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81.
Increased tumor cell dissemination and cellular senescence in the absence of beta1-integrin function 总被引:1,自引:0,他引:1
Kren A Baeriswyl V Lehembre F Wunderlin C Strittmatter K Antoniadis H Fässler R Cavallaro U Christofori G 《The EMBO journal》2007,26(12):2832-2842
Integrins are transmembrane receptors that bind extracellular matrix proteins and enable cell adhesion and cytoskeletal organization, as well as transduction of signals into cells, to promote various aspects of cellular behavior, such as proliferation or survival. Integrins participate in many aspects of tumor biology. Here, we have employed the Rip1Tag2 transgenic mouse model of pancreatic beta cell carcinogenesis to investigate the role of beta(1)-integrin in tumor progression. Specific ablation of beta(1)-integrin function in pancreatic beta cells resulted in a defect in sorting between insulin-expressing beta cells and glucagon-expressing alpha cells in islets of Langerhans. Ablation of beta(1)-integrin in beta tumor cells of Rip1Tag2 mice led to the dissemination of tumor cell emboli into lymphatic blood vessels in the absence of ongoing lymphangiogenesis. Yet, disseminating beta(1)-integrin-deficient beta tumor cells did not elicit metastasis. Rather, primary tumor growth was significantly impaired by reduced tumor cell proliferation and the acquisition of cellular senescence by beta(1)-integrin-deficient beta tumor cells. The results indicate a critical role of beta(1)-integrin function in mediating metastatic dissemination and preventing tumor cell senescence. 相似文献
82.
Ploquin M Petukhova GV Morneau D Déry U Bransi A Stasiak A Camerini-Otero RD Masson JY 《Nucleic acids research》2007,35(8):2719-2733
Genetic analysis of fission yeast suggests a role for the spHop2–Mnd1 proteins in the Rad51 and Dmc1-dependent meiotic recombination pathways. In order to gain biochemical insights into this process, we purified Schizosaccharomyces pombe Hop2-Mnd1 to homogeneity. spHop2 and spMnd1 interact by co-immunoprecipitation and two-hybrid analysis. Electron microscopy reveals that S. pombe Hop2–Mnd1 binds single-strand DNA ends of 3′-tailed DNA. Interestingly, spHop2-Mnd1 promotes the renaturation of complementary single-strand DNA and catalyses strand exchange reactions with short oligonucleotides. Importantly, we show that spHop2-Mnd1 stimulates spDmc1-dependent strand exchange and strand invasion. Ca2+ alleviate the requirement for the order of addition of the proteins on DNA. We also demonstrate that while spHop2-Mnd1 affects spDmc1 specifically, mHop2 or mHop2-Mnd1 stimulates both the hRad51 and hDmc1 recombinases in strand exchange assays. Thus, our results suggest a crucial role for S. pombe and mouse Hop2-Mnd1 in homologous pairing and strand exchange and reveal evolutionary divergence in their specificity for the Dmc1 and Rad51 recombinases. 相似文献
83.
The first agmatine/cadaverine aminopropyl transferase: biochemical and structural characterization of an enzyme involved in polyamine biosynthesis in the hyperthermophilic archaeon Pyrococcus furiosus
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Cacciapuoti G Porcelli M Moretti MA Sorrentino F Concilio L Zappia V Liu ZJ Tempel W Schubot F Rose JP Wang BC Brereton PS Jenney FE Adams MW 《Journal of bacteriology》2007,189(16):6057-6067
We report here the characterization of the first agmatine/cadaverine aminopropyl transferase (ACAPT), the enzyme responsible for polyamine biosynthesis from an archaeon. The gene PF0127 encoding ACAPT in the hyperthermophile Pyrococcus furiosus was cloned and expressed in Escherichia coli, and the recombinant protein was purified to homogeneity. P. furiosus ACAPT is a homodimer of 65 kDa. The broad substrate specificity of the enzyme toward the amine acceptors is unique, as agmatine, 1,3-diaminopropane, putrescine, cadaverine, and sym-nor-spermidine all serve as substrates. While maximal catalytic activity was observed with cadaverine, agmatine was the preferred substrate on the basis of the k(cat)/K(m) value. P. furiosus ACAPT is thermoactive and thermostable with an apparent melting temperature of 108 degrees C that increases to 112 degrees C in the presence of cadaverine. Limited proteolysis indicated that the only proteolytic cleavage site is localized in the C-terminal region and that the C-terminal peptide is not necessary for the integrity of the active site. The crystal structure of the enzyme determined to 1.8-A resolution confirmed its dimeric nature and provided insight into the proteolytic analyses as well as into mechanisms of thermal stability. Analysis of the polyamine content of P. furiosus showed that spermidine, cadaverine, and sym-nor-spermidine are the major components, with small amounts of sym-nor-spermine and N-(3-aminopropyl)cadaverine (APC). This is the first report in Archaea of an unusual polyamine APC that is proposed to play a role in stress adaptation. 相似文献
84.
