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71.
Shimojima M Nishimura Y Miyazawa T Tohya Y Akashi H 《Microbes and infection / Institut Pasteur》2003,5(13):1171-1176
It is well documented that several cell surface molecules of T lymphocytes are altered by immune activation. We previously reported that feline immunodeficiency virus (FIV) infection induces a reduction in CD8beta chain expression of peripheral blood lymphocytes (PBLs) in cats. In this study, we performed three-color flow-cytometric analysis for activation-associated cell surface molecules (CD2, CD11a, CD45RA-like and major histocompatibility complex antigen class II (MHC II)) and light scatters (cellular size and complexity) to examine whether phenotypic changes also occurred in CD4(+) PBLs in addition to CD8(+) PBLs, of five FIV-infected cats and one uninfected cat. It was shown that (i) CD8alpha(+) PBLs, but not CD4(+) PBLs, had a distinct subpopulation with increased CD11a expression accompanying a reduced CD8beta chain and increased intracellular granules (ii) CD8alpha(+) PBLs, but not CD4(+) PBLs, expressed CD45RA-like antigen with diverse expression levels and (iii) MHC II expression was greater in CD8alpha(+) PBLs than CD4(+) PBLs, and the CD8beta chain reduction was correlated with the MHC II decrease within CD8alpha(+) PBLs. These results suggest that FIV infection induces phenotypically heterogeneous subpopulations in CD8(+) PBLs, including activated phenotypes, rather than in CD4(+) PBLs. 相似文献
72.
A novel DNA polymerase homologous to Escherichia coli DNA polymerase I from a higher plant, rice (Oryza sativa L.)
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Kimura S Uchiyama Y Kasai N Namekawa S Saotome A Ueda T Ando T Ishibashi T Oshige M Furukawa T Yamamoto T Hashimoto J Sakaguchi K 《Nucleic acids research》2002,30(7):1585-1592
A novel DNA polymerase, designated as OsPolI-like, has been identified from the higher plant, rice (Oryza sativa L. cv. Nipponbare). The OsPolI-like cDNA was 3765 bp in length, and the open reading frame encoded a predicted product of 977 amino acid residues with a molecular weight of 100 kDa. The OsPolI-like gene has been mapped to chromosome 8 and contains 12 exons and 11 introns. The encoded protein showed a high degree of sequence and structural homology to Escherichia coli pol I protein, but differed from DNA polymerase γ and θ. The DNA polymerase domain of OsPolI-like showed DNA polymerase activity. Subcellular fractionation analysis suggested that the protein is localized in the plastid. Northern and western blotting, and in situ hybridization analyses demonstrated preferential expression of OsPolI-like in meristematic tissues such as shoot apical meristem, root apical meristem, leaf primordia and the marginal meristem. Interestingly, no expression was detected in mature leaves, although they have a high chloroplast content. These properties indicated that OsPolI-like is a novel plant DNA polymerase. The function of OsPolI-like is discussed in relation to plastid maturation. 相似文献
73.
74.
Empirical evaluation of a dynamic experiment design method for prediction of MHC class I-binding peptides 总被引:4,自引:0,他引:4
Udaka K Mamitsuka H Nakaseko Y Abe N 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(10):5744-5753
The ability to predict MHC-binding peptides remains limited despite ever expanding demands for specific immunotherapy against cancers, infectious diseases, and autoimmune disorders. Previous analyses revealed position-specific preference of amino acids but failed to detect sequence patterns. Efforts to use computational analysis to identify sequence patterns have been hampered by the insufficiency of the number/quality of the peptide binding data. We propose here a dynamic experiment design to search for sequence patterns that are common to the MHC class I-binding peptides. The method is based on a committee-based framework of query learning using hidden Markov models as its component algorithm. It enables a comprehensive search of a large variety (20(9)) of peptides with a small number of experiments. The learning was conducted in seven rounds of feedback loops, in which our computational method was used to determine the next set of peptides to be analyzed based on the results of the earlier iterations. After these training cycles, the algorithm enabled a real number prediction of MHC binding peptides with an accuracy surpassing that of the hitherto best performing positional scanning method. 相似文献
75.
