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   5690篇
  免费   655篇
  国内免费   3089篇
安全科学   278篇
废物处理   273篇
环保管理   629篇
综合类   5198篇
基础理论   1173篇
污染及防治   1233篇
评价与监测   445篇
社会与环境   168篇
灾害及防治   37篇
  2024年   33篇
  2023年   187篇
  2022年   298篇
  2021年   339篇
  2020年   357篇
  2019年   351篇
  2018年   319篇
  2017年   297篇
  2016年   404篇
  2015年   390篇
  2014年   410篇
  2013年   659篇
  2012年   588篇
  2011年   597篇
  2010年   416篇
  2009年   397篇
  2008年   358篇
  2007年   443篇
  2006年   416篇
  2005年   285篇
  2004年   252篇
  2003年   299篇
  2002年   231篇
  2001年   210篇
  2000年   178篇
  1999年   132篇
  1998年   129篇
  1997年   90篇
  1996年   57篇
  1995年   57篇
  1994年   61篇
  1993年   39篇
  1992年   34篇
  1991年   19篇
  1990年   12篇
  1989年   14篇
  1988年   12篇
  1987年   9篇
  1986年   6篇
  1985年   7篇
  1984年   7篇
  1983年   4篇
  1982年   5篇
  1981年   7篇
  1980年   2篇
  1979年   2篇
  1977年   2篇
  1972年   4篇
  1971年   2篇
  1970年   2篇
排序方式: 共有9434条查询结果,搜索用时 375 毫秒
891.
Zusammenfassung  Ein quecksilberkontaminierter Altstandort dient als Beispiel für eine umweltmedizinische Beurteilung der Belastung der im Umfeld wohnenden Personen durch Quecksilberimmissionen. Dabei wird die innere Exposition für sieben verschiedene Altersgruppen bezüglich der KontaktmedienBoden, Luft undNahrungsmittel anhand von konventionell festgelegten Szenarien abgesch?tzt und ein Vergleich mit den epidemiologischen Ergebnissen eines Humanmonitorings angestrebt. Die standortspezifisch und pfadspezifisch durchgeführte Expositionsabsch?tzung stützt sich auf cine Vielzahl von unterschiedlichen Probenehmern sowie auf über mehrere Jahre durchgeführte Konzentrationsmessungen in den aufnahmerelevanten Kompartimenten. Sowohl die Berechnungen als auch die epidemiologischen Untersuchungen zeigen eine leichte Erh?hung der Quecksilberexposition, gemessen an strengen Richtwerten.   相似文献   
892.
介绍了工厂有机溶剂废气处理方案和设计及实际运行效果,具有简单经济、净化彻底的特点.  相似文献   
893.
Phthalate esters are used as plasticizer in many plastics, and several studies have shown their toxicity. Phthalate esters are gradually emitted over time, and so it is conceivable that they pose a significant health risk. This study aims to investigate the temperature dependence of the emissions of various phthalate esters and to estimate the health risks of these emissions at various temperatures. A passive-type sampler was developed to measure the flux of phthalate esters from the surface of plastic materials. With this sampler, we examined three widely used plastic materials: synthetic leather, wallpaper and vinyl flooring. The observed maximum emissions of diethyl phthalate, dibutyl phthalate, and diethylhexyl phthalate (DEHP) from these materials at 20°C were 0.89, 0.77, and 14 μg m−2 h−1, respectively. Emissions at 80°C were 2.8, 4.5×102, and 1.5×103 μg m−2 h−1, respectively. The results showed this temperature dependence is determined primarily by the type of phthalate ester and less so by the type of material. The estimation from the results of temperature dependence indicated the concentration of DEHP in a vehicle left out in the sunshine during the day can exceed the recommended levels of Japan Ministry of Health, Labour and Welfare.  相似文献   
894.
An analytical procedure involving a three-step sequential extraction was used to determine the chemical association of heavy metals (Zn, Cr, Mn and Fe) with the major phases (exchangable, reducible and oxidizable) in samples from a fishpond of estuarine sediments. The pond is located in the Capibaribe River estuary, within the boundaries of the city of Recife, in the State of Pernambuco in the northeast of Brazil. The total metal content was determined as well. All metals were extracted from the residual fraction at a percentage greater than 50%.  相似文献   
895.
Zusammenfassung  Die durch die Fernstra?en versiegelte Fl?che in Deutschland betr?gt 0,47% der Oberfl?che, ohne die Seitenstreifen und Gemeindestra?en. Z?hlt man diese hinzu, so erh?ht sich der Wert auf 1,3%. In den dicht besiedelten Bundesl?ndern Hessen und Nordrhein-Westfalen erh?hen sich die Werte in Hessen auf 0,59 bzw. 1,59% und in NRW auf 0,68 bzw. 1,82%. In anderen OECD-L?ndern betragen die Prozents?tze des durch Fernstra?en versiegelten Bodens zwischen 0,2 und 3,0%. Bei diesem Vergleich liegt Deutschland an 5. Stelle hinter den Benelux-L?ndern und Japan. In der Verkehrsdichte (zugelassene Kraftfahrzeuge pro Stra?enkilometer) liegt Deutschland an 3. Stelle hinter Italien und Gro?britannien. Die Bodenversiegelung durch Stra?endecken sch?digt die Umwelt durch die Einbringung verkehrsbedingter Schadstoffe und St?rung des Grundwasserspiegels, aber noch mehr durch die Zerteilung und Zerst?rung von Biotopen. Online-First: 19. Mai 2000  相似文献   
896.
