全文获取类型
收费全文 | 496篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 5篇 |
废物处理 | 7篇 |
环保管理 | 34篇 |
综合类 | 234篇 |
基础理论 | 86篇 |
污染及防治 | 104篇 |
评价与监测 | 21篇 |
社会与环境 | 9篇 |
出版年
2021年 | 4篇 |
2018年 | 4篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 12篇 |
2013年 | 22篇 |
2012年 | 13篇 |
2011年 | 14篇 |
2010年 | 12篇 |
2009年 | 20篇 |
2008年 | 9篇 |
2007年 | 25篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 18篇 |
2003年 | 12篇 |
2002年 | 18篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 13篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1992年 | 4篇 |
1981年 | 4篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1967年 | 5篇 |
1966年 | 4篇 |
1965年 | 5篇 |
1964年 | 10篇 |
1963年 | 13篇 |
1962年 | 5篇 |
1961年 | 8篇 |
1960年 | 8篇 |
1959年 | 8篇 |
1958年 | 11篇 |
1957年 | 9篇 |
1956年 | 7篇 |
1955年 | 13篇 |
1954年 | 6篇 |
1953年 | 4篇 |
1952年 | 6篇 |
1950年 | 8篇 |
1947年 | 5篇 |
1943年 | 6篇 |
1939年 | 4篇 |
1924年 | 3篇 |
排序方式: 共有500条查询结果,搜索用时 15 毫秒
491.
492.
Oettl D Sturm PJ Pretterhofer G Bacher M Rodler J Almbauer RA 《Journal of the Air & Waste Management Association (1995)》2003,53(10):1233-1240
Transit traffic through the Austrian Alps is of major concern in government policy. Pollutant burdens resulting from such traffic are discussed widely in Austrian politics and have already led to measures to restrict traffic on transit routes. In the course of an environmental assessment study, comprehensive measurements were performed. These included air quality observations using passive samplers, a differential optical absorption spectroscopy system, a mobile and a fixed air quality monitoring station, and meteorological observations. As was evident from several previous studies, dispersion modeling in such areas of complex terrain and, moreover, with frequent calm wind conditions, is difficult to handle. Further, in the case presented here, different pollutant sources had to be treated simultaneously (e.g., road networks, exhaust chimneys from road tunnels, and road tunnel portals). No appropriate system for modeling all these factors has so far appeared in the literature. A prognostic wind field model coupled with a Lagrangian dispersion model is thus presented here and is designed to treat all these factors. A comparison of the modeling system with results from passive samplers and from a fixed air quality monitoring station proved the ability of the model to provide reasonable figures for concentration distributions along the A10. 相似文献
493.
494.
495.
By chance, we had the opportunity to make serial sonographic observations of the extrusion of meconium in a case of meconium peritonitis. Inflammation leads to exudative processes and production of fluid (ascites) in the fetal abdomen. Sonography at that stage of the disease may lead to a misdiagnosis such as ‘fetal ascites’ or ‘non-immune hydrops’. After bowel perforation and extrusion of meconium, the latter appears as a solitary mass inside fetal ascites or as disseminated echogenic masses distributed subdiaphragmatically or perihepatically. Within a couple of days, in most cases the echogenicity of the masses increases. Calcifications lead to distinct shadowing. These calcifications are often the only visible signs of a previous meconium peritonitis. Serial sonograms are essential for the management of pregnancies with meconium peritonitis. If the amount of fetal ascites does not increase and no signs of cardiovascular stagnation appear, no invasive intrauterine diagnostic and therapeutic steps are required. In none out of the nine cases was a cause found. 相似文献
496.
Managing soil remediation problems 总被引:1,自引:0,他引:1
Joop P. Okx Leen Hordijk Alfred Stein 《Environmental science and pollution research international》1996,3(4):229-235
Soil remediation has only a short history but the problem addressed is a significant one. Cost estimates for the clean-up of contaminated sites in the European Union and the United States are in the order of magnitude of 1,400 billion ECU. Such an enormous operation deserves the best management it can get. Reliable cost estimations per contaminated site are an important prerequisite. This paper addresses the problems related to site-wise estimations. When solving soil remediation problems, we have to deal with a large number of scientific disciplines. Too often solutions are presented from the viewpoint of only one discipline. In order to benefit from the combined disciplinary knowledge and experience, we think that it is necessary to describe the interrelations between these disciplines. This can be realized by developing an adequate model of the desired process which enables to consider and evaluate the essential factors as interdependent components of the total system. The resulting model provides a binding paradigm to the contributing disciplines which will result in improved efficiency and effectivity of the decision and the cost estimation process. In the near future, we will release the “Biosparging and Bioventing Expert Support System”, an expert support system for problem owners, consultants and authorities dealing with the design and operation of a biosparging and/or a bioventing system. 相似文献
497.
