全文获取类型
收费全文 | 643篇 |
免费 | 2篇 |
国内免费 | 6篇 |
专业分类
安全科学 | 8篇 |
废物处理 | 2篇 |
环保管理 | 28篇 |
综合类 | 369篇 |
基础理论 | 108篇 |
环境理论 | 2篇 |
污染及防治 | 96篇 |
评价与监测 | 19篇 |
社会与环境 | 16篇 |
灾害及防治 | 3篇 |
出版年
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2015年 | 9篇 |
2014年 | 8篇 |
2013年 | 28篇 |
2012年 | 12篇 |
2011年 | 13篇 |
2010年 | 17篇 |
2009年 | 15篇 |
2008年 | 16篇 |
2007年 | 20篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 19篇 |
1998年 | 6篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1992年 | 6篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1967年 | 6篇 |
1966年 | 8篇 |
1965年 | 7篇 |
1964年 | 8篇 |
1961年 | 9篇 |
1960年 | 6篇 |
1955年 | 7篇 |
1952年 | 6篇 |
1942年 | 6篇 |
1941年 | 8篇 |
1940年 | 9篇 |
1938年 | 6篇 |
1937年 | 12篇 |
1936年 | 10篇 |
1935年 | 9篇 |
1934年 | 11篇 |
1933年 | 7篇 |
1931年 | 7篇 |
1929年 | 8篇 |
1922年 | 6篇 |
1921年 | 7篇 |
1920年 | 5篇 |
排序方式: 共有651条查询结果,搜索用时 187 毫秒
71.
Measurements were made with a Clark electrode in a closed system under conditions of different, regulatable water current velocities. Six simultaneous parallel measurements are possible with only one electrode. The volume of respiration chambers amounts to 80 ml for small animals and 300 ml for larger ones. Technical details of the apparatus and measuring procedures are described. The accuracy amounts to 0.5 μl O2 for the 80 ml chamber, and 2 μl O2 for the 300 ml chambers. The apparatus has been successfully used on various marine evertebrates and algae. 相似文献
72.
During the demolition of an industrial building contaminated with chlorophenols and polychlorinated dibenzodioxins (from Boehringer & Sohn in Hamburg-Moorfleet, Germany), several measures must be taken in order to protect the surroundings. Since these compounds are strongly adsorbed by particulate matter, a mist is continuously sprayed over the whole building. The waste water is expected to be highly contaminated and must therefore undergo extensive purification procedures. The primary goal of the existing study is to examine whether or not the present effluent reprocessing unit, a system which is comprised of a charcoal filter, is able to clean the waste water according to legal requirements. Secondly, the main factors that influence the clean up of the effluent were investigated in order to design a suitable precleaning unit for the contaminated water should the present reprocessing unit not fulfill these requirements. By means of the factorial design technique, the effect of three factors (flow velocity of the water, amount of charcoal and the pH-value) on the efficiency of the cleaning process and with regard to chlorophenols was examined. Surprisingly, the pH-value does not have a significant effect on the efficiency. In addition, the results of the experiments show that a precleaning of the effluent is not required. 相似文献
73.
Sedimentation of particulate matter during a phytoplankton spring bloom in relation to the hydrographical regime 总被引:1,自引:0,他引:1
Data presented and discussed here were collected continuously during April/May 1975 in the Bornholm Basin of the Baltic Sea. Sedimentation rates of particulate matter were recorded with 5 multisample sediment traps from different depths in the water column at 2 positions 170 km apart. Current meter data collected during the same period and depths indicated that the positions remained hydrographically distinct during the investigation. Particulate matter from the euphotic zone including diatom cells formed the bulk of the material collected by all traps. This flux of organic particles to the bottom was unimpeded by the strong density stratification present in the water column. The upper traps always collected less material than lower ones. This paradox has been ascribed to diminishing current speeds with depth, concomitant with an increase in sinking rates of phytoplankton and phytodetritus. Both factors influence the sampling efficiency of sediment traps, which are thought to have underestimated actual sedimentation rates here. A time lag of 2 to 3 weeks in bloom development seemed responsible for the characteristic differences between the two positions. The phase of major sedimentation at one position covered about 18 days, and a distinct sequence in the composition of the material collected by the 6 glasses of each trap indicated phases of a progressively deteriorating phytoplankton population in the water column contributing the particulate material. A total of 6.2 g C m-2 in 34 days was recorded at this station. Apart from a trap situated in an oxygen deficient layer which collected 0.44 g C m-2 of zooplankton corpses, zooplankton mortality was overestimated by the traps. Large-scale sedimencation of fresh organic matter produced by the spring bloom is probably a regular feature in areas with low over-wintering zooplankton populations and, as such, possibly has a direct stimulatory effect on growth and reproduction of the benthos.Contribution No. 185 of the Joint Research Programme 95, Kiel University. 相似文献
74.
