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91.
Hsp27 protects mitochondria of thermotolerant cells against apoptotic stimuli 总被引:12,自引:0,他引:12 下载免费PDF全文
Samali A Robertson JD Peterson E Manero F van Zeijl L Paul C Cotgreave IA Arrigo AP Orrenius S 《Cell stress & chaperones》2001,6(1):49-58
Enhanced cell survival and resistance to apoptosis during thermotolerance correlates with an increased expression of heat shock proteins (Hsps). Here we present additional evidence in support of the hypothesis that the induction of Hsp27 and Hsp72 during acquired thermotolerance in Jurkat T-lymphocytes prevents apoptosis. In thermotolerant cells, Hsp27 was shown to associate with the mitochondrial fraction, and inhibition of Hsp27 induction during thermotolerance in cells transfected with hsp27 antisense potentiated mitochondrial cytochrome c release after exposure to various apoptotic stimuli, despite the presence of elevated levels of Hsp72. Caspase activation and apoptosis were inhibited under these conditions. In vitro studies revealed that recombinant Hsp72 more efficiently blocked cytochrome c-mediated caspase activation than did recombinant Hsp27. A model is presented for the inhibition of apoptosis during thermotolerance in which Hsp27 preferentially blocks mitochondrial cytochrome c release, whereas Hsp72 interferes with apoptosomal caspase activation. 相似文献
92.
Stimulation of Fas agonistic antibody-mediated apoptosis by heparin-like agents suppresses Hsp27 but not Bcl-2 protective activity 下载免费PDF全文
Manero F Ljubic-Thibal V Moulin M Goutagny N Yvin JC Arrigo AP 《Cell stress & chaperones》2004,9(2):150-166
We report that in Jurkat T cells or freshly isolated T lymphocytes, physiological concentrations of high-molecular weight sulfated polysaccharides such as heparin, heparan sulfate, and dextran sulfate significantly increased the percentage of cell death induced by Fas IgM agonistic antibody. The phenomenon was caspase dependent and P53 independent and correlated with an increased accessibility of cell surface Fas receptors. We also observed that the Fas IgM agonistic antibody-dependent formation of sodium dodecyl sulfate (SDS)-resistant large structures containing Fas receptor was decreased in the presence of heparin-like agents. In contrast, the different agents had no effect when cell death was triggered by FasL, the natural ligand of Fas that does not generate SDS-resistant forms of Fas. Interestingly, the synergistic effect of heparin-like agents toward Fas IgM agonistic antibody-mediated cell death abolished Hsp27 antiapoptotic activity but did not alter much the protection generated by Bcl-2 expression. 相似文献
93.
94.
Marta Romani Francesca Mancini Alessia Micalizzi Andrea Poretti Elide Miccinilli Patrizia Accorsi Emanuela Avola Enrico Bertini Renato Borgatti Romina Romaniello Serdar Ceylaner Giangennaro Coppola Stefano D’Arrigo Lucio Giordano Andreas R. Janecke Mario Lituania Kathrin Ludwig Loreto Martorell Tommaso Mazza Sylvie Odent Lorenzo Pinelli Pilar Poo Margherita Santucci Sabrina Signorini Alessandro Simonati Ronen Spiegel Franco Stanzial Maja Steinlin Brahim Tabarki Nicole I. Wolf Federica Zibordi Eugen Boltshauser Enza Maria Valente 《Human genetics》2015,134(1):123-126
95.
Padmini Dalpadado Kevin R. Arrigo Solfrid S. Hj?llo Francisco Rey Randi B. Ingvaldsen Erik Sperfeld Gert L. van Dijken Leif C. Stige Are Olsen Geir Ottersen 《PloS one》2014,9(5)
The temporal and spatial dynamics of primary and secondary biomass/production in the Barents Sea since the late 1990s are examined using remote sensing data, observations and a coupled physical-biological model. Field observations of mesozooplankton biomass, and chlorophyll a data from transects (different seasons) and large-scale surveys (autumn) were used for validation of the remote sensing products and modeling results. The validation showed that satellite data are well suited to study temporal and spatial dynamics of chlorophyll a in the Barents Sea and that the model is an essential tool for secondary production estimates. Temperature, open water area, chlorophyll a, and zooplankton biomass show large interannual variations in the Barents Sea. The climatic variability is strongest in the northern and eastern parts. The moderate increase in net primary production evident in this study is likely an ecosystem response to changes in climate during the same period. Increased open water area and duration of open water season, which are related to elevated temperatures, appear to be the key drivers of the changes in annual net primary production that has occurred in the northern and eastern areas of this ecosystem. The temporal and spatial variability in zooplankton biomass appears to be controlled largely by predation pressure. In the southeastern Barents Sea, statistically significant linkages were observed between chlorophyll a and zooplankton biomass, as well as between net primary production and fish biomass, indicating bottom-up trophic interactions in this region. 相似文献
96.
