全文获取类型
收费全文 | 394篇 |
免费 | 23篇 |
国内免费 | 1篇 |
出版年
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 12篇 |
2015年 | 27篇 |
2014年 | 29篇 |
2013年 | 31篇 |
2012年 | 33篇 |
2011年 | 38篇 |
2010年 | 15篇 |
2009年 | 9篇 |
2008年 | 12篇 |
2007年 | 18篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1971年 | 2篇 |
1960年 | 2篇 |
1927年 | 1篇 |
排序方式: 共有418条查询结果,搜索用时 31 毫秒
91.
Anders Helgeland Kent-Andre Mardal Victor Haughton Bjørn Anders Pettersson Reif 《Journal of biomechanics》2014
The flow of cerebrospinal fluid (CSF) in a patient-specific model of the subarachnoid space in a Chiari I patient was investigated using numerical simulations. The pulsating CSF flow was modeled using a time-varying velocity pulse based on peak velocity measurements (diastole and systole) derived from a selection of patients with Chiari I malformation. The present study introduces the general definition of the Reynolds number to provide a measure of CSF flow instability to give an estimate of the possibility of turbulence occurring in CSF flow. This was motivated by the fact that the combination of pulsating flow and the geometric complexity of the spinal canal may result in local Reynolds numbers that are significantly higher than the commonly used global measure such that flow instabilities may develop into turbulent flow in these regions. The local Reynolds number was used in combination with derived statistics to characterize the flow. The results revealed the existence of both local unstable regions and local regions with velocity fluctuations similar in magnitude to what is observed in fully turbulent flows. The results also indicated that the fluctuations were not self-sustained turbulence, but rather flow instabilities that may develop into turbulence. The case considered was therefore believed to represent a CSF flow close to transition. 相似文献
92.
Katharina V. Alheit Lucas Busemeyer Wenxin Liu Hans Peter Maurer Manje Gowda Volker Hahn Sigrid Weissmann Arno Ruckelshausen Jochen C. Reif Tobias Würschum 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2014,127(1):251-260
Key message
QTL mapping in multiple families identifies trait-specific and pleiotropic QTL for biomass yield and plant height in triticale.Abstract
Triticale shows a broad genetic variation for biomass yield which is of interest for a range of purposes, including bioenergy. Plant height is a major contributor to biomass yield and in this study, we investigated the genetic architecture underlying biomass yield and plant height by multiple-line cross QTL mapping. We employed 647 doubled haploid lines from four mapping populations that have been evaluated in four environments and genotyped with 1710 DArT markers. Twelve QTL were identified for plant height and nine for biomass yield which cross-validated explained 59.6 and 38.2 % of the genotypic variance, respectively. A major QTL for both traits was identified on chromosome 5R which likely corresponds to the dominant dwarfing gene Ddw1. In addition, we detected epistatic QTL for plant height and biomass yield which, however, contributed only little to the genetic architecture of the traits. In conclusion, our results demonstrate the potential of genomic approaches for a knowledge-based improvement of biomass yield in triticale. 相似文献93.
Xinrui Gui Shuang Feng Zilong Li Yanyan Li Bernd Reif Bingyang Shi Zheng Niu 《The Journal of biological chemistry》2023,299(3)
Soluble amyloid-β oligomers (AβOs) are proposed to instigate and mediate the pathology of Alzheimer’s disease, but the mechanisms involved are not clear. In this study, we reported that AβOs can undergo liquid–liquid phase separation (LLPS) to form liquid-like droplets in vitro. We determined that AβOs exhibited an α-helix conformation in a membrane-mimicking environment of SDS. Importantly, SDS is capable of reconfiguring the assembly of different AβOs to induce their LLPS. Moreover, we found that the droplet formation of AβOs was promoted by strong hydrated anions and weak hydrated cations, suggesting that hydrophobic interactions play a key role in mediating phase separation of AβOs. Finally, we observed that LLPS of AβOs can further promote Aβ to form amyloid fibrils, which can be modulated by (−)-epigallocatechin gallate. Our study highlights amyloid oligomers as an important entity involved in protein liquid-to-solid phase transition and reveals the regulatory role of LLPS underlying amyloid protein aggregation, which may be relevant to the pathological process of Alzheimer’s disease. 相似文献
94.
