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51.
建立了用于电子显微镜生物样品制备的接触式低温固定法中的传热过程模型,并求得了一维常物性条件下的精确解。讨论了样品内部冷却速率的一些变化规律及其与样品初始温度和固化温度的关系,为实际的低温固定操作提供了理论指导。 相似文献
52.
采用数值模拟的方法讨论了带反馈的腔內电光调制激光系统功率输出的分叉和混沌行为,得到了输出功率随控制参数变化的分叉图,和一些定量结果。 相似文献
53.
喻典 《湖北师范学院学报(哲学社会科学版)》1992,(6)
本文研究了原子价层轨道能与共价型分子氢化物中A-H键的振动频率v_(A-H)的关系,结果表明二者间有良好的线性关系,其计算式为: v_(A-H)=-a∑n_1E_1/∑n_1(A)+b (1) V_(A-H)=-c∑n_1E_1/∑n~(B)+d (2)利用上式计算的振动频率V_(A-H)值接近于文献值。从而验证了用韩长日方法计算电负性的合理性。 相似文献
54.
In this paper we present an approach to using historical control data to augment information from a randomized controlled clinical trial, when it is not possible to continue the control regimen to obtain the most reliable and valid assessment of long term treatment effects. Using an adjustment procedure to the historical control data, we investigate a method of estimating the long term survival function for the clinical trial control group and for evaluating the long term treatment effect. The suggested method is simple to interpret, and particularly motivated in clinical trial settings when ethical considerations preclude the long term follow-up of placebo controls. A simulation study reveals that the bias in parameter estimates that arises in the setting of group sequential monitoring will be attenuated when long term historical control information is used in the proposed manner. Data from the first and second National Wilms' Tumor studies are used to illustrate the method. 相似文献
55.
Joost R. Santos Lucia Castro Herrera Krista Danielle S. Yu Sheree Ann T. Pagsuyoin Raymond R. Tan 《Risk analysis》2014,34(6):1056-1068
The objective of this article is to discuss a needed paradigm shift in disaster risk analysis to emphasize the role of the workforce in managing the recovery of interdependent infrastructure and economic systems. Much of the work that has been done on disaster risk analysis has focused primarily on preparedness and recovery strategies for disrupted infrastructure systems. The reliability of systems such as transportation, electric power, and telecommunications is crucial in sustaining business processes, supply chains, and regional livelihoods, as well as ensuring the availability of vital services in the aftermath of disasters. There has been a growing momentum in recognizing workforce criticality in the aftermath of disasters; nevertheless, significant gaps still remain in modeling, assessing, and managing workforce disruptions and their associated ripple effects to other interdependent systems. The workforce plays a pivotal role in ensuring that a disrupted region continues to function and subsequently recover from the adverse effects of disasters. With this in mind, this article presents a review of recent studies that have underscored the criticality of workforce sectors in formulating synergistic preparedness and recovery policies for interdependent infrastructure and regional economic systems. 相似文献
56.
Land subsidence risk assessment (LSRA) is a multi‐attribute decision analysis (MADA) problem and is often characterized by both quantitative and qualitative attributes with various types of uncertainty. Therefore, the problem needs to be modeled and analyzed using methods that can handle uncertainty. In this article, we propose an integrated assessment model based on the evidential reasoning (ER) algorithm and fuzzy set theory. The assessment model is structured as a hierarchical framework that regards land subsidence risk as a composite of two key factors: hazard and vulnerability. These factors can be described by a set of basic indicators defined by assessment grades with attributes for transforming both numerical data and subjective judgments into a belief structure. The factor‐level attributes of hazard and vulnerability are combined using the ER algorithm, which is based on the information from a belief structure calculated by the Dempster‐Shafer (D‐S) theory, and a distributed fuzzy belief structure calculated by fuzzy set theory. The results from the combined algorithms yield distributed assessment grade matrices. The application of the model to the Xixi‐Chengnan area, China, illustrates its usefulness and validity for LSRA. The model utilizes a combination of all types of evidence, including all assessment information—quantitative or qualitative, complete or incomplete, and precise or imprecise—to provide assessment grades that define risk assessment on the basis of hazard and vulnerability. The results will enable risk managers to apply different risk prevention measures and mitigation planning based on the calculated risk states. 相似文献
57.
校友资源是高校最富饶的人才资源。本文试图在行业语境中,讨论高校发展与校友资源之间的辩证关系,并以此为基础,提出开发和利用高校校友资源的对策。 相似文献
58.
本文从蒙古族进入青海的不同历史阶段,简略的叙述了青海蒙古族服饰文化形成的历史脉络及形成后随着地域、自身的发展和周边民族的不同而又形成独特的服饰文化。 相似文献
59.
试论民族地区数字图书馆建设的意义 总被引:1,自引:0,他引:1
数字图书馆是信息时代的产物,是图书馆发展历史上的一次深刻革命。数字图书馆不仅代表着图书馆发展的最新方向,而且为文献信息的开发与利用提供了新的机遇。民族地区的数字图书馆建设是民族地区全面建设小康社会、适应信息社会以及进一步开发民族文化资源的迫切需要。 相似文献
60.
该文对西汉元鼎年间所设的西平亭的性质、设立时间、位置及其与东汉建安年间所设的西平郡的位置和相关方位做了简要考证,针对不同意见,提出了西平亭与西平郡在方位上有凭依关系,位置在西宁明清城恒之内的学术观点。 相似文献