全文获取类型
收费全文 | 345篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 9篇 |
废物处理 | 5篇 |
环保管理 | 18篇 |
综合类 | 124篇 |
基础理论 | 93篇 |
污染及防治 | 77篇 |
评价与监测 | 15篇 |
社会与环境 | 9篇 |
出版年
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 15篇 |
2012年 | 16篇 |
2011年 | 19篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 16篇 |
2005年 | 9篇 |
2004年 | 12篇 |
2003年 | 11篇 |
2002年 | 14篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1985年 | 4篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1966年 | 7篇 |
1965年 | 3篇 |
1964年 | 4篇 |
1963年 | 4篇 |
1962年 | 5篇 |
1960年 | 2篇 |
1958年 | 3篇 |
1957年 | 3篇 |
1955年 | 4篇 |
1954年 | 2篇 |
1952年 | 2篇 |
1951年 | 3篇 |
1943年 | 2篇 |
1940年 | 2篇 |
1939年 | 2篇 |
排序方式: 共有350条查询结果,搜索用时 31 毫秒
151.
152.
153.
154.
Ulrich Helfenstein Ursula Ackermann-Liebrich Charlotte Braun-Fahrländer Hans Urs Wanner 《Environmental monitoring and assessment》1991,17(2-3):147-156
The purpose of the present statistical analysis was the assessment of the relation between time series of environmental factors and of frequencies of diseases of the respiratory system in pre-school children. During about one year, daily measurements of air pollutants and climatic variables were taken. During the same period of time two series of medical data were collected: (i) The daily relative number of pre-school children, exhibiting diseases of the respiratory tracts who either came to the outpatients' clinic of the children's hospital or were reported by paediatricians in Basle (ENTRIES). (ii) The daily relative frequency of symptoms of the respiratory tracts observed in a group of randomly selected pre-school children (SYMPTOMS).By means of transfer function models the relation between the two target variables and the explaining variables was analysed. Several practical problems did arise: Choice of the appropriate transformation of the different series, interpretation of the crosscorrelation function using different methods of prewhitening, time splitting and nonstationarity of the crosscorrelation structure. In particular, it was found that after prewhitening the crosscorrelation function between the explanatory series SO2 and the response series SYMPTOMS changes with time. While during the winter period an instantaneous relation between these two series (and to a lesser extent between NO2 and SYMPTOMS) was identified, no such relation was found for the other seasons. 相似文献
155.
156.
Fleischer S 《Ambio》2003,32(1):2-5
Evidence is provided for an internal CO2 sink in forest soils, that may have a potential impact on the global CO2-budget. Lowered CO2 fraction in the soil atmosphere, and thus lowered CO2 release to the aboveground atmosphere, is indicated in high N-deposition areas. Also at forest edges, especially of spruce forest, where additional N-deposition has occurred, the soil CO2 is lowered, and the gradient increases into the closed forest. Over the last three decades the capacity of the forest soil to maintain the internal sink process has been limited to a cumulative supply of approximately 1000 and 1500 kg N ha(-1). Beyond this limit the internal soil CO2 sink becomes an additional CO2 source, together with nitrogen leaching. This stage of "nitrogen saturation" is still uncommon in closed forests in southern Scandinavia, however, it occurs in exposed forest edges which receive high atmospheric N-deposition. The soil CO2 gradient, which originally increases from the edge towards the closed forest, becomes reversed. 相似文献
157.
Ulrich H?pfner 《Umweltwissenschaften und Schadstoff-Forschung》2001,13(4):206-215
Zusammenfassung Heute gültige und zukünftige Grenzwerte für Abgasemissionen von Kraftfahrzeugen werden bewirken, dass die limitierten Emissionen
des motorisierten Stra?enverkehrs in Deutschland weiter zurückgehen werden, obwohl von einer weiteren Zunahme der Fahrleistungen
ausgegangen wird. Nach den berechneten Emissionsminderungen und den abgesch?tzten Verbesserungen der Immissionen werden zukünftig
wichtige Luftqualit?tsziele erreicht werden. Insbesondere wird das kanzerogene Risiko durch den Stra?enverkehr deutlich unter
die Zielwerte absinken. Wichtigstes Problem der verkehrsbedingten Luftschadstoffemissionen scheinen die Feinst?ube zu sein,
zu deren Minderung m?glicherweise auch die Stickoxidund NMVOC-Emissionen beitragen müssen.
Die effiziente Reduktion der klimarelevanten Emissionen des Stra?enverkehrs ist die gro?e Herausforderung an Technik, Kraftstoffbereitstellung
und Nutzerverhalten. Sie wird die Umweltdiskussion auf lange Zeit bestimmen.
OnlineFirst: 11. 07. 2001 相似文献
158.
Determination of mono-, di- and trinitronaphthalenes in soil samples contaminated by explosives 总被引:1,自引:0,他引:1
We investigated the extraction of eight mono-, di- and trinitronaphthalenes from soil samples by ultrasonic, respectively, soxhlet extraction. Sonication was the more convenient procedure with a usually higher repeatability than the soxhlet method. All extracts were analysed by high-performance liquid chromatography with diode array detection. These methods were used to determine the concentration of nitronaphthalenes in five soil samples polluted by explosives. The most abundant contaminants were 1,5- and 1,8-dinitronaphthalene as well as 1,3,5-, 1,3,8- and 1,4,5-trinitronaphthalene. In all samples the sum of trinitronaphthalenes exceeded the sum of mono- and dinitronaphthalenes. It is recommendable to include these eight compounds in the analytical exploration of sites contaminated by explosives. 相似文献
159.
The big flood in the upper Elbe River catchment area has revealed a wide spectrum of problems with contaminated sediments. So far, an effective strategy for managing contaminated sediments on a river basin scale is still missing and it seems that not much has been learned from the lessons received during the last decade. In the following overview, special emphasis is given to the utilization of geochemically-based techniques for sediment remediation, which can be applied in different parts of a river basin. The examples presented here are mostly from the Elbe River catchment area. In general, new technical problem solutions need a set of practical process knowledge that uses a wide range of simulation techniques, as well as models in different spatial and temporal scales. The evaluation of recent flood events clearly demonstrates the importance of chemical expertise in the decision-making process for the sustainable development in river basins. 相似文献
160.
Complications arise when ratios are used to present environmental data because ratios are an unbounded, multiplicative scale that can lead to asymmetrical (skewed) data distributions. Enantiomeric ratios (ERs), historically used in discussions of chiral signatures, often are published as mean ER+/-single-value standard deviation. Application of statistical summaries, such as the widely used sample mean and standard deviation, to skewed ratio data is misleading and often inappropriate. Comparison of statistically summarized ER and enantiomer fraction (EF) data (which are based on a bounded, additive scale) for a range of hypothetical values reveals substantial discrepancies when conversion between ER and EF formats is used. These discrepancies are largest when the ratio data are greater than one and have large variability, because the data are more skewed. In many cases, the use of fractions instead of ratios can help to minimize misrepresentation of environmental data, including chiral data. The use of nonparametric statistical summaries, e.g., median and percentiles, provides a more robust indicator of the typical value and spread for both ER and EF data. 相似文献