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排序方式: 共有156条查询结果,搜索用时 15 毫秒
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Annette Lasham Erno Vreugdenhil Alan N. Bateson Eric A. Barnard Mark G. Darlison 《Journal of neurochemistry》1991,57(1):352-355
A series of genomic clones containing DNA that encodes the chicken gamma-aminobutyric acidA (GABAA) receptor beta 4 subunit have been isolated. These have been restriction mapped and partially sequenced to determine the structural organization and the size of the beta 4-subunit gene. This gene, which comprises nine exons, spans more than 65 kb. The organization of the chicken GABAA receptor beta 4-subunit gene has been compared to that of the murine GABAA receptor delta-subunit gene and to those of the genes that encode other members of the ligand-gated ion-channel superfamily, namely muscle and neuronal nicotinic acetylcholine receptors (AChRs). Although the positions of the intron/exon boundaries of GABAA receptor subunit genes are seen to be highly conserved, there are significant differences between the genes that encode GABAA receptor and AChR subunits. These results are discussed in relation to the proposal that this superfamily of ligand-gated ion-channel receptor genes arose by duplication of an ancestral receptor gene. 相似文献
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Electrophoretic isolation and partial characterization of a major secretory glycoprotein from the submandibular glands of the mouse 总被引:3,自引:0,他引:3
A V Amerongen M E Aarsman A P Vreugdenhil P A Roukema 《Biochimica et biophysica acta》1978,534(1):26-37
After either cholinergic or adrenergic stimulation of the submandibular glands of the mouse, a major protein of the incubation medium could be isolated by electrophoresis, designated the AM2 protein. About 5 per cent of the secreted proteins and 2.4 per cent of the secreted protein-bound sialic acid was recovered as the purified AM2 protein. The AM2 protein appeared to be electrophoretically pure in 7.5% polyacrylamide gel both at pH 8.9 and at pH 4.3. In sodium dodecyl sulfate-electrophoresis the molecular weight was estimated to be about 80 000 for the major component and about 40 000 for the minor component. By isoelectric focusing the isoelectric point has been determined to be 4.7. The amino acid analysis indicated Glx, Asx, Leu and Ala as the major amino acids, comprising 15.0, 10.6, 9.2 and 9.1 per cent of the amino acid residues, respectively. The ratio of the acidic amino acids and their amides (Glx plus Asx) to the basic amino acids (Lys plus Arg) was 2.2. The sugar analysis showed that the AM2 glycoprotein consists of 17.3 per cent of carbohydrate, with as major carbohydrate component glucosamine. The molar ratio of the sugars was Man : Gal : Glc : GlcNH2 : sialic acid = 2.3 : 1.0 : 4.7 : 9.8 : 2.9. Galactosamine could be detected as a trace component and fucose was not detectable. 相似文献
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A mechanism suggested to cause injury to preserved organs is the generation of oxygen free radicals either during the cold-storage period or after transplantation (reperfusion). Oxygen free radicals can cause peroxidation of lipids and alter the structural and functional properties of the cell membranes. Methods to suppress generation of oxygen free radicals of suppression of lipid peroxidation may lead to improved methods of organ preservation. In this study we determined how cold storage of rat hepatocytes affected lipid peroxidation by measuring thiobarbituric acid reactive products (malondialdehyde, MDA). Hepatocytes were stored in the UW solution +/- glutathione (GSH) or +/- polyethylene glycol (PEG) for up to 96 h and rewarmed (resuspended in a physiologically balanced saline solution and incubated at 37 degrees C under an atmosphere of oxygen) after each day of storage. Hepatocytes rewarmed after storage in the UW solution not containing PEG or GSH showed a nearly linear increase in MDA production with time of storage and contained 1.618 +/- 0.731 nmol MDA/mg protein after 96 h. When the storage solution contained PEG and GSH there was no significant increase in MDA production after up to 72 h of storage and at 96 h MDA was 0.827 +/- 0.564 nmol/mg protein. When freshly isolated hepatocytes were incubated (37 degrees C) in the presence of iron (160 microM) MDA formation was maximally stimulated (3.314 +/- 0.941 nmol/mg protein). When hepatocytes were stored in the presence of PEG there was a decrease in the capability of iron to maximally stimulate lipid peroxidation. The decrease in iron-stimulated MDA production was dependent upon the time of storage in PEG (1.773 nmol/mg protein at 24 h and 0.752 nmol/mg protein at 48 h).