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41.
单世满 《东北师大学报(自然科学版)》1988,(3)
利用巳有的电子——空穴有效作用势,引进一校正因子ε/ε_0后,用变分法计算溴化铊和氯化铊中激子的结合能,得出的结果比现有的其它理论与实验结果符合得更好。 相似文献
42.
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Summary Hyperphnylalaninemia (experimental PKU) induced in developing rats by treatment with p-chlorophenylalanine (PCPA) plus phenylalanine (PHE) causes a significant reduction in the triphosphoinositide (TPI) and diphosphoinositide (DPI) content of brain. Since TPI and DPI play an important role in excitable nervous membranes, the functional abnormality in experimental and perhaps in genetic PKU may be related to the reduction in TPI and DPI content.This work was supported by research grant NS14938 from National Institutes of Health. 相似文献
44.
G. V. Sherbet M. S. Lakshmi G. P. Risely S. A. Shah M. E. Tindle 《Cellular and molecular life sciences : CMLS》1982,38(5):610-611
Summary An antiserum was raised in rabbits against a primary metastasizing lymphosarcoma (ML) of the hamster. This was made tumor-specific
by absorption with normal hamster tissue extracts. Immunoglobulin-G was prepared and tested for its cytotoxicity towards cells
derived from the primary tumor and its liver metastases. The ML-specific IgG was found to be 2–5 times more cytotoxic for
cells derived from the primary tumor compared to cells obtained from liver metastases.
Acknowledgments. The authors thank the North of England Cancer Research Campaign and the Manpower Services Commission for
financial support. 相似文献
45.
In the present work,we studied dissolution behavior of three glass ceramics samples each having 34 SiO2–14.5 P2O5–1 CaF2–0.5 MgF2(%wt)and ratio of CaO/MgO varying from 11.5:1 to 1:11.5 in conventional SBF(SBF-K9) and revised SBF(r-SBF) that has ionic concentration exactly equal to that of human blood plasma.For that purpose,samples were immersed in fluids for different time periods upto 25 days.Thin film XRD analysis revealed the diffusive nature of the phases on the surfaces of samples after soaking for different time periods in r-SBF.It showed the poor precipitation and small thickness of the HCAp layer on the samples as compared to that in SBF-K9,thus indicating the fitness and sensitivity of r-SBF for in-vitro characterization of samples.AAS,FTIR and EDS revealed slow bonding rate on the surfaces of the samples in r-SBF than that in SBF-K9 that showed the dependence of bond formation on the composition of the materials as well as on the physiological fluid used for in-vitro characterization.The rate of HCAp formation was slower in r-SBF due to more competitive adsorption of CO3 ions to Ca and Mg ions owing to greater amount of CO3 in r-SBF than that in SBF-K9.It shows the importance of CO3 content in the physiological fluids for the in-vitro assessment of samples.So,r-SBF is recommended to be used for assessment of samples to clearly understand their behavior in-vivo. 相似文献
46.
Lo I Denef VJ Verberkmoes NC Shah MB Goltsman D DiBartolo G Tyson GW Allen EE Ram RJ Detter JC Richardson P Thelen MP Hettich RL Banfield JF 《Nature》2007,446(7135):537-541
Microbes comprise the majority of extant organisms, yet much remains to be learned about the nature and driving forces of microbial diversification. Our understanding of how microorganisms adapt and evolve can be advanced by genome-wide documentation of the patterns of genetic exchange, particularly if analyses target coexisting members of natural communities. Here we use community genomic data sets to identify, with strain specificity, expressed proteins from the dominant member of a genomically uncharacterized, natural, acidophilic biofilm. Proteomics results reveal a genome shaped by recombination involving chromosomal regions of tens to hundreds of kilobases long that are derived from two closely related bacterial populations. Inter-population genetic exchange was confirmed by multilocus sequence typing of isolates and of uncultivated natural consortia. The findings suggest that exchange of large blocks of gene variants is crucial for the adaptation to specific ecological niches within the very acidic, metal-rich environment. Mass-spectrometry-based discrimination of expressed protein products that differ by as little as a single amino acid enables us to distinguish the behaviour of closely related coexisting organisms. This is important, given that microorganisms grouped together as a single species may have quite distinct roles in natural systems and their interactions might be key to ecosystem optimization. Because proteomic data simultaneously convey information about genome type and activity, strain-resolved community proteomics is an important complement to cultivation-independent genomic (metagenomic) analysis of microorganisms in the natural environment. 相似文献
47.
