全文获取类型
收费全文 | 162篇 |
免费 | 0篇 |
专业分类
安全科学 | 7篇 |
废物处理 | 7篇 |
环保管理 | 13篇 |
综合类 | 21篇 |
基础理论 | 28篇 |
污染及防治 | 67篇 |
评价与监测 | 4篇 |
社会与环境 | 15篇 |
出版年
2023年 | 1篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 7篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 10篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1961年 | 1篇 |
1956年 | 1篇 |
1938年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有162条查询结果,搜索用时 203 毫秒
151.
In marine tropical or subtropical plankton the filamentous, heterocyst-forming cyanobacterium Richelia intracellularis forms a symbiosis with the diatom Rhizosolenia clevei. An ultrastructural analysis of the apex of Rhizosolenia clevei showed that the cytoplasm in that particular part of the cell was present only where the cyanobiont was located. The cyanobiont was, however, always outside the host cytoplasm. Vegetative cells as well as the heterocysts of the cyanobiont were devoid of gas vesicles and cyanophycin granules, while carboxysomes and large glycogen granules were common. The cyanobacterial cell wall apparently remained intact in both vegetative and heterocyst cells. In green excitation light the heterocysts and vegetative cells emitted a bright yellow fluorescence, indicating that both cell types possessed high concentrations of the pigment phycoerythrin (PE) commonly associated with photosystem (PS) II. The presence of this pigment in both cell types was verified by immunogold localisation. Using the same technique, the nitrogenase (dinitrogenase reductase) enzyme was shown to be exclusively present in the heterocysts, while Rubisco was localised primarily to the carboxy-somes, which were only detected in vegetative cells. Using an antiserum against the ammonia assimilating enzyme glutamine synthetase (GS), we could demonstrate very low levels of this enzyme, indicating repression of GS in the cyanobiont. 相似文献
152.
Water, Air, &; Soil Pollution: Focus - 相似文献
153.
154.
Understanding the demography and function of biotope-forming seaweed species is of great importance for the conservation of
the target species itself, as well as its associated organisms. The brown seaweed Ascophyllum nodosum is fundamental for the functioning of coastal marine ecosystems in the North Atlantic. In this study, we use a data-based
size-classified matrix model to investigate the temporal and spatial variability in demography, and the environment-specific
stochastic sensitivity and elasticity, of two A. nodosum populations, one in western Sweden and one on the Isle of Man in the Irish Sea. A significant difference between the two
populations was that the Swedish population had comparably low and more variable stochastic population growth rate (λ
s). This pattern was partly explained by the relatively high and varying mortality rates during extreme ice-years in Sweden,
and by the lower survival of small individuals during all years. There were also fewer large individuals in Sweden due to
lower transitions to the larger size-classes and higher probability of shrinkage. Sensitivities were analogous in the two
populations, and showed a high selection pressure for increased individual growth. Elasticities were also similar, with the
exception that survival of the smallest individuals (i.e., transition a
1,1), had a higher elasticity on the Isle of Man. Overall, the stochastic growth rate (λ
s) was most sensitive to proportional changes in loop- (i.e., survival within size-class) and, to some extent, growth-transitions
in both study areas. These results show that structurally and demographically diverging A. nodosum populations may be similarly sensitive to changes in vital rates. This, in turn, indicates a plastic life history of A. nodosum that may cope with large environmental variability. The results further suggest that environmental change affecting the survival
or growth of the larger, reproductive A. nodosum individuals could have severe and regional effects on the abundance and biomass of this species, with potential negative
effects on the biodiversity of the associated communities. 相似文献
155.
Tal Falick Michaeli Adam Spiro Ofra Sabag Gilad Karavani Simha Yagel Smadar Eventov-Friedman Howard Cedar Yehudit Bergman Yuval Gielchinsky 《黑龙江环境通报》2019,39(11):1005-1010
Gestational age determination by traditional tools (last menstrual period, ultrasonography measurements and Ballard Maturational Assessment in newborns) has major limitations and therefore there is a need to find different approaches. In this study, we looked for a molecular marker that can be used to determine the accurate gestational age of the newborn. To this end, we performed reduced representation bisulfite sequencing (RRBS) on 41 cord blood and matching placenta samples from women between 25 and 40 weeks of gestation and generated an epigenetic clock based on the methylation level at different loci in the genome. We identified a set of 332 differentially methylated regions (DMRs) that undergo demethylation in late gestational age in cord blood cells and can predict the gestational age (r = −.7, P = 2E-05). Once the set of 411 DMRs that undergo de novo methylation in late gestational age was used in combination with the first set, it generated a more accurate clock (R = .77, P = 1.87E-05). We have compared gestational age determined by Ballard score assessment with our epigenetic clock and found high concordance. Taken together, this study demonstrates that DNA methylation can accurately predict gestational age and thus may serve as a good clinical predictor. 相似文献
156.
