg; Ni, 6.60 mg/kg; Pb, 718.44 mg/kg) and M. lupulina (Zn, 2415.73 mg/kg). The greatest BAF was calculated for W. nubigena (Cd, 1.92; Cu, 1.20; Ni, 6.50; Zn, 3.50) and J. bufonius (Ni, 3.02; Zn, 1.30); BCF for Calamagrostis recta (Cd, 1.09; Cu, 1.80; Ni, 1.09), J. bufonius (Cd, 3.91; Cu, 1.79; Ni, 18.36), and Achyrocline alata (Ni, 137; Zn, 1.85); and TF for W. nubigena (Cd, 2.36; Cu, 1.70; Ni, 2.42; Pb, 1.17; Zn, 1.43), A. alata (Cd, 1.14; Pb, 1.94), J. bufonius (Ni, 2.72; Zn, 1.63), and P. clandestinum (Zn, 1.14). Our results suggest that these plant species have a great potential for soil phytoremediation, given their capability to accumulate and transfer metals and their tolerance to highly metal-polluted environments in the Andean region.  相似文献   
65.
  针对目前生态气象监测轨道业务的特点,结合工作的实际需要,运用C和C++语言建立了生态气象监测评估业务平台。在程序设计中,采用了生成中间交换文件的结构组织,能够对各模块的输出结果进行详尽直观的分析,并提供了等值线色斑图与区域填充等多种图形绘制方式。该系统可处理AVHRR和EOS/MODIS卫星遥感资料,对气象观测报文进行解译、数据分类管理和质量控制,统计计算水体密度指数、湿润指数、植被覆盖指数、土地退化指数、灾害指数和生态质量综合评价指标,以图形、图像的形式输出生态气象监测评估产品,实现了卫星遥感与生态气象地面监测数据的有效组织和智能化管理。将系统应用于湖南省生态质量气象评价,业务化运行的结果表明,该系统具有较好的业务实用性。〖HJ1〗〖HJ〗
〖HT5”H〗  相似文献   
66.
Latin American subtropical dry ecosystems have experienced significant human impact for more than a century, mainly in the form of extensive livestock grazing, forest products extraction, and agriculture expansion. We assessed the regional-scale effect of land use and land cover (LULC) on patterns of richness distribution of trees, birds, amphibians, and mammals in the Northern Argentine Dry Chaco (NADC) over c. 19 million hectares. Using species distribution models in a hierarchical framework, we modeled the distributions of 138 species. First, we trained the models for the entire Argentinean Chaco with climatic and topographic variables. Second, we modeled the same species for the NADC including the biophysical variables identified as relevant in the first step plus four LULC-related variables: woody biomass, distance to crops, density of livestock-based rural settlements (puestos), and vegetation cover. Third, we constructed species richness maps by adding the models of individual species and considering two situations, with and without LULC variables. Four, richness maps were used for assessing differences when LULC variables are added and for determining the main drivers of current patterns of species richness. We found a marked decrease in species richness of the four groups as a consequence of inclusion of LULC variables in distribution models. The main factors associated with current richness distribution patterns (both negatively) were woody biomass and density of livestock puestos. Species richness in present-day Semiarid Chaco landscapes is strongly affected by LULC patterns, even in areas not transformed to agriculture. Regional-scale biodiversity planning should consider open habitats such as grasslands and savannas in addition to woodlands.  相似文献   
67.
R. Bishop  J. Torres 《Marine Biology》2001,138(6):1093-1098
The principles of energetics were used to examine the energetic requirements of leptocephali. Respiration and excretion rates and daily growth rates combined with proximate composition were used to examine the allocation of energy into each of the three main components of energetics: metabolism, excretion and growth. The daily energetic requirements for leptocephali, referred to as type 2 larvae based upon their unique developmental strategy, were compared to the requirements of non-leptocephalus larvae, known as type 1. Leptocephalus daily energetic requirements were also compared to the energy available from the leptocephalus' proposed food sources. The four species of eel larvae selected were all from the order Anguilliformes: Paraconger caudilimbatus (Poey), Ariosoma balearicum (Delaroche), Gymnothorax saxicola Jordan and Davis, and Ophichthus gomesii (Castelnau). The allocation of energy to each of the components of energetics as well as the total energetic requirements for the leptocephali proved to be very different from those of type 1 larvae. Metabolism received the majority, 60-92%, of the energy required per day. Growth and excretion were allocated 4-39% and <1-21%, respectively, of the total energy needed per day. Leptocephali required <50% of the energy needed by type 1 larvae of equal dry mass. The unique growth strategy used by leptocephali allows them to increase rapidly in size while allocating the majority of their energy, not to growth as in most larval fish, but to metabolism.  相似文献   
68.
