全文获取类型
收费全文 | 464篇 |
免费 | 48篇 |
国内免费 | 27篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 16篇 |
2020年 | 15篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 15篇 |
2016年 | 11篇 |
2015年 | 13篇 |
2014年 | 23篇 |
2013年 | 32篇 |
2012年 | 17篇 |
2011年 | 24篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 17篇 |
2007年 | 15篇 |
2006年 | 25篇 |
2005年 | 15篇 |
2004年 | 34篇 |
2003年 | 25篇 |
2002年 | 25篇 |
2001年 | 21篇 |
2000年 | 8篇 |
1999年 | 16篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 14篇 |
1992年 | 5篇 |
1991年 | 9篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 12篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 8篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有539条查询结果,搜索用时 15 毫秒
61.
Overview of Mathematical Approaches Used to Model Bacterial Chemotaxis II: Bacterial Populations 总被引:1,自引:0,他引:1
We review the application of mathematical modeling to understanding the behavior of populations of chemotactic bacteria. The
application of continuum mathematical models, in particular generalized Keller–Segel models, is discussed along with attempts
to incorporate the microscale (individual) behavior on the macroscale, modeling the interaction between different species
of bacteria, the interaction of bacteria with their environment, and methods used to obtain experimentally verified parameter
values. We allude briefly to the role of modeling pattern formation in understanding collective behavior within bacterial
populations. Various aspects of each model are discussed and areas for possible future research are postulated. 相似文献
62.
Overview of Mathematical Approaches Used to Model Bacterial Chemotaxis I: The Single Cell 总被引:1,自引:0,他引:1
Tindall MJ Porter SL Maini PK Gaglia G Armitage JP 《Bulletin of mathematical biology》2008,70(6):1525-1569
Mathematical modeling of bacterial chemotaxis systems has been influential and insightful in helping to understand experimental
observations. We provide here a comprehensive overview of the range of mathematical approaches used for modeling, within a
single bacterium, chemotactic processes caused by changes to external gradients in its environment. Specific areas of the
bacterial system which have been studied and modeled are discussed in detail, including the modeling of adaptation in response
to attractant gradients, the intracellular phosphorylation cascade, membrane receptor clustering, and spatial modeling of
intracellular protein signal transduction. The importance of producing robust models that address adaptation, gain, and sensitivity
are also discussed. This review highlights that while mathematical modeling has aided in understanding bacterial chemotaxis
on the individual cell scale and guiding experimental design, no single model succeeds in robustly describing all of the basic
elements of the cell. We conclude by discussing the importance of this and the future of modeling in this area. 相似文献
63.
HGF/SF Induces Mesothelial Cell Migration and Proliferation by Autocrine and Paracrine Pathways 总被引:7,自引:0,他引:7
Richard Warn Pascale Harvey Alba Warn Adam Foley-Comer Paraskevi Heldin Marjan Versnel Naokatu Arakaki Yasushi Daikuhara Geoffrey J. Laurent Sarah E. Herrick Steven E. Mutsaers 《Experimental cell research》2001,267(2):258-266
Mesothelial repair differs from that of other epithelial-like surfaces as healing does not occur solely by centripetal in-growth of cells as a sheet from the wound margins. Mesothelial cells lose their cell-cell junctions, divide, and adopt a fibroblast-like morphology while scattering across and covering the wound surface. These features are consistent with a cellular response to hepatocyte growth factor/scatter factor (HGF/SF). In this study, we examined the ability of mesothelial cells to secrete HGF/SF and investigated its possible role as an autocrine regulator of mesothelial cell motility and proliferation. We found that human primary mesothelial cells expressed HGF/SF mRNA and secreted active HGF/SF into conditioned medium as determined by ELISA and in a scattering bioassay. These cells also expressed the HGF/SF receptor, Met, as shown by RT-PCR and by Western blot analysis and immunofluorescence. Incubation of mesothelial cells with neutralizing antibodies to HGF/SF decreased cell migration to 25% of controls, whereas addition of HGF/SF disrupted cell-cell junctions and induced scattering and enhanced mesothelial cell migration. Furthermore, HGF/SF showed a small but significant mitogenic effect on all mesothelial cell lines examined. In conclusion, HGF/SF is produced by mesothelial cells and induces both motility and proliferation of these cells. These data are consistent with HGF/SF playing an autocrine role in mesothelial healing. 相似文献
64.
Dependence of motility and chemotaxis was studied in two strains of Bradyrhizobium japonicum upon several environmental factors. In both strains, chemotaxis was found to increase with an increasing concentration of the attractant (glucose) to 5.5 × 10–2 M. Both motility and chemotaxis reached their maximum in the two- to three-day cultures at neutral pH. The maximum motility of these bacteria occurred at 40°C. The maximum values of chemotaxis in these microorganisms were, however, observed at 20–25°C. Chemotaxis in acidic or alkaline media and at low temperatures was found to be markedly weaker. Nonoptimal values of these parameters in soil may be a limiting factor for the interaction of the given bacteria with soybean roots. 相似文献
65.
