全文获取类型
收费全文 | 92篇 |
免费 | 13篇 |
专业分类
105篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 9篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1955年 | 1篇 |
1953年 | 2篇 |
1951年 | 2篇 |
1942年 | 1篇 |
1941年 | 3篇 |
1940年 | 2篇 |
1922年 | 1篇 |
排序方式: 共有105条查询结果,搜索用时 0 毫秒
61.
We analysed the pattern of genetic differentiation among six newly established (around 10 generations) sites of the round
goby (Neogobius melanostomus) in the southern Baltic Sea by means of nine microsatellite loci and in total 183 individuals. All but one site were within
30 km from each other. We found statistically significant genetic differentiation in ten out of 15 comparisons after Bonferroni
correction, and since the species is newly introduced this has happened in less than ten generations. The largest genetic
differentiation was found between the two most divergent habitats, while sites with a similar habitat were not significantly
differentiated. Estimates of gene flow (Nm) were low and ranged from 1.5 to 5.5. A large proportion of individuals were assigned
to one site (Puck), suggesting that this site has acted as a source to the other sites. 相似文献
62.
63.
Tong Gong Cecilia Lundholm Gustaf Rejn? Carina Mood Niklas L?ngstr?m Catarina Almqvist 《PloS one》2014,9(9)
Background
Little is known about how parental socioeconomic status affects offspring asthma risk in the general population, or its relation to healthcare and medication use among diagnosed children.Methods
This register-based cohort study included 211,520 children born between April 2006 and December 2008 followed until December 2010. Asthma diagnoses were retrieved from the National Patient Register, and dispensed asthma medications from the Prescribed Drug Register. Parental socioeconomic status (income and education) were retrieved from Statistics Sweden. The associations between parental socioeconomic status and outcomes were estimated by Cox proportional hazard regression.Results
Compared to the highest parental income level, children exposed to all other levels had increased risk of asthma during their first year of life (e.g. hazard ratio, HR 1.19, 95% confidence interval, CI 1.09–1.31 for diagnosis and HR 1.17, 95% CI 1.08–1.26 for medications for the lowest quintile) and the risk was decreased after the first year, especially among children from the lowest parental income quintile (HR 0.84, 95% CI 0.77–0.92 for diagnosis, and HR 0.80, 95% CI 0.74–0.86 for medications). Further, compared to children with college-educated parents, those whose parents had lower education had increased risk of childhood asthma regardless of age. Children with the lowest parental education had increased risk of an inpatient (HR 2.07, 95% CI 1.61–2.65) and outpatient (HR 1.32, 95% CI 1.18–1.47) asthma diagnosis. Among diagnosed children, those from families with lower education used fewer controller medications than those whose parents were college graduates.Conclusions
Our findings indicate an age-varying association between parental income and childhood asthma and consistent inverse association regardless of age between parental education and asthma incidence, dispensed controller medications and inpatient care which should be further investigated and remedied. 相似文献64.
Adriana Puentes Gustaf Granath Jon Ågren 《Evolution; international journal of organic evolution》2016,70(10):2370-2386
Understanding the stability of the G matrix in natural populations is fundamental for predicting evolutionary trajectories; yet, the extent of its spatial variation and how this impacts responses to selection remain open questions. With a nested paternal half‐sib crossing design and plants grown in a field experiment, we examined differences in the genetic architecture of flowering time, floral display, and plant size among four Scandinavian populations of Arabidopsis lyrata. Using a multivariate Bayesian framework, we compared the size, shape, and orientation of G matrices and assessed their potential to facilitate or constrain trait evolution. Flowering time, floral display and rosette size varied among populations and significant additive genetic variation within populations indicated potential to evolve in response to selection. Yet, some characters, including flowering start and number of flowers, may not evolve independently because of genetic correlations. Using a multivariate framework, we found few differences in the genetic architecture of traits among populations. G matrices varied mostly in size rather than shape or orientation. Differences in multivariate responses to selection predicted from differences in G were small, suggesting overall matrix similarity and shared constraints to trait evolution among populations. 相似文献
65.
Thomas?MorelEmail author Francis?Arickx Gustaf?Befrits Paolo?Siviero Caroline?van der Meijden Entela?Xoxi Steven?Simoens 《Orphanet journal of rare diseases》2013,8(1):198
Background
National payers across Europe have been increasingly looking into innovative reimbursement approaches – called managed entry agreements (MEAs) – to balance the need to provide rapid access to potentially beneficial orphan medicinal products (OMPs) with the requirements to circumscribe uncertainty, obtain best value for money or to ensure affordability. This study aimed to identify, describe and classify MEAs applied to OMPs by national payers and to analyse their practice in Europe.Methods
To identify and describe MEAs, national health technology assessments and reimbursement decisions on OMPs across seven European countries were reviewed and their main characteristics extracted. To fill data gaps and validate the accuracy of the extraction, collaboration was sought from national payers. To classify MEAs, a bespoke taxonomy was implemented. Identified MEAs were analysed and compared by focusing on five key themes, namely by describing the MEAs in relation to: drug targets and therapeutic classes, geographical spread, type of MEA applied, declared rationale for setting-up of MEAs, and evolution over time.Results
42 MEAs for 26 OMPs, implemented between 2006 and 2012 and representing a variety of MEA designs, were identified. Italy was the country with the highest number of schemes (n=15), followed by the Netherlands (n=10), England and Wales (n=8), Sweden (n=5) and Belgium (n=4). No MEA was identified for France and Germany due to data unavailability. Antineoplastic agents were the primary targets of MEAs. 55% of the identified MEAs were performance-based risk-sharing arrangements; the other 45% were financial-based. Nine of these 26 OMPs were subject to MEAs in two or three different countries, resulting in 24 MEAs. 60% of identified MEAs focused on conditions whose prevalence is less than 1 per 10,000.Conclusions
This study confirmed that a variety of MEAs were increasingly used by European payers to manage aspects of uncertainty associated with the introduction of OMPs in the healthcare system, and which may be of a clinical, utilisation, or budgetary nature. It remains unclear whether differences in the use of MEAs reflect differences in how ‘uncertainty’ and ‘value’ are perceived across healthcare systems.66.
