全文获取类型
收费全文 | 183篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 7篇 |
废物处理 | 9篇 |
环保管理 | 22篇 |
综合类 | 51篇 |
基础理论 | 32篇 |
环境理论 | 1篇 |
污染及防治 | 39篇 |
评价与监测 | 10篇 |
社会与环境 | 14篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 2篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 13篇 |
2012年 | 7篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 12篇 |
2008年 | 11篇 |
2007年 | 16篇 |
2006年 | 6篇 |
2005年 | 15篇 |
2004年 | 8篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1975年 | 1篇 |
1970年 | 2篇 |
1968年 | 1篇 |
1966年 | 2篇 |
1963年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1952年 | 1篇 |
排序方式: 共有186条查询结果,搜索用时 15 毫秒
161.
162.
163.
Hopes are held out for chorion villus sampling, a technique which is gaining more and more importance for the first trimester prenatal diagnosis of chromosomal aberrations and metabolic abnormalities. A variety of inherited skin diseases can be diagnosed postnatally and prenatally (in the second trimester) by ultrastructural diagnostic markers. For evaluation of prenatal diagnosis in the first trimester, we investigated chorionic villi derived from the trophoblast layer of the early pregnancy by light microscopy and conventional electron microscopy. The ultrastructure of the cellular layers covering the villi, i.e., the inner cytotrophoblast and the outer syncytiotrophoblast, as well as that of the connective tissue of the inner extraembryonic mesoderm, are thoroughly described in relation to the ultra-structural changes in certain genodermatoses including epidermolyses and keratinization disorders. We found that chorionic villi have only a few of the characteristics differentiated in skin, and none of the structures which are relevant to the diagnosis of genodermatoses. In our view, the ultrastructural approach is not suitable for first trimester prenatal diagnosis of genodermatoses in chorionic villi. 相似文献
164.
Ingrid Langer Doris Krpata Walter J. Fitz Walter W. Wenzel Peter F. Schweiger 《Environmental pollution (Barking, Essex : 1987)》2009,157(10):2871-2877
The effect of increasing soil Zn concentrations on growth and Zn tissue concentrations of a metal-accumulating aspen clone was examined in a dose–response study. Plants were grown in a soil with a low native Zn content which was spiked with Zn salt solutions and subsequently aged. Plant growth was not affected by NH4NO3-extractable soil Zn concentrations up to 60 μg Zn g?1 soil, but it was completely inhibited at extractable concentrations above 90 μg Zn g?1 soil. From these data an effective concentration of 68.5 μg extractable Zn g?1 soil was calculated at which plant growth was reduced by 50%. The obtained information on toxicity threshold concentrations, and the relation between plant Zn accumulation and extractable soil Zn concentrations may be used to assess the suitability of the investigated Populus canescens clone for various phytoremediation strategies. The potential risk of metal transfer into food webs associated with P. canescens stands on Zn-polluted sites may also be estimated. 相似文献
165.
166.
Benthic epifauna in three areas of the northern North Sea was studied from 1999 to 2007 to investigate the effect of temperature
changes on community structure and species abundance and biomass. Abundance and/or biomass of 16 epifauna species was significantly
correlated with temperature anomalies of the mean sea surface temperature (SST) from 1971 to 2000. The response of species
to SST changes was different in the study areas depending on species life history and, most likely on food supply, which in
turn is strongly influenced by the timing and duration of primary production and regional hydrographical conditions (e.g.
stratification). Also, changes in community structure were obvious in the three areas between 2002 and 2003 coinciding with
high temperature anomalies and SST. On the other hand, these changes were mainly caused by the variability in abundance of
dominant species and altogether no clear trends in community structure were found. In contrast to epifauna communities in
the shallow southern North Sea temperature changes in the northern North Sea affected only single epifauna species until now. 相似文献
167.
Charlyn Partridge Ingrid Ahnesjö Charlotta Kvarnemo Kenyon B. Mobley Anders Berglund Adam G. Jones 《Behavioral ecology and sociobiology》2009,63(3):345-354
The last several decades of research in behavioral ecology have resulted in a deeper appreciation of post-mating processes
and sexual conflict in sexual selection. One of the most controversial aspects of sexual selection is cryptic mate choice.
Here, we take advantage of male pregnancy in a sex-role-reversed pipefish (Syngnathus typhle) to quantify cryptic choice based on perceived parasite load and other sources of variance in female fitness. Studies have
shown that S. typhle males preferentially mate with females with lower parasite loads and that a male’s perception of female parasite load can
be altered by tattooing females. We manipulated the apparent parasite load of females in controlled mating experiments to
test the hypothesis that post-copulatory sexual selection is dependent on a male’s perception of female parasite load in pipefish.
Our results provided no evidence for cryptic male choice based on perceived female parasite load. However, we found evidence
that eggs from larger females were more likely to result in viable offspring than eggs from smaller females and that the first
female to mate with a male transferred more eggs per copulation on average. Overall, our results show that potential for post-copulatory
sexual selection does exist in pipefish, but the male’s perception of female parasite load does not play a major role in this
process. 相似文献
168.
Upward-facing echosounders that provided continuous, long-term measurements were applied to address the surfacing behavior and gas release of the physostome sprat (Sprattus sprattus) throughout an entire winter in a 150-m-deep Norwegian fjord. During ice-free conditions, the sprat surfaced and released gas bubbles at night with an estimated surfacing rate of 3.5 times per fish day?1. The vertical swimming speeds during surfacing were considerably higher (~10 times) than during diel vertical migrations, especially when returning from the surface, and particularly when the fjord was not ice covered. The sprat released gas a few hours after surfacing, suggesting that the sprat gulped atmospheric air during its excursions to the surface. While the surface activity increased after the fjord became ice covered, the records of gas release decreased sharply. The under-ice fish then displayed a behavior interpreted as “searching for the surface” by repeatedly ascending toward the ice, apparently with limited success of filling the swim bladder. This interpretation was supported by lower acoustic target strength in ice-covered waters. The frequent surfacing behavior demonstrated in this study indicates that gulping of atmospheric air is an important element in the life of sprat. While at least part of the population endured overwintering in the ice-covered habitat, ice covering may constrain those physostome fishes that lack a gas-generating gland in ways that remain to be established. 相似文献
169.
170.
Kivimäenpää M Jönsson AM Stjernquist I Selldén G Sutinen S 《Environmental pollution (Barking, Essex : 1987)》2004,127(3):441-453
Light (LM) and transmission electron (TEM) microscopy were used to study previously specified ozone symptoms in the foliage of Norway spruce. The three youngest green needle generations from twenty mature trees in two stands on sites of different soil fertility at Asa, southern Sweden, were sampled in 1999. The critical dose of ozone, expressed as AOT40, was 6,362 ppb.h. LM showed ozone-specific symptoms: decreased chloroplast size with electron dense stroma advancing gradually from the outer to the inner cell layers, being most severe in the needle side facing the sky. The symptoms were expressed as ozone syndrome indices at the needle generation, tree and stand levels. The index had higher values at the low fertility site. TEM was used to confirm the LM results. The study shows that LM can be used for diagnosis of the impact of ozone on conifers in the field. 相似文献