Minami T Kubo K Ichida S 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2002,779(2):211-219
Metallothionein (MT) isoforms, MT-1 and MT-2, in biological specimens are clearly separated by capillary zone electrophoresis (CZE) using a polyacrylamide-coated capillary. The effectiveness of CZE analysis in the study of MT isoforms in biological specimens is discussed. We did two experiments to determine the MT-1/MT-2 ratio in biological specimens. The ratio of MT-1/MT-2 can be determined by CZE under a neutral pH without any detergents. One of these studies is time-dependent changes of the MT-1/MT-2 ratio in the cytosol of the pancreas and liver in mice after Zn or Cd injection. In the pancreas, both isoforms were detected in the control mice and the ratio of MT-1/MT-2 was below 1.0. When Zn was injected, the maximum peak areas of both isoforms were obtained at 24 h, and the ratios increased over a value of 1.0 at 3 h and peaked at 10 h. However, in the Cd-injected mice, the peak areas of both isoforms increased up to 72 h, and the ratios were below 1.0 up to 72 h. On the contrary, neither isoform was detected in the livers of control mice. The ratios of Zn-injected mice liver were near the value 1.0 between 6 and 72 h, although the areas of both isoforms showed peaks at 48 h. The ratios of Cd-injected mice livers were detected to be over 1.0 from 10 h, but there were no significant difference between 10 and 72 h, and the areas of both isoforms showed peaks at 24 h. The other experiment investigated the ratio in each fraction of cell fractionation. Cell fractionation was done in the livers of Zn-treated mice. Twenty-four hours after the injection, the ratio of MT-1/MT-2 was 0.80+/-0.12 and 1.19+/-0.21 (mean+/-SD) in nuclear and cytosol fractions, respectively. Neither isoform was detected in mitochondrial or microsomal fraction. From the present results, CZE analysis is a suitable method for observation of the ratio of MT-1/MT-2 in biological specimens, and dynamic changes in both isoforms can be detected. 相似文献
76.
K. Kuriyama H. Nakayasu H. Mizutani R. Narihara T. Ichida 《Neurochemical research》1993,18(4):377-383
The GABAB receptor in brain is one of the GABA receptor subtypes, and has been found to be negatively coupled to adenylate cyclase and phosphatidylinositide turnover. This receptor easily solubilizes from cerebral synaptic membrane preparations by 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) in the presence of asolectin. GABAB receptor solubilized from bovine cerebral cortex was purified using baclofen-coupled affinity beads (baclofen-coupled Toyopearl beads). Using these procedures, almost pure GABAB receptor (80 KDa protein) was obtained in the affinity eluate. A monoclonal antibody has been also raised against the purified GABAB receptor. The antibody recognized a protein of about 80 KDa in bovine brain synaptic membrane. Immunoabsorbent agarose beads conjugated with the antibody were able to remove more than 90% of the baclofen suppressive GABA binding activity in the solubilized synaptic membrane, and this system was found to be useful for the immunoaffinity column chromatographic separation of GABAB receptor. Preliminary studies of immunohistochemical visualization of GABAB receptor in the rat cerebellum suggested that this receptor may be exclusively localized at the presynaptic site of GABAergic neurons.Special issue dedicated to Dr. Claude Baxter. 相似文献
77.
The effects of ATP and ATP analogues on the brain acetyl-CoA hydrolase (EC 3.1.2.1) were studied. The enzyme was stimulated reversibly by ATP-Mg2+ the presence of Mg2+ being absolutely required for the stimulation. The stimulatory effect of ATP was highly specific since adenine nucleotides other than ATP had no stimulatory effects and nucleoside triphosphates other than ATP stimulated the enzyme much less than ATP in the following order: ATP > ITP CTP, UTP GTP. A phosphate modified analogue of ATP, AMP-PNP had a similar stimulatory effect to that of ATP. Other ATP analogues such as AMP-PCP and AMPCPP showed less stimulatory effect than ATP. The order of the stimulatory effects of these ATP analogues was: ATP > AMP-PNP > AMP-PCP > AMPCPP. The concentrations needed for half-maximal stimulation of ATP, AMP-PNP and AMP-PCP were approx 0.11 mm , 0.22 mm, and 0.22 mm , respectively. Double reciprocal plots demonstrated that ATP as well as AMP-PNP produced a significant decrease in the apparent Km, value for acetyl-CoA and an increase in Vmax indicating that these nucleotides increased the affinity for acetyl-CoA through binding at a site other than the catalytic site. The data described above suggest that the rate of hydrolysis of acetyl-CoA may be regulated by the concentration of ATP in the micro-environment of the enzyme. 相似文献
78.
