全文获取类型
收费全文 | 190篇 |
免费 | 20篇 |
出版年
2023年 | 2篇 |
2021年 | 9篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 12篇 |
2015年 | 10篇 |
2014年 | 16篇 |
2013年 | 14篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 8篇 |
2007年 | 9篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 10篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1996年 | 1篇 |
1994年 | 3篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有210条查询结果,搜索用时 15 毫秒
31.
32.
Hannah L. Harrison Stine Rybråten Øystein Aas 《Human ecology: an interdisciplinary journal》2018,46(4):449-459
We investigate drivers of hybridization of local ecological knowledge (LEK) and scientific knowledge (SK) in small-scale Atlantic salmon (Salmo salar) fisheries in western Norway through a case study from the Ørsta River. We find three primary drivers of knowledge hybridization in local fishing groups as part of wild Atlantic salmon cultivation activities: facilitating intergenerational knowledge exchange, coping with regulatory change, and improving the perceived validity of local knowledge sets. We also identify three challenges to knowledge hybridization, and discuss how both drivers and challenges relate to once complementary SK and LEK sets that have diverged as SK has become more technical and complex. We examine the processes by which LEK and SK develop, evolve, and are used to facilitate wild salmon conservation in these fisheries and discuss the role hatcheries can play adapting and utilizing large-scale SK and salmon policy to the local environment through hybridization processes. We conclude with recommendations as to how reframing managerial views on hatcheries as facilitators of knowledge production and transfer may improve both the accessibility of SK to local communities and the integration of LEK into Norwegian wild salmon management. 相似文献
33.
The devil is in the detail: Nonadditive and context‐dependent plant population responses to increasing temperature and precipitation
下载免费PDF全文
![点击此处可从《Global Change Biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Joachim P. Töpper Eric Meineri Siri L. Olsen Knut Rydgren Olav Skarpaas Vigdis Vandvik 《Global Change Biology》2018,24(10):4657-4666
In climate change ecology, simplistic research approaches may yield unrealistically simplistic answers to often more complicated problems. In particular, the complexity of vegetation responses to global climate change begs a better understanding of the impacts of concomitant changes in several climatic drivers, how these impacts vary across different climatic contexts, and of the demographic processes underlying population changes. Using a replicated, factorial, whole‐community transplant experiment, we investigated regional variation in demographic responses of plant populations to increased temperature and/or precipitation. Across four perennial forb species and 12 sites, we found strong responses to both temperature and precipitation change. Changes in population growth rates were mainly due to changes in survival and clonality. In three of the four study species, the combined increase in temperature and precipitation reflected nonadditive, antagonistic interactions of the single climatic changes for population growth rate and survival, while the interactions were additive and synergistic for clonality. This disparity affects the persistence of genotypes, but also suggests that the mechanisms behind the responses of the vital rates differ. In addition, survival effects varied systematically with climatic context, with wetter and warmer + wetter transplants showing less positive or more negative responses at warmer sites. The detailed demographic approach yields important mechanistic insights into how concomitant changes in temperature and precipitation affect plants, which makes our results generalizable beyond the four study species. Our comprehensive study design illustrates the power of replicated field experiments in disentangling the complex relationships and patterns that govern climate change impacts across real‐world species and landscapes. 相似文献
34.
35.
36.
M Otterlei E Warbrick T A Nagelhus T Haug G Slupphaug M Akbari P A Aas K Steinsbekk O Bakke H E Krokan 《The EMBO journal》1999,18(13):3834-3844
Base excision repair (BER) is initiated by a DNA glycosylase and is completed by alternative routes, one of which requires proliferating cell nuclear antigen (PCNA) and other proteins also involved in DNA replication. We report that the major nuclear uracil-DNA glycosylase (UNG2) increases in S phase, during which it co-localizes with incorporated BrdUrd in replication foci. Uracil is rapidly removed from replicatively incorporated dUMP residues in isolated nuclei. Neutralizing antibodies to UNG2 inhibit this removal, indicating that UNG2 is the major uracil-DNA glycosylase responsible. PCNA and replication protein A (RPA) co-localize with UNG2 in replication foci, and a direct molecular interaction of UNG2 with PCNA (one binding site) and RPA (two binding sites) was demonstrated using two-hybrid assays, a peptide SPOT assay and enzyme-linked immunosorbent assays. These results demonstrate rapid post-replicative removal of incorporated uracil by UNG2 and indicate the formation of a BER complex that contains UNG2, RPA and PCNA close to the replication fork. 相似文献
37.
