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241.
Role of SGT1 in resistance protein accumulation in plant immunity 总被引:20,自引:0,他引:20
Azevedo C Betsuyaku S Peart J Takahashi A Noël L Sadanandom A Casais C Parker J Shirasu K 《The EMBO journal》2006,25(9):2007-2016
A highly conserved eukaryotic protein SGT1 binds specifically to the molecular chaperone, HSP90. In plants, SGT1 positively regulates disease resistance conferred by many Resistance (R) proteins and developmental responses to the phytohormone, auxin. We show that silencing of SGT1 in Nicotiana benthamiana causes a reduction in steady-state levels of the R protein, Rx. These data support a role of SGT1 in R protein accumulation, possibly at the level of complex assembly. In Arabidopsis, two SGT1 proteins, AtSGT1a and AtSGT1b, are functionally redundant early in development. AtSGT1a and AtSGT1b are induced in leaves upon infection and either protein can function in resistance once a certain level is attained, depending on the R protein tested. In unchallenged tissues, steady-state AtSGT1b levels are at least four times greater than AtSGT1a. While the respective tetratricopeptide repeat (TPR) domains of SGT1a and SGT1b control protein accumulation, they are dispensable for intrinsic functions of SGT1 in resistance and auxin responses. 相似文献
242.
Ramos AS Chambergo FS Bonaccorsi ED Ferreira AJ Cella N Gombert AK Tonso A El-Dorry H 《Biochemistry》2006,45(26):8184-8192
The filamentous fungus Trichoderma reesei is adapted to nutrient-poor environments, in which it uses extracellular cellulases to obtain glucose from the available cellulose biomass. We have isolated and characterized Trhxt1, a putative glucose transporter gene, as judged by the glucose accumulation phenotype of a DeltaTrhxt1 mutant. This gene is repressed at high glucose concentrations and expressed at micromolar levels and in the absence of glucose. The gene is also induced during the growth of T. reesei on cellulose when the glucose concentration generated from the hydrolysis of cellulose present in the culture medium is in the micromolar range. We also show that oxygen availability controls the expression of the Trxht1 gene. In this regard, the gene is down-regulated by hypoxia and also by the inhibition of the flow of electrons through the respiratory chain using antimycin A. Intriguingly, anoxia but not hypoxia strongly induces the expression of the gene in the presence of an otherwise repressive concentration of glucose. These results indicate that although the absence of repressing concentrations of glucose and an active respiratory chain are required for Trhxt1 expression under normoxic conditions these physiological processes have no effect on the expression of this gene under an anoxic state. Thus, our results highlight the presence of a novel coordinated interaction between oxygen and the regulatory circuit for glucose repression under anoxic conditions. 相似文献
243.
Tumors are dependent on oncogenic proteins for their maintenance and survival. The ideal cancer therapy would include drugs that specifically target these proteins. Many such proteins function through interfaces that can be difficult to target effectively with small molecules. However, recent advances in cell-permeable peptide technology, improving cellular penetration and stability, raise the possibility that specific peptide interference of oncogenic proteins could be successfully translated to the clinic. Several active anti-tumor peptides were recently described. For example, a stable peptide inhibitor of the Hsp90 ATP-binding pocket killed a wide range of tumors in vitro and in vivo, and a peptide inhibitor of the BCL6 oncoprotein was active in B-cell lymphomas; both peptides functioned without toxicity to normal tissues. 相似文献
244.
Mähönen AP Higuchi M Törmäkangas K Miyawaki K Pischke MS Sussman MR Helariutta Y Kakimoto T 《Current biology : CB》2006,16(11):1116-1122
The cytokinin class of plant hormones plays key roles in regulating diverse developmental and physiological processes. Arabidopsis perceives cytokinins with three related and partially redundant receptor histidine kinases (HKs): CRE1 (the same protein as WOL and AHK4), AHK2, and AHK3 (CRE-family receptors). It is suggested that binding of cytokinins induces autophosphorylation of these HKs and subsequent transfer of the phosphoryl group to a histidine phosphotransfer protein (HPt) and then to a response regulator (RR), ultimately regulating downstream signaling events. Here we demonstrate that, in vitro and in a yeast system, CRE1 is not only a kinase that phosphorylates HPts in the presence of cytokinin but is also a phosphatase that dephosphorylates HPts in the absence of cytokinin. To explore the roles of these activities in planta, we replaced CRE1 with mutant versions of the gene or with AHK2. Replacing CRE1 with CRE1(T278I), which lacks cytokinin binding activity and is locked in the phosphatase form, decreased cytokinin sensitivity. Conversely, replacing CRE1 with AHK2, which favors kinase activity, increased cytokinin sensitivity. These results indicate that in the presence of cytokinins, cytokinin receptors feed phosphate to phosphorelay-integrating HPt proteins. In the absence of cytokinins, CRE1 removes phosphate from HPt proteins, decreasing the system phosphoload. 相似文献
245.
