期刊文献+
共找到8篇文章
< 1 >
每页显示 20 50 100
国家电压量值保存和量传方法的研究
1
作者 周庚如 赵桂芬 +1 位作者 王路 胡毅飞 《宇航计测技术》 CSCD 北大核心 1995年第3期47-51,共5页
叙述了国家临时电压自然基准量值保存和量传方法研究。该基准复现电压单位的不确定度为0.024×10 ̄(-6),传递到传递标准的不确定度小于0.1×10 ̄(-6).
关键词 电压 自然基准 保存 传递 电压标准
下载PDF
造血干细胞采集、分离与冻存的研究 被引量:2
2
作者 徐群 武正炎 《南京医科大学学报(自然科学版)》 CAS CSCD 北大核心 2001年第3期255-257,共3页
目的 :研究外周血造血干细胞的采集、分离、冻存及干细胞活性的检测。方法 :用封闭式动脉采血法采集 10例脐血 ,经Ficoll溶液分离获得干细胞 ,分成 3组 ,分别用 10 %二甲亚矾 (DMSO)、自配的 5 % DMSO+6 %羟乙基淀粉 (HES) +4 %人体白... 目的 :研究外周血造血干细胞的采集、分离、冻存及干细胞活性的检测。方法 :用封闭式动脉采血法采集 10例脐血 ,经Ficoll溶液分离获得干细胞 ,分成 3组 ,分别用 10 %二甲亚矾 (DMSO)、自配的 5 % DMSO+6 %羟乙基淀粉 (HES) +4 %人体白蛋白及 CP- 13种不同的冷冻保存液冻存于 196℃的液氮和 80℃的低温冰箱中 ,对冷冻后的样本进行单个核细胞 (MNC)计数。锥虫蓝拒染试验及流式细胞仪 CD+ 34 细胞计数。结果 :采集的血量平均数为 (72 .2± 17.3) ml,3种不同冷冻保存液对造血干细胞的保存效果在 1、3、6个月差异无显著性 (P>0 .0 5 )。随着冷冻时间的延长 ,特别是 6个月后 ,流式细胞仪对 CD+ 34 细胞检测的相对数逐渐增高。在 6个月内 ,80℃低温冰箱中的冻存与 196℃液氮内的冻存相比 ,对造血干细胞的影响差异无显著性 (P>0 .0 5 )。结论 :自配的冷冻保存液效果良好 ,短期造血干细胞的冻存可以在 80℃低温冰箱内进行 ,冷冻保存造血干细胞 1、3、6个月对细胞的活性影响不大。 展开更多
关键词 造血干细胞 细胞保存值 采集 分离 冻存
下载PDF
精密直流电压测量随机不确定度计算方法(下)
3
作者 周玉清 钟国林 +1 位作者 张朝军 唐国民 《实用测试技术》 1998年第5期1-6,共6页
阐述测量标准成组时组合测量的数据处理与随机不确定度计算方法。
关键词 组合测量 保存值 直流电压 精密测量
下载PDF
Historicity: Preservation or Revitalization Planning Tools?
4
作者 Mariana Seara Paixao Antonio Ricardo da Costa Jorge Goncalves 《Journal of Civil Engineering and Architecture》 2013年第10期1196-1202,共7页
The historic centres revitalization addresses the challenges related to the preservation of fundamental heritage values. At a time, when everyone looks with concern to our cities' future, it is important to reflect o... The historic centres revitalization addresses the challenges related to the preservation of fundamental heritage values. At a time, when everyone looks with concern to our cities' future, it is important to reflect on the received heritage, seeking the most appropriate answers to the planning of the historic centres. These fabrics are reference places in the urban space, due to their role of memorial testimony and of generators of cultural and economic dynamics. However, often times, inherited urban fabrics are affected by the limitations of the heritage policies which, for being too general and based on theoretical and abstract frameworks, have difficulty incorporating the characteristics of each area and neglect the formulation of specific criteria and intervention methods. The purpose of this paper is to provide a comparative reading of the levels of urban renewal allowed by the planning tools. This study chooses two historic centers in Portugal: Oporto and Guimarfies historic centres (World Heritage Sites since 1996 and 2001, respectively, and were the last to get this classification in Portugal). This reflection is a contribution to peer trends and raise the discussion on the role that the different heritage policies have to the revitalization of the historic centres. 展开更多
关键词 Historical centre planning tool urban renewal HERITAGE urban planning.
