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71.
A.M. Helmus A.G. Fernald D.M. VanLeeuwen L.B. Abbott A.L. Ulery T.T. Baker 《Journal of the American Water Resources Association》2009,45(2):407-418
Abstract: Interactions between surface irrigation water, shallow ground water, and river water may have effects on water quality that are important for both drinking water supplies and the ecological function of rivers and floodplains. We investigated water quality in surface water and ground water, and how water quality is influenced by surface water inputs from an unlined irrigation system in the Alcalde Valley of the Rio Grande in northern New Mexico. From August 2005 to July 2006, we sampled ground water and surface water monthly and analyzed for concentrations of major cations and anions, specific conductance, pH, dissolved oxygen, and water levels. Results indicate that irrigation ditch seepage caused an increase in ground water levels and that the Rio Grande is a gaining stream in this region. Temporal and spatial differences were found in ion concentrations in shallow ground water as it flowed from under the ditch toward the river. Ground‐water ion concentrations were higher when the ditch was not flowing compared with periods during peak irrigation season when the ditch was flowing. Ditch inputs diluted ion concentrations in shallow ground water at well positions near the ditch. Specifically, lower ion concentrations were detected in ground water at well positions located near the ditch and river compared with well positions located in the middle of an agricultural field. Results from this project showed that ditch inputs influenced ion concentrations and were associated with ground‐water recharge. In arid region river valleys, careful consideration should be given to management scenarios that change seepage from irrigation systems, because in some situations reduced seepage could negatively affect ground‐water recharge and water quality. 相似文献
72.
本文综述了高效液相色谱法在无机分析中的应用进展。分别介绍了正相、反相、离子对、离子交换、排阻和胶束流动相等液相色谱法在有机金属化合物、金属络合物、无机阳离子和阴离子分离及测定上的实际应用。 相似文献
73.
Veni Pillay Sreekanth B. Jonnalagadda 《Journal of environmental science and health. Part. B》2013,48(4):423-428
The total concentration of toxic elements (aluminum, cadmium, chromium and lead) and selected macro and micro elements (iron, manganese, copper and zinc) are reported in six leafy edible vegetation species, namely lettuce, spinach, cabbage, chards and green and red types of Amaranth herbs. Although spinach and chards had greater than 125 mv of iron, both the amaranthus herbs recorded > than 320 μ g g? 1 dry weight. In both the spinach and chard species, the Mn and Zn levels were appreciable recording > 225 μ g g? 1 and 150 μ g g? 1 dry weight, respectively. Aluminum concentrations were (in μ g g? 1 dry weight) lettuce (10), cabbage (11), spinach (167), chards (65), amaranthus green (293) and amaranthus red (233). All the micro and macro elements and the toxic elements (Ni, Cr, Cd and Pb) elements analyzed, were below the recommended maximum permitted levels (RMI) in vegetables. Further the elemental uptake and distribution of the nine elements, at three growth stages of the lettuce plant grown on soil bed under controlled conditions are detailed. In the soil, except for iron (16%), greater than 33% of the other cations were in exchangeable form. Generally in the lettuce plant, roots retained much of the iron (> 224 μ g g? 1) and aluminum (> 360 μ g g? 1), while leaves had less than 200 μ g g? 1 of iron and 165 μ g g? 1 of Al. Although the concentrations of elements marginally decreased with growth, the lettuce leaves had significant amounts of Mn (30 μ g g? 1), Zn (50 μ g g? 1) and Cu (3.6 μ g g? 1). Some presence of lead in leaves (2.0 μ g g? 1) was noticed, but all the toxic and other elements analyzed were well below the RMI values for the vegetables. 相似文献
74.
75.
新型城镇化迫切需要推进城乡环境基本公共服务均等化,而农村环境公共服务的不足成为实现环境基本公共服务均等化的阻碍和制约。在阐述新型城镇化和城乡环境基本公共服务均等化之间关系的基础上,从环境基本公共服务投入总体不足、供给主体单一、城乡不均等突出等方面指出:当前阶段城乡环境基本公共服务均等化现状和面临的问题。探讨了城镇化背景下城乡环境基本公共服务均等化的发展重点领域,包括饮用水安全保障、清洁的大气、污水垃圾治理设施、环境信息服务等,认为推进城乡环境基本公共服务均等化宜采用政府推动、市场参与、多元化供给的协调推进路径,并提出政策建议。 相似文献
76.
77.
