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   418篇
  免费   16篇
  国内免费   187篇
安全科学   21篇
废物处理   21篇
环保管理   37篇
综合类   236篇
基础理论   82篇
污染及防治   174篇
评价与监测   25篇
社会与环境   8篇
灾害及防治   17篇
  2023年   6篇
  2022年   20篇
  2021年   16篇
  2020年   12篇
  2019年   12篇
  2018年   16篇
  2017年   19篇
  2016年   20篇
  2015年   30篇
  2014年   30篇
  2013年   51篇
  2012年   36篇
  2011年   45篇
  2010年   33篇
  2009年   22篇
  2008年   32篇
  2007年   32篇
  2006年   23篇
  2005年   13篇
  2004年   13篇
  2003年   12篇
  2002年   21篇
  2001年   11篇
  2000年   13篇
  1999年   13篇
  1998年   12篇
  1997年   19篇
  1996年   17篇
  1995年   6篇
  1994年   2篇
  1993年   1篇
  1992年   4篇
  1991年   4篇
  1988年   1篇
  1987年   1篇
  1986年   2篇
  1984年   1篇
排序方式: 共有621条查询结果,搜索用时 15 毫秒
541.
高文琪  孔秀琴 《环境工程》2012,(Z2):158-161
采用驯化SBR法来处理明胶生产工序段的磷钙水,研究了该法的可行性及污泥活性抑制后的恢复措施。结果表明:驯化SBR法处理磷钙废水有一定的处理效果,COD去除率最高可达88%,除磷效果明显,24h去除率维持在85%;反应器运行7~8天后,污泥活性受高氯根和碳酸钙的积累而被抑制,经更换部分污泥和添加低浓度废水等措施,可使污泥生物活性得到恢复。  相似文献   
542.
Lake Taihu, a large, shallow hypertrophic freshwater lake in eastern China, has experienced lake-wide toxic cyanobacterial blooms annually during summer season in the past decades. Spatial changes in the abundance of hepatotoxin microcystin-producing and non-microcystin producing Microcystis populations were investigated in the lake in August of 2009 and 2010. To monitor the densities of the total Microcystis population and the potential microcystin-producing subpopulation, we used a quantitative real-time PCR assay targeting the phycocyanin intergenic spacer (PC-IGS) and the microcystin synthetase gene (mcyD), respectively. On the basis of quantification by real-time PCR analysis, the abundance of potential toxic Microcystis genotypes and the ratio of the mcyD subpopulation to the total Microcystis varied significantly, from 4.08× 104 to 5.22× 107 copies/mL, from 5.7% to 65.8%, respectively. Correlation analysis showed a strong positive relationship between chlorophyll-a, toxic Microcystis and total Microcystis; the abundance of toxic Microcystis correlated positively with total phosphorus and ortho-phosphate concentrations, but negatively with TN:TP ratio and nitrate concentrations. Meanwhile the proportion of potential toxic genotypes within Microcystis population showed positive correlation with total phosphorus and ortho-phosphate concentrations. Our data suggest that increased phosphorus loading may be a significant factor promoting the occurrence of toxic Microcystis bloom in Lake Taihu.  相似文献   
543.
“十一五”河南省城市环境空气污染特征及原因分析   总被引:1,自引:0,他引:1  
文章通过对平均综合污染指数,城市空气质量级别的变化对比分析,认为"十一五"期间河南省城市环境空气质量整体呈现改善的变化趋势。基于监测数据,从河南省城市主要污染物、污染特性空间分布、季节性污染特性等方面对环境空气污染特征进行了深入分析,并从污染负荷、气候影响、产业地域布局、产业结构调整、环境管理和污染防治措施等方面深入探讨了产生这种变化趋势和污染特征的内在原因。  相似文献   
544.
随着社会的发展和人民物质生活水平的提高,人们更加注意身体健康,因而饮水安全也倍受关注。本文就离子色谱在环境监测中的应用和锦州市饮用水监测数据图表,集中阐述了环境监测工作对人们饮水安全保障所作的努力。  相似文献   
545.
为了开发除磷填料,以红壤为基本材料,并以烧结温度、粉煤灰添加量、外加剂A用量和外加剂B用量作为4个因素设计正交实验,制造了不同配方的红壤烧结填料,进行等温吸附实验并利用Langmuir模型拟合最大吸磷量进行比较。结果表明,通过烧结可使粉末状红壤成型,同时提高了其除磷能力;对填料理论吸磷量的影响因素主次顺序为外加剂B用量、外加剂A用量、粉煤灰用量及烧结温度;通过比较理论吸附量,同时考虑到成本,可以确定正交实验结果中较优填料配方组成为(重量比):61%红壤,30%粉煤灰,0%外加剂A,9%外加剂B,烧结温度1150℃,其最大理论的磷吸附量2.274mg/cm^2,单位除磷原料成本约0.047元/g.  相似文献   
546.