The chemotactic character of the nonapeptide bradykinin (BK1-9) and its derivatives was studied in the eukaryotic ciliated model Tetrahymena pyriformis. The results demonstrate that BK1-9 has a direct and ligand-specific chemoattractant effect (maximal at 10(-11) m) without any intermediate substance as is essential in some mammalian test systems. Evaluation of the chemotactic effect elicited by derivatives showed that the presence of N- and C-terminal arginines can influence chemotactic potency of the molecule via expression of pyrrolidine and aromatic ring structures of terminal amino acid residues. Removal of the N-terminal Arg (expression of Pro) results in a significant decrease in chemotaxis (BK2-9), while further truncation of the C-terminal, causing expression of the aromatic ring of Phe (BK2-8), results in a highly chemoattractant variant. A single pyrrolidine ring on the C-terminus BK1-7 also has a positive effect on the chemotactic character, however further truncation (BK1-6, BK1-5) causes the chemoattractant character to become chemorepellent. Study of chemotactic selection with BK derivatives supports our previous findings that only phylogenetically selected ligands or their close derivatives are able to induce long-term selection with chemotaxis. 相似文献
66.
Adiponectin promotes human jaw bone marrow mesenchymal stem cell chemotaxis via CXCL1 and CXCL8 下载免费PDF全文
《Journal of cellular and molecular medicine》2017,21(7):1411-1419
Adiponectin (APN) is known to promote the osteogenic differentiation of human jaw bone marrow mesenchymal stem cells (h‐JBMMSCs). However, the underlying mechanism has not been fully elucidated. Previously, we showed that APN could promote h‐JBMMSC osteogenesis via APPL1‐p38 by up‐regulating osteogenesis‐related genes. Here, we aimed to determine whether APN could promote h‐JBMMSC chemotaxis through CXCL1/CXCL8. The CCK‐8, wound healing and transwell assays were used to evaluate the proliferation, migration and chemotaxis of h‐JBMMSCs with or without APN treatment. Chemotaxis‐related genes were screened using RNA‐seq, and the results were validated using real‐time PCR and ELISA. We also performed Western blot using the AMPK inhibitor, WZ4003, and the p38 MAPK inhibitor, SB203580, to identify the signalling pathway involved. We found that APN could promote h‐JBMMSC chemotaxis in the co‐culture transwell system. CXCL1 and CXCL8 were screened and confirmed as the up‐regulated target genes. The APN‐induced CXCL1/8 up‐regulation to promote chemotaxis could be blocked by CXCR2 inhibitor SB225002. Western blot revealed that the phosphorylation of AMPK and p38 MAPK increased in a time‐dependent manner with APN treatment. Additionally, WZ4003 and SB203580 could suppress the APN‐induced overexpression of CXCL1 and CXCL8. The results of the transwell chemotaxis assay also supported the above results. Our data suggest that APN can promote h‐JBMMSC chemotaxis by up‐regulating CXCL1 and CXCL8. 相似文献
67.
Site-directed mutations altering methyl-accepting residues of a sensory transducer protein 总被引:15,自引:0,他引:15
The Trg protein is one of a family of transducer proteins that mediate chemotactic response in Escherichia coli. Transducers are methyl-accepting proteins that gain or lose methyl esters on specific glutamyl residues during sensory adaptation. In this study, the significance of multiple sites of methylation on transducer proteins was addressed by using oligonucleotide-directed, site-specific mutagenesis to substitute an alanyl residue at each of the five methyl-accepting sites in Trg. The resulting collection of five mutations, each inactivating a single site, was analyzed for effects on covalent modification at the remaining sites on Trg and for the ability of the altered proteins to mediate sensory adaptation. Most of the alanyl substitutions had substantial biochemical effects, enhancing or reducing methyl-accepting activity of other sites, including one case of activation of a site not methylated in wild-type protein. Analysis of the altered proteins provided explanations for many features of the complex pattern of electrophoretic forms exhibited by Trg. The mutant proteins were less efficient than normal Trg in mediating adaptation. Correlation of biochemical and behavioral data indicated that reduction in the number of methyl-accepting sites on the transducer lengthened the time required to reach an adapted state. 相似文献
68.
69.
Serine proteases in mast cell granules, such as chymase, atypical chymase, and tryptase, which are major proteins in the granules, may play important roles in the process of immunoglobulin E (IgE)-mediated degranulation and in pathobiological alterations in tissues. Indeed, inhibitors of chymase, substrate analogs, and antichymase F(ab')2, but not inhibitors of tryptase, markedly inhibited histamine release induced by IgE-receptor bridging but not that induced by Ca ionophore. In contrast, inhibitors of metalloprotease inhibited histamine release induced not only by IgE-receptor bridging but also by Ca ionophore. These results suggest that chymase and metalloprotease are involved at different steps in the process of degranulation. The extents of inhibition of histamine release were closely correlated with the amounts of the inhibitors of chymase accumulated in the granules. After degranulation, the released proteases may in part contribute to pathobiological alterations in allergic disorders through generations of C3a anaphylatoxin and thrombin by human and rat tryptase, respectively, and those of angiotensin II and a chemotactic factor of neutrophils by human and rat chymase, respectively. Moreover, chymase and atypical chymase from rat were shown to destroy type IV collagen, and human tryptase was found to hydrolyze various plasma proteins, such as fibrinogen and high-molecular-weight kininogen. The biological activities of tryptase and chymase from rat may be regulated by their dissociation from and association with trypstatin, an endogenous inhibitor of these proteases. 相似文献
70.