以浙江南部重金属镉(Cd)轻度污染酸性稻田为对象,以当地应用最广泛的3种无机钝化剂(硅钙镁钾肥、钙镁磷肥和石灰)为材料,通过田间试验研究了不同用量(750、1500和2250 kg ·hm-2)钝化剂阻控土壤酸化与稻米Cd积累的效果与化学机制.结果表明,3种钝化剂可有效地改良土壤酸化和降低水稻稻米Cd积累,施用2250 kg ·hm-2硅钙镁钾肥、钙镁磷肥和石灰分别增加土壤pH值0.62、0.65和0.86单位,减少交换性酸总量67%、69%和78%,降低糙米镉含量73%、68%和77%.施用2250 kg ·hm2钝化剂可使Cd轻度污染稻田上种植水稻糙米中ω(Cd)低于0.2 mg ·kg-1,达到国家食品安全标准;与对照比较,3种钝化剂均显著降低土壤中DTPA提取有效态镉含量,降低弱酸提取态(F1)和可还原态(F2) Cd含量,增加残渣态(F4) Cd含量;相关分析表明糙米Cd含量与土壤pH与交换性阳离子含量呈显著负相关,与DTPA-Cd、F1-Cd、F2-Cd和交换铝含量呈显著正相关.应用最小二乘路径模型分析了糙米Cd含量、Cd有效性和化学形态与土壤性质的关系,土壤交换性阳离子对糙米Cd含量、有效镉和水稻产量直接影响的路径系数分别为-0.566、-0.866和0.873,土壤pH主要通过直接影响有效镉而间接影响糙米镉含量.田间试验证明,这3种钝化剂是实现镉污染酸性水稻土水稻安全生产的有效技术,它们主要通过影响土壤交换性阳离子而直接影响土壤镉生物有效性,进而影响糙米中镉的积累,研究结果可为受污染耕地水稻安全生产和酸化土壤改良提供科学依据. 相似文献
78.
青岛大气气溶胶水溶性无机离子研究:季节分布特征 总被引:5,自引:4,他引:5
为了全面了解当前青岛地区大气气溶胶中水溶性组分的特征及来源,于2008年1~12月在青岛市区连续采集了总悬浮颗粒物(TSP)样品,运用离子色谱法对其主要的水溶性阴阳离子进行了分析.结果表明,SO24-、NO3-、NH4+和Cl-是TSP中水溶性离子的主要成分,四者质量浓度之和占总水溶性离子质量浓度的86.9%.TSP及其水溶性组分存在明显的季节变化,其来源也存在多源性.Na+、NH4+、Ca2+、F-、Mg2+均为冬季最高,夏季最低,K+、PO34-为秋季最高,夏季最低,Cl-为冬季最高,秋季最低,NO3-则为春季最高,夏季最低,而SO24-为春季最高,秋季最低.不同天气对颗粒物和气溶胶中水溶性离子影响很大.颗粒物浓度在晴天时最低,其次是雾天,再次是烟雾和霾,沙尘天气下质量浓度最高.Na+、Mg2+、Ca2+、F-、Cl-和PO34-在烟雾天气下的平均浓度最高,而NH4+、K+、NO3-和SO24-则是在霾天气下质量浓度最高. 相似文献
79.
震灾保险的一种实用技术途径及其实施保障 总被引:3,自引:1,他引:2
本文提出一种独特的实用型震灾保险模式,通过烈度当量折合费率(CRPIE)的实时判定及延时承保机制(DIAM)的有效运行,对投保与灾后理赔进行科学、客观的动态调制,促成自然科学与社会科学的有机结合,从而可能使震灾保险所面临的一些难题得以解决,文中还从软科学的角度提出了对上述震灾保险新机制的实施保障。 相似文献
80.
A new treatment method is developed to degrade 4-chlorophenol (4-cp) and its oxidation intermediates. The experimental results of this research demonstrate that 4-cp and its oxidation intermediates can be decomposed completely by basic oxygen furnace slag (BOF slag) with hydrogen peroxide (H2O2) in an acid solution. The factors that effect the treatment efficiency were studied including initial concentration of 4-cp, pH of the solution, concentration of H2O2 and amount of BOF slag. The BOF slags are final waste materials in the steel making process. The major components of BOF slag are CaO, SiO2, Fe2O3, FeO, MgO and MnO. As the BOF slag in an acid solution, FeO and Fe2O3 can be dissociated to produce ferrous ion and ferric ion. Ferrous ion reacts with hydrogen peroxide to form “Fenton's reagent” which can produce hydroxyl radicals (OH.). Hydroxyl radical possession of high oxidation ability can oxidize organic chemicals effectively. Results show that 100 mg/l of 4-cp is decomposed completely within 30 min by 438.7 g/l BOF slag with 8.2 mM hydrogen peroxide in pH=2.8±0.2 solution. The COD value of the solution is reduced from 290 to 90 mg/l. The factors studied which affect the 4-cp decomposition efficiency were the hydrogen peroxide concentration, BOF slag concentration, pH of the solution and initial concentration of 4-cp. Because large amounts of Fe2O3 and FeO are present in the BOF slag, the BOF slag not only has a high treatment efficiency, but also can be used repeatedly. 相似文献