Kimura S Saotome A Uchiyama Y Mori Y Tahira Y Sakaguchi K 《Biochemical and biophysical research communications》2005,329(2):668-672
We isolated and characterized the rice homologue of the DNA repair gene Snm1 (OsSnm1). The length of the cDNA was 1862bp; the open reading frame encoded a predicted product of 485 amino acid residues with a molecular mass of 53.2kDa. The OsSnm1 protein contained the conserved beta-lactamase domain in its internal region. OsSnm1 was expressed in all rice organs. The expression was induced by MMS, H(2)O(2), and mitomycin C, but not by UV. Transient expression of an OsSnm1/GFP fusion protein in onion epidermal cells revealed the localization of OsSnm1 to the nucleus. These results suggest that OsSnm1 is involved not only in the repair of DNA interstrand crosslinks, but also in various other DNA repair pathways. 相似文献
79.
Ichida S Abe J Zhang YA Sugihara K Imoto K Wada T Fujita N Sohma H 《Neurochemical research》2000,25(12):1629-1635
The characteristics of the inhibitory effect of calcium ion (Ca2+)/calmodulin (CaM) on specific [125I]-omega-conotoxin GVIA (125I--CTX) binding and on the labeling of 125I--CTX to crude membranes from chick brain were investigated. The inhibitory effect of Ca2+/CaM depended on the concentrations of free Ca2+ and CaM. The IC50 values for free Ca2+ and CaM were about 2.0 × 10–8 M and 3.0 g protein/ml, respectively. The inhibitory effect of Ca2+/CaM was attenuated by the CaM antagonists W-7, prenylamine and CaM-kinase II fragment (290–309), but not by the calcineurin inhibitor FK506. Ca2+/CaM also inhibited the labeling of a 135-kDa band (which was considered to be part of N-type Ca2+ channel 1 subunits) with 125I--CTX using a cross-linker. These results suggest that Ca2+/CaM affects specific 125I--CTX binding sites, probably N-type Ca2+ channel 1 subunits, in crude membranes from chick whole brain. 相似文献
80.
Ichida M Hakamata Y Hayakawa M Ueno E Ikeda U Shimada K Hamamoto T Kagawa Y Endo H 《The Journal of biological chemistry》2000,275(21):15992-16001
Muscle-specific isoform of the mitochondrial ATP synthase gamma subunit (F(1)gamma) was generated by alternative splicing, and exon 9 of the gene was found to be lacking particularly in skeletal muscle and heart tissue. Recently, we reported that alternative splicing of exon 9 was induced by low serum or acidic media in mouse myoblasts, and that this splicing required de novo protein synthesis of a negative regulatory factor (Ichida, M., Endo, H., Ikeda, U., Matsuda, C., Ueno, E., Shimada, K., and Kagawa, Y. (1998) J. Biol. Chem. 273, 8492-8501; Hayakawa, M., Endo, H., Hamamoto, T., and Kagawa, Y. (1998) Biochem. Biophys. Res. Commun. 251, 603-608). In the present report, we identified a cis-acting element on the muscle-specific alternatively spliced exon of F(1)gamma gene by an in vivo splicing system using cultured cells and transgenic mice. We constructed a F(1)gamma wild-type minigene, containing the full-length gene from exon 8 to exon 10, and two mutants; one mutant involved a pyrimidine-rich substitution on exon 9, whereas the other was a purine-rich substitution, abbreviated as F(1)gamma Pu-del and F(1)gamma Pu-rich mutants, respectively. Based on an in vivo splicing assay using low serum- or acid-stimulated splicing induction system in mouse myoblasts, Pu-del mutation inhibited exon inclusion, indicating that a Pu-del mutation would disrupt an exonic splicing enhancer. On the other hand, the Pu-rich mutation blocked muscle-specific exon exclusion following both inductions. Next, we produced transgenic mice bearing both mutant minigenes and analyzed their splicing patterns in tissues. Based on an analysis of F(1)gamma Pu-del minigene transgenic mice, the purine nucleotide of this element was shown to be necessary for exon inclusion in non-muscle tissue. In contrast, analysis of F(1)gamma Pu-rich minigene mice revealed that the F(1)gamma Pu-rich mutant exon had been excluded from heart and skeletal muscle of these transgenic mice, despite the fact mutation of the exon inhibited muscle-specific exon exclusion in myotubes of early embryonic stage. These results suggested that the splicing regulatory mechanism underlying F(1)gamma pre-mRNA differed between myotubes and myofibers during myogenesis and cardiogenesis. 相似文献