下载PDF
Augmenting the conservation value of rehabilitated wildlife by integrating genetics and population modeling in the post-rehabilitation decision process
5
作者 Carlo PACIONI Chris RAFFERTY +7 位作者 Kelly MORLEY Sarah STEVENSON Andrew CHAPMAN Michael WICKINS Terry VERNEY Gerry DEEGAN Sabrina TROCINI Peter B. S, SPENCER 《Current Zoology》 SCIE CAS CSCD 2018年第5期593-601,共9页
Insular populations are particularly vulnerable to the effects of stochastic events, epidemics, and loss of genetic diversity due to inbreeding and genetic drift. The development of successful man- agement options wil... Insular populations are particularly vulnerable to the effects of stochastic events, epidemics, and loss of genetic diversity due to inbreeding and genetic drift. The development of successful man- agement options will require accurate baseline data, establishment of clear objectives, and finally monitoring and implementation of corrective measures, if and when required. This study assessed management options for the genetic rehabilitation of highly inbred woylies obtained from wildlife rehabilitation centers. The study generated genetic data for the woylie Bettongia penicillata from a conservation reserve and calculated measures of genetic diversity and individual relatedness. These data were fed into a population viability analysis (PVA) to test genetic outcomes in relation to different management actions. We demonstrated that a careful selection of the founder cohort produced a population with an expected heterozygosity of -70% for a window of approximately 10 years. A proposal to increase the size of the reserve available to the colony was shown to almost double the time at which the colony would retain heterozygosity levels of≥70%. Additionally, developing a regular program of supplementation of unrelated woylies would result in a further improvement in their genetic value. This study demonstrated how the application of molecular techniques in combination with PVA can be beneficial for the management of rehabilitated wildlife otherwise considered of little conservation value. This approach can be applied to the management of breeding programs, but also to small, closed populations such as those found on islands, fenced enclosures, insurance populations, and in zoological collections. 展开更多
关键词 Bettongia penicillata conservation genetics microsatellite loci rescue centres VORTEX vortexR.
原文传递
Population genetic structure in the paddyfield warbler (Acrocephalus agricola Jerd.)
6
作者 Pavel ZEHTINDJIEV Mihaela ILIEVA +3 位作者 Bengt HANSSON Olga OPARINA Mihail OPARIN Staffan BENSCH 《Current Zoology》 SCIE CAS CSCD 北大核心 2011年第1期63-71,共9页
Population genetic structure was studied in paddyfield warblers Acrocephalus agricola breeding in NE Bulgaria, SE Russia and S Kazakhstan. We were particularly interested in the degree of genetic differentiation and g... Population genetic structure was studied in paddyfield warblers Acrocephalus agricola breeding in NE Bulgaria, SE Russia and S Kazakhstan. We were particularly interested in the degree of genetic differentiation and gene flow of the Bulgarian population due to its geographical isolation, recent origin and unique migratory strategy. Analyses of mitochondrial DNA (mtDNA) showed that there was no divergence between Bulgarian and Russian populations (FsT = 0.007), whereas those in Ka- zakhstan differed significantly from the European breeding populations (Russia: FsT = 0.058; Bulgaria: FsT = 0.114). The degree of differentiation between populations at nuclear markers (five microsatellite loci; FsT ~ 0) was weaker than for mtDNA. We suggest that this relatively weak differentiation over the range of this species reflects a recent postglacial expansion, and results from mismatch distribution analyses and Fu's Fs tests are in agreement. Preservation of small and geographically isolated popula- tions which may contain individuals with unique adaptive traits, such as the studied Bulgarian population of paddyfield warbler, is valuable for the long-term conservation of expanding migratory bird species 展开更多
关键词 PHYLOGEOGRAPHY Post-glacial expansion Population structure Mitochondria MICROSATELLITE
原文传递
Multi-period Bank Hedging with Interest Rate Futures
7
作者 Hezhong Li Haibo Kuang 《Journal of Systems Science and Information》 2009年第1期65-76,共12页
In this paper, a model for multi-period bank hedging with interest rate futures is set up. Formulas for the optimal dynamic multi-period bank and static bank hedge ratio are derived. The described model offers the pot... In this paper, a model for multi-period bank hedging with interest rate futures is set up. Formulas for the optimal dynamic multi-period bank and static bank hedge ratio are derived. The described model offers the potential benefits of: (1) although these formulas are developed for the case of direct sheet balance multi-period hedging, the framework used is sufficiently flexible so that these formulas can be applied to bank loan or deposit multi-period hedging situations respectively. (2) Periodic modification and updating of the interest rate futures position, as suggested by interest rates, throughout the bank hedging horizons. (3) This paper examines a situation in which the return of loan, the interest rate of deposit and the equity capital of bank, and interest rate futures prices are cointergrated, Multi-period bank hedging formulas are derived under three-dimensional stochastic volatility model. However, empirical research is required for validating this model. 展开更多
关键词 interest rate futures multi-period bank hedging stochastic volatility model
原文传递
中南軍政委員會文化部、中南財經委員會物資管理局,中國土產公司中南區公司擬定雜铜中之古文物檢查、保管、價撥辦法聯合通知
8
《文物》 1953年第1期64-65,共2页
查我國爲歷史悠久的國家,歷代遺留下來的古銅器皿、貨幣,及銅質貴重古物爲數很多,這收購雜銅時應注意檢查保存文化遺物在案外。
关键词 古文物 文化部 管理局 保管 器皿 通知 保存值 公司 古代文化 古铜
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部