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51.
Philippe H Brinkmann H Copley RR Moroz LL Nakano H Poustka AJ Wallberg A Peterson KJ Telford MJ 《Nature》2011,470(7333):255-258
Xenoturbellida and Acoelomorpha are marine worms with contentious ancestry. Both were originally associated with the flatworms (Platyhelminthes), but molecular data have revised their phylogenetic positions, generally linking Xenoturbellida to the deuterostomes and positioning the Acoelomorpha as the most basally branching bilaterian group(s). Recent phylogenomic data suggested that Xenoturbellida and Acoelomorpha are sister taxa and together constitute an early branch of Bilateria. Here we assemble three independent data sets-mitochondrial genes, a phylogenomic data set of 38,330 amino-acid positions and new microRNA (miRNA) complements-and show that the position of Acoelomorpha is strongly affected by a long-branch attraction (LBA) artefact. When we minimize LBA we find consistent support for a position of both acoelomorphs and Xenoturbella within the deuterostomes. The most likely phylogeny links Xenoturbella and Acoelomorpha in a clade we call Xenacoelomorpha. The Xenacoelomorpha is the sister group of the Ambulacraria (hemichordates and echinoderms). We show that analyses of miRNA complements have been affected by character loss in the acoels and that both groups possess one miRNA and the gene Rsb66 otherwise specific to deuterostomes. In addition, Xenoturbella shares one miRNA with the ambulacrarians, and two with the acoels. This phylogeny makes sense of the shared characteristics of Xenoturbellida and Acoelomorpha, such as ciliary ultrastructure and diffuse nervous system, and implies the loss of various deuterostome characters in the Xenacoelomorpha including coelomic cavities, through gut and gill slits. 相似文献
52.
53.
Whole-genome sequencing and comprehensive variant analysis of a Japanese individual using massively parallel sequencing 总被引:1,自引:0,他引:1
Fujimoto A Nakagawa H Hosono N Nakano K Abe T Boroevich KA Nagasaki M Yamaguchi R Shibuya T Kubo M Miyano S Nakamura Y Tsunoda T 《Nature genetics》2010,42(11):931-936
We report the analysis of a Japanese male using high-throughput sequencing to × 40 coverage. More than 99% of the sequence reads were mapped to the reference human genome. Using a Bayesian decision method, we identified 3,132,608 single nucleotide variations (SNVs). Comparison with six previously reported genomes revealed an excess of singleton nonsense and nonsynonymous SNVs, as well as singleton SNVs in conserved non-coding regions. We also identified 5,319 deletions smaller than 10 kb with high accuracy, in addition to copy number variations and rearrangements. De novo assembly of the unmapped sequence reads generated around 3 Mb of novel sequence, which showed high similarity to non-reference human genomes and the human herpesvirus 4 genome. Our analysis suggests that considerable variation remains undiscovered in the human genome and that whole-genome sequencing is an invaluable tool for obtaining a complete understanding of human genetic variation. 相似文献
54.
Riassunto Metionina-S35 è stata incorporata in uova vergini diParacentrotus lividus. In queste l'isotopo si trova per la più gran parte nella frazione solubile in acido tricloracetico al 10%. Attivando le uova partenogeneticamente con acido butirrico si osserva una progressiva perdita di attività di questa frazione ed una rapida incorporazione nei mitocondri. L'andamento del fenomeno è del tutto identico a quello già descritto (Nakano eMonroy) nelle uova normalmente fecondate.
Aided by a Grant from the Rockefeller Foundation. 相似文献
Aided by a Grant from the Rockefeller Foundation. 相似文献
55.
Hiroaki Iwasa Shakhawoat Hossain Yutaka Hata 《Cellular and molecular life sciences : CMLS》2018,75(10):1773-1787
Human genome has ten genes that are collectedly called Ras association domain family (RASSF). RASSF is composed of two subclasses, C-RASSF and N-RASSF. Both N-RASSF and C-RASSF encode Ras association domain-containing proteins and are frequently suppressed by DNA hypermethylation in human cancers. However, C-RASSF and N-RASSF are quite different. Six C-RASSF proteins (RASSF1–6) are characterized by a C-terminal coiled-coil motif named Salvador/RASSF/Hippo domain, while four N-RASSF proteins (RASSF7–10) lack it. C-RASSF proteins interact with mammalian Ste20-like kinases—the core kinases of the tumor suppressor Hippo pathway—and cross-talk with this pathway. Some of them share the same interacting molecules such as MDM2 and exert the tumor suppressor role in similar manners. Nevertheless, each C-RASSF protein has distinct characters. In this review, we summarize our current knowledge of how C-RASSF proteins play tumor suppressor roles and discuss the similarities and differences among C-RASSF proteins. 相似文献
56.
