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71.
Homologous recombination is associated with the dynamic assembly and disassembly of DNA–protein complexes. Assembly of a nucleoprotein filament comprising ssDNA and the RecA homolog, Rad51, is a key step required for homology search during recombination. The budding yeast Srs2 DNA translocase is known to dismantle Rad51 filament in vitro. However, there is limited evidence to support the dismantling activity of Srs2
in vivo. Here, we show that Srs2 indeed disrupts Rad51-containing complexes from chromosomes during meiosis. Overexpression of Srs2 during the meiotic prophase impairs meiotic recombination and removes Rad51 from meiotic chromosomes. This dismantling activity is specific for Rad51, as Srs2 Overexpression does not remove Dmc1 (a meiosis-specific Rad51 homolog), Rad52 (a Rad51 mediator), or replication protein A (RPA; a single-stranded DNA-binding protein). Rather, RPA replaces Rad51 under these conditions. A mutant Srs2 lacking helicase activity cannot remove Rad51 from meiotic chromosomes. Interestingly, the Rad51-binding domain of Srs2, which is critical for Rad51-dismantling activity in vitro, is not essential for this activity in vivo. Our results suggest that a precise level of Srs2, in the form of the Srs2 translocase, is required to appropriately regulate the Rad51 nucleoprotein filament dynamics during meiosis. 相似文献
72.
Shunsuke X. Furihata Hitoshi Matsumoto Masahito T. Kimura Yoichi Hayakawa 《Archives of insect biochemistry and physiology》2013,83(2):86-100
The endoparasitoid wasp Asobara japonica has highly poisonous venom: the host Drosophila larvae are killed by envenomation at a dose that is naturally injected by the female wasp at parasitism. This insecticidal venom is neutralized, however, because A. japonica introduces lateral oviduct components soon after venom injection at oviposition. Although the venom and lateral oviduct components of this parasitoid have been partially characterized, how the venom components favor successful development of wasp eggs and larvae in the host remains ambiguous. Here, we demonstrated that A. japonica venom did not affect host humoral immune responses, determined as expression of antimicrobial peptide (AMP) genes, but significantly diminished two cellular responses, spreading and phagocytosis, by host hemocytes. Moreover, venom components drastically elevated a serine protease‐like activity 4 h after its injection. The lateral oviduct components did not negate the detrimental effects of the venom on host cellular immunities, but significantly reduced the venom‐induced elevation of protease activity. Both active factors in venom and lateral oviduct components were roughly characterized as heat‐labile substances with a molecular mass of at least 10 kDa. Finally, venom of A. japonica, with a wide host range, was found to be much more toxic than that of Asobara rossica, which has a limited host range. These results reveal that A. japonica venom toxicity allows exploitation of a broader range of host insects because it is essential to overcome cellular immune responses of the host for successful parasitism. 相似文献
73.
Sato A Nagasaka S Furihata K Nagata S Arai I Saruwatari K Kogure T Sakuda S Nagasawa H 《Nature chemical biology》2011,7(4):197-199
It has been thought that phosphorus in biominerals made of amorphous calcium carbonate (ACC) might be related to ACC formation, but no such phosphorus-containing compounds have ever been identified. Crustaceans use ACC biominerals in exoskeleton and gastroliths so that they will have easy access to calcium carbonate inside the body before and after molting. We have identified phosphoenolpyruvate and 3-phosphoglycerate, intermediates of the glycolytic pathway, in exoskeleton and gastroliths and found them important for stabilizing ACC. 相似文献
74.
M Imajoh Y Hashida Y Nemoto H Oguri N Maeda M Furihata T Fukaya M Daibata 《Virology journal》2012,9(1):154
ABSTRACT: BACKGROUND: Merkel cell polyomavirus (MCPyV) was identified originally in Merkel cell carcinoma (MCC), a rare form of human skin neuroendocrine carcinoma. Evidence of MCPyV existence in other forms of malignancy such as cutaneous squamous cell carcinomas (SCCs) is growing. Cervical cancers became the focus of our interest in searching for potentially MCPyV-related tumors because: (i) the major histological type of cervical cancer is the SCC; (ii) the uterine cervix is a common site of neuroendocrine carcinomas histologically similar to MCCs; and (iii) MCPyV might be transmitted during sexual interaction as demonstrated for human papillomavirus (HPV). In this study, we aimed to clarify the possible presence of MCPyV in cervical SCCs from Japanese patients. Cervical adenocarcinomas (ACs) were also studied. RESULTS: Formalin-fixed paraffin-embedded tissue samples from 48 cervical SCCs and 16 cervical ACs were examined for the presence of the MCPyV genome by polymerase chain reaction (PCR) and sequencing analyses. PCR analysis revealed that 9/48 cervical SCCs (19 %) and 4/16 cervical ACs (25 %) were positive for MCPyV DNA. MCPyV-specific PCR products were sequenced to compare them with reference sequences. The nucleotide sequences in the MCPyV large-T (LT)-sequenced region were the same among MCPyV-positive cervical SCCs and AC. Conversely, in the MCPyV viral protein 1 (VP1)-sequenced, two cervical SCCs and three cervical ACs showed several nucleotide substitutions, of which three caused amino acid substitutions. These sequencing results suggested that three MCPyV variants of the VP1 were identified in our cases. Immunohistochemistry showed that the LT antigen was expressed in tumor cells in MCPyV-positive samples. Genotyping of human HPV in the MCPyV-positive samples revealed that infected HPVs were HPV types 16, 31 and 58 for SCCs and HPV types 16 and 18 for ACs. CONCLUSIONS: This study provides the first observation that MCPyV coexists in a subset of HPV-associated cervical cancers from Japanese patients. The prevalence of MCPyV in these lesions was close to that observed in the cutaneous SCCs. Further worldwide epidemiological surveys are warranted to determine the possible association of MCPyV with pathogenesis of cervical cancers. 相似文献
75.
