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11.
Escriche M Burgueño J Ciruela F Canela EI Mallol J Enrich C Lluís C Franco R 《Experimental cell research》2003,285(1):72-90
The involvement of caveolae in the internalization of A(1) adenosine receptors (A(1)R) and the receptor sorting and recycling was studied in the smooth muscle cell line DDT(1)MF-2, by binding assays, by confocal microscopy, and at the structural level. The use of cholera toxin-binding subunit adsorbed to gold as a specific probe for labeling the ganglioside GM(1) and immunoelectron microscopy techniques showed that agonist stimulation produced a clustering and sequestration of adenosine receptors in caveolae. Furthermore, pull-down experiments showed there to be a direct interaction between the C-terminal domain of A(1)R and caveolin-1. Addition of exogenous adenosine deaminase (ADA), a protein that binds to A(1)R and acts as a receptor activity modifying protein (RAMP) stimulated R-PIA-induced A(1) receptor internalization. Finally, the sorting and recycling of A(1)R/ADA complexes was analyzed. Detailed electron microscopy revealed that A(1)R/ADA complexes internalize together through caveolae, are differentially sorted in endosomes, and are recycled back to the cell surface by different groups of recycling endosomes. These results give insight into the spatiotemporal regulation and traffic of A(1)R and RAMPs. 相似文献
12.
It is agreed that nuclear-encoded mitochondrial proteins are post-translationally targeted to mitochondria, even if, in some cases, a co-translational phase can assist the import of precursor proteins. We used yeast DNA microarrays to analyse the mRNA populations associated with free and mitochondrion-bound polysomes. As expected, many mRNAs, known to encode mitochondrial proteins, are localized to free cytoplasmic polysomes, but many are localized to mitochondrion-bound polysomes. Furthermore, the 3′-UTR of six randomly chosen mitochondrion-bound mRNAs contains sufficient information to target, in vivo, non-translatable RNA to the vicinity of mitochondria. Interestingly, genes producing mRNAs that are targeted to mitochondria are mainly of ancient bacterial origin, whereas those producing mRNAs that are translated in the cytoplasm are mainly of eukaryotic origin. These observations, which support the recent hypotheses concerning the dual origin of the mitochondrial proteome, provide new insights into the biogenesis of mitochondria. 相似文献
13.
Puentes A García J Ocampo M Rodríguez L Vera R Curtidor H López R Suarez J Valbuena J Vanegas M Guzman F Tovar D Patarroyo ME 《Peptides》2003,24(7):1015-1023
This work determined Plasmodium falciparum merozoite surface protein-8 (MSP-8) regions specifically binding to membrane surface receptors on human erythrocytes. Five high activity binding peptides (HABPs), whose binding to erythrocytes became saturable and sensitive on being treated with neuraminidase and chymotrypsin were identified from the MSP-8 protein. Those amino acids directly involved in interaction with erythrocytes were also determined for each one of the HABPs. Some of them specifically recognized 28, 46, and 73 kDa erythrocyte membrane proteins. Some HABPs inhibited in vitro P. falciparum merozoite invasion of erythrocytes by up to 98%, suggesting the MSP-8 protein's possible role in the invasion process. 相似文献
14.
García JE Puentes A López R Vera R Suárez J Rodríguez L Curtidor H Ocampo M Tovar D Forero M Bermudez A Cortés J Urquiza M Patarroyo ME 《Peptides》2003,24(5):647-657
Synthetic peptides from the liver stage antigen-1 (LSA-1) antigen sequence were used in HepG2 cell and erythrocyte binding assays to identify regions that could be involved in parasite invasion. LSA-1 protein peptides 20630 ((21)INGKIIKNSEKDEIIKSNLRY(40)), 20637 ((157)KEKLQGQQSDSEQERRAY(173)), 20638 ((174)KEKLQEQQSDLEQERLAY(190)) and 20639 (191KEKLQEQQSDLEQERRAY(207)) had high binding activity in HepG2 assays. Were located in immunogenic regions; peptide cell binding was saturable. Peptide 20630 bound specifically to 48kDa HepG2 membrane surface protein. LSA-1 peptides 20630 ((21)INGKIIKNSEKDEIIKSNLRY(40)) and 20633 ((81)DKELTMSNVKNVSQTNFKSLY(100)) showed specific erythrocyte binding activity and inhibited merozoite invasion of erythrocytes in vitro. A monkey serum prepared against LSA-1 20630 peptide analog (CGINGKNIKNAEKPMIIKSNLRGC) inhibited merozoite invasion in vitro. The data suggest LSA-1 "High Activity Binding Peptides" could play a possible role in hepatic cell invasion as well as merozoite invasion of erythrocytes. 相似文献
15.
