全文获取类型
收费全文 | 247篇 |
免费 | 44篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 5篇 |
2015年 | 23篇 |
2014年 | 14篇 |
2013年 | 21篇 |
2012年 | 8篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 5篇 |
2008年 | 6篇 |
2007年 | 12篇 |
2006年 | 14篇 |
2005年 | 12篇 |
2004年 | 14篇 |
2003年 | 16篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 3篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1967年 | 3篇 |
1966年 | 4篇 |
排序方式: 共有291条查询结果,搜索用时 859 毫秒
21.
Martin Husemann Jan Christian Habel Suk Namkung Axel Hochkirch Daniel Otte Patrick D. Danley 《PloS one》2015,10(2)
Patterns of colonization and diversification on islands provide valuable insights into evolutionary processes. Due to their unique geographic position and well known history, the Galapagos Islands are an important model system for evolutionary studies. Here we investigate the evolutionary history of a winged grasshopper genus to infer its origin and pattern of colonization in the Galapagos archipelago. The grasshopper genus Sphingonotus has radiated extensively in the Palaearctic and many species are endemic to islands. In the New World, the genus is largely replaced by the genus Trimerotropis. Oddly, in the Caribbean and on the Galapagos archipelago, two species of Sphingonotus are found, which has led to the suggestion that these might be the result of anthropogenic translocations from Europe. Here, we test this hypothesis using mitochondrial and nuclear DNA sequences from a broad sample of Sphingonotini and Trimerotropini species from the Old World and New World. The genetic data show two distinct genetic clusters representing the New World Trimerotropini and the Old World Sphingonotini. However, the Sphingonotus species from Galapagos and the Caribbean split basally within the Old World Sphingonotini lineage. The Galapagos and Caribbean species appear to be related to Old World taxa, but are not the result of recent anthropogenic translocations as revealed by divergence time estimates. Distinct genetic lineages occur on the four investigated Galapagos Islands, with deep splits among them compared to their relatives from the Palaearctic. A scenario of a past wider distribution of Sphingonotus in the New World with subsequent extinction on the mainland and replacement by Trimerotropis might explain the disjunct distribution. 相似文献
22.
Adriana Turqueti-Neves Manuel Otte Christian Schwartz Michaela Erika Renate Schmitt Cornelia Lindner Oliver Pabst Philipp Yu David Voehringer 《PLoS biology》2015,13(11)
IgE-mediated activation of mast cells and basophils contributes to protective immunity against helminths but also causes allergic responses. The development and persistence of IgE responses are poorly understood, which is in part due to the low number of IgE-producing cells. Here, we used next generation sequencing to uncover a striking overlap between the IgE and IgG1 repertoires in helminth-infected or OVA/alum-immunized wild-type BALB/c mice. The memory IgE response after secondary infection induced a strong increase of IgE+ plasma cells in spleen and lymph nodes. In contrast, germinal center B cells did not increase during secondary infection. Unexpectedly, the memory IgE response was lost in mice where the extracellular part of IgG1 had been replaced with IgE sequences. Adoptive transfer studies revealed that IgG1+ B cells were required and sufficient to constitute the memory IgE response in recipient mice. T cell-derived IL-4/IL-13 was required for the memory IgE response but not for expansion of B cells from memory mice. Together, our results reveal a close relationship between the IgE and IgG1 repertoires in vivo and demonstrate that the memory IgE response is mainly conserved at the level of memory IgG1+ B cells. Therefore, targeting the generation and survival of allergen-specific IgG1+ B cells could lead to development of new therapeutic strategies to treat chronic allergic disorders. 相似文献
23.
Marcel Otte 《L'Anthropologie》2014,118(5):483-494
Colonized by mammoths, the Eurasian steppe witnessed the birth of religious performances that are based on the reciprocation of life with the human populations moving apace. Plastic art codes attest to this balanced equilibrium with an up-to-present untamed environment, which is still in evidence among some Siberian peoples and the Saami (Lapps) in Europe. Such persistence can be seen as direct legacies and displays an environment that allows a range of attitudes towards animals incompatible with the notion of animal “domestication” as we commonly associate to the European Neolithic. 相似文献
24.
Alexey Rivkin Sean P. Ahearn Stephanie M. Chichetti Christopher L. Hamblett Yudith Garcia Michelle Martinez Jed L. Hubbs Michael H. Reutershan Matthew H. Daniels Phieng Siliphaivanh Karin M. Otte Chaomin Li Andrew Rosenau Laura M. Surdi Joon Jung Bethany L. Hughes Jamie L. Crispino George N. Nikov Richard E. Middleton Christopher M. Moxham Mark S. Shearman 《Bioorganic & medicinal chemistry letters》2010,20(7):2279-2282
The development of a novel series of purines as γ-secretase modulators for potential use in the treatment of Alzheimer’s disease is disclosed herein. Optimization of a previously disclosed pyrimidine series afforded a series of potent purine-based γ-secretase modulators with 300- to 2000-fold in vitro selectivity over inhibition of Notch cleavage and that selectively reduces Αβ42 in an APP-YAC transgenic mouse model. 相似文献
25.
26.
