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   182篇
  免费   13篇
  国内免费   80篇
安全科学   6篇
废物处理   4篇
环保管理   10篇
综合类   133篇
基础理论   43篇
污染及防治   40篇
评价与监测   20篇
社会与环境   19篇
  2024年   1篇
  2023年   3篇
  2022年   4篇
  2021年   4篇
  2020年   5篇
  2019年   6篇
  2018年   7篇
  2017年   4篇
  2016年   10篇
  2015年   7篇
  2014年   12篇
  2013年   18篇
  2012年   12篇
  2011年   18篇
  2010年   21篇
  2009年   14篇
  2008年   14篇
  2007年   38篇
  2006年   10篇
  2005年   11篇
  2004年   4篇
  2003年   7篇
  2002年   8篇
  2001年   5篇
  2000年   6篇
  1999年   3篇
  1998年   4篇
  1997年   7篇
  1996年   5篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
排序方式: 共有275条查询结果,搜索用时 46 毫秒
51.
亳州中药材及产地土壤和地下水中氟化物含量   总被引:1,自引:0,他引:1  
分析了毫州典型中药材及产地土壤和地下水中氟化物的含量.结果表明,中药材基地表层土壤全氟平均和水溶性氟含量分别在278.4-625.6 mg·kg-1和5.02-16.3 mg·kg-1之间,均值分别为532.8 mg·kg-1和9.88 mg·kg-1.表层土壤全氟平均含量高于全国土壤总氟背景值(478 mg·kg-1...  相似文献   
52.
摘要:运用测量不确定度评定的方法和程序,分析了快速消解分光光度法(HJ/T399—2007)测量水质化学需氧量测试过程中不确定度的来源,主要是标准溶液配制、标准曲线拟合、样品重复测定、分光光度计、取水样体积这五部分引入的不确定度。本次测量相对合成不确定度为0.027;最大的相对不确定度分量是标准曲线拟合引起的,相对不确定度为0.015;最小的相对不确定度分量是取水样体积引起的,相对不确定度为0.0032;本次测量结果为:56.0mg/L±3.04mg/L,k=2。  相似文献   
53.
根据川西气田的实际情况,对致密砂岩层回注选井选层技术进行研究,初步建立了致密砂岩层回注选井选层技术,优选出川西气田1、2、3号等5个回注井区。目前,注水规模300m3/d,累计注水量达75 698.8m3,节约生产成本约200万元,且有效缓解了高浓度氯离子地层水外排带来的环保压力。现场回注试验表明:致密砂岩层回注高浓度氯离子地层水是可行的,回注选井选层技术具有现场推广应用价值。  相似文献   
54.
杭州地区大气细颗粒物浓度变化特征分析   总被引:4,自引:0,他引:4  
利用2012年杭州地区(杭州、桐庐、建德、淳安)大气颗粒物监测仪TEOM1405D的连续观测资料,对该地区PM2.5质量浓度的变化特征及其与气象条件的关系进行了分析研究.结果表明,2012年杭州、桐庐、建德、淳安PM2.5年平均浓度分别为50.0±25.7、46.5±22.0、42.1±21.8、36.9±21.2μg·m-3,空间上呈现至北向南逐渐下降的变化趋势.受边界层高度、降水等气象条件影响,4个站点PM2.5浓度的季节变化基本表现为秋季冬季春季夏季,其中秋、冬季PM2.5超标日数高达80%左右.杭州地区PM2.5日变化呈现明显的双峰型特征,其峰值出现时间与人们的早晚出行高峰有较好的对应关系.对比不同站点PM2.5浓度变化可以看出人口密集城市区域气溶胶浓度要显著高于乡村地区.通过拟合小时平均值最大出现频率得出杭州地区最具代表性大气状态下PM2.5的浓度值为21.2μg·m-3.风向风速与PM2.5浓度的关系表明杭州主要以本地污染为主,桐庐受本地污染和区域输送双重影响,建德主要表现为区域输送.  相似文献   
55.
Residues of PCDDs/F, non-ortho, mono-ortho PCBs, and other PCBs were monitored in the tissues of mullet fish, bolti fish, bivalves and crab taken from Lake Temsah, at Ismailia, Egypt.

Results showed that 2,3,7,8 Tetra CDD and 1,2,3,7,8 Penta CDD were the most frequently detected PCDD congeners. Similarly, 2,3,7,8 Tetra CDF, 1,2,3,7,8 Penta CDF and 2,3,4,7,8 Penta CDF were the most frequently detected PCDF congeners. No relationship was apparent between the concentrations of detected PCDDs congeners and the degree of chlorination, except with crab samples in which an increase in the chlorination coincided with a decrease in the concentrations of the congeners.

In PCDF congeners, detected residues have had a reversed relationship with chlorination increase. In PCDD congeners, Octa CDD had the highest detected concentrations in the two fish species, while in the bivalves and crab, 2,3,7,8 Tetra CDD had the highest concentrations. The mullet fish had the highest total PCDDs concentration, at 0.398?pg/g fresh weight, followed by crab at 0.395?pg/g fresh weight, then bivalves and bolti fish at 0.187 and 0.062?pg/g fresh weight, respectively. In all the examined organisms, the total concentrations of PCDFs were much higher than the total concentrations of the PCDD congeners. The WHO–TEQ values were 11.92, 39.12, 25, and 3.6?pg/g fresh weight, for mullet fish, bolti fish, bivlaves and crab, respectively. The concentration of the mono-ortho congeners CB 118 was the highest detected of all non-ortho and mono-ortho PCBs congeners, with values of 0.382, 0.022, 0.231 and 0.357?ng/g fresh weight, in mullet fish, bolti fish, bivalves and crab, respectively. The WHO–TEQ concentrations were 0.799, 0.003?pg/g fw, 0.05?pg/g fresh weight, 0.676?pg/g, and 0.799?pg/g fresh weight, for the same species, respectively. The total concentration of PCBs 28, 52, 95, 99, 101, 105, 110, 118, 138, 146, 149, 151, 153, 170, 177, 180, 187 were 6.86?ng/g fresh weight for mullet fish, 0.2?ng/g fresh weight, for bolti fish, 2.72?ng/g fresh weight for bivalves and 2.8?ng/g fresh weight for crab, respectively.  相似文献   
56.
