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81.
Inactivation of sodium conductance has been studied in squid axons with voltage clamp techniques and with the enzyme pronase which selectively destroys inactivation. Comparison of the sodium current before and after pronase treatment shows a lag of several hundred microseconds in the onset of inactivation after depolarization. This lag can of several hundred microseconds in the onset of inactivation after polarization. This lag can also be demonstrated with double-pulse experiments. When the membrane potential is hyperpolarized to -140 mV before depolarization, both activation and inactivation are delayed. These findings suggest that inactivation occurs only after activation are delayed. These findings suggest that inactivation occurs only after activation; i.e. that the channels must open before they can inactivate. The time constant of inactivation measured with two pulses (τ(c)) is the same as the one measured from the decay of the sodium current during a single pulse (τ(h)). For large depolarizations, steady-state inactivation becomes more incomplete as voltage increases; but it is relatively complete and appears independent of voltage when determined with a two- pulse method. This result confirms the existence of a second open state for Na channels, as proposed by Chandler and Meves (1970. J. Physiol. [Lond.]. 211:653-678). The time constant of recovery from inactivation is voltage dependent and decreases as the membrane potential is made more negative. A model for Na channels is presented which has voltage-dependent transitions between the closed and open states, and a voltage-independent transition between the open and the inactivated state. In this model the voltage dependence of inactivation is a consequence of coupling to the activation process. 相似文献
82.
Glycosylation is a widespread modification of plant secondary metabolites. It is involved in various functions, including the regulation of hormone homeostasis, the detoxification of xenobiotics and the biosynthesis and storage of secondary compounds. In plants, these reactions are controlled by a specific subclass of the ubiquitous glycosyltransferase family. Although these enzymes have been studied intensively for many years, to date only a handful have been characterized in planta. Plant genome projects have uncovered unsuspected complexity within this family that is hindering the characterization of single genes. However, genome information also paves the way for the development of functional genomic approaches. Here, we highlight recent progress and the outcomes of novel strategies developed to uncover the physiological roles of these glycosyltransferases. 相似文献
83.
H?Bukulmez AL?Matthews CM?Sullivan C?Chen MJ?Kraay RC?Elston RW?Moskowitz VM?Goldberg ML?WarmanEmail author 《Arthritis research & therapy》2005,8(1):R25
In order to determine whether there is a genetic component to hip or knee joint failure due to idiopathic osteoarthritis (OA),
we invited patients (probands) undergoing hip or knee arthroplasty for management of idiopathic OA to provide detailed family
histories regarding the prevalence of idiopathic OA requiring joint replacement in their siblings. We also invited their spouses
to provide detailed family histories about their siblings to serve as a control group. In the probands, we confirmed the diagnosis
of idiopathic OA using American College of Rheumatology criteria. The cohorts included the siblings of 635 probands undergoing
total hip replacement, the siblings of 486 probands undergoing total knee replacement, and the siblings of 787 spouses. We
compared the prevalence of arthroplasty for idiopathic OA among the siblings of the probands with that among the siblings
of the spouses, and we used logistic regression to identify independent risk factors for hip and knee arthroplasty in the
siblings. Familial aggregation for hip arthroplasty, but not for knee arthroplasty, was observed after controlling for age
and sex, suggesting a genetic contribution to end-stage hip OA but not to end-stage knee OA. We conclude that attempts to
identify genes that predispose to idiopathic OA resulting in joint failure are more likely to be successful in patients with
hip OA than in those with knee OA. 相似文献
84.
Flendrie M Vissers WH Creemers MC de Jong EM van de Kerkhof PC van Riel PL 《Arthritis research & therapy》2005,7(3):R666-R676
Various dermatological conditions have been reported during tumor necrosis factor (TNF)-α-blocking therapy, but until now
no prospective studies have been focused on this aspect. The present study was set up to investigate the number and nature
of clinically important dermatological conditions during TNF-α-blocking therapy in patients with rheumatoid arthritis (RA).
RA patients starting on TNF-α-blocking therapy were prospectively followed up. The numbers and natures of dermatological events
giving rise to a dermatological consultation were recorded. The patients with a dermatological event were compared with a
group of prospectively followed up RA control patients, naive to TNF-α-blocking therapy and matched for follow-up period.
289 RA patients started TNF-α-blocking therapy. 128 dermatological events were recorded in 72 patients (25%) during 911 patient-years
of follow-up. TNF-α-blocking therapy was stopped in 19 (26%) of these 72 patients because of the dermatological event. More
of the RA patients given TNF-α-blocking therapy (25%) than of the anti-TNF-α-naive patients (13%) visited a dermatologist
during follow-up (P < 0.0005). Events were recorded more often during active treatment (0.16 events per patient-year) than during the period
of withdrawal of TNF-α-blocking therapy (0.09 events per patient-year, P < 0.0005). The events recorded most frequently were skin infections (n = 33), eczema (n = 20), and drug-related eruptions (n = 15). Other events with a possible relation to TNF-α-blocking therapy included vasculitis, psoriasis, drug-induced systemic
lupus erythematosus, dermatomyositis, and a lymphomatoid-papulosis-like eruption. This study is the first large prospective
study focusing on dermatological conditions during TNF-α-blocking therapy. It shows that dermatological conditions are a significant
and clinically important problem in RA patients receiving TNF-α-blocking therapy. 相似文献
85.