Otte JM Schwenger M Brunke G Schmitz F Otte C Kiehne K Kloehn S Mönig H Schmidt WE Herzig KH 《Regulatory peptides》2007,144(1-3):82-90
BACKGROUND AND AIM: Immunomodulatory and protective properties have been identified for the keratinocyte growth factor (KGF). For hepatocytes, pro-proliferative and anti-apoptotic effects of this growth factor have been reported in vitro. This study was designed to characterize a putative role of KGF in observed histomorphological changes in both, human and experimental liver fibrosis. METHODS: Liver fibrosis and cirrhosis was induced in rats by repetitive exposure to phenobarbitone and increasing doses of carbon tetrachloride. Human samples were obtained from patients undergoing surgery for partial hepatectomy or transplantation. Organ samples were scored for inflammation and morphological changes. Expression of KGF and its receptor (KGFR) mRNA was quantified by real-time RT-PCR. Protein expression and receptor phosphorylation was determined by Western blot analysis. In-situ hybridization and immunohistochemistry were utilized to determine distribution of KGF and KGFR in the liver. RESULTS: Expression of KGF was significantly increased in damaged liver tissue in correlation to the degree of fibrosis, whereas expression of the receptor was up-regulated in early stages of liver fibrosis and down-regulated in cirrhotic organs. Protein expression of this growth factor and its receptor correlated with the alterations in mRNA. KGF expression was restricted to mesenchymal cells, whereas expression of KGFR was detected on hepatocytes only. CONCLUSION: The expression of KGF and KGFR is differentially and significantly regulated in damaged liver tissue. This growth factor might therefore not only contribute to morphological alterations but also regeneration of liver parenchyma most likely mediated by indirect mechanisms of action. 相似文献
27.
The aim of the present study was to identify food sources of bark-living oribatid mites to investigate if trophic niche differentiation
contributes to the diversity of bark living Oribatida. We measured the natural variation in stable isotope ratios (15N/14N, 13C/12C) in oribatid mites from the bark of oak (Quercus robur), beech (Fagus sylvatica), spruce (Picea abies) and pine (Pinus sylvestris) trees and their potential food sources, i.e., the covering vegetation of the bark (bryophytes, lichens, algae, fungi). As
a baseline for calibration the stable isotope signatures of the bark of the four tree species were measured and set to zero.
Oribatid mite stable isotope ratios spanned over a range of about 13 δ units for 15N and about 7 δ units for 13C suggesting that they span over about three trophic levels. Different stable isotope signatures indicate that bark living
oribatid mites feed on different food sources, i.e., occupy distinct trophic niches. After calibration stable isotope signatures
of respective oribatid mite species of the four tree species were similar indicating close association of oribatid mites with
the corticolous cover as food source. Overall, the results support the hypothesis that trophic niche differentiation of bark
living oribatid mites contributes to the high diversity of the group. 相似文献
28.
Populations of the introduced Heracleum mantegazzianum consist of dense central stands, which gradually give way to open stands towards the margins. To analyse whether open stands
are due to unsuitable conditions or represent the invading front for further spread, we studied life-cycle, population dynamics,
stand structure and soil conditions of open and dense stands over two transition periods. Populations decreased during the
first interval but increased after the extremely dry and warm summer of 2003 during the second interval. Open stands had shorter
generation times, lower height, smaller proportions of small individuals and were less in equilibrium with the environment
than dense stands. In open stands, growth to higher stages was most important, while in dense stands delayed development (self-loops)
had a strong effect on population growth; stasis and fecundity contributed most to the difference in λ between stand types.
By petiole extension H. mantegazzianum may raise its leaves just above the resident vegetation. Therefore, younger stages develop faster in open stands, whereas
strong competition by conspecific adults leads to longer generation times and a higher proportion of small individuals in
dense stands. Disturbance due to extreme climatic conditions in summer 2003 equalised population dynamics of both stand types.
Life-cycle variation between stand types makes it difficult to infer simple management rules. However, our data suggest that
small and/or open stands of H. mantegazzianum may eventually serve as initials for further spread after land-use changes, whereas dense stands are stable and may represent
sources of propagules. 相似文献
29.
Relocation,high‐latitude warming and host genetic identity shape the foliar fungal microbiome of poplars
下载免费PDF全文
![点击此处可从《Molecular ecology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Miklós Bálint László Bartha Robert B. O'Hara Matthew S. Olson Jürgen Otte Markus Pfenninger Amanda L. Robertson Peter Tiffin Imke Schmitt 《Molecular ecology》2015,24(1):235-248
Micro‐organisms associated with plants and animals affect host fitness, shape community structure and influence ecosystem properties. Climate change is expected to influence microbial communities, but their reactions are not well understood. Host‐associated micro‐organisms are influenced by the climate reactions of their hosts, which may undergo range shifts due to climatic niche tracking, or may be actively relocated to mitigate the effects of climate change. We used a common‐garden experiment and rDNA metabarcoding to examine the effect of host relocation and high‐latitude warming on the complex fungal endophytic microbiome associated with leaves of an ecologically dominant boreal forest tree (Populus balsamifera L.). We also considered the potential effects of poplar genetic identity in defining the reactions of the microbiome to the treatments. The relocation of hosts to the north increased the diversity of the microbiome and influenced its structure, with results indicating enemy release from plausible pathogens. High‐latitude warming decreased microbiome diversity in comparison with natural northern conditions. The warming also caused structural changes, which made the fungal communities distinct in comparison with both low‐latitude and high‐latitude natural communities, and increased the abundance of plausible pathogens. The reactions of the microbiome to relocation and warming were strongly dependent on host genetic identity. This suggests that climate change effects on host–microbiome systems may be mediated by the interaction of environmental factors and the population genetic processes of the hosts. 相似文献
30.