Arrigo Moro Tjeerd Blacquire Bjrn Dahle Vincent Dietemann Yves Le Conte Barbara Locke Peter Neumann Alexis Beaurepaire 《Ecology and evolution》2021,11(11):5937
Comparative studies of genetic diversity and population structure can shed light on the ecological and evolutionary factors governing host–parasite interactions. Even though invasive parasites are considered of major biological importance, little is known about their adaptative potential when infesting the new hosts. Here, the genetic diversification of Varroa destructor, a novel parasite of Apis mellifera originating from Asia, was investigated using population genetics to determine how the genetic structure of the parasite changed in distinct European populations of its new host. To do so, mites infesting two categories of hosts in four European regions were compared: (a) adapted hosts surviving through means of natural selection, thereby expected to impose strong selective pressure on the mites, and (b) treated host populations, surviving mite infestations because acaricides are applied, therefore characterized by a relaxed selection imposed by the host on the mites. Significant genetic divergence was found across regions, partially reflecting the invasion pattern of V. destructor throughout Europe and indicating local adaptation of the mite to the host populations. Additionally, varying degrees of genotypic changes were found between mites from adapted and treated colonies. Altogether, these results indicate that V. destructor managed to overcome the genetic bottlenecks following its introduction in Europe and that host‐mediated selection fostered changes in the genetic structure of this mite at diverse geographic scales. These findings highlight the potential of parasites to adapt to their local host populations and confirm that adaptations developed within coevolutionary dynamics are a major determinant of population genetic changes. 相似文献
97.
Daniela Calzia Stefano Barabino Paolo Bianchini Greta Garbarino Michele Oneto Federico Caicci Alberto Diaspro Carlo Tacchetti Lucia Manni Simona Candiani Silvia Ravera Alessandro Morelli Carlo Enrico Traverso Isabella Panfoli 《Biology of the cell / under the auspices of the European Cell Biology Organization》2013,105(8):345-358
98.
Polyploid speciation entails substantial and rapid postzygotic reproductive isolation of nascent species that are initially sympatric with one or both parents. Despite strong postzygotic isolation, ecological niche differentiation has long been thought to be important for polyploid success. Using biogeographic data from across vascular plants, we tested whether the climatic niches of polyploid species are more differentiated than their diploid relatives and if the climatic niches of polyploid species differentiated faster than those of related diploids. We found that polyploids are often more climatically differentiated from their diploid parents than the diploids are from each other. Consistent with this pattern, we estimated that polyploid species generally have higher rates of multivariate niche differentiation than their diploid relatives. In contrast to recent analyses, our results confirm that ecological niche differentiation is an important component of polyploid speciation and that niche differentiation is often significantly faster in polyploids. 相似文献
99.
Stéphanie Simon Valeriya Dimitrova Benjamin Gibert Sophie Virot Nicole Mounier Mathieu Nivon Carole Kretz-Remy Véronique Corset Patrick Mehlen André-Patrick Arrigo 《PloS one》2013,8(8)
Several human small heat shock proteins (sHsps) are phosphorylated oligomeric chaperones that enhance stress resistance. They are characterized by their ability to interact and form polydispersed hetero-oligomeric complexes. We have analyzed the cellular consequences of the stable expression of either wild type HspB5 or its cataracts and myopathies inducing R120G mutant in growing and oxidative stress treated HeLa cells that originally express only HspB1. Here, we describe that wild type and mutant HspB5 induce drastic and opposite effects on cell morphology and oxidative stress resistance. The cellular distribution and phosphorylation of these polypeptides as well as the oligomerization profile of the resulting hetero-oligomeric complexes formed by HspB1 with the two types of exogenous polypeptides revealed the dominant effects induced by HspB5 polypeptides towards HspB1. The R120G mutation enhanced the native size and salt resistance of HspB1-HspB5 complex. However, in oxidative conditions the interaction between HspB1 and mutant HspB5 was drastically modified resulting in the aggregation of both partners. The mutation also induced the redistribution of HspB1 phosphorylated at serine 15, originally observed at the level of the small oligomers that do not interact with wild type HspB5, to the large oligomeric complex formed with mutant HspB5. This phosphorylation stabilized the interaction of HspB1 with mutant HspB5. A dominant negative effect towards HspB1 appears therefore as an important event in the cellular sensitivity to oxidative stress mediated by mutated HspB5 expression. These observations provide novel data that describe how a mutated sHsp can alter the protective activity of another member of this family of chaperones. 相似文献
100.
Molly A. Palmer Kevin R. Arrigo C. J. Mundy Jens K. Ehn Michel Gosselin David G. Barber Johannie Martin Eva Alou Suzanne Roy Jean-��ric Tremblay 《Polar Biology》2011,34(12):1915-1928
During summer 2008, as part of the Circumpolar Flaw Lead system study, we measured phytoplankton photosynthetic parameters
to understand regional patterns in primary productivity, including the degree and timescale of photoacclimation and how variability
in environmental conditions influences this response. Photosynthesis–irradiance measurements were taken at 15 sites primarily
from the depth of the subsurface chlorophyll a (Chl a) maximum (SCM) within the Beaufort Sea flaw lead polynya. The physiological response of phytoplankton to a range of light
levels was used to assess maximum rates of carbon (C) fixation (P
m*), photosynthetic efficiency (α
*), photoacclimation (E
k), and photoinhibition (β
*). SCM samples taken along a transect from under ice into open water exhibited a >3-fold increase in α
* and P
m*, showing these parameters can vary substantially over relatively small spatial scales, primarily in response to changes in
the ambient light field. Algae were able to maintain relatively high rates of C fixation despite low light at the SCM, particularly
in the large (>5 μm) size fraction at open water sites. This may substantially impact biogenic C drawdown if species composition
shifts in response to future climate change. Our results suggest that phytoplankton in this region are well acclimated to
existing environmental conditions, including sea ice cover, low light, and nutrient pulses. Furthermore, this photoacclimatory
response can be rapid and keep pace with a developing SCM, as phytoplankton maintain photosynthetic rates and efficiencies
in a narrow “shade-acclimated” range. 相似文献