95.
96.
97.
Interspecific competition promotes habitat and morphological divergence in a secondary contact zone between two hybridizing songbirds
下载免费PDF全文
![点击此处可从《Journal of evolutionary biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Camille Sottas Jiří Reif Lechosław Kuczyński Radka Reifová 《Journal of evolutionary biology》2018,31(6):914-923
Interspecific competition is assumed to play an important role in the ecological differentiation of species and speciation. However, empirical evidence for competition's role in speciation remains surprisingly scarce. Here, we studied the role of interspecific competition in the ecological differentiation and speciation of two closely related songbird species, the Common Nightingale (Luscinia megarhynchos) and the Thrush Nightingale (Luscinia luscinia). Both species are insectivorous and ecologically very similar. They hybridize in a secondary contact zone, which is a mosaic of sites where both species co‐occur (syntopy) and sites where only one species is present (allotopy). We analysed fine‐scale habitat data for both species in both syntopic and allotopic sites and looked for associations between habitat use and bill morphology, which have been previously shown to be more divergent in sympatry than in allopatry. We found that the two nightingale species differ in habitat use in allotopic sites, where L. megarhynchos occurred in drier habitats and at slightly higher elevations, but not in syntopic sites. Birds from allotopic sites also showed higher interspecific divergence in relative bill size compared to birds from syntopic sites. Finally, we found an association between bill morphology and elevation. Our results are consistent with the view that interspecific competition in nightingales has resulted in partial habitat segregation in sympatry and that the habitat‐specific food supply has in turn very likely led to bill size divergence. Such ecological divergence may enhance prezygotic as well as extrinsic postzygotic isolation and thus accelerate the completion of the speciation process. 相似文献
98.
99.
Continent‐scale global change attribution in European birds ‐ combining annual and decadal time scales
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)
Peter Søgaard Jørgensen Katrin Böhning‐Gaese Kasper Thorup Anders P. Tøttrup Przemysław Chylarecki Frédéric Jiguet Aleksi Lehikoinen David G. Noble Jiri Reif Hans Schmid Chris van Turnhout Ian J. Burfield Ruud Foppen Petr Voříšek Arco van Strien Richard D. Gregory Carsten Rahbek 《Global Change Biology》2016,22(2):530-543
Species attributes are commonly used to infer impacts of environmental change on multiyear species trends, e.g. decadal changes in population size. However, by themselves attributes are of limited value in global change attribution since they do not measure the changing environment. A broader foundation for attributing species responses to global change may be achieved by complementing an attributes‐based approach by one estimating the relationship between repeated measures of organismal and environmental changes over short time scales. To assess the benefit of this multiscale perspective, we investigate the recent impact of multiple environmental changes on European farmland birds, here focusing on climate change and land use change. We analyze more than 800 time series from 18 countries spanning the past two decades. Analysis of long‐term population growth rates documents simultaneous responses that can be attributed to both climate change and land‐use change, including long‐term increases in populations of hot‐dwelling species and declines in long‐distance migrants and farmland specialists. In contrast, analysis of annual growth rates yield novel insights into the potential mechanisms driving long‐term climate induced change. In particular, we find that birds are affected by winter, spring, and summer conditions depending on the distinct breeding phenology that corresponds to their migratory strategy. Birds in general benefit from higher temperatures or higher primary productivity early on or in the peak of the breeding season with the largest effect sizes observed in cooler parts of species' climatic ranges. Our results document the potential of combining time scales and integrating both species attributes and environmental variables for global change attribution. We suggest such an approach will be of general use when high‐resolution time series are available in large‐scale biodiversity surveys. 相似文献
100.
Multiple-trait- and selection indices-genomic predictions for grain yield and protein content in rye for feeding purposes 总被引:1,自引:0,他引:1