全文获取类型
收费全文 | 278篇 |
免费 | 5篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 12篇 |
废物处理 | 3篇 |
环保管理 | 57篇 |
综合类 | 94篇 |
基础理论 | 45篇 |
污染及防治 | 52篇 |
评价与监测 | 11篇 |
社会与环境 | 12篇 |
出版年
2019年 | 7篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 13篇 |
2012年 | 10篇 |
2011年 | 18篇 |
2009年 | 12篇 |
2008年 | 6篇 |
2007年 | 11篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 5篇 |
2003年 | 10篇 |
2002年 | 3篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1974年 | 5篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 5篇 |
1967年 | 3篇 |
1957年 | 3篇 |
1955年 | 3篇 |
1954年 | 4篇 |
1953年 | 2篇 |
1942年 | 3篇 |
1923年 | 2篇 |
1922年 | 2篇 |
1920年 | 9篇 |
1919年 | 2篇 |
1918年 | 2篇 |
排序方式: 共有286条查询结果,搜索用时 531 毫秒
31.
32.
J. Ben-Asher N. Diner A. Brandt D. Goldberg 《Journal of the American Water Resources Association》1975,11(6):1187-1196
ABSTRACT: Two soil water functions, hydraulic conductivity K(θ) and diffusivity D(θ), were estimated by two methods In one method D(θ) was estimated according to Bruce and Klute (1956), and K(θ) was calculated from D(θ) and the retention curve. In the second, K(θ) was obtained by field estimation, with D(θ) being calculated from K(θ) and the retention curve. The criterion of reliability for both methods was agreement between experimental and predicted distribution of soil water content. The prediction was made using the functions K(θ) and D(θ) as soil water parameters in both methods. Theoretical and experimental agreement was generally good. The first method, however, was found to be best for high soil water content and the second for low soil water content. In addition, the water content at the end of the monotonic increase of function D(θ) (estimated according to Bruce and Klute 1956) was found to be about the upper limit of field soil water content. It can be used as a boundary condition in the numerical solution of a cylindrical model of infiltration from a trickle source. It was concluded that the best agreement between theory and experiment can be found when the combined values of D(θ) and K(θ) from both methods of estimation are used. 相似文献
33.
34.
Diadema antillarum populations at many Caribbean locations have failed to recover from a wide-spread mortality event during the early 1980s. Quantitative assessments of Diadema in Dominica have only recently begun and can now be put into a regional context. Diadema and benthic algae were monitored in 4-month intervals at six 100 m2 sites, spread over a distance of 38 km, along the west coast of Dominica. Diadema density surveys began in July 2001, while algal cover was monitored as of November 2001. Mean densities of individual sites ranged from 0.81 m−2 (SD=1.02) to 2.98 m−2 (SD=1.33), and overall means increased from 1.50 m−2 (SD=0.12) in 2001, to 2.00 m−2 (SD=0.05) in 2004. The weak negative relationship observed between the Diadema density and macroalgal cover (R
2=0.25, P=0.0030), indicates that Diadema play a limited role in controlling macroalgal species. In contrast, the abundance of turf algae was positively related to low Diadema densities, yet this relationship becomes negative beyond a critical point between 2.0 and 3.0 Diadema per m2 (R
2=0.25, P=0.0075). As of November 2001 size measurements of 100 randomly sampled urchins at each site were included in the surveys, resulting in overall mean test size diameters ranging between 5.54 cm (SD=1.55) and 6.00 cm (SD=0.96). The mean test size diameter per site ranged from 4.54 cm (SD=1.91) at Tarou Point in November 2003 to 6.77 cm (SD=0.83) at Salisbury November 2001. Across all sites except Tarou Point, the most commonly occurring Diadema sizes throughout this study were within 1 cm, in the range between 4.5 and 7.5 cm. It is unclear how this Dominica scenario fits into the context of the pathogen-induced mass mortality events of the 1980s because neither qualitative nor quantitative records exist for that time in Dominica. The recent increase in Diadema density may be a symptom of recovery from Hurricane Lenny. Given the indiscriminant local pressure (affecting herbivorous fishes as well as fish predators of Diadema) Diadema’s role as grazer of algal turfs is highlighted. On a regional scale, its stable population of reproductive size classes may serve as source of larvae for nearby downstream islands. 相似文献
35.
