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61.
为了探讨模式美拉德反应产物对面包制作工艺及品质的影响,本文将该模式美拉德反应产物添加至面团中,并采用二次发酵法来制作面包,研究了不同比例的模式美拉德反应产物对面包醒发时间、比容、质构及水分迁移的影响,并从感官上对面包的品质进行了评价.实验结果表明,模式美拉德反应产物的添加量对面包制作工艺和品质有不同程度的影响,当添加量... 相似文献
62.
This paper undertakes an in-sample and rolling-window comparative analysis of dependence, market, and portfolio investment risks on a 10-year global index portfolio of developed, emerging, and commodity markets. We draw our empirical results by fitting vine copulas (e.g., r-vines, c-vines, d-vines), IGARCH(1,1) RiskMetrics value-at-risk (VaR), and portfolio optimization methods based on risk measures such as the variance, conditional value-at-risk, conditional drawdown-at-risk, minimizing regret (Minimax), and mean absolute deviation. The empirical results indicate that all international indices tend to correlate strongly in the negative tail of the return distribution; however, emerging markets, relative to developed and commodity markets, exhibit greater dependence, market, and portfolio investment risks. The portfolio optimization shows a clear preference towards the gold commodity for investment, while Japan and Canada are found to have the highest and lowest market risk, respectively. The vine copula analysis identifies symmetry in the dependence dynamics of the global index portfolio modeled. Large VaR diversification benefits are produced at the 95% and 99% confidence levels by the modeled international index portfolio. The empirical results may appeal to international portfolio investors and risk managers for advanced portfolio management, hedging, and risk forecasting. 相似文献
63.
This paper presents a new spatial dependence model with an adjustment of feature difference. The model accounts for the spatial autocorrelation in both the outcome variables and residuals. The feature difference adjustment in the model helps to emphasize feature changes across neighboring units, while suppressing unobserved covariates that are present in the same neighborhood. The prediction at a given unit incorporates components that depend on the differences between the values of its main features and those of its neighboring units. In contrast to conventional spatial regression models, our model does not require a comprehensive list of global covariates necessary to estimate the outcome variable at the unit, as common macro-level covariates are differenced away in the regression analysis. Using the real estate market data in Hong Kong, we applied Gibbs sampling to determine the posterior distribution of each model parameter. The result of our empirical analysis confirms that the adjustment of feature difference with an inclusion of the spatial error autocorrelation produces better out-of-sample prediction performance than other conventional spatial dependence models. In addition, our empirical analysis can identify components with more significant contributions. 相似文献
64.
近年来,阳离子聚合物、阳离子脂质体等非病毒载体在基因递送中的应用越来越受到人们的关注.然而,血清的存在会降低它们的转染效率,从而阻碍它们在临床中的使用.因此,非常有必要开发能抵抗血清干扰的非病毒基因载体.本工作合成了一种新型的锌离子配位的脂质,其与1, 2-二油酰-SN-甘油-3-磷酰乙醇胺脂质(DOPE)共自组装形成阳离子脂质体(Zn-DTAc脂质体).实验结果表明,Zn-DTAc脂质体可以有效地压缩质粒形成纳米复合物.即使在50%胎牛血清存在的情况下,该复合物也能进行有效的细胞内化和内涵体逃逸,并实现高效的基因转染. 相似文献
65.
西班牙大学技术转移中心的成功经验分析 总被引:1,自引:0,他引:1
随着西班牙国家创新体系战略的实施,西班牙大学与产业界的技术转移活动日趋活跃,逐渐成为了大学技术转移活动开展得比较好的欧盟国家之一。首先从许可合同和衍生企业两个方面介绍了西班牙大学技术转移的具体情况,提出了大学技术转移中心的重要作用。继而提出政府法律法规的建立是西班牙大学技术转移中心成功运作的指导因素,国家大学技术转移协会是其组织保障,技术转移中心的人力资源是其决定因素,高水平的专利管理是其坚实基础,充足的资金资助是其支撑因素。最后,提出了对我国大学技术转移中心的借鉴意义。 相似文献
66.
Torsional Models of Two - ply Yarn 总被引:1,自引:0,他引:1
In this paper,the vector equation of a generaliseddoubly wound helix was derived.Treloar's pliedyarn geometry could be obtained as a special case ofthe generalised doubly wound helix.The shortest fi-bre length around the surface of a helical tube(formed by fibre helices)was determined by apply-ing variational principles.The fibre length as calcu-lated by using Treloar's geometry was compared in-directly with the shortest possible fibre length at dif-ferent levels of yarn deformation when some of Tre-loar's rigid geometrical constraints were relaxed.Anew idea based on non-concentric circles was intro-duced to approximate the fibre helix movement in atwo-ply yarn.A torsional model of two-ply yarnwas developed and the theoretical predictions werecompared with some preliminary experimental re-sults. 相似文献
67.
