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101.
102.
Pritsch K Courty PE Churin JL Cloutier-Hurteau B Ali MA Damon C Duchemin M Egli S Ernst J Fraissinet-Tachet L Kuhar F Legname E Marmeisse R Müller A Nikolova P Peter M Plassard C Richard F Schloter M Selosse MA Franc A Garbaye J 《Mycorrhiza》2011,21(7):589-600
The aim of a joint effort by different research teams was to provide an improved procedure for enzyme activity profiling of field-sampled ectomycorrhizae, including recommendations on the best conditions and maximum duration for storage of ectomycorrhizal samples. A more simplified and efficient protocol compared to formerly published procedures was achieved by using manufactured 96-filter plates in combination with a vacuum manifold and by optimizing incubation times. Major improvements were achieved by performing the series of eight enzyme assays with a single series of root samples instead of two series, reducing the time needed for sample preparation, minimizing error-prone steps such as pipetting and morphotyping, and facilitating subsequent DNA analyses due to the reduced sequencing effort. The best preservation of samples proved to be storage in soil at 4?C6°C in the form of undisturbed soil cores containing roots. Enzyme activities were maintained for up to 4?weeks under these conditions. Short-term storage of washed roots and ectomycorrhizal tips overnight in water did not cause substantial changes in enzyme activity profiles. No optimal means for longer-term storage by freezing at ?20°C or storage in 100% ethanol were recommended. 相似文献
103.
Lundstrom K Wagner R Reinhart C Desmyter A Cherouati N Magnin T Zeder-Lutz G Courtot M Prual C André N Hassaine G Michel H Cambillau C Pattus F 《Journal of structural and functional genomics》2006,7(2):77-91
Production of recombinant receptors has been one of the major bottlenecks in structural biology on G protein-coupled receptors
(GPCRs). The MePNet (Membrane Protein Network) was established to overexpress a large number of GPCRs in three major expression
systems, based on Escherichia coli, Pichia pastoris and Semliki Forest virus (SFV) vectors. Evaluation by immunodetection demonstrated that 50% of a total of 103 GPCRs were
expressed in bacterial inclusion bodies, 94% in yeast cell membranes and 95% in SFV-infected mammalian cells. The expression
levels varied from low to high and the various GPCR families and subtypes were analyzed for their expressability in each expression
system. More than 60% of the GPCRs were expressed at milligram levels or higher in one or several systems, compatible to structural
biology applications. Functional activity was determined by binding assays in yeast and mammalian cells and the correlation
between immunodetection and binding activity was analyzed. 相似文献
104.
Hassaine G Wagner R Kempf J Cherouati N Hassaine N Prual C André N Reinhart C Pattus F Lundstrom K 《Protein expression and purification》2006,45(2):343-351
Semliki Forest virus vectors were applied for the evaluation of 101 G protein-coupled receptors in three mammalian cell lines. Western blotting demonstrated that 95 of the 101 tested GPCRs showed positive signals. A large number of the GPCRs were expressed at high levels suggesting receptor yields in the range of 1 mg/L or higher, suitable for structural biology applications. Specific binding assays on a selected number of GPCRs were carried out to compare the correlation between total and functional protein expression. Ligands and additives supplemented to the cell culture medium were evaluated for expression enhancement. Selected GPCRs were also expressed from mutant SFV vectors providing enhanced protein expression and reduced host cell toxicity in attempts to further improve receptor yields. 相似文献
105.
106.
Brillet K Journet L Célia H Paulus L Stahl A Pattus F Cobessi D 《Structure (London, England : 1993)》2007,15(11):1383-1391
Transport of molecules larger than 600 Da across the outer membrane involves TonB-dependent receptors and TonB-ExbB-ExbD of the inner membrane. The transport is energy consuming, and involves direct interactions between a short N-terminal sequence of receptor, called the TonB box, and TonB. We solved the structure of the ferric pyoverdine (Pvd-Fe) outer membrane receptor FpvA from Pseudomonas aeruginosa in its apo form. Structure analyses show that residues of the TonB box are in a beta strand which interacts through a mixed four-stranded beta sheet with the periplasmic signaling domain involved in interactions with an inner membrane sigma regulator. In this conformation, the TonB box cannot form a four-stranded beta sheet with TonB. The FhuA-TonB or BtuB-TonB structures show that the TonB-FpvA interactions require a conformational change which involves a beta strand lock-exchange mechanism. This mechanism is compatible with movements of the periplasmic domain deduced from crystallographic analyses of FpvA, FpvA-Pvd, and FpvA-Pvd-Fe. 相似文献
107.
