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91.
Immunolocalization of a novel, cytoskeleton-associated polypeptide of Mr 230,000 daltons (p230) 总被引:15,自引:8,他引:7 下载免费PDF全文
Antibodies were raised against a cytoskeleton-associated, nonphosphorylated, 230,000-dalton bovine lens polypeptide (designated p230), and rendered monospecific by using a novel immunoaffinity technique. In immunofluorescence and electron microscopy of cultured fibroblasts, as well as of various other cells (endothelial, epithelial, lenticular, monocytes, neuroblastoma cells) and tissues (human kidney and liver), p230 was localized as a distinct subplasmalemmal layer in the peripheral cytoplasm of the cells. It constituted less than 0.3% of the total cellular protein in cultured fibroblasts and was not extractable with Triton X-100. In detergent-extracted cytoskeletal preparations of cultured fibroblasts, p230 remained as an elaborate peripheral network that showed a distribution distinctly different from that of the major cytoskeletal structures, stress fibers, cortical myosin, vinculin, and intermediate filaments (IF). The distribution was not dependent on the presence of intact stress fibers or microtubules, as shown by double-fluorescence microscopy of cells exposed to cytochalasin B or cultured in the presence of monensin and of cold-treated cells. Upon demecolcine-induced reorganization of intermediate filaments, however, the localization of p230 was rapidly altered to a dense plaque underneath the perinuclear aggregate of intermediate filaments. On the other hand, p230 seemed to colocalize with the detergent-resistant cell surface lamina, visualized in fluorescence microscopy with fluorochrome-coupled wheat germ agglutinin-lectin. The results suggest that p230 is part of a cell surface- and cytoskeleton-associated subplasmalemmal structure that may play an important role in cell surface-cytoskeleton interaction in various cells both in vitro and in vivo. 相似文献
92.
The myelin-associated glycoprotein is a transmembrane cell adhesion molecule expressed specifically by myelinating glial cells of the nervous system. Its two isoforms, whose amino acid sequences differ only by their respective cytoplasmic carboxy-terminal domains, are important for the formation and maintenance of a normal functional myelin sheath. In this study, by using recombinant proteins, we identify the cytoplasmic domain of the small isoform of the myelin-associated glycoprotein as a zinc-binding protein. The observed dissociation constant lies in the low micromolar range (K(D) = 6-7 microM). The binding of zinc by the small myelin-associated glycoprotein induces a conformational change that enables the protein to reversibly bind to a hydrophobic phenyl-Sepharose matrix. Our results also suggest that zinc may induce dimerization of the small myelin-associated glycoprotein. We suggest roles for zinc in the stabilization of the structure of the cytoplasmic domain of the small myelin-associated glycoprotein and in protein-protein interactions that involve this short domain. 相似文献
93.
BVOC Emissions From a Subarctic Ecosystem,as Controlled by Insect Herbivore Pressure and Temperature
Ghimire Rajendra P. Silfver Tarja Myller Kristiina Oksanen Elina Holopainen Jarmo K. Mikola Juha 《Ecosystems》2022,25(4):872-891
Ecosystems - The biogenic volatile organic compounds, BVOCs have a central role in ecosystem–atmosphere interactions. High-latitude ecosystems are facing increasing temperatures and insect... 相似文献
94.
Annina Lyly Carina von Schantz Tarja Salonen Outi Kopra Jani Saarela Matti Jauhiainen Aija Kyttälä Anu Jalanko 《BMC cell biology》2007,8(1):1-14
Background
About 20 % of nemaline myopathies are thus far related to skeletal muscle alpha-actin. Seven actin mutants located in different parts of the actin molecule and linked to different forms of the disease were selected and expressed as EGFP-tagged constructs in differentiated C2C12 mytoubes. Results were compared with phenotypes in patient skeletal muscle fibres and with previous expression studies in fibroblasts and C2C12 myoblasts/myotubes.Results
Whereas EGFP wt-actin nicely incorporated into endogenous stress fibres and sarcomeric structures, the mutants showed a range of phenotypes, which generally changed upon differentiation. Many mutants appeared delocalized in myoblasts but integrated into endogenous actin structures after 4–6 days of differentiation, demonstrating a poor correlation between the appearance in myotubes and the severity of the disease. However, for some mutants, integration into stress fibres induced aberrant structures in differentiated cells, like thickening or fragmentation of stress fibres. Other mutants almost failed to integrate but formed huge aggregates in the cytoplasm of myotubes. Those did not co-stain with alpha-actinin, a main component of nemaline bodies found in patient muscle. Interestingly, nuclear aggregates as formed by two of the mutants in myoblasts were found less frequently or not at all in differentiated cells.Conclusion
Myotubes are a suitable system to study the capacity of a mutant to incorporate into actin structures or to form or induce pathological changes. Some of the phenotypes observed in undifferentiated myoblasts may only be in vitro effects. Other phenotypes, like aberrant stress fibres or rod formation may be more directly correlated with disease phenotypes. Some mutants did not induce any changes in the cellular actin system, indicating the importance of additional studies like functional assays to fully characterize the pathological impact of a mutant. 相似文献95.