In vivo functions of mitogen-activated protein kinases: conclusions from knock-in and knock-out mice 总被引:4,自引:0,他引:4
Multicellular organisms achieve intercellular communication by means of signalling molecules whose effect on the target cell
is mediated by signal transduction pathways. Such pathways relay, amplify and integrate signals to elicit appropriate biological
responses. Protein kinases form crucial intermediate components of numerous signalling pathways. One group of protein kinases,
the mitogen-activated protein kinases (MAP kinases) are kinases involved in signalling pathways that respond primarily to
mitogens and stress stimuli. In vitro studies revealed that the MAP kinases are implicated in several cellular processes,
including cell division, differentiation, cell survival/apoptosis, gene expression, motility and metabolism. As such, dysfunction
of specific MAP kinases is associated with diseases such as cancer and immunological disorders. However, the genuine in vivo
functions of many MAP kinases remain elusive. Genetically modified mouse models deficient in a specific MAP kinase or expressing
a constitutive active or a dominant negative variant of a particular MAP kinase offer valuable tools for elucidating the biological
role of these protein kinases. In this review, we focus on the current status of MAP kinase knock-in and knock-out mouse models
and their phenotypes. Moreover, examples of the application of MAP kinase transgenic mice for validating therapeutic properties
of specific MAP kinase inhibitors, and for investigating the role of MAP kinase in pathogen-host interactions will be discussed. 相似文献
85.
Masotti A Moretti F Mancini F Russo G Di Lauro N Checchia P Marianecci C Carafa M Santucci E Ortaggi G 《Bioorganic & medicinal chemistry》2007,15(3):1504-1515
Non-viral gene therapy is based on the development of efficient and safe gene carrier systems able to transfer DNA into cells. Polyethylenimine (PEI), the most promising non-viral vector, with its high cationic-charge-density potential is able (1) to compact DNA in complexes (polyplexes) smaller than those formed by liposomes (lipoplexes) and (2) to destabilize the endosomal membrane by a 'proton sponge' effect. Several PEI's hydrophobic modifications were reported in the last several years but in some cases a reduced transfection efficiency was observed. The mechanism underlying this phenomenon is not well understood so far. In order to extensively investigate these mechanisms, we reported a physicochemical and biological study of selected hydrophobic PEI's derivatives grafted with chains of different length and percentages of substitution able to form vesicles (polycationic liposomes) and to bind DNA. Their properties were studied by means of dynamic light scattering, freeze-fracture microscopy, potentiometric titrations, gel retardation assays, polyanion exchange reactions, toxicity assays, in vitro transfections, and fluorescence microscopy. Our results indicate that even if polyplexes are able to pass through the cellular membrane, the stability of PEI's hydrophobic polyplexes likely explain their different transfection efficiency in vitro. 相似文献
86.
87.
Marta Murgia Nagarjuna Nagaraj Atul S Deshmukh Marlis Zeiler Pasqua Cancellara Irene Moretti Carlo Reggiani Stefano Schiaffino Matthias Mann 《EMBO reports》2015,16(3):387-395
Mammalian skeletal muscles are composed of multinucleated cells termed slow or fast fibers according to their contractile and metabolic properties. Here, we developed a high‐sensitivity workflow to characterize the proteome of single fibers. Analysis of segments of the same fiber by traditional and unbiased proteomics methods yielded the same subtype assignment. We discovered novel subtype‐specific features, most prominently mitochondrial specialization of fiber types in substrate utilization. The fiber type‐resolved proteomes can be applied to a variety of physiological and pathological conditions and illustrate the utility of single cell type analysis for dissecting proteomic heterogeneity. 相似文献
88.
89.
Mazzoli A Carlotti B Bonaccorso C Fortuna CG Mazzucato U Miolo G Spalletti A 《Photochemical & photobiological sciences》2011,10(11):1830-1836
The relaxation properties of the excited states of three iodides of trans-1,2-diarylethene analogues (where one aryl group is a methylpyridinium, methylquinolinium or dimethylimidazolium group and the other one is a phenyl ring para-substituted by a pyrimidine ring) have been investigated in buffered (pH = 7) aqueous solution. As found in previous works for several analogues, these quaternized salts undergo efficient trans→cis photoisomerization while the yield of the radiative deactivation is very small at room temperature. The solvent effect on the spectral behaviour indicates the occurrence of intramolecular charge transfer which can induce interesting non-linear optical properties. The results of a study of the interactions of these salts with DNA, which might affect the cell metabolism, showed a relatively modest binding affinity for the pyridinium and imidazolium salts and a more substantial affinity for the quinolinium analogue. The formation of ligand-DNA complexes affects only slightly the radiative relaxation yield while leading to a relevant reduction of the isomerization yield. Measurements of the linear dichroism behaviour of the three compounds and comparison with three analogues bearing furan or thienyl groups, which have been found to display different affinity with DNA in previous works, gave interesting information on the nature of the ligand-DNA binding of these compounds. 相似文献
90.
Ugo Lucca Mariateresa Garrì Angela Recchia Giancarlo Logroscino Pietro Tiraboschi Massimo Franceschi Chiara Bertinotti Anna Biotti Elena Gargantini Marilena Maragna Alessandro Nobili Luca Pasina Carlotta Franchi Emma Riva Mauro Tettamanti 《BMC neurology》2011,11(1):1-14