Jenny Mattisson Peter Segerström Jens Persson Malin Aronsson Geir Rune Rauset Gustaf Samelius Henrik Andrén 《Mammalian Biology》2013,78(4):304-308
Eurasian lynx (Lynx lynx) is considered a solitary, territorial felid with a low degree of direct intraspecific interactions. Between 2002 and 2011 we observed four aggressive interactions between five different male Eurasian lynx, where two were lethal. All interactions occurred during the mating season and three of the interactions resulted in takeover of the home range by the intruder. Thus, in this study we demonstrate that aggressive interactions, sometimes with severe consequences, occur in male Eurasian lynx and suggest that they are driven primarily by access to female lynx in the mating season. 相似文献
67.
Gustaf Rejn? Cecilia Lundholm Tong Gong Kjell Larsson Sissel Saltvedt Catarina Almqvist 《PloS one》2014,9(8)
Background
Asthma is one of the most common chronic diseases, and prevalence, severity and medication may have an effect on pregnancy. We examined maternal asthma, asthma severity and control in relation to pregnancy complications, labour characteristics and perinatal outcomes.Methods
We retrieved data on all singleton births from July 1, 2006 to December 31, 2009, and prescribed drugs and physician-diagnosed asthma on the same women from multiple Swedish registers. The associations were estimated with logistic regression.Results
In total, 266 045 women gave birth to 284 214 singletons during the study period. Maternal asthma was noted in 26 586 (9.4%) pregnancies. There was an association between maternal asthma and increased risks of pregnancy complications including preeclampsia or eclampsia (adjusted OR 1.15; 95% CI 1.06–1.24) and premature contractions (adj OR 1.52; 95% CI 1.29–1.80). There was also a significant association between maternal asthma and emergency caesarean section (adj OR 1.29; 95% CI 1.23–1.34), low birth weight, and small for gestational age (adj OR 1.23; 95% CI 1.13–1.33). The risk of adverse outcomes such as low birth weight increased with increasing asthma severity. For women with uncontrolled compared to those with controlled asthma the results for adverse outcomes were inconsistent displaying both increased and decreased OR for some outcomes.Conclusion
Maternal asthma is associated with a number of serious pregnancy complications and adverse perinatal outcomes. Some complications are even more likely with increased asthma severity. With greater awareness and proper management, outcomes would most likely improve. 相似文献68.
David Singer Edward A. D. Mitchell Richard J. Payne Quentin Blandenier Clment Duckert Leonardo D. Fernndez Bertrand Fournier Cristin E. Hernndez Gustaf Granath Hkan Rydin Luca Bragazza Natalia G. Koronatova Irina Goia Lorna I. Harris Katarzyna Kajukao Anush Kosakyan Mariusz Lamentowicz Natalia P. Kosykh Kai Vellak Enrique Lara 《Molecular ecology》2019,28(12):3089-3100
Recent studies show that soil eukaryotic diversity is immense and dominated by micro‐organisms. However, it is unclear to what extent the processes that shape the distribution of diversity in plants and animals also apply to micro‐organisms. Major diversification events in multicellular organisms have often been attributed to long‐term climatic and geological processes, but the impact of such processes on protist diversity has received much less attention as their distribution has often been believed to be largely cosmopolitan. Here, we quantified phylogeographical patterns in Hyalosphenia papilio, a large testate amoeba restricted to Holarctic Sphagnum‐dominated peatlands, to test if the current distribution of its genetic diversity can be explained by historical factors or by the current distribution of suitable habitats. Phylogenetic diversity was higher in Western North America, corresponding to the inferred geographical origin of the H. papilio complex, and was lower in Eurasia despite extensive suitable habitats. These results suggest that patterns of phylogenetic diversity and distribution can be explained by the history of Holarctic Sphagnum peatland range expansions and contractions in response to Quaternary glaciations that promoted cladogenetic range evolution, rather than the contemporary distribution of suitable habitats. Species distributions were positively correlated with climatic niche breadth, suggesting that climatic tolerance is key to dispersal ability in H. papilio. This implies that, at least for large and specialized terrestrial micro‐organisms, propagule dispersal is slow enough that historical processes may contribute to their diversification and phylogeographical patterns and may partly explain their very high overall diversity. 相似文献
69.
70.