Zhu C  Wang L  Kong L  Yang X  Wang L  Zheng S  Chen F  MaiZhi F  Zong H 《Chemosphere》2000,41(3):303-309
The photocatalytic degradation performance of photocatalysts TiO2 supported on 13-X, Na-Y, 4A zeolites with different loading content was evaluated using the photocatalytic oxidation of dyes direct fast scarlet 4BS and acid red 3B in aqueous medium. The results showed that the best reaction dosage of TiO2-zeolite catalysts is about 2 g/l and the photocatalytic kinetics follows first order for all supported catalysts. The photocatalytic activity order of the three series catalysts is 13X type >Y type >4A type. The physical state of titanium dioxide on the supports is evaluated by X-ray photoelectron spectra (XPS), powder X-ray diffraction (XRD), BET, and FTIR.  相似文献   
547.
本文利用向含氟废水中加入适量石灰和聚合氯化铝PAC ,然后投加适量钙盐、磷酸和聚丙烯酰胺PAM的二级处理工艺除氟。通过控制合适的 pH、钙盐和磷酸的投加量、反应时间、反应温度、搅拌强度和絮凝剂的投加量 ,确定了最佳的除氟工艺 ,可以使氟的浓度降至 5mg/L ,达到国家一级排放标准GB8978 1996。  相似文献   
548.
Nordberg G  Jin T  Bernard A  Fierens S  Buchet JP  Ye T  Kong Q  Wang H 《Ambio》2002,31(6):478-481
This paper presents the main findings of a study on health effects of environmental cadmium pollution in China, performed in 1998, i.e. approximately 25 years after the first warnings of such effects were published in Ambio. Forearm bone mineral density (BMD) and renal dysfunction were assessed in population groups exposed to cadmium via rice. Decreased BMD was found in postmenopausal women with elevated urinary cadmium (CdU) or cadmium in blood (CdB) and among men with elevated CdB. Also, clear and statistically significant dose-effect and dose-response relationships were found between CdB or CdU and renal dysfunction (increased excretion of retinol-binding protein). This is the first report of bone effects among Cd-exposed population groups in Asia outside Japan. The report is also of interest since it demonstrates that bone effects, a comparatively severe adverse health effect of Cd, in combination with renal dysfunction, still occurs in environmentally exposed population groups in Asia. Recent reports on bone effects in Cd-exposed population groups in Europe are discussed.  相似文献   
549.
Urban grasslands not only provide a recreational venue for urban residents, but also sequester organic carbon in vegetation and soils through photosynthesis, and release carbon dioxide through respiration, which largely contribute to carbon storage and fluxes at regional and global scales. We investigated organic carbon and nitrogen pools in subtropical turfs and found that dissolved organic carbon(DOC) and dissolved organic nitrogen(DON)were regulated by several factors including microbial activity which is indicated by soil enzymatic activity. We observed a vertical variation and different temporal patterns in both soil DOC, DON and enzyme activities, which decreased significantly with increasing soil depths. We further found that concentration of soil DON was linked with turf age. There were correlations between grass biomass and soil properties, and soil enzyme activities. In particular, soil bulk density was significantly correlated with soil moisture and soil organic carbon(SOC). In addition, DOC correlated significantly with DON. Significant negative correlations were also observed between soil total dissolved nitrogen(TDN) and grass biomass of Axonopus compressus and Zoysia matrella. Specifically, grass biomass was significantly correlated with the soil activity of urease and β-glucosidase. Soil NO3-N concentration also showed negative correlations with the activity of both β-glucosidase and protease but there were no significant correlations between cellulase and soil properties or grass biomass. Our study demonstrated a relationship between soil C and N dynamics and soil enzymes that could be modulated to enhance SOC pools through management and maintenance practices.  相似文献   
550.
研究了在溴化十六烷基吡啶存在下,邻硝基苯基荧光酮与铝显色反应的条件,结果表明,在pH5.0的乙酸-乙酸钠缓冲溶液中,A1(Ⅲ)与邻硝基苯基荧光酮生成一种玫瑰红色给合物,其最大吸收波长在559nm,摩尔吸光系数为7.82×104,比耳定律范围0~10μg/25ml,拟定了测定饮茶、饮水中微量铝的方法,结果令人满意。  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