Dr. Roland Zimmermann Urs Lauper Anja Streicher Renate Huch Albert Hugh 《黑龙江环境通报》1995,15(12):1121-1124
In a series of 2961 consecutive cases with second-trimester biochemical triple screening for Down's syndrome and neural tube defect (NTD), ten (0.3 per cent) showed an apparent increased risk for both conditions. Three cases had chromosomal abnormalities, namely trisomy 16 confined to the placenta. Since placental trisomy 16 as well as cases with increased alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG) are associated with (intrauterine growth retardation (IUGR), oligohydramnios, and fetal demise, at least some cases with this atypical biochemical profile could be explained by this chromosomal abnormality. From our results we recommend that in cases with increased risk for both Down's syndrome and NTD, fetal karyotyping should preferably be done on a placental biopsy, especially when ultrasound in the absence of anomalies demonstrates early IUGR. 相似文献
36.
Urs Baumann Hanspeter Indermaur und Ernst Pletscher 《Umweltwissenschaften und Schadstoff-Forschung》2000,12(2):63-67
Zusammenfassung Zur ?kotoxikologischen Beurteilung von belastetem Wasser werden h?ufig einfache Biotests eingesetzt. Nicht selten werden dabei
toxische Effekte festgestellt. Es stellt sich dann die Frage nach den verantwortlichen Wasserinhalts-stoffen. Durch Festphasenextraktion
(SPE) werden diese angereichert, gewonnen und dünnschichtchromatographisch unter Verwendung der automatisierten Mehrfachentwicklung
aufgetrennt. Von der DC-Platte wird ein Streifen abgetrennt und darauf direkt die biologische Detektion mit Mikroorganismen
(Bacillus subtilis, Leuchtbakterien) durchgeführt. Dadurch k?nnen toxische Banden erkannt werden, Auf dem DC-Plattenrest wird von der toxischen
Bande mit einem DC-scanner ein UV-Spektrum aufgenommen, die entsprechende Bande herausgekratzt, der toxische Stoff eluiert
und infrarotspektroskopisch untersucht. Durch Spektrenvergleich gelingt es meistens, den Stoff zu charakterisieren.
In der vorliegenden Arbeit wird am Beispiel eines Zitzengummieluates das Analysenkonzept vorgestelit. Es zeigte sich, dass
dieser Gummiartikel einen Vulkanisationsbeschleuniger (2-Mercaptobenzothiazol) freisetzt.
Online-Publikation am: 21.12.1999 相似文献
37.
Tagungsakündigungen
Rückst?nde und Kontaminanten in Lebensmitteln 29. und 30. Oktober 2002, Atrium Hotel, Mainz 相似文献38.
Elisabeth Görge Sebastian Brandt Dietrich Werner 《Environmental science and pollution research international》1994,1(4):229-233
The fate of the explosive 2,4,6-TNT in plants is of major interest. Therefore, a method was developed to analyse TNT and derivatives in plant tissue. The method was utilized to investigate the uptake and metabolism of TNT inMedicago sativa andAllium schoenoprasum grown in hydroponic cultures containing TNT levels of 0.1 to 10 mg/1. Detectable concentrations of nitrotoluenes were significantly higher inAllium schoenoprasum than inMedicago sativa. The uptake of TNT in plants was directly related to the initial TNT level. The principal nitroaromatic components in roots and shoots of both plant species were identified as 4-ADNT and 2-ADNT in equal amounts, with substantially less TNT. 相似文献
39.
Gerolf Steiner 《Die Naturwissenschaften》1942,30(41-42):647-648
40.