Summary I125 insulin binding and the uptake of oxygen and 2-deoxyglucose are increased in skeletal muscle after denervation, suggesting an increase in insulin receptors (IR). Sustained increases in the number of affinity of IR molecules may account for some properties of denervated muscle fibres.Supported by the Medical Research Service of the Veterans Administration. 相似文献
57.
Nakamura T Liu YJ Nakashima H Umehara H Inoue K Matoba S Tachibana M Ogura A Shinkai Y Nakano T 《Nature》2012,486(7403):415-419
The modification of DNA by 5-methylcytosine (5mC) has essential roles in cell differentiation and development through epigenetic gene regulation. 5mC can be converted to another modified base, 5-hydroxymethylcytosine (5hmC), by the tet methylcytosine dioxygenase (Tet) family of enzymes. Notably, the balance between 5hmC and 5mC in the genome is linked with cell-differentiation processes such as pluripotency and lineage commitment. We have previously reported that the maternal factor PGC7 (also known as Dppa3, Stella) is required for the maintenance of DNA methylation in early embryogenesis, and protects 5mC from conversion to 5hmC in the maternal genome. Here we show that PGC7 protects 5mC from Tet3-mediated conversion to 5hmC by binding to maternal chromatin containing dimethylated histone H3 lysine 9 (H3K9me2) in mice. In addition, imprinted loci that are marked with H3K9me2 in mature sperm are protected by PGC7 binding in early embryogenesis. This type of regulatory mechanism could be involved in DNA modifications in somatic cells as well as in early embryos. 相似文献
58.
Cytotoxic T lymphocytes specific for self H-2 antigens are generated by murine F1 hybrid (H-2 heterozygous) spleen cells cultured with irradiated parental (H-2 homozygous) splenocytes. The effectors bind to heterozygous and homozygous cells bearing the appropriate H-2 alleles but only lyse homozygous targets. Autoreactivity for membrane-bound molecules of normal cells may be a mechanism for regulating cellular interactions. 相似文献
59.
Suga H Kadoshima T Minaguchi M Ohgushi M Soen M Nakano T Takata N Wataya T Muguruma K Miyoshi H Yonemura S Oiso Y Sasai Y 《Nature》2011,480(7375):57-62
The adenohypophysis (anterior pituitary) is a major centre for systemic hormones. At present, no efficient stem-cell culture for its generation is available, partly because of insufficient knowledge about how the pituitary primordium (Rathke's pouch) is induced in the embryonic head ectoderm. Here we report efficient self-formation of three-dimensional adenohypophysis tissues in an aggregate culture of mouse embryonic stem (ES) cells. ES cells were stimulated to differentiate into non-neural head ectoderm and hypothalamic neuroectoderm in adjacent layers within the aggregate, and treated with hedgehog signalling. Self-organization of Rathke's-pouch-like three-dimensional structures occurred at the interface of these two epithelia, as seen in vivo, and various endocrine cells including corticotrophs and somatotrophs were subsequently produced. The corticotrophs efficiently secreted adrenocorticotropic hormone in response to corticotrophin releasing hormone and, when grafted in vivo, these cells rescued the systemic glucocorticoid level in hypopituitary mice. Thus, functional anterior pituitary tissue self-forms in ES cell culture, recapitulating local tissue interactions. 相似文献
60.
In modern organisms, protein enzymes are solely responsible for the aminoacylation of transfer RNA. However, the evolution of protein synthesis in the RNA world required RNAs capable of catalysing this reaction. Ribozymes that aminoacylate RNA by using activated amino acids have been discovered through selection in vitro. Flexizyme is a 45-nucleotide ribozyme capable of charging tRNA in trans with various activated l-phenylalanine derivatives. In addition to a more than 10(5) rate enhancement and more than 10(4)-fold discrimination against some non-cognate amino acids, this ribozyme achieves good regioselectivity: of all the hydroxyl groups of a tRNA, it exclusively aminoacylates the terminal 3'-OH. Here we report the 2.8-A resolution structure of flexizyme fused to a substrate RNA. Together with randomization of ribozyme core residues and reselection, this structure shows that very few nucleotides are needed for the aminoacylation of specific tRNAs. Although it primarily recognizes tRNA through base-pairing with the CCA terminus of the tRNA molecule, flexizyme makes numerous local interactions to position the acceptor end of tRNA precisely. A comparison of two crystallographically independent flexizyme conformations, only one of which appears capable of binding activated phenylalanine, suggests that this ribozyme may achieve enhanced specificity by coupling active-site folding to tRNA docking. Such a mechanism would be reminiscent of the mutually induced fit of tRNA and protein employed by some aminoacyl-tRNA synthetases to increase specificity. 相似文献