全文获取类型
收费全文 | 7777篇 |
免费 | 596篇 |
国内免费 | 1686篇 |
学科分类
环境安全 | 10059篇 |
出版年
2024年 | 21篇 |
2023年 | 144篇 |
2022年 | 208篇 |
2021年 | 256篇 |
2020年 | 242篇 |
2019年 | 338篇 |
2018年 | 341篇 |
2017年 | 396篇 |
2016年 | 483篇 |
2015年 | 425篇 |
2014年 | 418篇 |
2013年 | 673篇 |
2012年 | 590篇 |
2011年 | 655篇 |
2010年 | 498篇 |
2009年 | 614篇 |
2008年 | 413篇 |
2007年 | 491篇 |
2006年 | 439篇 |
2005年 | 384篇 |
2004年 | 292篇 |
2003年 | 267篇 |
2002年 | 228篇 |
2001年 | 195篇 |
2000年 | 202篇 |
1999年 | 172篇 |
1998年 | 103篇 |
1997年 | 102篇 |
1996年 | 80篇 |
1995年 | 86篇 |
1994年 | 55篇 |
1993年 | 62篇 |
1992年 | 40篇 |
1991年 | 29篇 |
1990年 | 31篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 12篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 8篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Bunge Michael Khknen Mika A. Rmisch Winfried Opel Matthias Vogler Susanne Walkow Fred Salkinoja-Salonen Mirja Lechner Ute 《Environmental science and pollution research international》2007,14(1):3-10
Background, Aims and Scope Sediments of the Spittelwasser creek are highly polluted with organic compounds and heavy metals due to the discharge of untreated
waste waters from the industrial region of Bitterfeld-Wolfen, Germany over the course of more than one century. However, relatively
few data have been published about the chloroorganic contamination of the sediment. This paper reports on the content of different
(chloro)organic compounds with special emphasis on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), and chlorobenzenes. Existing concepts for the remediation of Spittelwasser sediment include
the investigation of natural attenuation processes, which largely depend on the presence of an intact microbial food web.
In order to gain more insight in terms of biological activity, we analyzed the capacity of sediment microflora to degrade
organic matter by measuring the activities of extracellular hydrolytic enzymes involved in the biogeochemical cycling of carbon,
nitrogen, phosphorus and sulfur. Furthermore, the detection of physiologically active bacteria in the sediment, particularly
of those known for their capability to reductively dehalogenate organochlorine compounds, illustrates the potential for intrinsic
bioremediation processes.
Methods PCDD/F and chlorobenzenes were analyzed by gas chromatography(GC)/mass spectrometry and GC/flame ionization detection, respectively.
The activities of hydrolytic enzymes were determined from freshly sampled sediment layers using 4-methylumbelliferyl (MUF)
or 7-amino-4-methylcoumarin-conjugated model compounds and kinetic fluorescence measurements. Physiologically active bacteria
from different sediment layers were microscopically visualized by fluorescence in situ hybridization (FISH). Specific bacteria were identified by 16S rRNA gene amplification and sequencing.
Results and Discussion The PCDD/F congener profile was dominated by dibenzofurans. In addition, the presence of specific tetra and pentachlorinated
dibenzofurans supported the assumption that extensive magnesium production was one possible source for the high contamination.
A range of other chloroorganic compounds, including several isomers of chlorobenzenes, hexachlorocyclohexane and 1,1,1-trichloro-2,2-bis
(p-chloro-phenyl)ethane (DDT), was present in the sediment. Activities of extracellular hydrolytic enzymes showed a strong
decrease in those sediment layers that were characterized by high contents of absorbable organic halogen (AOX), indicating
disturbed organic matter decay. Interestingly, an abnormal increase of cellulolytic enzyme activities below the organochlorine-rich
layers was observed, possibly caused by residual cellulose from discharges of sulfite pulping wastes. FISH revealed physiologically
active bacteria in most sediment layers from the surface down to the depth of about 60 cm, including members of Desulfitobacterium (D.) and Sulfurospirillum. The presence of D. dehalogenans was confirmed by its partial 16S rRNA gene sequence.
Conclusions Results of chemical sediment analyses demonstrated high loads of organochlorine compounds, particularly of PCDD/F. Several
years after stopping the waste water discharge to Spittelwasser creek, this sediment remains a main source for pollution of
the downstream river system by way of the ongoing mobilization of sediment during high floods. As indicated by our enzyme
activity measurements, the decomposition potential for organic matter is low in organochlorine-rich sediment layers. In contrast,
the comparably higher enzyme activities in less organochlorine-polluted sediment layers as well as the presence of physiologically
active bacteria suggest a considerable potential for natural attenuation.
Recommendations and Perspectives From our data we strongly recommend to explore the degradative capacity of sediment microorganisms and the limits for in situ activity towards specific sediment pollutants in more detail. This will give a sound basis for the integration of bioremediation
approaches into general concepts to reduce the risk that permanently radiates from this highly contaminated sediment.
Submission Editor: Dr. Henner Hollert (Henner.Hollert@urz.uniheidelberg.de) 相似文献
2.
国际海事组织目前正在对《MARPOL73/78公约》附则Ⅱ-控制散装液体有毒物质污染规则作重大修改,内容包手胡毒液体物质和化学品,这很可能对主管机关、船公司和化工界造成严重的冲击。 相似文献
3.
