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   505篇
  免费   25篇
  国内免费   53篇
安全科学   46篇
废物处理   14篇
环保管理   45篇
综合类   223篇
基础理论   61篇
污染及防治   67篇
评价与监测   31篇
社会与环境   87篇
灾害及防治   9篇
  2024年   1篇
  2023年   6篇
  2022年   35篇
  2021年   26篇
  2020年   28篇
  2019年   14篇
  2018年   19篇
  2017年   22篇
  2016年   27篇
  2015年   24篇
  2014年   32篇
  2013年   40篇
  2012年   23篇
  2011年   23篇
  2010年   28篇
  2009年   27篇
  2008年   13篇
  2007年   14篇
  2006年   16篇
  2005年   17篇
  2004年   13篇
  2003年   26篇
  2002年   31篇
  2001年   31篇
  2000年   21篇
  1999年   3篇
  1998年   2篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   4篇
  1990年   1篇
  1988年   2篇
  1984年   1篇
  1982年   2篇
  1980年   1篇
  1978年   1篇
  1971年   1篇
排序方式: 共有583条查询结果,搜索用时 875 毫秒
551.
关于消费者对转基因农产品认知的调查   总被引:8,自引:0,他引:8  
调查发现有不少声称调查前就对转基因农产品“知道一点”,但了解的程度却有很大差别,其实更多的人并不真正了解,在对待基因农产品的态度上表现出相当的规律性:虽然都比较关注对生产转基因农产品给农民带来的收入,但更多的是关注对生态环境和人体健康的影响,希望加强管理。不同年龄、婚姻状态、性别和不同收入水平的人对转基因农产品的认知程度和态度虽然有很大程度的相似性,但也有相当程度的不同。  相似文献   
552.
旅游业可持续发展的指标体系研究   总被引:22,自引:1,他引:21  
本文提出旅游业可持续发展指标体系的构建思路 ,指出指标体系应以可持续发展的社会、经济和环境多元目标为标准 ,全面衡量旅游业可持续发展水平、可持续发展能力和可持续发展的协调性。文章给出可持续旅游指标体系的 4个层 :状态层、诊断层、趋势层和目标层 ,并在建立指标体系基础上构筑可持续旅游目标判断模型  相似文献   
553.
Lin CJ  Lo SL  Liou YH 《Chemosphere》2005,59(9):1299-1307
Nanoscale zerovalent copper supported on a cation resin was successfully synthesized to enhance the removal of carbon tetrachloride (CCl(4)) from contaminated water. The use of the cation resin as a support prevents the reduction of surface area due to agglomeration of nanoscale zerovalent copper particles. Moreover, the cation resin recycles the copper ions resulting from the reaction between CCl(4) and Cu(0) by simultaneous ion exchange. The decline in the amount of CCl(4) in aqueous solution results from the combined effects of degradation by nanoscale zerovalent copper and sorption by the cation resin; thus the amount of CCl(4) both in aqueous solution and sorbed onto the resin were measured. The pseudo-first-order rate constant normalized by the surface-area and the mass concentration of nanoscale zerovalent copper (k(SA)) was 2.1+/-0.1 x 10(-2)lh(-1)m(-2), approximately twenty times that of commercial powdered zerovalent copper (0.04 mm). Due to the exchange between Cu(2+) and the strongly acidic ions (H(+) or Na(+)), the pH was between 3 and 4 in unbuffered solution and Cu(2+) at the concentration of less than 0.1 mg l(-1) was measured after the dechlorination reaction. In the above-ground application, resin as a support would facilitate the development of a process that could be designed for convenient emplacement and regeneration of porous reductive medium.  相似文献   
554.
The optimized production of a novel bioflocculant M-C11 produced by Klebsiella sp. and its application in sludge dewatering were investigated. The optimal medium carbon source,nitrogen source, metal ion, initial pH and culture temperature for the bioflocculant production were glucose, NaNO3, MgSO4, and pH 7.0 and 25°C, respectively. A compositional analysis indicated that the purified M-C11 consisted of 91.2% sugar, 4.6% protein and 3.9% nucleic acids(m/m). A Fourier transform infrared spectrum confirmed the presence of carboxyl, hydroxyl,methoxyl and amino groups. The microbial flocculant exhibited excellent pH and thermal stability in a kaolin suspension over a pH range of 4.0 to 8.0 and a temperature range of 20 to 60°C.The optimum bioflocculating activity was observed as 92.37% for 2.56 mL M-C11 and 0.37 g/L CaCl2 dosages using response surface methodology. The sludge resistance in filtration(SRF)decreased from 11.6 × 1012 to 4.7 × 1012m/kg, which indicated that the sludge dewaterability was remarkably enhanced by the bioflocculant conditioning. The sludge dewatering performance conditioned by M-C11 was more efficient than that of inorganic flocculating reagents,such as aluminum sulfate and polymeric aluminum chloride. The bioflocculant has advantages over traditional sludge conditioners due to its lower cost, benign biodegradability and negligible secondary pollution. In addition, the bioflocculant was favorably adapted to the specific sludge pH and salinity.  相似文献   
555.
