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排序方式: 共有157条查询结果,搜索用时 15 毫秒
71.
Chi Chiu Wang Ellen Billett Astrid Borchert Hartmut Kuhn Christoph Ufer 《Cellular and molecular life sciences : CMLS》2013,70(4):599-630
Monoamine oxidases (MAOs) are flavoproteins of the outer mitochondrial membrane that catalyze the oxidative deamination of biogenic and xenobiotic amines. In mammals there are two isoforms (MAO-A and MAO-B) that can be distinguished on the basis of their substrate specificity and their sensitivity towards specific inhibitors. Both isoforms are expressed in most tissues, but their expression in the central nervous system and their ability to metabolize monoaminergic neurotransmitters have focused MAO research on the functionality of the mature brain. MAO activities have been related to neurodegenerative diseases as well as to neurological and psychiatric disorders. More recently evidence has been accumulating indicating that MAO isoforms are expressed not only in adult mammals, but also before birth, and that defective MAO expression induces developmental abnormalities in particular of the brain. This review is aimed at summarizing and critically evaluating the new findings on the developmental functions of MAO isoforms during embryogenesis. 相似文献
72.
Cummins JM Rago C Kohli M Kinzler KW Lengauer C Vogelstein B 《Nature》2004,428(6982):1 p following 486
73.
Wnt and Hedgehog family proteins are secreted signalling molecules (morphogens) that act at both long and short range to control growth and patterning during development. Both proteins are covalently modified by lipid, and the mechanism by which such hydrophobic molecules might spread over long distances is unknown. Here we show that Wingless, Hedgehog and glycophosphatidylinositol-linked proteins copurify with lipoprotein particles, and co-localize with them in the developing wing epithelium of Drosophila. In larvae with reduced lipoprotein levels, Hedgehog accumulates near its site of production, and fails to signal over its normal range. Similarly, the range of Wingless signalling is narrowed. We propose a novel function for lipoprotein particles, in which they act as vehicles for the movement of lipid-linked morphogens and glycophosphatidylinositol-linked proteins. 相似文献
74.
Gohle C Udem T Herrmann M Rauschenberger J Holzwarth R Schuessler HA Krausz F Hänsch TW 《Nature》2005,436(7048):234-237
Since 1998, the interaction of precision spectroscopy and ultrafast laser science has led to several notable accomplishments. Femtosecond laser optical frequency 'combs' (evenly spaced spectral lines) have revolutionized the measurement of optical frequencies and enabled optical atomic clocks. The same comb techniques have been used to control the waveform of ultrafast laser pulses, which permitted the generation of single attosecond pulses, and have been used in a recently demonstrated 'oscilloscope' for light waves. Here we demonstrate intra-cavity high harmonic generation in the extreme ultraviolet, which promises to lead to another joint frontier of precision spectroscopy and ultrafast science. We have generated coherent extreme ultraviolet radiation at a repetition frequency of more than 100 MHz, a 1,000-fold improvement over previous experiments. At such a repetition rate, the mode spacing of the frequency comb, which is expected to survive the high harmonic generation process, is large enough for high resolution spectroscopy. Additionally, there may be many other applications of such a quasi-continuous compact and coherent extreme ultraviolet source, including extreme ultraviolet holography, microscopy, nanolithography and X-ray atomic clocks. 相似文献
75.
76.
Van Steen K McQueen MB Herbert A Raby B Lyon H Demeo DL Murphy A Su J Datta S Rosenow C Christman M Silverman EK Laird NM Weiss ST Lange C 《Nature genetics》2005,37(7):683-691
The Human Genome Project and its spin-offs are making it increasingly feasible to determine the genetic basis of complex traits using genome-wide association studies. The statistical challenge of analyzing such studies stems from the severe multiple-comparison problem resulting from the analysis of thousands of SNPs. Our methodology for genome-wide family-based association studies, using single SNPs or haplotypes, can identify associations that achieve genome-wide significance. In relation to developing guidelines for our screening tools, we determined lower bounds for the estimated power to detect the gene underlying the disease-susceptibility locus, which hold regardless of the linkage disequilibrium structure present in the data. We also assessed the power of our approach in the presence of multiple disease-susceptibility loci. Our screening tools accommodate genomic control and use the concept of haplotype-tagging SNPs. Our methods use the entire sample and do not require separate screening and validation samples to establish genome-wide significance, as population-based designs do. 相似文献
77.
