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排序方式: 共有234条查询结果,搜索用时 250 毫秒
191.
Suzuki K Nagasawa H Uto Y Sugimoto Y Noguchi K Wakida M Wierzba K Terada T Asao T Yamada Y Kitazato K Hori H 《Bioorganic & medicinal chemistry》2005,13(12):4014-4021
192.
Yamamoto H Kamegaya E Hagino Y Imai K Fujikawa A Tamura K Enokiya T Yamamoto T Takeshima T Koga H Uhl GR Ikeda K Sora I 《Neurochemistry international》2007,51(2-4):237-244
Our aim was to investigate whether a defect in vesicular monoamine transporter-2 (VMAT2) activities would affect dopaminergic cell functions or not. We examined mesencephalon dopaminergic cultures prepared from VMAT2 wild-type, heterozygous or homozygous knockout (KO) 14-day-old mouse fetuses to determine the number of tyrosine hydroxylase (TH)-positive cells and dopamine transporter activity. The number of TH-positive cells remained unchanged in the VMAT2-KO cultures. Of interest, the dopamine transporter activity in the homozygous cells was significantly decreased, but not in the heterozygous cells, suggesting that complete deletion of VMAT2 inhibited dopamine transporter function. Furthermore, dopamine transporter activity was prominently decreased in the synaptosomal fraction of neonatal homozygous VMAT2-KO mice compared with that of wild-type/heterozygous VMAT2-KO ones, indicating that VMAT2 activity might be one of the factors regulating dopamine transporter activities. To test this possibility, we used reserpine, a VMAT2 inhibitor. Reserpine (1muM) decreased dopamine transporter activity (approx. 50%) in wild-type and heterozygous VMAT2-KO cultures but not in homozygous ones, indicating that blockade of VMAT2 activity reduced dopamine transporter activity. To investigate possible mechanisms underlying the decreased dopamine transporter activity in VMAT2-KO mice, we measured dopamine transporter activities after 24-48h exposure of primary cultures of mesencephalic neurons to dopamine receptor antagonists, PKC inhibitor, PI(3)K inhibitor, and l-DOPA. Among these drugs, l-DOPA slightly reduced the dopamine transporter activities of all genotypes, but the other drugs could not. Since the ratios of reduction in dopamine transporter activity of each genotype treated with l-DOPA were similar, substrate inhibition of dopamine transporters was not the main mechanism underlying the reduced dopamine transporter activity due to genetic deletion of VMAT2. Our results demonstrate that genetic deletion of VMAT2 did not induce immediate cell death but did markedly inhibit dopamine transporter activity. 相似文献
193.
Borovinskaya MA Pai RD Zhang W Schuwirth BS Holton JM Hirokawa G Kaji H Kaji A Cate JH 《Nature structural & molecular biology》2007,14(8):727-732
Aminoglycosides are widely used antibiotics that cause messenger RNA decoding errors, block mRNA and transfer RNA translocation, and inhibit ribosome recycling. Ribosome recycling follows the termination of protein synthesis and is aided by ribosome recycling factor (RRF) in bacteria. The molecular mechanism by which aminoglycosides inhibit ribosome recycling is unknown. Here we show in X-ray crystal structures of the Escherichia coli 70S ribosome that RRF binding causes RNA helix H69 of the large ribosomal subunit, which is crucial for subunit association, to swing away from the subunit interface. Aminoglycosides bind to H69 and completely restore the contacts between ribosomal subunits that are disrupted by RRF. These results provide a structural explanation for aminoglycoside inhibition of ribosome recycling. 相似文献
194.
Makiko Orita Naomi Hayashida Yumi Nakayama Tetsuko Shinkawa Hideko Urata Yoshiko Fukushima Yuuko Endo Shunichi Yamashita Noboru Takamura 《PloS one》2015,10(6)
The late health effects of low-dose rate radiation exposure are still a serious public concern in the Fukushima area even four years after the accident at Fukushima Daiichi Nuclear Power Plant (FNPP). To clarify the factors associated with residents’ risk perception of radiation exposure and consequent health effects, we conducted a survey among residents of Kawauchi village in May and June 2014, which is located within 30 km of FNPP. 85 of 285 residents (29.8%) answered that acute radiation syndrome might develop in residents after the accident, 154 (54.0%) residents responded that they had anxieties about the health effects of radiation on children, and 140 (49.1%) residents indicated that they had anxieties about the health effects of radiation on offspring. Furthermore, 107 (37.5%) residents answered that they had concerns about health effects that would appear in the general population simply by living in an environment with a 0.23 μSv per hour ambient dose for one year, 149 (52.2%) residents reported that they were reluctant to eat locally produced foods, and 164 (57.5%) residents believed that adverse health effects would occur in the general population by eating 100 Bq per kg of mushrooms every day for one year. The present study shows that a marked bipolarization of the risk perception about the health effects of radiation among residents could have a major impact on social well-being after the accident at FNPP. 相似文献
195.