患心血管病老年人夏季PM2.5和CO的暴露特征及评价   总被引:2,自引:0,他引:2       下载免费PDF全文
王媛  黄薇  汪彤  陈娅  苏聿  张利文 《中国环境科学》2009,29(9):1005-1008
运用室内外环境监测与问卷调查法相结合的研究方法,对北京市某社区33名患心血管疾病的老年人夏季PM2.5、CO的暴露特征作了研究评价.结果表明,老年人夏季PM2.5、CO的24h个体平均暴露浓度分别为89.6μg/m3,1.9×10-6.PM2.5室内外浓度呈现明显的时间变化特征,并受到气象因素及室内外源排放的共同影响.对老年人群室内外与固定站点CO、PM2.5质量浓度变化的相关性分析显示,室外及固定站点的PM2.5浓度受区域污染源影响较大,CO浓度受局地源影响较大;大气PM2.5可能是影响该社区老年人健康的主要污染物.  相似文献   
556.
调查了星云湖径流区内磷矿和磷化工企业的分布情况,并对入湖河流水质现状进行了监测,结果表明:磷矿开采开发的磷污染入湖负荷量为46.6 t/a,其中螺蛳铺河径流区占84%。因此,治理星云湖流域磷矿开采加工区域磷流失是关键,重点是螺蛳铺磷化工业区。  相似文献   
557.
目前在农村环境中大量的类激素物质不断以各种途径进入地表和地下水体,对环境造成了极大的危害。严重威胁着居民的身体健康。我们应该密切关注这个问题,严加控制类激素物质的用量,选择合适的处理方法如物理吸附、光化学或电化学催化氧化、生物处理等,有效去除进入农村环境的类激素物质。并对农村饮用水进行严格的处理,采取集中供水方式,保障农村的饮用水安全,促进新农村建设。  相似文献   
558.
Four typical coastal sites (rocky shore, sandy shore, mud flat shore, and artificial harbor) at the Yellow Sea were chosen to investigate the spatial and seasonal variations in bacterial communities. This was accomplished by using terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR amplified 16S rDNA fragments. Two kinds of tetrameric restriction enzymes, HhaI and MspI, were used in the experiment to depict the bacterial community diversity in different marine environments. It was found that the community compositions digested by the two enzymes separately were different. However, the results of bacterial community diversity derived from them were similar. The MDA analysis results of T-RFLP profiles coming from HhaI and MspI both exhibited a significant seasonal community shift for bacteria and a relatively low spatial variation among the four locations. With HhaI as the sample, the pair wise T-tests also revealed that variations were minor between each pair of marine environments, with R ranging from 0.198 to 0.349. However, the bacterial community structure in the mud flat site depicted a larger difference than each of the other three sites (R ranging from 0.282 to 0.349).  相似文献   
559.
An intensive sampling program had been undertaken in autumn (October, 2008) and winter (December, 2008 and January, 2009) at urban (Xiamen University and Xianyue residential area), suburban (Institute of Urban Environment), industrial area (Lulian Hotel) and background (Tingxi Reservoir) in Xiamen, Fujian Province, to characterize the atmospheric concentration and gas-particle phase partitioning of PAHs. The average concentration of total PAHs in winter was almost 1.7 times higher than those in autumn. The log scale plot of Kp versus sub-cooled liquid vapor pressure (P0 L) for all the data of autumn and winter season samples gave significantly di erent slopes. The slope for the winter samples (–0.72) was steeper than that for the autumn samples (–0.58). The partitioning results indicated that slope values varied depending on characteristics of specific site, source region and meteorological conditions which play important roles in the partitioning of PAHs. In addition, local emission sources had a stronger e ect on partitioning results than long-transported polluted plume. The sources of PAHs in five sampling sites in Xiamen also have been discussed initially. Diagnostic ratios showed that the primary source of PAHs in urban, suburban and industrial area was from vehicle exhausts. While emission from petrochemical factory and power plant was another main contributor to industrial area.  相似文献   
560.
印染废水具有水量大、有机污染物浓度高、色度深、碱性大、水质变化大、成分复杂等特点,属较难处理的工业废水之一。印染废水治理方法研究与应用针对问题提出了一种完整的处理工艺,该处理工艺采用物化与生化技术相结合并以生化处理为主的优化组合,并以实例进行了详细说明。  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