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   1508篇
  免费   108篇
  国内免费   409篇
安全科学   102篇
废物处理   82篇
环保管理   145篇
综合类   849篇
基础理论   281篇
污染及防治   401篇
评价与监测   59篇
社会与环境   58篇
灾害及防治   48篇
  2023年   11篇
  2022年   75篇
  2021年   58篇
  2020年   61篇
  2019年   51篇
  2018年   54篇
  2017年   50篇
  2016年   59篇
  2015年   67篇
  2014年   99篇
  2013年   126篇
  2012年   145篇
  2011年   138篇
  2010年   98篇
  2009年   97篇
  2008年   121篇
  2007年   106篇
  2006年   88篇
  2005年   67篇
  2004年   70篇
  2003年   60篇
  2002年   50篇
  2001年   35篇
  2000年   34篇
  1999年   30篇
  1998年   18篇
  1997年   23篇
  1996年   36篇
  1995年   30篇
  1994年   21篇
  1993年   14篇
  1992年   8篇
  1991年   9篇
  1990年   8篇
  1987年   1篇
  1986年   1篇
  1985年   3篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
排序方式: 共有2025条查询结果,搜索用时 78 毫秒
541.
The liquid chromatography–electrospray ionization-tandem mass spectrometer (LC–MS/MS) method coupled with an automated solid-phase extraction procedure has been developed to identify 22 psychiatric pharmaceuticals, including seven anxiolytic-sedative-hypnotics, six antidepressants, and nine anti-schizophrenia drugs, in wastewater samples from two psychiatric hospital wastewater treatment plants (P-WWTPs) and three municipal wastewater treatment plants (M-WWTPs) in Beijing, China. Analyte recoveries from spiking experiments in the WWTP influent and effluent at three concentrations ranged from 70% to 110%, excluding sulpiride, ziprasidone, and olanzapine. Method detection limits for five, eight, and nine analytes in the WWTP influent and effluent were 20–80, 1–16, and <1 ng L?1, respectively. High psychiatric pharmaceutical concentrations (e.g., ~942 ng L?1oxazepam, 5552–12,782 ng L?1 clozapine, 2762–9832 ng L?1sulpiride, and 2030–4967 ng L?1quetiapine) were frequently observed in P-WWTP influent compared to M-WWTPs. Although P-WWTPs typically had higher removal rates, significantly higher concentrations of the target compounds were observed in the P-WWTP secondary effluent than in the M-WWTP influent (e.g., ~752 ng L?1oxazepam, ~8183 ng L?1 clozapine, ~10,833 ng L?1sulpiride, and ~1168 ng L?1quetiapine). Thus, the discharge control of psychiatric pharmaceuticals from psychiatric hospitals requires improvement.  相似文献   
542.
543.
基于江苏省"十二五"环境质量监测网络优化调整工作,指出监测点位设置和管理工作中存在的问题,讨论了点位优化调整的原则和思路,总结监测网络调整结果,并开展点位优化调整的成效分析,提出进一步优化监测网络设置的建议。  相似文献   
544.
以生产烟碱及茄尼醇后的烟叶废渣为原料,采用酸水解及活性炭脱色处理提取氨基酸,研究了酸水解中HCl用量、水解时间以及活性炭脱色处理中活性炭处理方式、pH、活性炭用量、脱色温度和脱色时间等因素对氨基酸收率和脱色率的影响。结果表明,最佳水解条件:以6 mol/L HCl溶液为水解液,在120℃、料液比1∶18条件下,水解12 h,所得水解液经以下工艺脱色处理:0.25%KOH处理活性炭、pH=10、活性炭用量为2.5%、脱色温度80℃、脱色40 min,所得产物氨基酸收率86.65%,脱色率达84.31%。  相似文献   
545.
以重庆某非规范填埋场为例,针对西南地区已封场非规范垃圾填埋场的稳定化进程进行了分析。按照场地布局选取4个采样点,在垃圾体上进行钻孔取样,分析不同深度的垃圾样pH值、有机质、含水率、生物可降解度以及垃圾样浸出液和填埋气组成以及各个指标随着填埋深度的变化规律,确定不同深度垃圾体的稳定化程度。结果表明,场内垃圾已呈现矿化垃圾特征;有机质、BDM、浸出液COD以及填埋气CH4含量等4个指标与填埋深度均较好地符合一级降解反应,可以预测垃圾体稳定化临界填埋深度。根据有机质、BDM、浸出液COD以及填埋气CH4含量等4个指标与填埋深度一级降解反应函数预测临界稳定化深度为15 m,与实测值判定的稳定化填埋深度相一致性。在对非规范垃圾填埋场场地利用过程中,需要先对未稳定的上层垃圾进行清理,并在已稳定的底层垃圾体上充填其他稳定介质后利用该地块。  相似文献   
546.