Isolation and Characterization of Dictyostelium Mutants Defective in Sexual Cell Fusion 总被引:3,自引:3,他引:0
Hideko Urushihara Kazuhiro Aiba Kaichiro Yanagisawa 《Development, growth & differentiation》1991,33(5):517-523
Sexual cell fusion in the cellular slime mold Dictyostelium discoideum occurs between cells of opposite (heterothallic system) or same (homothallic system) mating types. It also requires certain environmental conditions such as darkness and abundance of water, and thus offers an interesting model system for analyzing mechanisms of cell recognition and of cellular response to environmental factors. We have been studying the mechanism of sexual cell fusion, using two heterothallic strains, NC4 and HM1 of D. discoideum. Two cell-surface glycoproteins, gp70 and gp138, have been identified as relevant molecules in the cell fusion of these strains. The former is specific to mat a cells (HM1) and the latter, common to both mat a and mat A (NC4). Involvement of cell-surface carbohydrates has also been suggested. However, the fuctions of the above fusion-related molecules are still elusive. In the present study, we isolated fusion-deficient mutants from a mutagenized mat A strain of D. discoideum to set up combined genetic and biochemical analyses. Among the three nonconditional mutants obtained, two were normal in the fruiting-body formation, asexual development, but one was aggregateless ( agg − ). Further analysis of these mutants would provide detailed information on the mechanism of sexual cell fusion. 相似文献
196.
We had previously developed an efficient procedure for selective cloning of rare-cutter linking fragments that is based on physical separation of linking clone DNAs by pulsed-field polyacrylamide gel electrophoresis (PF-PAGE). An advantage of the physical selection procedure over the conventional cloning-based ones utilizing the insertion of selection marker or vector sequences into the rare-cutter sites is that it can be readily applied to the selection of linking gragments for rare-cutters, generating ambiguous cohesive end sequences such as SfiI (GGCCNNNN/NGGCC). In the present work, the physical separation procedure was improved by introducing a discontinuous buffer system into PF-PAGE, and its feasibility was exemplified by the selective isolation of SfiI linking clones from a human chromosome 21-specific library. This simple and efficient procedure will provide a useful tool for genome analysis. 相似文献
197.
Nobutoshi Kawai Toshifumi Yamamoto Hideko Yamamoto Richard M. McCarron Maria Spatz 《Journal of neurochemistry》1995,65(4):1588-1596
Abstract: The effect of endothelins (ET-1 and ET-3) on 86Rb+ uptake as a measure of K+ uptake was investigated in cultured rat brain capillary endothelium. ET-1 or ET-3 dose-dependently enhanced K+ uptake (EC50 = 0.60 ± 0.15 and 21.5 ± 4.1 nM, respectively), which was inhibited by the selective ETA receptor antagonist BQ 123 (cyclo-d -Trp-d -Asp-Pro-d -Val-Leu). Neither the selective ETB agonists IRL 1620 [N-succinyl-(Glu9,-Ala11,15)-ET-1] and sarafotoxin S6c, nor the ETB receptor antagonist IRL 1038 [(Cys11,Cys15)-ET-1] had any effect on K+ uptake. Ouabain (inhibitor of Na+,K+-ATPase) and bumetanide (inhibitor of Na+-K+-Cl? cotransport) reduced (up to 40% and up to 70%, respectively) the ET-1-stimulated K+ uptake. Complete inhibition was seen with both agents. Phorbol 12-myristate 13-acetate (PMA), activator of protein kinase C (PKC), stimulated Na+,K+-ATPase and Na+-K+-Cl? cotransport. ET-1-but not PMA-stimulated K+ uptake was inhibited by 5-(N-ethyl-N-isopropyl)amiloride (inhibitor of Na+/H+ exchange system), suggesting a linkage of Na+/H+ exchange with ET-1-stimulated Na+,K+-ATPase and Na+-K+-Cl? cotransport activity that is not mediated by PKC. 相似文献
198.