Alzheimer's disease (AD) is a neurodegenerative syndrom involving many different biological parameters, including the accumulation of copper metal ions in Aβ amyloid peptides due to a perturbation of copper circulation and homeostasis within the brain. Copper-containing amyloids activated by endogenous reductants are able to generate an oxidative stress that is involved in the toxicity of abnormal amyloids and contribute to the progressive loss of neurons in AD. Since only few drugs are currently available for the treatment of AD, we decided to design small molecules able to interact with copper and we evaluated these drug-candidates with non-transgenic mice, since AD is mainly an aging disease, not related to genetic disorders. We created a memory deficit mouse model by a single icv injection of Aβ(1-42) peptide, in order to mimic the early stage of the disease and the key role of amyloid oligomers in AD. No memory deficit was observed in the control mice with the antisense Aβ(42-1) peptide. Here we report the capacity of a new copper-specific chelating agent, a bis-8-aminoquinoline PA1637, to fully reverse the deficit of episodic memory after three weeks of treatment by oral route on non-transgenic amyloid-impaired mice. Clioquinol and memantine have been used as comparators to validate this fast and efficient mouse model. 相似文献
108.
Apoptosis, a genetically programmed cell death, allows for homeostasis and tissue remodelling during development of all multi-cellular organisms. Phagocytes swiftly recognize, engulf and digest apoptotic cells. Yet, to date the molecular mechanisms underlying this phagocytic process are still poorly understood. To delineate the molecular mechanisms of apoptotic cell clearance in Drosophila, we have carried out a deficiency screen and have identified three overlapping phagocytosis-defective mutants, which all delete the fly homologue of the ced-12 gene, known as Dmel\ced12. As anticipated, we have found that Dmel\ced-12 is required for apoptotic cell clearance, as for its C. elegans and mammalian homologues, ced-12 and elmo, respectively. However, the loss of Dmel\ced-12 did not solely account for the phenotypes of all three deficiencies, as zygotic mutations and germ line clones of Dmel\ced-12 exhibited weaker phenotypes. Using a nearby genetically interacting deficiency, we have found that the polycystic kidney disease 2 gene, pkd2, which encodes a member of the TRPP channel family, is also required for phagocytosis of apoptotic cells, thereby demonstrating a novel role for PKD2 in this process. We have also observed genetic interactions between pkd2, simu, drpr, rya-r44F, and retinophilin (rtp), also known as undertaker (uta), a gene encoding a MORN-repeat containing molecule, which we have recently found to be implicated in calcium homeostasis during phagocytosis. However, we have not found any genetic interaction between Dmel\ced-12 and simu. Based on these genetic interactions and recent reports demonstrating a role for the mammalian pkd-2 gene product in ER calcium release during store-operated calcium entry, we propose that PKD2 functions in the DRPR/RTP pathway to regulate calcium homeostasis during this process. Similarly to its C. elegans homologue, Dmel\Ced-12 appears to function in a genetically distinct pathway. 相似文献
109.
110.
Petra Prijatelj Jernej Sribar Gabriela Ivanovski Igor Krizaj Franc Gubensek Joze Pungercar 《European journal of biochemistry》2003,270(14):3018-3025
The molecular mechanism of the presynaptic neurotoxicity of snake venom phospholipases A2 (PLA2s) is not yet fully elucidated. Recently, new high-affinity binding proteins for PLA2 toxins have been discovered, including the important intracellular Ca2+ sensor, calmodulin (CaM). In the present study, the mode of interaction of group IIA PLA2s with the Ca2+-bound form of CaM was investigated by mutational analysis of ammodytoxin A (AtxA) from the long-nosed viper (Vipera ammodytes ammodytes). Several residues in the C-terminal part of AtxA were found to be important in this interaction, particularly those in the region 115-119. In support of this finding, introduction of Y115, I116, R118 and N119, present in AtxA, into a weakly neurotoxic PLA2 from Russell's viper (Daboia russellii russellii) increased by sevenfold its binding affinity for CaM. Furthermore, two out of four peptides deduced from different regions of AtxA were able to compete with the toxin in binding to CaM. The nonapeptide showing the strongest inhibition was that comprising the AtxA region 115-119. This stretch contributes to a distinct hydrophobic patch within the region 107-125 in the C-terminal part of the molecule. This lacks any substantial helical structure and is surrounded by several basic residues, which may form a novel binding motif for CaM on the molecular surface of the PLA2 toxin. 相似文献