14-3-3Sigma is required to prevent mitotic catastrophe after DNA damage. 总被引:42,自引:0,他引:42
14-3-3Sigma is a member of a family of proteins that regulate cellular activity by binding and sequestering phosphorylated proteins. It has been suggested that 14-3-3sigma promotes pre-mitotic cell-cycle arrest following DNA damage, and that its expression can be controlled by the p53 tumour suppressor gene. Here we describe an improved approach to the generation of human somatic-cell knockouts, which we have used to generate human colorectal cancer cells in which both 14-3-3sigma alleles are inactivated. After DNA damage, these cells initially arrested in the G2 phase of the cell cycle, but, unlike cells containing 14-3-3sigma, the 14-3-3sigma-/- cells were unable to maintain cell-cycle arrest. The 14-3-3sigma-/- cells died ('mitotic catastrophe') as they entered mitosis. This process was associated with a failure of the 14-3-3sigma-deficient cells to sequester the proteins (cyclin B1 and cdc2) that initiate mitosis and prevent them from entering the nucleus. These results may indicate a mechanism for maintaining the G2 checkpoint and preventing mitotic death. 相似文献
78.
ForaminiferabelongstoSarcodina(Protozoa)andexhibitscytoplasmicorganizationandpseudopdial streamingcharacteristicbroadlyofamoeboidorgan ism[1].Itmainlylivesinthemarineenvironment withamembranous,agglutinatedorcalcareousshell.Asoneofthemostimportantgroupsinmicropaleon tology,Foraminiferahasbeenwidelyusedforthe stratigraphicsubdivision,correlationinpetroleum wellsandforthereconstructionofpaleo environments duringthelastseveraldecades[2,3].Furthermore,sincethe1960swiththestartofDeepSeaDrilling … 相似文献
79.
Accessibility of host cell lineages to medaka stem cells depends on genetic background and irradiation of recipient embryos 总被引:1,自引:0,他引:1
Ni Hong Mingyou Li Zhiqiang Zeng Meisheng Yi Jiaorong Deng Jianfang Gui Christoph Winkler Manfred Schartl Yunhan Hong 《Cellular and molecular life sciences : CMLS》2010,67(7):1189-1202
Chimera formation is a powerful tool for analyzing pluripotency in vivo. It has been widely accepted that host cell lineages
are generally accessible to embryonic stem (ES) cells with the actual contribution depending solely on the intrinsic pluripotency
of transplanted donor cells. Here, we show in the fish medaka (Oryzias latipes) that the host accessibility to ES cell contribution exhibits dramatic differences. Specifically, of three albino host strains
tested (i
1
, i
3 and af), only strain i
1 generated pigmented chimeras. Strikingly, this accessibility is completely lost in i
1 but acquired in i
3 after host γ-irradiation. Host irradiation also differentially affected ES cell contribution to somatic organs and gonad.
Therefore, the accessibility of various host cell lineages can vary considerably depending on host strains and cell lineages
as well as on irradiation. Our findings underscore the importance of host genotypes for interpreting donor cell pluripotency
and for improving ES-derived chimera production. 相似文献
80.
Liora Lindenboim Elisa Ferrando-May Christoph Borner Reuven Stein 《Cellular and molecular life sciences : CMLS》2013,70(16):3013-3027
Bax and Bak (Bax/Bak) are essential pro-apoptotic proteins of the Bcl-2 family that trigger mitochondrial outer membrane permeabilization (MOMP) in a Bcl-2/Bcl-xL-inhibitable manner. We recently discovered a new stress-related function for Bax/Bak—regulation of nuclear protein redistribution (NPR) from the nucleus to cytoplasm. This effect was independent of Bax/Bak N-terminus exposure and not inhibited by Bcl-xL over-expression. Here, we studied the molecular mechanism governing this novel non-canonical response. Wild-type (WT) and mutant versions of Bax were re-expressed in Bax/Bak double-knockout mouse embryonic fibroblasts and their ability to promote NPR, apoptotic events, and changes in lamin A mobility was examined. Our results show that, in this system, Bax expression was sufficient to restore NPR such as in WT cells undergoing apoptosis. This activity of Bax was uncoupled from cytochrome c release from the mitochondria (indicative of MOMP) and required its membrane localization, α helices 5/6, and the Bcl-2 homology 3 (BH3) domain. Moreover, enrichment of Bax in the nuclear envelope by the so-called Klarsicht/ANC-1/Syne-1 homology domain effectively triggered NPR as in WT Bax, but without inducing MOMP or cell death. Bax-induced NPR was associated with impairment in lamin A mobility, implying a connection between these two nuclear envelope-associated events. Overall, the results indicate a new MOMP-independent, stress-induced Bax function on the nuclear envelope. 相似文献