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排序方式: 共有1593条查询结果,搜索用时 125 毫秒
51.
Salman M. A. Salman 《国际水》2013,38(2):283-288
Abstract Water is a finite resource, and with the considerable upsurge in population, urbanization, and industrialization, it is also becoming an increasingly scarce resource. Many countries in the world rely on river waters, and many of those rivers are shared by two or more countries. Dams on those rivers have been a major source of tensions, disputes, and, in some cases, even conflict between riparian countries because dams could result in massive diversion of river flows. Those developments have, inter alia, highlighted the relevance and importance of the principles of international water law, as reflected in the United Nations Convention on the Law of the Non-Navigational Uses of International Watercourses. The World Commission on Dams has also underscored the importance of, and elaborated on, those principles with regard to dams on shared rivers. This article discusses and analyzes the recommendations of the Commission in this area, and compares them with the principles of international water law as enunciated in the United Nations Convention 相似文献
52.
《Energy Materials: Materials Science and Engineering for Energy Systems》2013,8(4):1184-1190
AbstractDegradation of AISI 410 martensitic stainless steel, a typical alloy for many applications such as steam turbine blade, could impair its efficiency and lifetime. To overcome this problem, critical surfaces could be modified by weld cladding via gas tungsten arc welding technique. In the present research, a comparative study of Stellite 21 weld overlays deposited in three different thicknesses, i.e. dilutions, at various preheat and post-weld heat treatment temperatures on the surface of AISI 410 martensitic stainless steel, has been made. The surface of coatings has been examined to reveal their microstructures, phase characterisation and mechanical properties using XRD, microhardness tester and metallographic techniques. The results showed that the deposition of Stellite 21 coating on AISI 410 martensitic stainless steel improved its corrosion resistance. Moreover, the volumetric dilution had a considerable effect on the hardness, microstructure and electrochemical corrosion behaviour of Stellite 21 weld overlays. 相似文献
53.
This study explores the relationship between self‐employment and income growth, employment growth, and change in poverty in metro and non‐metro areas in the United States using county‐level panel data. We investigate the impact of the relative size of the self‐employment sector measured by the share of non‐farm proprietorships (NFPs) in total full and part‐time employment on three key economic performance indicators. We first estimate an income growth model to analyse the effects of self‐employment on income growth. Then we investigate the independent effects of self‐employment on employment growth and changes in family poverty rates. Our results indicate that higher self‐employment rates are associated with statistically significant increases over time in income and employment growth, and reductions in poverty rates in non‐metro counties. We find similar effects on metro county income and employment, but not on poverty dynamics. 相似文献
54.
We estimate the spatial substitution bias based on the difference between a price index (PI) and the true cost of living (COL). This bias is computed at three geographical scales, using several fixed baskets and across different expenditures quartiles. Our results show a significant substitution bias for small geographical units. The choice of the base basket is also relevant for the bias estimation. Finally, the spatial substitution bias is larger for upper side of the expenditure distribution due to the heterogeneity in the consumption basket. This exercise shows that the spatial dimension affects the construction of a price index and that the approach of fixed baskets should be carefully considered in the estimation of spatial price differentials. 相似文献
55.
Christa D. Jensen Donald J. Lacombe Stuart G. McIntyre 《Papers in Regional Science》2013,92(3):651-666
The Conservative Party won the 2010 General Election in the United Kingdom, gaining the most votes and seats of any single party. Using Bayesian spatial econometric methods, we show that significant spatial dependence exists in Conservative voting behaviour and select the spatial Durbin model as the best model to explain this phenomenon. This paper examines these spatial effects as well as the effects of a range of economic, socio‐economic, and political variables. Perhaps the most interesting result is that incumbency has effects beyond an incumbent's own constituency. 相似文献
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根据FDA21 CFR Part 11条款的规范要求,在色谱仪器综合系统中,建立符合该条款的系统并对其进行验证,并对过程中出现的问题进行总结。使系统达到精确、可靠、持续稳定,具有识别非法记录或被篡改记录的能力。 相似文献
58.
Xiao‐Min Qian Zhen‐Dong Shi Yu Ren Chao‐Yong Liu Ya‐Ru Ji Li‐Xia Long Peiyu Pu Jing Sheng Xu‐Bo Yuan Chun‐Sheng Kang 《应用聚合物科学杂志》2013,127(1):570-576
Temozolomide (TMZ) is a promising chemotherapeutic agent for treating glioblastomas. However, resistance develops quickly and with a high frequency. Efforts to overcome chemoresistance are, therefore, critically needed. In present study, a poly(amidoamine; PAMAM) dendrimer was used as a vector to deliver microRNA‐21 inhibitor (miR‐21i) into U87 cells and the chemosensitivity of the combination effect of miR‐21i and TMZ for glioma therapy was investigated. Flow cytometry analysis showed the uptake efficiency of microRNA‐21 inhibitor after complexation with PAMAM. Real‐time PCR and in situ hybridization indicated that, compared with TMZ or miR‐21i treated cells, cells simultaneously treated with miR‐21i and TMZ showed a remarkable decrease in the microRNA‐21 (miR‐21) level. The transfection of miR‐21i enhanced the chemosensitivity by significantly decreasing the IC50 value of TMZ to glioma cells. Knockdown of miR‐21 promoted the cells' apoptosis, and at the same time, inhibited cell invasion. In conclusion, the combination treatment of glioma cells with TMZ and miR‐21i could yield a synergistic effect in inhibition of human glioma cell line. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
59.
研究了工艺参数、变质和热处理对冲头式挤压铸造ZA43合金组织和性能的影响。结果表明:控制工艺参数可获得高塑性的ZA43合金(δ5=22%,σb=385 MPa)。变质处理使铸件组织分布更趋于均匀,性能更稳定,B-Ti变质的效果好于RE变质。经过320℃固溶处理可获得高强度(σb=485 MPa,δ5=13%),选择250℃热处理则获得良好的综合性能(σb=470MPa,δ5=16%)。 相似文献
60.
目的:评价miR-21的高表达与结直肠癌预后的相关性.方法:通过全面检索PubMed、EMBASE、Google scholar、维普、CNKI等数据库,收集关于miR-21的高表达与结直肠癌预后相关性的文献,用meta分析方法评价miR-21的高表达是否与结直肠癌的预后相关.结果:共纳入4篇文献(共783个病例),总生存率(OS)HR的合并值为1.42,95%CI:1.21至1.66,P<0.05.结论:miR-21的高表达是结直肠癌预后的一个危险因素. 相似文献