Iivari Kleino Rebekka M. Ortiz Miljamartta Yritys Ari‐Pekka J. Huovila Kalle Saksela 《Journal of cellular biochemistry》2009,108(4):877-885
A Disintegrin And Metalloprotease (ADAM15) is a member of the adamalysin protein family and has been associated with cancer, possibly via its role in ectodomain shedding of cadherins. Alternative mRNA splicing generates several ADAM15 isoforms containing different combinations of putative Src homology‐3 (SH3) domain binding sites in their cytosolic tails. Here we present a comprehensive characterization of SH3 binding potential of different ADAM15 isoforms. Alternative use of ADAM15 exons was found to profoundly influence selection of SH3‐containing cellular partner proteins, including the avid interactions with nephrocystin and sorting nexin‐33 (SNX33 a.k.a. SNX30). Specifically, strong co‐precipitation of nephrocystin from cell lysates was specific to ADAM15 isoforms i4, i5, and i6. These isoforms contain one or both of the two almost identical proline‐rich regions encoded by exons 20 and 21, wherein the residues RxLPxxP were found to be indispensable for nephrocystin SH3 binding. Similarly, robust cellular association with SNX33 was observed only for ADAM15 isoforms containing the most carboxyterminal proline cluster lacking in isoforms i1 and i3. Thus, alternative mRNA splicing provides a versatile mechanism for regulation of intracellular protein interactions and thereby likely the cellular functions of ADAM15, which could explain the association with cancer of some but not all ADAM15 isoforms. J. Cell. Biochem. 108: 877–885, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
246.
Tarmo Lipping Michael Rorarius Ville Jäntti Kari Annala Ari Mennander Rain Ferenets Tommi Toivonen Tim Toivo Alpo Värri Leena Korpinen 《Nonlinear biomedical physics》2009,3(1):5-10
Background
In this study, investigating the effects of mobile phone radiation on test animals, eleven pigs were anaesthetised to the level where burst-suppression pattern appears in the electroencephalogram (EEG). At this level of anaesthesia both human subjects and animals show high sensitivity to external stimuli which produce EEG bursts during suppression. The burst-suppression phenomenon represents a nonlinear control system, where low-amplitude EEG abruptly switches to very high amplitude bursts. This switching can be triggered by very minor stimuli and the phenomenon has been described as hypersensitivity. To test if also radio frequency (RF) stimulation can trigger this nonlinear control, the animals were exposed to pulse modulated signal of a GSM mobile phone at 890 MHz. In the first phase of the experiment electromagnetic field (EMF) stimulation was randomly switched on and off and the relation between EEG bursts and EMF stimulation onsets and endpoints were studied. In the second phase a continuous RF stimulation at 31 W/kg was applied for 10 minutes. The ECG, the EEG, and the subcutaneous temperature were recorded. 相似文献247.
Tan Q Balofsky A Weisz K Peng C 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2009,153(1):18-23
The transforming growth factor-beta (TGF-beta) superfamily is a large group of peptide growth and differentiation factors that have important functions in many physiological processes, including reproduction. We previously reported that several members of the TGF-beta superfamily, including activin-A, bone morphogenetic protein-15 (BMP-15) and TGF-beta1, regulate oocyte maturation in zebrafish. The aim of this study was to further examine the functions and mechanisms of these growth factors in regulating zebrafish oocyte maturation. First, the interaction among three regulators was examined. Overexpression of BMP-15 reduced the effect of activin-A on oocyte maturation. Inhibition of BMP-15 function or expression increased oocyte maturation but had no additive effect with activin-A. TGF-beta1 suppressed activin-A-, as well as BMP-15 antiserum-induced oocyte maturation. Second, the role of Smad 2, an intracellular mediator of activin and TGF-beta, in oocyte maturation was investigated. Western blot analysis revealed that both activin-A and TGF-beta1 activate Smad2 in zebrafish follicles. Injection of morpholino antisense olignucleotides against Smad2 into oocytes reduced Smad2 expression and completely blocked activin-A-induced oocyte maturation. Knockdown of Smad 2 also significantly decreased basal and hCG-induced oocyte maturation. These findings suggest that activin-A, TGF-beta1, and BMP-15 may target common gene(s) to regulate oocyte maturation and demonstrate that Smad2 plays an important role in oocyte maturation. 相似文献
248.
Michal Kirshner Moran Rathavs Anat Nizan Jeroen Essers Roland Kanaar Yosef Shiloh Ari Barzilai 《DNA Repair》2009,8(2):253-261
Ataxia-telangiectasia is a pleiotropic genomic instability disorder caused by lack or inactivation of the ATM protein kinase and characterized by progressive ataxia, immunodeficiency, ionizing radiation sensitivity and cancer predisposition. ATM mobilizes the cellular response to DNA double strand breaks by phosphorylating key players in this response. Double strand breaks are repaired by either nonhomologous end-joining or homologous recombination (HR) in which the Rad54 and Rad54B paralogs function. Here, we investigated the functional relationships between Atm and the Rad54 proteins by constructing compound genotypes in mice. Mouse strains were generated that combined inactivation of the Atm, Rad54 and Rad54B genes. All mutant genotypes were viable, but obtained at sub-Mendelian ratios. Double mutants for Atm and each Rad54 paralog exhibited reduced body weight and shorter lifespan, but no distinct neurological phenotype. Concomitant inactivation of ATM and Rad54 did not increase IR sensitivity; however, the triple Atm/Rad54/Rad54B mutant exhibited a significant IR hypersensitivity compared to the other genotypes. Interestingly, Atm?/? animals also exhibited hypersensitivity to the crosslinking agent mitomycin C, which was increased by deficiency of either one of the Rad54 paralogs. Our results reveal a differential interaction of the ATM-mediated DNA damage response and Rad54 paralog-mediated HR depending on the DNA damaging agent that initiates the response. 相似文献
249.
250.
Stéphane Leteurtre Alain Duhamel Bruno Grandbastien Fran?ois Proulx Jacques Cotting Ronald Gottesman Ari Joffe Bendicht Wagner Philippe Hubert Alain Martinot Jacques Lacroix Francis Leclerc 《CMAJ》2010,182(11):1181-1187