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Vreugdenhil AC Snoek AM Greve JW Buurman WA 《Journal of immunology (Baltimore, Md. : 1950)》2000,165(8):4561-4566
Lipopolysaccharide-binding protein (LBP) is an important modulator of the host's response to endotoxin. In a previous study, we found evidence for the synthesis of LBP by intestinal epithelial cells. In this study, we explored the polarity of LBP secretion by these cells. Polarized monolayers of Caco-2 cells were used as intestinal mucosa model. Cells were stimulated apically or basally with cytokines, and LBP secretion was analyzed. Furthermore, the presence of LBP in intestinal mucus of healthy and endotoxemic mice was studied using a mucus-sampling technique. The constitutive unipolar LBP secretion from the apical cell surface was markedly enhanced when cells were exposed to cytokines at their apical surface. However, bioactive LBP was secreted from both cell surfaces after basolateral stimulation of cells. Cytokines also influenced the secretion of the acute phase proteins serum amyloid A, apoA-I, and apoB from both surfaces of Caco-2 cells. Furthermore, transport of exogenous LBP from the basolateral to the apical cell surface was demonstrated. In line with these in vitro data, the presence of LBP in intestinal mucus was strongly enhanced in mice after a challenge with endotoxin. The results indicate that LBP is present at the mucosal surface of the intestine, a phenomenon for which secretion and transport of LBP by intestinal epithelial cells may be responsible. 相似文献
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Cutting edge: cationic antimicrobial peptides block the binding of lipopolysaccharide (LPS) to LPS binding protein 总被引:7,自引:0,他引:7
Scott MG Vreugdenhil AC Buurman WA Hancock RE Gold MR 《Journal of immunology (Baltimore, Md. : 1950)》2000,164(2):549-553
We investigated the mechanism by which cationic antimicrobial peptides block the activation of macrophages by LPS. The initial step in LPS signaling is the transfer of LPS to CD14 by LPS binding protein (LBP). Because many cationic antimicrobial peptides bind LPS, we asked whether these peptides block the binding of LPS to LBP. Using an assay that measures the binding of LPS to immobilized LBP, we show for the first time that a variety of structurally diverse cationic antimicrobial peptides block the interaction of LPS with LBP. The relative ability of different cationic peptides to block the binding of LPS to LBP correlated with their ability to block LPS-induced TNF-alpha production by the RAW 264.7 macrophage cell line. 相似文献
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Simulated brain tumor growth dynamics using a three-dimensional cellular automaton 总被引:10,自引:0,他引:10
Kansal AR Torquato S Harsh GR IV Chiocca EA Deisboeck TS 《Journal of theoretical biology》2000,203(4):367-382
We have developed a novel and versatile three-dimensional cellular automaton model of brain tumor growth. We show that macroscopic tumor behavior can be realistically modeled using microscopic parameters. Using only four parameters, this model simulates Gompertzian growth for a tumor growing over nearly three orders of magnitude in radius. It also predicts the composition and dynamics of the tumor at selected time points in agreement with medical literature. We also demonstrate the flexibility of the model by showing the emergence, and eventual dominance, of a second tumor clone with a different genotype. The model incorporates several important and novel features, both in the rules governing the model and in the underlying structure of the model. Among these are a new definition of how to model proliferative and non-proliferative cells, an isotropic lattice, and an adaptive grid lattice. 相似文献