聚苯乙烯基离子交换纤维去除铅离子的应用研究   总被引:5,自引:0,他引:5  
聚苯乙烯其离子交换纤维是一种理想的离子交换材料。它的特殊的物理形态决定它对一些有害气体如铅烟、颗粒铅等具有很好的净化作用,铅烟净化效率可达80%;对水溶液中毒性铅离子去除率可达86%。该纤维可做为治理毒性铅离子的材料。  相似文献   
897.
898.
有机物的结构──活性定量关系及其在环境化学和环境毒理学中的应用王飞越(北京大学城市与环境学系,北京100871)陈雁飞(武汉大学环境科学系)最近几十年来,有机物结构──活性定量关系研究(QSAR,QuantitativeStructure-Activ...  相似文献   
899.
Background, Goal and Scope Cleaner CRYSTAL Simple Green (SG) was used for the cleanup of the oil spill in the Baltic Sea near Lithuania in 2001. No scientific data are available on the effects and consequences of its application for local aquatic life. The aim of this study was to determine and compare sublethal effects of a) solution SG; b) crude oil alone; c) SG in combination with oil on rainbow trout Oncorhynchus mykiss at different stages of its development in laboratory conditions.Methods Laboratory studies were performed on adult rainbow trout (4-day duration) and on yolk-sac larvae (25-day duration) evaluating their biological parameters. Concentrations of water-soluble and thin-dispersed fractions of petroleum hydrocarbons were measured using gas chromatography.Results and Discussion SG solution (0.5 mg/l) did not affect the survival of larvae and adult fish, and no significant changes were determined in respiratory parameters of the exposed larvae and adult fish. The most expressed alterations were found in morphological parameters (a decrease in the average body mass) of larvae and in haematological indices (a decrease in the leukocyte count) of adult fish at the end of the tests. Crude oil (1610 mg/l) did not affect the survival of adult fish during the 4-day exposure. An increase in larvae mortality rate (~ 36%) was recorded at the end of the tests. A significant decrease in the average body mass and heart rate of larvae as well as in gill ventilation frequency of larvae and adult fish were determined. SG combined with oil induced an increase in larval mortality  46% of individuals died at the end of the tests. No mortality was recorded in adult fish. The average body mass and heart rate of larvae were significantly decreased. Marked changes were also found in respiratory parameters (gill ventilation frequency of larvae and adult fish significantly decreased, while “coughing” rate increased). A 1-day, 2-day exposure of fish to SG combined with oil induced a significant decrease in the leukocyte count of adult fish, which was also determined at the end of the tests. The augmentation of adverse impact could be explained by the data obtained from our studies. When SG was added into dilution water with crude oil the concentration of petroleum hydrocarbons in the mixture increased 3 ~ 4.5 times after 24 h and 96 h, respectively. Conclusions The comparative study of the effects of crude oil alone, SG and SG combined with oil showed that their toxic effects on fish differed. Oil combined with SG was found to be more toxic to fish (larvae and adults) than SG alone and oil alone. Fish at early stages of development (yolk-sac larvae) were more sensitive to the effects of the compounds studied than adults.Recommendations and Outlook To diminish the negative impact of oil spill cleanup using chemicals on aquatic ecosystems, it is recommended to carry out more comprehensive studies of their effects and after-effects in laboratory conditions using a wide scale of local aquatic organisms. The selected species of the most sensitive aquatic organisms should include those which are unable to escape the impact of combined action of oil and cleaners. Special attention should be directed to the research of effects of these pollutants on studied organisms at their most sensitive stages of life (reproduction, hatching, early stages of development), as after-effects of exposure to pollutants may be observed in future generations.  相似文献   
900.
于2016年7~8月采集了陕西省西安市(城市)及蔺村(农村)夏季昼夜PM2.5样品,分析其有机碳(OC)、元素碳(EC)和无机离子等化学组分的含量,探讨关中平原城市和农村地区PM2.5的化学组成和来源的差异.结果表明,采样期间西安和蔺村的PM2.5浓度分别为(49.7±22.8)和(62.6±14.2)μg/m3.西安PM2.5中OC和EC的浓度[(6.5±2.5)μg/m3,(3.2±1.8)μg/m3]与蔺村[(6.8±1.8)μg/m3,(3.8±2.3)μg/m3]相当.西安OC/EC比值白天(2.6)高于夜晚(1.9),蔺村反之(白天:1.6;夜晚:2.7),主要是因为夜间城市地区重型卡车运输活动增强导致排放更多EC,而夜间农村地区人为活动较少导致EC排放显著降低.西安和蔺村无机离子总浓度分别为(20.2±14.6)和(30.1±10.5)μg/m3,占PM2.5浓度的40.6%和47.6%.蔺村SO42-的平均浓度高达19.0μg/m3,占PM2.5浓度的30%以上,远高于西安(9.4μg/m3和18.9%),主要与农村固体燃料(煤和生物质)使用有关.西安NO3-和Ca2+的浓度及其对PM2.5的贡献、NO3-/SO42-比值均明显大于蔺村,表明城市地区受机动车尾气和扬尘的影响更大.西安K+与Ca2+和Mg2+的相关性较强,而蔺村K+与EC的相关性显著强于西安,说明西安市区K+由粉尘源主导,而农村地区则主要来自生物质燃烧.  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