Olivier De Clerck Shu-Min Kao Kenny A. Bogaert Jonas Blomme Fatima Foflonker Michiel Kwantes Emmelien Vancaester Lisa Vanderstraeten Eylem Aydogdu Jens Boesger Gianmaria Califano Benedicte Charrier Rachel Clewes Andrea Del Cortona Sofie D’Hondt Noe Fernandez-Pozo Claire M. Gachon Marc Hanikenne John H. Bothwell 《Current biology : CB》2018,28(18):2921-2933.e5
86.
Claire M.M. Gachon Martina Strittmatter Yacine Badis Kyle I. Fletcher Pieter Van West Dieter G. Müller 《欧洲藻类学杂志》2017,52(2):133-148
Using laboratory cultures, we have documented the life cycle of Anisolpidium ectocarpii, a pathogen of Ectocarpus and other filamentous brown algae, and presented preliminary observations on Anisolpidium rosenvingei, a pathogen of Pylaiella littoralis. Consistent with earlier reports, the zoospores of both species have a single anterior flagellum, which justified the placement of Anisolpidium amongst the Hyphochytriales (Hyphochytridiomycota). We have also shown that A. ectocarpii can complete its infection cycle in a broad selection of species from various brown algal orders, whereas A. rosenvingei seemingly exhibits a strict specificity for unilocular sporangia of P. littoralis. Unexpectedly, nuclear (18S rRNA) and mitochondrial (cox1, cox2) markers regroup A. ectocarpii and A. rosenvingei, into a hitherto unrecognized monophyletic clade within the oomycetes (Oomycota), most closely related to the Olpidiopsidales. The Anisolpidium genus is therefore entirely distinct from the Hyphochytridiomycota and represents the first confirmed instance of an anteriorly uniciliate oomycete. Finally, we suggest that a valid morphological criterion to separate true hyphochytrids from oomycetes is the timing of zoospore cleavage. Given the evidence, we propose to transfer the Anisolpidiales from the Hyphochytriales to the Oomycetes. 相似文献
87.
We investigated the cytotoxic, neurotoxic, apoptotic and antiproliferative effects of extracts from Petalonia fascia, Jania longifurca and Halimeda tuna on the MCF-7 breast cancer cell line. J. longifurca extracts were more toxic than those of P. fascia and H. tuna. The algal extracts showed significant toxic effects at different dilutions. The toxic effects were due to increased oxidative stress and resulted in apoptosis. Algal toxicity may exert negative effects through the food chain or by direct interaction. Algal toxicity also has potential for cancer therapy. The toxic effects that we observed may be especially important for therapy for breast tumors. 相似文献
88.
Eddy J Smid Oylum Erkus Maciej Spus Judith CM Wolkers-Rooijackers Svetlana Alexeeva Michiel Kleerebezem 《Microbial cell factories》2014,13(Z1):S2
This review describes the recent advances made in the studies of the microbial community of complex and undefined cheese starter cultures. We report on work related to the composition of the cultures at the level of genetic lineages, on the presence and activity of bacteriophages and on the population dynamics during cheese making and during starter culture propagation. Furthermore, the link between starter composition and starter functionality will be discussed. Finally, recent advances in predictive metabolic modelling of the multi-strain cultures will be discussed in the context of microbe-microbe interactions. 相似文献
89.
C André Lévesque Henk Brouwer Liliana Cano John P Hamilton Carson Holt Edgar Huitema Sylvain Raffaele Gregg P Robideau Marco Thines Joe Win Marcelo M Zerillo Gordon W Beakes Jeffrey L Boore Dana Busam Bernard Dumas Steve Ferriera Susan I Fuerstenberg Claire MM Gachon Elodie Gaulin Francine Govers Laura Grenville-Briggs Neil Horner Jessica Hostetler Rays HY Jiang Justin Johnson Theerapong Krajaejun Haining Lin Harold JG Meijer Barry Moore Paul Morris Vipaporn Phuntmart Daniela Puiu Jyoti Shetty Jason E Stajich Sucheta Tripathy Stephan Wawra Pieter van West Brett R Whitty Pedro M Coutinho Bernard Henrissat Frank Martin Paul D Thomas Brett M Tyler Ronald P De Vries Sophien Kamoun Mark Yandell Ned Tisserat C Robin Buell 《Genome biology》2010,11(7):1-22
90.
Konstantinos Doris Sophia P Karabela Chrysoula A Kairi Davina CM Simoes Charis Roussos Spyros G Zakynthinos Ioannis Kalomenidis Timothy S Blackwell Georgios T Stathopoulos 《Respiratory research》2010,11(1):118