Andreas Sundelöf Stuart R. Jenkins Carl J. Svensson Jane Delany Stephen J. Hawkins Per Åberg 《Marine Biology》2010,157(4):779-789
The importance of external and internal population processes in determining variation in reproductive output and variation
in population size were quantified with model simulations for open populations of the sequentially hermaphroditic limpet Patella vulgata using field data from the Isle of Man and South West Ireland. Cross-correlation analyses of model outputs and elasticity
analyses show that population dynamics are dominated by the effects of large females, and that recruitment adds little to
reproductive output. However, populations experiencing low but highly variable recruitment appear male limited and recruitment
pulses carrying young males into the population are correlated to reproductive output with a 2–5-year lag. We conclude that
pulses in recruitment can be a major structuring force in these limpet populations, but site-specific post-recruitment processes
will determine the relative importance of recruitment to population dynamics and the lag between recruitment and reproductive
output. 相似文献
157.
Jannika E. Boström Thord Fransson Ian Henshaw Sven Jakobsson Cecilia Kullberg Susanne Åkesson 《Behavioral ecology and sociobiology》2010,64(11):1725-1732
Recent experiments exposing migratory birds to altered magnetic fields simulating geographical displacements have shown that
the geomagnetic field acts as an external cue affecting migratory fuelling behaviour. This is the first study investigating
fuel deposition in relation to geomagnetic cues in long-distance migrants using the western passage of the Mediterranean region.
Juvenile wheatears (Oenanthe oenanthe) were exposed to a magnetically simulated autumn migration from southern Sweden to West Africa. Birds displaced parallel
to the west of their natural migration route, simulating an unnatural flight over the Atlantic Ocean, increased their fuel
deposition compared to birds experiencing a simulated migration along the natural route. These birds, on the other hand, showed
relatively low fuel loads in agreement with earlier data on wheatears trapped during stopover. The experimental displacement
to the west, corresponding to novel sites in the Atlantic Ocean, led to a simulated longer distance to the wintering area,
probably explaining the observed larger fuel loads. Our data verify previous results suggesting that migratory birds use geomagnetic
cues for fuelling decisions and, for the first time, show that birds, on their first migration, can use geomagnetic cues to
compensate for a displacement outside their normal migratory route, by adjusting fuel deposition. 相似文献
158.
159.
The two isomers 1,2,3,5,6,7- and 1,2,3,4,6,7-hexachloronaphthalene are shown to be selectively retained in the liver of rats orally dosed with the commercial PCN product Halowax 1014. The retention was further studied by dosing rats orally with a mixture of the two compounds. The rats were sacrificed after 1, 10, 35 and 120 days, respectively. The two hexachloronaphthalenes were found to be strongly retained in the liver and the concentration ratios liver/adipose tissue were remarkably high. 1,2,3,5,6,7- And 1,2,3,4,6,7-hexachloronaphthalene were also found to be present in two environmental samples from the Swedish east coast, cod liver and guillemot egg. 相似文献
160.
María del Carmen Triana Christopher O. L. H. Porter Sandra W. DeGrassi Mindy Bergman 《组织行为杂志》2013,34(8):1124-1144
We draw from social categorization theory and the actor–observer hypothesis to extend previous research regarding receiving high levels of help from team members. Specifically, we explore how a team member's performance feedback on how they handled a disproportionately heavy share of the team's workload and how their racial distance from the rest of their teammates affect the amount of helping that person receives from their teammates. Results from a laboratory study in which 79 teams worked on a computerized, decision‐making task demonstrated a three‐way interaction between workload, performance feedback, and the racial distance between the feedback recipient and the rest of their teammates. Racially distant negative feedback recipients who had a disproportionately heavy share of their team's workload received less help from teammates than their racially similar counterparts. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献