A study was made on the vertical distribution of Chaetognatha in the Hilutangan Channel, based on analyses of 48 plankton samples. Thirty-min horizontal plankton tows were performed at depths of 1, 20, 50, 70 and 100 m in January 1972. Thirteen species of 3 genera of maturing and mature chaetognaths were identified and counted. Sagitta inflata was the most common and abundant species (63.0%), folloed by S. neglecta (9.7%), S. robusta (8.6%), S. regularis (5.4%), S. serratodentata (4.2%), Krohnitta pacifica (2.9%), S. bedoti (2.3%) and S. decipiens (2.0%). S. pulchra (0.7%), S. ferox (0.5%), K. subtilis (0.3%), Pterosagitta draco (0.2%) and S. hexaptera (0.2%) were represented by less than 1% each. Of these 13 species in the upper 100 m, 12 were epiplanktonic while one species, S. decipiens, is generally considered to be mesoplanktonic. Three species were classified as neritic, 3 as neritic-oceanic, and 6 as oceanic, indicating the dominant influence and strong influx of oceanic water into the Hilutangan Channel. Temperature, salinity and dissolved oxygen content did not seem to influence the vertical distribution. Examination of gut contents showed that copepods, followed by arrow worms, were most common in the guts of the chaetognaths studied. 相似文献
75.
76.
77.
78.
Interactive effects of elevated ozone and carbon dioxide on growth and yield of leaf rust-infected versus non-infected wheat 总被引:2,自引:0,他引:2
Spring wheat (Triticum aestivum L. cv. Turbo) was grown from seedling emergence to maturity (129 days) in chambers simulating the physical climate and ozone pollution of a field site in Northern Germany from 1 April to 31 July with a mean 1-h daily maximum of 61.5-62.4 nl l(-1) ozone compared to a constant low level of 21.5-22.8 nl l(-1) ozone. The two ozone levels were combined with either a current (374.1-380.2 microl l(-1)) or enriched (610.6-615.0 microl l(-1)) CO(2) atmosphere. Additionally, a leaf rust epidemic (Puccinia recondita f. sp. tritici) was induced at tillering stage by repeated re-inoculations with the inoculum formed on the plants. Leaf rust disease was strongly inhibited by ozone, but largely unaffected by elevated CO(2). Ozone damage on leaves was strongly affected by CO(2) and infection. On infected plants, ozone lesions appeared 2-4 weeks earlier and were up to fourfold more severe compared to non-infected plants. Elevated CO(2) did not delay the onset of ozone lesions but it significantly reduced the severity of leaf damage. It also enhanced the photosynthetic rate of flag leaves and increased the water use efficiency, biomass formation and grain yield. The relative increases in growth and yield induced by CO(2) were much larger on ozone-stressed than on non-stressed plants. Both ozone and fungal infection reduced biomass formation, number of grains per plant, thousand grain weight and grain yield; however, adverse effects of leaf rust infection were more severe. Elevated CO(2) largely equalized the negative effects of ozone on the photosynthetic rate, growth and yield parameters, but was not capable of compensating for the detrimental effects of fungal infection. The data imply that the impact of ozone in the field cannot be estimated without considering the predisposing effects deriving from fungal infections and the compensating effects deriving from elevated CO(2). 相似文献
79.
Andreas Ahrens Arnim von Gleich und Lothar Li?ner 《Umweltwissenschaften und Schadstoff-Forschung》2002,14(3):165-169
Ohne Zusammenfassung
Online First: 27. 03. 2002
‚Sustainable Substitution of Hazardous Substances‚; Projektbeschreibung unter wwwoekopolde oder wwwfh-hamburgdelpers/gleich_von bzw. www.uni-hamburgde/kooperationssteI1e-hh. Das Vorhaben wird vom Bundesministerium für Bildung und Forschung (BMBF) im F?rderschwerpunkt ‚Rahmenbedingungen für Innovationen
zum nachhaitigen Wirtschaften’ (RIW) gef?rdert und von der GSF als Projekttr?ger betreut (FkZ. O7Riw4). 相似文献
80.