Vainio L Perjes A Ryti N Magga J Alakoski T Serpi R Kaikkonen L Piuhola J Szokodi I Ruskoaho H Kerkelä R 《The Journal of biological chemistry》2012,287(7):4572-4580
Neuronostatin, a recently discovered peptide encoded by somatostatin gene, is involved in regulation of neuronal function, blood pressure, food intake, and drinking behavior. However, the biological effects of neuronostatin on cardiac myocytes are not known, and the intracellular signaling mechanisms induced by neuronostatin remain unidentified. We analyzed the effect of neuronostatin in isolated perfused rat hearts and in cultured primary cardiomyocytes. Neuronostatin infusion alone had no effect on left ventricular (LV) contractile function or on isoprenaline- or preload-induced increase in cardiac contractility. However, infusion of neuronostatin significantly decreased the positive inotropic response to endothelin-1 (ET-1). This was associated with an increase in phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase (JNK). Treatment of both neonatal and adult cardiomyocytes with neuronostatin resulted in reduced cardiomyocyte viability. Inhibition of JNK further increased the neuronostatin-induced cell death. We conclude that neuronostatin regulates cardiac contractile function and cardiomyocyte survival. Receptors for neuronostatin need to be identified to further characterize the biological functions of the peptide. 相似文献
96.
Petäjä-Repo UE Hogue M Leskelä TT Markkanen PM Tuusa JT Bouvier M 《The Journal of biological chemistry》2006,281(23):15780-15789
Protein palmitoylation is a reversible lipid modification that plays important roles for many proteins involved in signal transduction, but relatively little is known about the regulation of this modification and the cellular location where it occurs. We demonstrate that the human delta opioid receptor is palmitoylated at two distinct cellular locations in human embryonic kidney 293 cells and undergoes dynamic regulation at one of these sites. Although palmitoylation could be readily observed for the mature receptor (Mr 55,000), [3H]palmitate incorporation into the receptor precursor (Mr 45,000) could be detected only following transport blockade with brefeldin A, nocodazole, and monensin, indicating that the modification occurs initially during or shortly after export from the endoplasmic reticulum. Blocking of palmitoylation with 2-bromopalmitate inhibited receptor cell surface expression, indicating that it is needed for efficient intracellular transport. However, cell surface biotinylation experiments showed that receptors can also be palmitoylated once they have reached the plasma membrane. At this location, palmitoylation is regulated in a receptor activation-dependent manner, as was indicated by the opioid agonist-promoted increase in the turnover of receptor-bound palmitate. This agonist-mediated effect did not require receptor-G protein coupling and occurred at the cell surface without the need for internalization or recycling. The activation-dependent modulation of receptor palmitoylation may thus contribute to the regulation of receptor function at the plasma membrane. 相似文献
97.
Johanna Riikonen Maarit Mäenpää Marjo Alavillamo Tarja Silfver Elina Oksanen 《Planta》2009,230(2):419-427
We studied the effects of slightly elevated temperature (T), O3 concentration (O3) and their combination (T + O3) on the antioxidant defense, gas exchange and total leaf area of Betula pendula saplings in field conditions. During the second year of the experiment, T enhanced the total leaf area, net photosynthesis (P
n) and maximum capacity of carboxylation, redox state of ascorbate and total antioxidant capacity in the apoplast. O3 did not affect the total leaf area, but P
n was slightly and g
s significantly reduced. The saplings responded to elevated O3 level by closing the stomata and by developing leaves with a lower leaf area per mass, rather than by accumulating ascorbate
in the apoplast. The effects of T and O3 on total leaf area and P
n were counteractive. Elevated O3 reduced the saplings’ ability to utilize the warmer growth environment by increasing the stomatal limitation for photosynthesis
and by reducing the redox state of ascorbate in the apoplast in the combination treatment as compared to T alone. 相似文献
98.
Urszula M. Polanska Laurence Duchesne Janet C. Harries David G. Fernig Tarja K. Kinnunen 《The Journal of biological chemistry》2009,284(48):33030-33039
The regulation of cell function by fibroblast growth factors (FGFs) classically occurs through a dual receptor system of a tyrosine kinase receptor (FGFR) and a heparan sulfate proteoglycan co-receptor. Mutations in some consensus N-glycosylation sites in human FGFR result in skeletal disorders and craniosynostosis syndromes, and biophysical studies in vitro suggest that N-glycosylation of FGFR alters ligand and heparan sulfate binding properties. The evolutionarily conserved FGFR signaling system of Caenorhabditis elegans has been used to assess the role of N-glycosylation in the regulation of FGFR signaling in vivo. The C. elegans FGF receptor, EGL-15, is N-glycosylated in vivo, and genetic substitution of specific consensus N-glycosylation sites leads to defects in the maintenance of fluid homeostasis and differentiation of sex muscles, both of which are phenotypes previously associated with hyperactive EGL-15 signaling. These phenotypes are suppressed by hypoactive mutations in EGL-15 downstream signaling components or activating mutations in the phosphatidylinositol 3-kinase pathway, respectively. The results show that N-glycans negatively regulate FGFR activity in vivo supporting the notion that mutation of N-glycosylation sites in human FGFR may lead to inappropriate activation of the receptor. 相似文献
99.
100.
Wessel M. A. van Leeuwen Maili Lehto Piia Karisola Harri Lindholm Ritva Luukkonen Mikael Sallinen Mikko H?rm? Tarja Porkka-Heiskanen Harri Alenius 《PloS one》2009,4(2)