Lissauer JJ Fabrycky DC Ford EB Borucki WJ Fressin F Marcy GW Orosz JA Rowe JF Torres G Welsh WF Batalha NM Bryson ST Buchhave LA Caldwell DA Carter JA Charbonneau D Christiansen JL Cochran WD Desert JM Dunham EW Fanelli MN Fortney JJ Gautier TN Geary JC Gilliland RL Haas MR Hall JR Holman MJ Koch DG Latham DW Lopez E McCauliff S Miller N Morehead RC Quintana EV Ragozzine D Sasselov D Short DR Steffen JH 《Nature》2011,470(7332):53-58
When an extrasolar planet passes in front of (transits) its star, its radius can be measured from the decrease in starlight and its orbital period from the time between transits. Multiple planets transiting the same star reveal much more: period ratios determine stability and dynamics, mutual gravitational interactions reflect planet masses and orbital shapes, and the fraction of transiting planets observed as multiples has implications for the planarity of planetary systems. But few stars have more than one known transiting planet, and none has more than three. Here we report Kepler spacecraft observations of a single Sun-like star, which we call Kepler-11, that reveal six transiting planets, five with orbital periods between 10 and 47?days and a sixth planet with a longer period. The five inner planets are among the smallest for which mass and size have both been measured, and these measurements imply substantial envelopes of light gases. The degree of coplanarity and proximity of the planetary orbits imply energy dissipation near the end of planet formation. 相似文献
68.
Kaneko H Dridi S Tarallo V Gelfand BD Fowler BJ Cho WG Kleinman ME Ponicsan SL Hauswirth WW Chiodo VA Karikó K Yoo JW Lee DK Hadziahmetovic M Song Y Misra S Chaudhuri G Buaas FW Braun RE Hinton DR Zhang Q Grossniklaus HE Provis JM Madigan MC Milam AH Justice NL Albuquerque RJ Blandford AD Bogdanovich S Hirano Y Witta J Fuchs E Littman DR Ambati BK Rudin CM Chong MM Provost P Kugel JF Goodrich JA Dunaief JL Baffi JZ Ambati J 《Nature》2011,471(7338):325-330
69.
Wertz IE Kusam S Lam C Okamoto T Sandoval W Anderson DJ Helgason E Ernst JA Eby M Liu J Belmont LD Kaminker JS O'Rourke KM Pujara K Kohli PB Johnson AR Chiu ML Lill JR Jackson PK Fairbrother WJ Seshagiri S Ludlam MJ Leong KG Dueber EC Maecker H Huang DC Dixit VM 《Nature》2011,471(7336):110-114
Microtubules have pivotal roles in fundamental cellular processes and are targets of antitubulin chemotherapeutics. Microtubule-targeted agents such as Taxol and vincristine are prescribed widely for various malignancies, including ovarian and breast adenocarcinomas, non-small-cell lung cancer, leukaemias and lymphomas. These agents arrest cells in mitosis and subsequently induce cell death through poorly defined mechanisms. The strategies that resistant tumour cells use to evade death induced by antitubulin agents are also unclear. Here we show that the pro-survival protein MCL1 (ref. 3) is a crucial regulator of apoptosis triggered by antitubulin chemotherapeutics. During mitotic arrest, MCL1 protein levels decline markedly, through a post-translational mechanism, potentiating cell death. Phosphorylation of MCL1 directs its interaction with the tumour-suppressor protein FBW7, which is the substrate-binding component of a ubiquitin ligase complex. The polyubiquitylation of MCL1 then targets it for proteasomal degradation. The degradation of MCL1 was blocked in patient-derived tumour cells that lacked FBW7 or had loss-of-function mutations in FBW7, conferring resistance to antitubulin agents and promoting chemotherapeutic-induced polyploidy. Additionally, primary tumour samples were enriched for FBW7 inactivation and elevated MCL1 levels, underscoring the prominent roles of these proteins in oncogenesis. Our findings suggest that profiling the FBW7 and MCL1 status of tumours, in terms of protein levels, messenger RNA levels and genetic status, could be useful to predict the response of patients to antitubulin chemotherapeutics. 相似文献
70.
Hussein SM Batada NN Vuoristo S Ching RW Autio R Närvä E Ng S Sourour M Hämäläinen R Olsson C Lundin K Mikkola M Trokovic R Peitz M Brüstle O Bazett-Jones DP Alitalo K Lahesmaa R Nagy A Otonkoski T 《Nature》2011,471(7336):58-62
The mechanisms underlying the low efficiency of reprogramming somatic cells into induced pluripotent stem (iPS) cells are poorly understood. There is a clear need to study whether the reprogramming process itself compromises genomic integrity and, through this, the efficiency of iPS cell establishment. Using a high-resolution single nucleotide polymorphism array, we compared copy number variations (CNVs) of different passages of human iPS cells with their fibroblast cell origins and with human embryonic stem (ES) cells. Here we show that significantly more CNVs are present in early-passage human iPS cells than intermediate passage human iPS cells, fibroblasts or human ES cells. Most CNVs are formed de novo and generate genetic mosaicism in early-passage human iPS cells. Most of these novel CNVs rendered the affected cells at a selective disadvantage. Remarkably, expansion of human iPS cells in culture selects rapidly against mutated cells, driving the lines towards a genetic state resembling human ES cells. 相似文献