以南水北调中线工程水源区为研究区域,采用1961~2007年9个气象站点气象观测数据和黄家港水文站实测径流资料,以FAO彭曼蒙特斯公式和水文模拟法为标准分别对多种潜在蒸散发计算方法和实际蒸散发计算方法进行比较研究,并分析了陆面蒸散发的影响因素。研究表明:南水北调中线工程水源区存在“蒸发悖论”现象,Priestley Taylor公式计算结果偏大,但与FAO 彭曼蒙特斯公式存在良好的相关关系,在气象资料较少时可以考虑建立相关方程进行推求。傅抱璞公式与水文模拟法计算结果较为接近,相关关系最优。潜在蒸散发与平均温度、气温日较差、实际水汽压、降雨量、风速、净太阳辐射、日照时数呈正相关,而实际蒸散发与平均温度、气温日较差、实际水汽压、降雨量、净太阳辐射、日照时数呈正相关,与风速呈负相关。净太阳辐射是影响陆面蒸散发的核心因素  相似文献   
547.
Many studies indicate that lead (Pb) and cadmium (Cd) exposure may alter bone development through both direct and indirect mechanisms, increasing the risk of osteoporosis later in life. The aim of this study was to investigate the association between Pb and Cd exposure, physical growth, and bone and calcium metabolism in children of an electronic waste (e-waste) processing area. We recruited 246 children (3–8 years) in a kindergarten located in Guiyu, China. Blood lead levels (BLLs) and blood cadmium levels (BCLs) of recruited children were measured as biomarkers for exposure. Serum calcium, osteocalcin, bone alkaline phosphatase, and urinary deoxypyridinoline were used as biomarkers for bone and calcium metabolism. Physical indexes such as height, weight, and head and chest circumference were also measured. The mean values of BLLs and BCLs obtained were 7.30 μg/dL and 0.69 μg/L, respectively. The average of BCLs increased with age. In multiple linear regression analysis, BLLs were negatively correlated with both height and weight, and positively correlated with bone resorption biomarkers. Neither bone nor calcium metabolic biomarkers showed significant correlation with cadmium. Childhood lead exposure affected both physical development and increased bone resorption of children in Guiyu. Primitive e-waste recycling may threaten the health of children with elevated BLL which may eventually cause adult osteoporosis.  相似文献   
548.
Field studies were conducted to investigate arsenic (As), copper (Cu), and zinc (Zn) contamination in agricultural soils and wheat crops at two areas in Huaibei, China. Area A is in the proximity of Shuoli coal mine. In area B, three coal mines and a coal cleaning plant were distributed. The potential health risk of As, Cu, and Zn exposure to the local inhabitants through consumption of wheat grains was also estimated. The results showed that significantly higher (p?<?0.05) concentrations of As, Cu, and Zn were found in soils collected from area B than in those from area A. Arsenic concentrations in wheat sampled from area A were negatively correlated with the distance from the coal mine (p?<?0.001). Concentrations of Cu and Zn in wheat seedlings and grains collected from area B were significantly higher (p?<?0.05) than in those collected from area A, with the exception of Zn in wheat seedlings. Concentrations of Cu and Zn in most wheat grain samples were above the permissible limits of Cu and Zn in edible plants set by the Food and Agriculture Organization/World Health Organization. The hazard index of aggregate risk through consumption of wheat grains was 2.3–2.4 for rural inhabitants and 1.4–1.5 for urban inhabitants. The average intake of inorganic As for rural inhabitants in Huaibei was above 10 μg day?1. These findings indicated that the inhabitants around the coal mine are experiencing a significant potential health risk due to the consumption of locally grown wheat.  相似文献   
549.
对具有催化功能的负载Fe(Ⅲ)的活性炭进行了表征,与母体活性炭相比,其比表面积以及微孔体积均有所下降,酸性官能团的量有所增加;考察了普通浸渍法和超声浸渍法制备的双功能活性炭对毒死蜱的吸附和降解性能,结果表明,双功能活性炭对毒死蜱的吸附量有所降低,但对毒死蜱的降解能力增强,超声浸渍法所制备的活性炭对毒死蜱的降解能力要优于普通浸渍法所制备的活性炭。  相似文献   
550.
利用双通道工业循环冷却水分析测试台和高压静电水处理器,对火电厂的冷却水进行阻垢效果和机理研究。结果表明,施加工作电压2.0~4.0kV时,平均阻垢率随电压的升高而增大,达到61.7%,以后随着电压的升高平均阻垢率呈下降趋势,在7.5kV电压作用下平均阻垢率43.4%。对垢样晶体的SEM扫描图片表明,经高压静电场处理前的水垢晶体以方解石型硬垢为主,处理后发生了晶型转化,转化为文石型软垢,有利于垢的去除。  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