Keishiro Yoshida Kazuo Furihata Hiroshi Habe Hisakazu Yamane Toshio Omori 《Biotechnology letters》2001,23(11):873-879
Transposon Tn5 mutagenesis was carried out to clarify the metabolism of 18-glycyrrhetinic acid (18-GRA) in Sphingomonas paucimobilis G5. A Tn5-induced mutant strain, named TM9638 that was affected in its metabolism of 18-GRA, was isolated. This mutant accumulated three metabolites, designated as M-A, M-B and M-C, from 18-GRA in the culture broth. M-A was accumulated in the culture broth of wild type strain, but M-B and M-C were not accumulated in the culture broth of wild type strain. M-B and M-C were isolated from the culture broth of TM9638 and the chemical structures were elucidated by NMR and GC-MS. 相似文献
76.
Keishiro Yoshida Kazuo Furihata Hisakazu Yamane Toshio Omori 《Biotechnology letters》2001,23(4):253-258
Seven strains capable of utilizing 18-glycyrrhetinic acid (18-GRA) as a sole carbon and energy source were isolated from soil samples by enrichment culture technique. One of these strains, named strain G5, was identified as Sphingomonas paucimobilis. When this strain grew on 18-GRA, several metabolites were detected in the culture broth. A major metabolite, tentatively named M-A, was isolated and its chemical structure was determined by nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS). 相似文献
77.
Identification of novel metabolites in the degradation of phenanthrene by Sphingomonas sp. strain P2
Pinyakong O Habe H Supaka N Pinpanichkarn P Juntongjin K Yoshida T Furihata K Nojiri H Yamane H Omori T 《FEMS microbiology letters》2000,191(1):115-121
Sphingomonas sp. strain P2, which is capable of utilizing phenanthrene as a sole carbon and energy source, was isolated from petroleum-contaminated soil in Thailand. Gas chromatography-mass spectrometry and (1)H and (13)C nuclear magnetic resonance analyses revealed two novel metabolites from the phenanthrene degradation pathway. One was identified as 5,6-benzocoumarin, which was derived by dioxygenation at the 1- and 2-positions of phenanthrene, and the other was determined to be 1,5-dihydroxy-2-naphthoic acid. Other metabolites from phenanthrene degradation were identified as 7, 8-benzocoumarin, 1-hydroxy-2-naphthoic acid and coumarin. From these results, it is suggested that strain P2 can degrade phenanthrene via dioxygenation at both 1,2- and 3,4-positions followed by meta-cleavage. 相似文献
78.
Hypomethylation and expression of pepsinogen A genes in the fundic mucosa of human stomach 总被引:1,自引:0,他引:1
M Ichinose K Miki M Tatematsu C Furihata M Nobuhara Y Ichihara M Tanji K Sogawa Y Fujii-Kuriyama H Oka 《Biochemical and biophysical research communications》1988,151(1):275-282
We have examined the correlation between the extents of methylation and expression of pepsinogen A genes in normal human tissues. Expression of pepsinogen A mRNA was detected only in the fundic mucosa of the stomach and both CCGG and GCGC sites in the genes region were less methylated in the fundic mucosa than in other non-expressing tissues. Thus, there was an inverse correlation between the extents of methylation and expression of pepsinogen A genes and the role of DNA methylation in the regulation of pepsinogen A genes expression during normal differentiation was suggested. 相似文献
79.
Kinetic Characterization of Two Phosphate Uptake Systems with Different Affinities in Suspension-Cultured Catharanthus roseus Protoplasts 总被引:2,自引:0,他引:2
We studied the kinetics of inorganic phosphate (P1) uptake from0.11,000 µM P1 by protoplasts from suspension-culturedcells of Catharanthus roseus (L.) G. Don. Concentration dependenceof [32P]P1 uptake revealed two kinetically different uptakesystems, a high-affinity system and a low-affinity system, withKm values of 3.0 and 47 µM, respectively. Protoplastsfrom cells grown in Pi-rich media had a medium level of thelow-affinity activity and a very low level of the high-affinityactivity. It appeared low-affinity system is expressed constitutively,while the high-affinity system is regulated by the availabilityof Pi. When cells grown in a Pi-rich media were transferredto Pi-depleted media, the high-affinity activity increased significantlyafter 2 d, but the low-affinity activity was barely changed.Upon addition of 10 mM Pi, the high level of the high-affinityactivity fell to almost undetectable level in 1d. Both uptakesystems exhibited maximum activity between pH 5 and 6.
1 Present address: Tokyo Research Laboratories, Kyowa HakkoKogyo Co., Ltd., 3-6-6 Asahi-cho, Machida, Tokyo, 194 Japan. 相似文献
80.