Tetanus Toxin Enhances Protein Kinase C Activity Translocation and Increases Polyphosphoinositide Hydrolysis in Rat Cerebral Cortex Preparations 总被引:2,自引:2,他引:0
Carles Gil Marisol Ruiz-Meana María Álava †Ephraim Yavin José Aguilera 《Journal of neurochemistry》1998,70(4):1636-1643
Abstract: Tetanus toxin (TeTx) has been recently demonstrated to be a Zn2+-dependent endopeptidase that cleaves synaptobrevin, a protein in part responsible for neurotransmitter release. Nevertheless, certain aspects of TeTx action, for example, the causal relationship between TeTx and protein kinase C (PKC; EC 2.7.1.37) activity cannot be explained by this cleavage alone. In the present study, primary neurons from fetal rat brain, synaptosomes, and whole slices have been used to examine this issue. Low doses of TeTx (≤ 10?8M) caused PKC activity translocation in a manner similar to that produced by 12-O-tetradecanoylphorbol 13-acetate (TPA). TPA (≤ 10?7M) caused sustained PKC activity translocation, whereas TeTx produced translocation followed by relocation, depending on the dose and time of exposure. Immunoidentification with a monoclonal antibody recognizing both α and β isoforms revealed that TeTx induced moderate losses of PKC in the cytosolic fraction, without a comparable increase in the particulate fraction. Although moderate losses of activity were also noticed in the cytosolic fraction, the inconsistency with respect to activity translocation may be explained by translocation of additional PKC isoforms that are not identified by the antibody. Comparable levels of water-soluble inositol phosphate-labeled intermediates were obtained after treatment of cerebral cells and/or cortical brain slices with TeTx. Significant increases of 19 and 114% in the water-soluble myo-[2-3H]inositol-labeled inositol phosphate metabolites were found in cerebral cell culture and brain slices, respectively, after treatment with 10?8M TeTx. TeTx (10?8M) increased to the same degree the water-soluble inositol phosphate levels as did serotonin (10?5M) or carbachol (10?6M). It is suggested that part of the signaling cascade of TeTx consists of a component involving inositol phospholipid hydrolysis, which is associated with PKC activity translocation. 相似文献
16.
Abundance, morphology and distribution of planktonic virus-like particles in two high-mountain lakes 总被引:5,自引:0,他引:5
Pina Sonia; Creus Andreu; Gonzaalez Nuria; Gironees Rosina; Felip Marisol; Sommaruga Ruben 《Journal of plankton research》1998,20(12):2413-2421
Direct counts of virus-like particles (VLP) by transmissionelectron microscopy revealed abundances of up to 3 x 107 ml1in the plankton of two remote high-mountain lakes in the Alpsand the Pyrenees. Most VLP were icosahedric without a tail,and with diameters between 40 and 90 nm, but very large oneswith diameters of up to 325 run were also observed. VLP outnumberedbacteria by a factor of 4.242.8 and bacterial cells wereinfected with large numbers (>50) of viral particles. Thisstudy constitutes the first report on aquatic viruses for alpinelakes and it suggests that they may be an important additionalsource of bacterial mortality in these systems. 相似文献
17.
18.
Laura Mazzaferro Lucrecia Piñuel Marisol Minig Javier D. Breccia 《Archives of microbiology》2010,192(5):383-393
We screened for microorganisms able to use flavonoids as a carbon source; and one isolate, nominated Stilbella fimetaria SES201, was found to possess a disaccharide-specific hydrolase. It was a cell-bound ectoenzyme that was released to the medium
during conidiogenesis. The enzyme was shown to cleave the flavonoid hesperidin (hesperetin 7-O-α-rhamnopyranosyl-β-glucopyranoside)
into rutinose (α-rhamnopyranosyl-β-glucopyranose) and hesperetin. Since only intracellular traces of monoglycosidase activities
(β-glucosidase, α-rhamnosidase) were produced, the disaccharidase α-rhamnosyl-β-glucosidase was the main system utilized by
the microorganism for hesperidin hydrolysis. The enzyme was a glycoprotein with a molecular weight of 42224 Da and isoelectric
point of 5.7. Even when maximum activity was found at 70°C, it was active at temperatures as low as 5°C, consistent with the
psychrotolerant character of S. fimetaria. Substrate preference studies indicated that the enzyme exhibits high specificity toward 7-O-linked flavonoid β-rutinosides.
It did not act on flavonoid 3-O-β-rutinoside and 7-O-β-neohesperidosides, neither monoglycosylated substrates. In an aqueous
medium, the α-rhamnosyl-β-glucosidase was also able to transfer rutinose to other acceptors besides water, indicating its
potential as biocatalyst for organic synthesis. The monoenzyme strategy of S. fimetaria SES201, as well as the enzyme substrate preference for 7-O-β-flavonoid rutinosides, is unique characteristics among the microbial
flavonoid deglycosylation systems reported. 相似文献
19.
Three 2,3‐dihydro‐1H‐isoindol‐1‐ones structurally related with piracetam (=2‐oxopyrrolidine‐1‐acetamide) have been synthesized and tested for their nootropic effects in the passive avoidance test in mice. Compounds (RS)‐ 2 , (R,R)‐ 3 , and (R,S)‐ 3 were obtained in good yields in only two steps starting from methyl dl ‐phthaloylalanine. Compound (RS)‐ 2 exhibited nootropic activity at lower doses than piracetam, used as reference drug, but it showed lower efficacy. Whereas diastereoisomers (R,R)‐ 3 and (R,S)‐ 3 were as potent as piracetam to revert amnesia induced by scopolamine, (R,S)‐ 3 showed lower efficacy than (R,R)‐ 3 . Only (R,R)‐ 3 showed myorelaxant effect at doses of 10 and 30 mg/kg; other compounds did not exhibit any anticonvulsant, sedative, myorelaxant, or impaired motor‐coordination effect in mice. These synthesized 2,3‐dihydro‐1H‐isoindol‐1‐one derivatives constitute a new kind of nootropic compounds. 相似文献
20.