H. Kobayashi Hiroko Oyamada Naoko Iwadate Hiromi Suzuki Hideko Mitobe Kaori Takahashi Nobuyuki Shibata Shigeo Suzuki Yoshio Okawa 《Archives of microbiology》1998,169(3):188-194
A mannan of Candida glabrata IFO 0622 digested by Arthrobacter exo-α-mannosidase and a β-1,2-linked mannobiose obtained from the parent mannan by acid treatment was analyzed using 13C nuclear magnetic resonance spectroscopy. The results show that the β-1,2-linked mannobiosyl residue is esterified to a phosphate
group through position C-1 in the α-configuration, Manβ1– 2Manα1–HPO3–. The results of immunochemical assays of these mannans using the commercial antigenic factor sera of the genus Candida (Candida Check, Iatron) indicate that the main recognition site of serum no. 6 in this kit is the mannotetraosyl side-chain
Manβ1–2Manα1– 2Manα1–2Man in C. glabrata mannan and also suggest that the phosphate-containing unit (such as Manβ1– 2Manα1–HPO3– in this mannan) behaves as one of the antigenic determinants of serum no. 6, but not of serum no. 5. Therefore, the present
and previous findings indicate that serum no. 5 recognizes relatively longer β-1,2-linked oligomannosyl side-chains, Manβ1–[2Manβ1–]n 2Man (n = 1–6), attached to the phosphate groups previously observed in the cell wall mannans of Candida albicans, Candida stellatoidea, and Candida tropicalis.
Received: 18 March 1997 / Accepted: 16 September 1997 相似文献
199.
Enhanced tolerance to light stress of transgenic Arabidopsis plants that express the codA gene for a bacterial choline oxidase 总被引:9,自引:0,他引:9
Alia Kondo Y Sakamoto A Nonaka H Hayashi H Saradhi PP Chen TH Murata N 《Plant molecular biology》1999,40(2):279-288
Arabidopsis thaliana was transformed with the codA gene from Arthrobacter globiformis. This gene encodes choline oxidase, an enzyme that converts choline to glycinebetaine. The photosynthetic activity, monitored in terms of chlorophyll fluorescence, of transformed plants was more tolerant to light stress than that of wild-type plants. This enhanced tolerance to light stress was caused by acceleration of the recovery of the photosystem II (PS II) complex from the photo-inactivated state. The transformed plants synthesized glycinebetaine, but no changes were detected in the relative levels of membrane lipids or in the relative levels of fatty acids in the various membrane lipids. Transformation with the codA gene increased levels of H2O2, a by-product of the reaction catalyzed by choline oxidase, by only 50% to 100% under stress or non-stress conditions. The activity of ascorbate peroxidase and, to a lesser extent, that of catalase in transformed plants were significantly higher than in the wild-type plants. These observations suggest that H2O2 produced by choline oxidase in the transformed plants might have stimulated the expression of H2O2 scavenging enzymes, with resultant maintenance of the level of H2O2 within a certain limited range. It appears that glycinebetaine produced in vivo, but not changes in membrane lipids or in the level of H2O2, protected the PS II complex in transformed plants from damage due to light stress. 相似文献
200.
Pai RD Zhang W Schuwirth BS Hirokawa G Kaji H Kaji A Cate JH 《Journal of molecular biology》2008,376(5):1334-1347
At the end of translation in bacteria, ribosome recycling factor (RRF) is used together with elongation factor G to recycle the 30S and 50S ribosomal subunits for the next round of translation. In x-ray crystal structures of RRF with the Escherichia coli 70S ribosome, RRF binds to the large ribosomal subunit in the cleft that contains the peptidyl transferase center. Upon binding of either E. coli or Thermus thermophilus RRF to the E. coli ribosome, the tip of ribosomal RNA helix 69 in the large subunit moves away from the small subunit toward RRF by 8 Å, thereby disrupting a key contact between the small and large ribosomal subunits termed bridge B2a. In the ribosome crystals, the ability of RRF to destabilize bridge B2a is influenced by crystal packing forces. Movement of helix 69 involves an ordered-to-disordered transition upon binding of RRF to the ribosome. The disruption of bridge B2a upon RRF binding to the ribosome seen in the present structures reveals one of the key roles that RRF plays in ribosome recycling, the dissociation of 70S ribosomes into subunits. The structures also reveal contacts between domain II of RRF and protein S12 in the 30S subunit that may also play a role in ribosome recycling. 相似文献