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991.
Martine Malissard Frédéric Chavagnat Colette Duez Marie-Jeanne Vacheron Micheline Guinand Georges Michel Jean-Marie Ghuysen 《FEMS microbiology letters》1995,126(2):105-111
Abstract In previous studies (Malissard et al., FEMS Microbiol. Lett. (1993) 110, 101–106), the alginate lyase AlxM of the marine bacterium ATCC 433367 was produced in Escherichia coli TC4/pAL-A3 with a yield of 50 μg per litre of culture. The polypeptide chain was cleaved between two cysteine residues, C169 and C183, themselves linked by a disulphide bridge. AlxM has now been overproduced in E. coli BL21(DE3)/pAL-Sur/pLysS. Under conditions in which formation of inclusion bodies can be avoided, the enzyme is synthesized as a catalytically active, water-soluble, unnicked polypeptide with a yield of 32 mg per litre of culture. It has been purified to protein homogeneity using a one-step procedure. The nicked AlxMA and unnicked AlxMB alginate lyases have identical alginate-degrading activities at high salt concentrations. 相似文献
992.
GABA added to rat hepatoma (HTC) cells in spinner culture at the time of induction of cell proliferation increased levels of ornithine decarboxylase (ODC) up to two- to threefold above that of control cells. The increases in ODC were also reflected by concomitant increases of intracellular putrescine levels, while spermidine and spermine were unchanged. GABA seems to have a direct stabilizing effect on ODC, since the turnover of the enzyme was slowed almost twofold when measured in cells treated with 10–2 M GABA. The stabilizing effect is most pronounced for GABA, although some amino acids such as asparagine, glutamine, and lysine as well as some GABA analogues and homologues also tend to increase ODC but to a significantly lesser extent than GABA itself. GABA metabolites had no effect on ODC.S-Adenosylmethionine decarboxylase and tyrosine aminotransferase were not affected by the presence of GABA. The GABA effect on ODC may be important in certain types of cells for the regulation of polyamine biosynthesis. 相似文献
993.
994.
Maik Münzinger Kambiz Taraz Herbert Budzikiewicz Hartmut Drechsel Petra Heymann Günther Winkelmann Jean-Marie Meyer 《Biometals》1999,12(2):189-193
From the culture medium of Ralstonia (formerly Burkholderia or Pseudomonas) pickettii DSM 6297 grown under iron-limited conditions an iron complexing compound (siderophore) could be isolated. The structure of the isolated polycarboxylate siderophore was determined by spectroscopic methods as S,S-rhizoferrin, the enantiomer of R,R-rhizoferrin produced by fungi (Zygomycetes). Transport experiments with radiolabelled iron using S,S- and R,R-rhizoferrin showd no differences in the bacterial Ralstonia strain, while transport of R,R-rhizoferrin was superior in the producing fungal Rhizopus strain, suggesting stereoselective recognition in the fungus. 相似文献
995.
996.
Lauriane Bray Carine Froment Pierre Pardo Cédric Candotto Odile Burlet-Schiltz Jean-Marie Zajac Catherine Mollereau Lionel Moulédous 《The Journal of biological chemistry》2014,289(49):33754-33766
The neuropeptide FF2 (NPFF2) receptor belongs to the rhodopsin family of G protein-coupled receptors and mediates the effects of several related RFamide neuropeptides. One of the main pharmacological interests of this system resides in its ability to regulate endogenous opioid systems, making it a potential target to reduce the negative effects of chronic opioid use. Phosphorylation of intracellular residues is the most extensively studied post-translational modification regulating G protein-coupled receptor activity. However, until now, no information concerning NPFF2 receptor phosphorylation is available. In this study, we combined mass spectrometric analysis and site-directed mutagenesis to analyze for the first time the phosphorylation pattern of the NPFF2 receptor and the role of the various phosphorylation sites in receptor signaling, desensitization, and trafficking in a SH-SY5Y model cell line. We identified the major, likely GRK-dependent, phosphorylation cluster responsible for acute desensitization, 412TNST415 at the end of the C terminus of the receptor, and additional sites involved in desensitization (372TS373) and internalization (Ser395). We thus demonstrate the key role played by phosphorylation in the regulation of NPFF2 receptor activity and trafficking. Our data also provide additional evidence supporting the concept that desensitization and internalization are partially independent processes relying on distinct phosphorylation patterns. 相似文献
997.
Alkaline treatment of 2-acetamido-2-deoxy-3,4:5,6-di-O-isopropylidene-aldehydo-d-glucose, or of the analogous d-mannose derivative, 相似文献
998.
Photosomes are the characteristic organelles of the luminous epithelium in the elytral appendages of polynoïd annelids. They are paracrystals of endoplasmic reticulum and emit a flash of bioluminescence in response to stimulation. The series of flashes in response to repetitive stimulation begins with a period of facilitation because the number of reacting photosomes increases in each photogenic cell. Reacting photosomes are coupled to the plasma membrane by dyad junctions which are established under stimulation and dedifferentiate in the resting system. The calcium influx of an action potential propagated through the conducting elytral epithelium triggers the luminous reaction. This reaction is based on a membrane photoprotein, polynoidin, which is specifically triggered by superoxide radicals. These oxy radicals result from the oxydation of riboflavin, which is present in a compartment of the photosomes. Polynoidin proved to be an interesting probe in the detection of superoxide radicals produced by activated white blood cells. Its potential applications are discussed. 相似文献
999.
Gilles Bena Jean-Marie Prosperi Bernard Lejeune Isabelle Olivieri 《Molecular phylogenetics and evolution》1998,9(3):552-559
We performed a molecular phylogenetic study based on the nuclear ribosomal internal and external transcribed spacer (ITS and ETS). Thirty-one annualMedicagospecies were included in the study, representing more than half of the genus and 85% of the annuals of the genus. Major incongruences were found between phylogenetic relationships and morphological classification of the genus. Morphological and cytological traits were mapped onto the phylogeny. The most parsimonious reconstruction suggested an ancestral spiny state and a recurrent transition from spiny to spineless state. From the ancestral state of 2n=16, three loss events of chromosomes must have occurred leading to the same specific number of 14 chromosomes whereas species having 30 chromosomes form a monophyletic clade. 相似文献
1000.
Morando MA Nurisso A Grenouillat N Vauzeilles B Beau JM Cañada FJ Jiménez-Barbero J Imberty A 《Glycobiology》2011,21(6):824-833
Nod factors are lipochitoligosaccharides originally produced by the soil bacteria Rhizobia that are involved in the symbiotic process with leguminous plants. Some synthetic analogs of the Nod factors present a strong biological activity, and the conformational behavior of these molecules is of interest for structure/function studies. Nod factor analogs containing an insertion of a phenyl group in the acyl chain at the oligosaccharidic non-reducing end were previously synthesized (Grenouillat N, Vauzeilles B, Bono J-J, Samain E, Beau J-M. 2004. Simple synthesis of nodulation-factor analogues exhibiting high affinity towards a specific binding protein. Angew Chem Int Ed Engl. 43:4644). Conformational studies of natural compounds and synthetic analogs have been performed combining molecular dynamics simulations in explicit water and NMR. Data revealed that the glycosidic head group can adopt only restricted conformations, whereas chemical modifications of the lipid chains, highly flexible in a water environment, influence the global shape of the molecules. Collected structural data could be used in the future to rationalize and understand their biological activity and affinity toward a putative receptor. 相似文献