Corneo B Wendland RL Deriano L Cui X Klein IA Wong SY Arnal S Holub AJ Weller GR Pancake BA Shah S Brandt VL Meek K Roth DB 《Nature》2007,449(7161):483-486
Mammalian cells repair DNA double-strand breaks (DSBs) through either homologous recombination or non-homologous end joining (NHEJ). V(D)J recombination, a cut-and-paste mechanism for generating diversity in antigen receptors, relies on NHEJ for repairing DSBs introduced by the Rag1-Rag2 protein complex. Animals lacking any of the seven known NHEJ factors are therefore immunodeficient. Nevertheless, DSB repair is not eliminated entirely in these animals: evidence of a third mechanism, 'alternative NHEJ', appears in the form of extremely rare V(D)J junctions and a higher rate of chromosomal translocations. The paucity of these V(D)J events has suggested that alternative NHEJ contributes little to a cell's overall repair capacity, being operative only (and inefficiently) when classical NHEJ fails. Here we find that removing certain portions of murine Rag proteins reveals robust alternative NHEJ activity in NHEJ-deficient cells and some alternative joining activity even in wild-type cells. We propose a two-tier model in which the Rag proteins collaborate with NHEJ factors to preserve genomic integrity during V(D)J recombination. 相似文献
48.
49.
Shah SP Roth A Goya R Oloumi A Ha G Zhao Y Turashvili G Ding J Tse K Haffari G Bashashati A Prentice LM Khattra J Burleigh A Yap D Bernard V McPherson A Shumansky K Crisan A Giuliany R Heravi-Moussavi A Rosner J Lai D Birol I Varhol R Tam A Dhalla N Zeng T Ma K Chan SK Griffith M Moradian A Cheng SW Morin GB Watson P Gelmon K Chia S Chin SF Curtis C Rueda OM Pharoah PD Damaraju S Mackey J Hoon K Harkins T Tadigotla V Sigaroudinia M Gascard P Tlsty T Costello JF Meyer IM Eaves CJ Wasserman WW 《Nature》2012,486(7403):395-399
Primary triple-negative breast cancers (TNBCs), a tumour type defined by lack of oestrogen receptor, progesterone receptor and ERBB2 gene amplification, represent approximately 16% of all breast cancers. Here we show in 104 TNBC cases that at the time of diagnosis these cancers exhibit a wide and continuous spectrum of genomic evolution, with some having only a handful of coding somatic aberrations in a few pathways, whereas others contain hundreds of coding somatic mutations. High-throughput RNA sequencing (RNA-seq) revealed that only approximately 36% of mutations are expressed. Using deep re-sequencing measurements of allelic abundance for 2,414 somatic mutations, we determine for the first time-to our knowledge-in an epithelial tumour subtype, the relative abundance of clonal frequencies among cases representative of the population. We show that TNBCs vary widely in their clonal frequencies at the time of diagnosis, with the basal subtype of TNBC showing more variation than non-basal TNBC. Although p53 (also known as TP53), PIK3CA and PTEN somatic mutations seem to be clonally dominant compared to other genes, in some tumours their clonal frequencies are incompatible with founder status. Mutations in cytoskeletal, cell shape and motility proteins occurred at lower clonal frequencies, suggesting that they occurred later during tumour progression. Taken together, our results show that understanding the biology and therapeutic responses of patients with TNBC will require the determination of individual tumour clonal genotypes. 相似文献
50.
The genomic and transcriptomic architecture of 2,000 breast tumours reveals novel subgroups 总被引:1,自引:0,他引:1
Curtis C Shah SP Chin SF Turashvili G Rueda OM Dunning MJ Speed D Lynch AG Samarajiwa S Yuan Y Gräf S Ha G Haffari G Bashashati A Russell R McKinney S;METABRIC Group Langerød A Green A Provenzano E Wishart G Pinder S Watson P Markowetz F Murphy L Ellis I Purushotham A Børresen-Dale AL Brenton JD Tavaré S Caldas C Aparicio S 《Nature》2012,486(7403):346-352