全文获取类型
收费全文 | 7122篇 |
免费 | 646篇 |
国内免费 | 1941篇 |
专业分类
安全科学 | 521篇 |
废物处理 | 182篇 |
环保管理 | 1303篇 |
综合类 | 4433篇 |
基础理论 | 1058篇 |
污染及防治 | 884篇 |
评价与监测 | 478篇 |
社会与环境 | 591篇 |
灾害及防治 | 259篇 |
出版年
2024年 | 16篇 |
2023年 | 117篇 |
2022年 | 221篇 |
2021年 | 271篇 |
2020年 | 234篇 |
2019年 | 249篇 |
2018年 | 254篇 |
2017年 | 292篇 |
2016年 | 394篇 |
2015年 | 349篇 |
2014年 | 414篇 |
2013年 | 524篇 |
2012年 | 599篇 |
2011年 | 642篇 |
2010年 | 481篇 |
2009年 | 583篇 |
2008年 | 407篇 |
2007年 | 487篇 |
2006年 | 438篇 |
2005年 | 402篇 |
2004年 | 322篇 |
2003年 | 281篇 |
2002年 | 267篇 |
2001年 | 217篇 |
2000年 | 208篇 |
1999年 | 182篇 |
1998年 | 129篇 |
1997年 | 113篇 |
1996年 | 112篇 |
1995年 | 123篇 |
1994年 | 71篇 |
1993年 | 63篇 |
1992年 | 55篇 |
1991年 | 33篇 |
1990年 | 32篇 |
1989年 | 11篇 |
1988年 | 21篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
排序方式: 共有9709条查询结果,搜索用时 234 毫秒
61.
The purpose of this work was to study the distribution of airborne particles in the surroundings of an iron and steel factory in southern Finland. Several sources of particulate emissions are lying side by side, causing heavy dust loading to the environment. This complicated multi-pollutant situation was studied mainly by SEM/EDX methodology.Particles accumulated on Scots pine bark were identified andquantitatively measured according to their element content,size and shape. As a result, distribution maps of particulateelements were drawn and the amount of different particle typesalong the study lines was plotted. Particulate emissions fromthe industrial or energy production processes were not themain dust source. Most emissions were produced from theclinker crusher. Numerous stockpiles of the industrial wastesand raw materials also gave rise to particulate emissions as aresult of wind erosion. It was concluded that SEM/EDXmethodology is a useful tool for studying the distribution ofparticulate pollutants. 相似文献
62.
63.
64.
Assessing protected area effectiveness using surrounding (buffer) areas environmentally similar to the target area 总被引:7,自引:0,他引:7
Mas JF 《Environmental monitoring and assessment》2005,105(1-3):69-80
Many studies are based on the assumption that an area and its surrounding (buffer) area present similar environmental conditions and can be compared. For example, in order to assess the effectiveness of a protected area, the land use/cover changes are compared inside the park with its surroundings. However, the heterogeneity in spatial variables can bias this assessment: we have shown that most of the protected areas in Mexico present significant environmental differences between their interior and their surroundings. Therefore, a comparison that aims at assessing the effectiveness of conservation strategies, must be cautioned. In this paper, a simple method which allows the generation of a buffer area that presents similar conditions with respect to a set of environmental variables is presented. The method was used in order to assess the effectiveness of the Calakmul Biosphere Reserve, a protected area located in the south-eastern part of Mexico. The annual rate of deforestation inside the protected area, the standard buffer area (based upon distance from the protected area only) and the similar buffer area (taking into account distance along with some environmental variables) were 0.3, 1.3 and 0.6%, respectively. These results showed that the protected area was effective in preventing land clearing, but that the comparison with the standard buffer area gave an over-optimistic vision of its effectiveness. 相似文献
65.
详细介绍了“城市空气质量日报自动发布系统”的开发背景和开发过程 ,并对系统整体的架构和所用到的技术作了针对性的说明 ,阐明了作者对此类系统的前景和发展方向的看法。 相似文献
66.
67.
Wong MY Sauser KR Chung KT Wong TY Liu JK 《Environmental monitoring and assessment》2001,67(3):361-378
The green alga Selenastrum capricornutum expresses a uniqueascorbate peroxidase, that responds to copper and lead. Attemptswere made to test if this peroxidase could be used to monitor thelevels of copper and lead in natural waters. When S.capricornutum was exposed to a stormwater sample, the specificactivity of the peroxidase in the cell extract was commensuratewith the combined copper and lead contents in the sample. Theperoxidase responses were also correlated with the 96 hr biomasstoxicity assay of S. capricornutum. However, unlike thebiomass toxicity assay, the peroxidase activity was not affectedby the anions in the samples. The use of this peroxidase can beused as a marker for testing heavy metal toxicity in the water. 相似文献
68.
固相萃取-气质联机测定水中嗅味物质2-甲基异茨醇和土霉素 总被引:4,自引:0,他引:4
分别利用固相萃取剂XAD-2树脂和C18SEP柱富集,二氯甲烷洗脱,固相萃取装置浓缩,通过气质联机(GC/MS)测定了水中土霉化合物MIB和Geosmin。该方法重现性好,相对标准偏差5.4%~7.0%,回收率80%~92%,MIB和Geosmin检出限分别为5ng/L和2ng/L。两种固相萃取剂对MIB和Geosmin吸附效率相当,吸附效率不受嗅味物质浓度影响,但当水溶液中其它有机质增多时,C18SPE的回收率明显下降。利用该方法对不同培养时间的放线菌代谢产物进行了测定,培养25天后代谢产物MIB和Geosmin的浓度达到200ng/L和130ng/L。 相似文献
69.
中国水环境的NPSP问题及对策 总被引:1,自引:0,他引:1
介绍了我国水环境中的非点源污染(NonpointSourcepollution,缩写为NPSP)的情况,强调农业生产是最主要的非点源污染。同时,针对我国水污染防治的政策目标,提出一些建议。 相似文献
70.
为修复灌区内土壤有机氯农药污染,降低六氯环己烷对土壤环境的危害,对内蒙古某灌域表层土壤进行采样,利用气相色谱测定50个土壤样品中六氯环己烷及其异构体的含量,并利用ArcGIS空间分析技术确定表层土壤中六氯环己烷的分布状况。样本中六氯环己烷的检出率为96%,各样本中六氯环己烷的浓度范围为未检出~23.0 ng/g,平均浓度为4.4 ng/g。4种异构体含量平均值顺序为γ-六氯环己烷>δ-六氯环己烷>β-六氯环己烷>α-六氯环己烷。灌域东北部和西南部残留浓度较高,并由这2个方向向中部地区逐渐递减,表层土壤中的六氯环己烷分布受土壤黏粒量、不同种植种类和灌溉水源的影响较大。虽受人类耕作的影响,但表层土壤中的六氯环己烷污染水平相对较低。 相似文献