Abstract. We investigated germination responses and seed recruitment in the clonal grassland herb Knautia arvensis (Dipsacaceae) throughout its distributional range in Norway. Four predicted relationships between germination responses and field regeneration behaviour were tested using phytotron experiments and experimental and observational field studies. Seedlings appeared in all experimental microsites in the field, corroborating phytotron predictions that gap‐ or depth‐sensing strategies should be absent in the species. Seasonal timing patterns were predicted from a cold stratification response in the phytotron, but these were not supported in the field. The relationship between dormancy, germinability during storage, and seed carry‐over in the field largely conformed to expectations. Seeds from four different geographical regions responded differently to temperature and cold stratification and storage. Dormancy and seed carry‐over was higher in seeds from a coastal population, where winters are relatively mild and the probability of repeated freeze‐thaw events is high, than in populations from mountain and inland areas, where winters are colder. This is discussed against two alternative hypotheses about the relationship between climate and dormancy in seasonal climates. 相似文献
38.
Tissue estradiol is selectively elevated in receptor positive breast cancers while tumour estrone is reduced independent of receptor status 总被引:1,自引:0,他引:1
P.E. Lnning H. Helle N.K. Duong D. Ekse T. Aas J. Geisler 《The Journal of steroid biochemistry and molecular biology》2009,117(1-3):31-41
Previous studies have suggested elevated estrogen production in tumour-bearing breast quadrants as well as in breast cancers versus benign tissue. Using highly sensitive assays, we determined breast cancer tissue estrogen concentrations together with plasma and benign tissue estrogen concentrations in each quadrant obtained from mastectomy specimens (34 postmenopausal and 13 premenopausal women). We detected similar concentrations of each of the three major estrogens estradiol (E2), estrone (E1) and E1S in tumour-bearing versus non-tumour-bearing quadrants. Considering malignant tumours, intratumour E1 levels were reduced in cancer tissue obtained from pre- as well as postmenopausal women independent of tumour ER status (average ratio E1 cancer: benign tissue of 0.2 and 0.3, respectively; p < 0.001 for both groups), suggesting intratumour aromatization to be of minor importance. The most striking finding was a significant (4.1–8.6-fold) increased E2 concentration in ER positive tumours versus normal tissue (p < 0.05 and <0.001 for pre- and postmenopausal patients, respectively), contrasting low E2 concentrations in ER− tumours (p < 0.01 and <0.001 comparing E2 levels between ER+ and ER− tumours in pre- and postmenopausals, respectively). A possible explanation to our finding is increased ligand receptor binding capacity for E2 in receptor positive tumours but alternative factors influencing intratumour estrogen disposition cannot be excluded. 相似文献
39.
40.
Inger E. Måren Zdeněk Janovský Joachim P. Spindelböck Matthew I. Daws Peter E. Kaland Vigdis Vandvik 《Plant Ecology》2010,207(2):245-256
The European coastal heathlands are important habitats for international conservation. Today, these low-intensity farming
systems are threatened by the cessation of traditional management regimes, such as grazing and prescribed burning. In natural
systems, the effects of fire on germination responses are often explained by adaptation to fire over extended periods of time.
However, Northern heathlands are semi-natural systems with only a limited fire history. We investigated whether and how the
keystone species in this system, Calluna vulgaris, responded to prescribed burning, based on previous findings where Calluna germinable seed-bank densities showed a pronounced peak right after fire. Our main findings were (i) an ecophysiological
response to smoke; (ii) a potential explanation for this pattern, revealed by a seed-bank experiment where we managed to
re-create the germination pattern experimentally by using an aqueous plant-derived smoke solution; and (iii) a history of
anthropogenic use of fire and the development of heathlands in the region documented through palaeoecological investigations. 相似文献