Gerhard Bringmann 《Die Naturwissenschaften》1979,66(1):22-27
The formation of tetrahydro-isoquinoline alkaloids in human and animal metabolisms subsequent to alcohol consumption is reported. The spectrum of identified products ranges from simple structures such as salsolinol to the complicated skeleton of protoberberines. These substances, hitherto found exclusively in plants, interfere with the biosynthesis, biodegradation and neurotransmission of the structurally closely related biogenic amines from which they are formed, and thus affect the vegetative nervous system. 相似文献
498.
Biological Report 88(41):1–103), assessment of credits and determination of a compensation ratio that reflects existing and/or potential functional
condition in a mitigation bank has been a formidable task. This study presents a framework for a systematic approach for determination
of credits and debits and subsequently the compensation ratio. A model for riparian systems is developed based on this framework
that evaluates credits and debits for spatial and structural diversity, contiguity of habitats, invasive vegetation, hydrology,
topographic complexity, characteristics of flood-prone areas, and biogeochemical processes. The goal of developing this crediting
and debiting framework is to provide an alternative to the current methods of determining credits and debits in a mitigation
bank and assigning mitigation ratios, such as best professional judgement or use of preset ratios. The purpose of this crediting
and debiting framework is to develop a method that (1) can be tailored to evaluate ecological condition based on the target
resources of a specific mitigation bank, (2) is flexible enough to be used for evaluation of existing or potential ecologic
condition at a mitigation bank, (3) is a structured and systematic way to apply data and professional judgment to the decision-making
process, (4) has an ecologically defensible basis, (5) has ease of use such that the level of expertise and time required
to employ the method is not a deterrent to its application, and (6) provides a semiquantitative measure of the condition of
aquatic resources that can be translated to a mitigation ratio. 相似文献
499.
Mammalian hibernation, which lasts on average for about 6 months, can reduce energy expenditure by >90% in comparison to active
individuals. In contrast, the widely held view is that daily torpor reduces energy expenditure usually by about 30%, is employed
for a few hours every few days, and often occurs only under acute energetic stress. This interpretation is largely based on
laboratory studies, whereas knowledge on daily torpor in the field is scant. We used temperature telemetry to quantify thermal
biology and activity patterns of a small arid-zone marsupial, the stripe-faced dunnart Sminthopsis macroura (16.9 g), in the wild and to test the hypothesis that daily torpor is a crucial survival strategy of this species in winter.
All individuals entered torpor daily with the exception of a single male that remained normothermic for a single day (torpor
on 212 of 213 observation days, 99.5%). Torpor was employed at air temperatures (T
a) ranging from approximately −1°C to 36°C. Dunnarts usually entered torpor during the night and aroused at midday with the
daily increase of T
a. Torpor was on average about twice as long (mean 11.0 ± 4.7 h, n = 8) than in captivity. Animals employed sun basking during rewarming, reduced foraging time significantly, and occasionally
omitted activity for several days in sequence. Consequently, we estimate that daily torpor in this species can reduce daily
energy expenditure by up to 90%. Our study shows that for wild stripe-faced dunnarts daily torpor is an essential mechanism
for overcoming energetic challenges during winter and that torpor data obtained in the laboratory can substantially underestimate
the ecological significance of daily torpor in the wild. 相似文献
500.
Storch G 《Die Naturwissenschaften》2008,95(10):927-930
Most living mammal orders, including our own, started their career during the first 10 million years of the Cenozoic, the
Age of Mammals. The fossil record documents that early Paleogene adaptive radiations of various clades included tiny species
of the size of living shrews. Remains of particularly diminutive limb bones are described from the late Paleocene site of
Walbeck, Sachsen-Anhalt. Discovered in 1939, it has remained the only known Paleocene mammal-bearing locality from Germany.
The remains are referred to the family Adapisoriculidae, which is considered on the basis of the present postcranial evidence
to represent plesiadapiform primates rather than alleged lipotyphlan insectivores as previously proposed. The Walbeck fossils
compete with the Early Eocene species Toliapina vinealis from Europe and Picromomys petersonorum from North America for the status of the smallest known primate, fossil and living. Their estimated body weights are as small
as 10 g. The limb bones show features related to enhanced flexion at the elbow and hip joint, suggesting arboreal habits and
environments such as terminal branches. The diminutive size and tooth morphology suggest feeding on small insects and other
invertebrates. Postcranials are important to assess early radiations, such tiny specimens as the present ones are extremely
scarce in the fossil record, however. 相似文献