The growing use of pharmaceutical drug is mainly due to several diseases in human and in animal husbandry. As these drugs are discharged into waterways via wastewater, they cause a major impact on the environment. Many of these drugs are hormones; in which even at low concentrations can alter metabolic and physiological functions in many organisms. Hormones were found in surface water, groundwater, soil, and sediment at concentrations from nanograms to milligrams per liter of volume—quantities known to cause changes in the endocrine system of aquatic organisms. This study aimed to develop a methodology for hormone detection (estriol, estrone, 17β-estradiol, 17α-ethinylestradiol, progesterone, and testosterone) on surface and treated water samples. Sample toxicity was assessed by ecotoxicology tests using Daphnia magna. A liquid chromatograph coupled to a mass spectrometer with an electrospray ionization source (LC-ESI-MS/MS) was used for the analysis. The results showed that samples were contaminated by the hormones estriol, estrone, progesterone, 17β-estradiol, and 17α-ethinylestradiol during the sampling period, and the highest concentrations measured were 90, 28, 26, 137, and 194 ng·L?1, respectively. This indicates the inflow of sewage containing these hormones at some points in the Piracicaba River in the State of Sao Paulo—Brazil. Results indicated little toxicity of the hormone estriol in D. magna, indicating that chronic studies with this microcrustacean are necessary.  相似文献   
69.
Epiphytic lichens, collected from 119 sampling sites grown over “Roistonea Royal Palm” trees, were used to assess the spatial distribution pattern of lead (Pb) and identify possible pollution sources in Havana (Cuba). Lead concentrations in lichens and topsoils were determined by flame atomic absorption spectrophotometry and inductively coupled plasma (ICP) atomic emission spectrometry, respectively, while Pb in crude oils and gasoline samples were measured by ICP-time of flight mass spectrometry (ICP-ToF-MS). Lead isotopic ratios measurements for lichens, soils, and crude oils were obtained by ICP-ToF-MS. We found that enrichment factors (EF) reflected a moderate contamination for 71% of the samples (EF > 10). The 206Pb/207Pb ratio values for lichens ranged from 1.17 to 1.20 and were a mixture of natural radiogenic and industrial activities (e.g., crude oils and fire plants). The low concentration of Pb found in gasoline (<7.0 μg L?1) confirms the official statement that leaded gasoline is no longer used in Cuba.  相似文献   
70.
The purpose of this work was to investigate the effects of spreading olive oil mill wastewater (OMWW) on soil biochemical parameters and olive production in an organically managed olive orchard. The experiment was carried out with three different doses of OMWW (80, 160 and 500 m3 ha?1) and a control (untreated soil). Three samplings were done at 10, 30 and 90 days after the administration of the byproduct. OMWW application differentially modified the biochemical properties of the soil analyzed. Organic matter, organic carbon, total nitrogen and extractable phosphorus soil contents increased proportionally with each increasing dose. The values of these parameters decreased gradually with time. Total microbial activity was altered and the OMWW 500 m3 ha?1 treatment proved to be the most active when compared with the other applied doses. OMWW agricultural application also modified the structure of soil microbial communities, particularly affecting Gram positive and negative bacteria, while fungal biomass did not show consistent changes. Although there was a salinity increase in the treated soil, especially at the highest dose, the productive parameters analyzed (fruit and oil tree?1) were not affected. In light of the obtained results, we consider that low dose of OMWW could be considered an alternative farming practice for semiarid regions.  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