选取塑胶零件、印刷线路板及主板3类消费电子产品部件为研究对象,利用活性炭管采样,样品溶剂解吸后采用GC/MS分析,获得了各排气筒及车间内VOCs含量水平与组分特征.通过计算排放量,得出了分物种VOCs排放系数.结果表明,塑胶零件生产线排气筒总挥发性有机物(TVOCs)浓度为48.01~115.05 mg·m-3,印刷线路板为6.08~11.36 mg·m-3,主板为29.81~30.21 mg·m-3.塑胶零件生产车间内TVOCs浓度为4.23~120.58 mg·m-3,印刷线路板为1.50~2.02 mg·m-3,主板为7.01~9.93 mg·m-3.环烷烃类、酯类、苯类为主要排放物质.对于不同产品生产线的排气筒及车间废气,浓度和物种均有很大差异;对于相同产品,浓度有差异但物种基本相同.按产品分类,共计算得出了36个分物种VOCs排放系数,其中,塑胶零件、印刷线路板及主板TVOCs排放系数分别为0.626 kg·kg-1涂料用量、0.123 kg·kg-1油墨用量、0.028 kg·kg-1印刷线路板用量.通过排放量计算结果分析,3种产品中,塑胶零件生产为VOCs主要排放源,车间内无组织排放为主要排放方式.  相似文献   
57.
Earthworm toxicity tests are useful tools for terrestrial risk assessment but require a hierarchy of test designs that differ in effect levels (behavior, sublethal, lethal). In this study, the toxicity of chlorpyrifos contaminated soil on earthworms was assessed. In addition to the acute and chronic tests, an avoidance response test was applied. Earthworms were exposed to sublethal and lethal concentration of chlorpyrifos, and evaluated for acute toxicity, growth, fecundity and avoidance response after a certain exposure period. The test methods covered all important ecological relevant endpoints (acute, chronic, behavioral). Concentration of 78.91 mg/kg, chlorpyrifos caused significant toxic effects in all test methods, but at lower test concentrations, only significant chronic toxic effects could be observed. In the present study, chlorpyrifos had adverse effect on growth and fecundity in earthworm exposed to 5 mg/kg chlorpyrifos after eight weeks. The avoidance response test, however, showed significant repellent effects concentration of 40 mg/kg chlorpyrifos. For chlorpyrifos, concentration affecting avoidance response was far greater than growth and fecundity, it seemed likely that earthworms were not able to escape from pesticide-contaminated soil into the clean soil in field and hence were exposed continuously to elevated concentrations of pesticides.  相似文献   
58.
珠三角秋冬季节长时间灰霾污染特性与成因   总被引:1,自引:6,他引:1  
利用珠三角大气超级站2012年10月与2013年1月能见度、不同粒径颗粒物与BC质量浓度、气溶胶光散射系数、O3、相对湿度等在线监测数据,分析秋冬季节2次持续时间超过10 d的长时间灰霾过程污染特性与成因。结果表明,冬季灰霾过程中气溶胶吸光系数和光散射系数对大气总消光系数的贡献分别为13%和67%;PM2.5、PM1占PM10质量浓度分别为66%和39%;较高的PM2.5与BC日均浓度相关系数(R2=0.88)体现了一次排放对颗粒物质量浓度及能见度的显著影响。秋季灰霾过程中气溶胶吸光系数和光散射系数对大气总消光系数的贡献分别为11%和69%,由BC导致的吸光效应较冬季下降了约20%;PM2.5和PM1占PM10质量浓度比例分别为68%和45%,均高于冬季;O3浓度日最大小时值的平均值接近冬季的2倍;二次来源对PM2.5浓度升高和能见度下降起主导作用。来自不同方向的2种气团在珠三角僵持,大气扩散条件差是导致这2次灰霾过程的重要外在条件,应成为灰霾预报预警的重点关注对象。  相似文献   
59.
王佳  张瑛  徐鸣 《干旱环境监测》2010,24(4):222-225
以2005—2009年乌鲁木齐市城市大气降尘数据为依据,对乌鲁木齐市城市自然降尘的浓度水平和变化规律进行了研究,用Arc-GIS绘出乌鲁木齐市城市自然降尘的空间分布图,并分析和探讨了城市降尘与PM10相关性及防治对策。  相似文献   
60.
Bottled water may not be safer, or healthier, than tap water. The present studies have proved that styrene and some other aromatic compounds leach continuously from polystyrene (PS) bottles used locally for packaging. Water sapmles in contact with PS were extracted by a preconcentration technique called as "purge and trap" and analysed by gas chromatograph-mass spectrometer (GC/MS). Eleven aromatic compounds were identified in these studies. Maximum concentration of styrene in PS bottles was 29.5 μg/L. Apart from styrene, ethyl benzene, toluene and benzene were also quantified but their concentrations were much less than WHO guide line values. All other compounds were in traces. Quality of plastic and storage time were the major factor in leaching of styrene. Concentration of styrene was increased to 69.53 μg/L after one-year storage. In Styrofoam and PS cups studies, hot water was found to be contaminated with styrene and other aromatic compounds. It was observed that temperature played a major role in the leaching of styrene monomer from Styrofoam cups. Paper cups were found to be safe for hot drinks.  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