Influence of new town development on the urban heat island - The case of the Bundang area 总被引:3,自引:0,他引:3
SONG Young-bae 《环境科学学报(英文版)》2005,17(4):641-645
Five new towns have been developed around the Seoul metropolitan area since 1996. However, these new towns generate lots of traffic and related problems in the areas including those new towns and Seoul as a result of increases in population and a lack of ecological-self-sufficiency. Currently, construction of another new town is under deliberation, and what should be a major consider is the notion that the new town be located within a wide, green zone. Many studies have revealed that green space can play an important role in improving urban eco-meteorological capability and air quality. In order to analyze the urban heat island which will be created by the new urban development, and to investigate the local thermal environment and its negative effects caused by a change of land use type and urbanization, Landsat TM images were used for extraction of urban surface temperature according to changes of land use over the last 15 years. These data are analyzed together with digital land use and topographic information. As a study result, it was found the urban heat island of the study area from 198.5 to 1999 rapidly developed which showed a difference of mean temperature above 2.0. Before the Bundang new town construction the temperature of the residential area was the same as a forest, but during the new town construction in 1991 analysis revealed the creation of an urban heat island. The temperature of a forest whose size is over 50% of the investigation area was lowest, and thus the presence of a forest is believed to have a direct cooling effect on the urban environment and its surroundings. The mean temperature of the residential and commercial areas in the study was found to be 4.5 higher than the forest, and therefore this part of land use is believed to be the main factor causing the temperature increase of the urban heat island. 相似文献
4.
5.
Human adaptation to climate change: a review of three historical cases and some general perspectives
To study mitigation and adaptation to climate change, social scientists have drawn on different approaches, particularly sociological approaches to the future and comparative history of past societies. These two approaches frame the social and temporal boundaries of decision-making collectivities in different ways. A consideration of the responses to climate variability in three historical cases, the Classic Maya of Mexico and Central America, the Viking settlements in Greenland, and the US Dust Bowl, shows the value of integrating these two approaches. 相似文献
6.
全球环境变化给发展中国家和南北关系带来深刻影响,理解环境问题的全球不平等需要以发展中国家80年代开始的经济结构调整和沉重债务为背景。南方的环境政策优先在很大程度上与其生活的可持续性相连,而不是通常与全球环境变化的长期性风险相关,然而,全球环境变化又与发展中国家贫困人口的日常生活紧密相关。从南方的立场看,当“问题”对他们不十分迫切时,就很难同意采取措施,仅此原因,北方对全球环境变化的关切要得到成功回应,真正的全球契约就需要解决基本“发展”问题,主要是贫困。 相似文献
7.
针对鱼油工业废水排放特点及处理技术难点,结合实例,采用混凝、破乳进行物化预处理;采用A/O生化处理技术,提出合适的工艺流程。 相似文献
8.
IntroductionChlorinatedorganiccompoundshavebeenusedonalargescaleinthechemical,petrochemical,andelectronicindustries.Inrecentyears ,worldwideattentionhasbeengiventotheenvironmentalandhealthimpactofthemasaclassofcontaminants .Severalareknowntocauseozonedepletion ,whileothersproduceadverseeffectsonthehumancentralnervoussystemandhavebeenlinkedtodiseasessuchascancer.Almostallofthechlorinatedaromaticcompoundsaretoxicandthermallystable .Oncereleasedintoenvironment,theywillaccumulateinthesurroundings… 相似文献
9.
从二(?)(?)类化合物的结构、来源、毒性等简要说明对其监测的必要性,且从仪器监测(包括气相色谱、气质联用、串联质谱等)和生物监测(包括利用指示生物、生物标志物等)概述了80年代以来国内外对二(?)(?)类物质尤其是几种极毒性化合物如多氯代二苯二(?)(?)(PCDDs)和多氯代二苯呋喃(PCDFs)等化合物的检测技术成果。 相似文献
10.
Robert France 《Environmental management》1996,20(2):249-255
Due to assimilation of recycled CO2 from litter decomposition and photosynthetic changes in carbon fractionation at low light levels, the foliage at the base of a forest is often more depleted in13C compared to that exposed to the atmosphere in either the canopy or in open clearings. This is referred to as the canopy effect. African research has indicated that these habitat differences in foliar 13C can be substantial enough to affect the carbon isotope ratios of resident fauna. Previous work documenting a 30-year chronology on moose teeth from Isle Royale National Park indicated a progressive depletion in13C and suggested that this could be due to forest regrowth following extensive burning. The present study examined the assumption implicit in this hypothesis that foliar 13C varies between open and closed boreal forest sites. I found a marginal canopy effect of 2 13C difference between upper canopy and ground flora for a forest in northwestern Ontario and an average difference of 1.2 in under- and mid-story vegetation between closed forests and open clear-cuts. Because of these small differences, the utility of carbon isotope analysis in quantifying temporally integrated exploitation of deforested habitats will be low for northern boreal locations. In denser forests, such as those in the tropics or western North American where the canopy effect can be expected to be much greater, 13C analysis may still offer some promise for determining selection by wildlife of disturbed habitats. 相似文献