电子封装热应力数值分析

针对目前电子封装的封装密度越来越高、封装厚度越来越薄、封装体在基板上所占面积越来越大,发热引起的失效越来越严重等问题,以晶体管瞬态热应力分析为例,建立热力耦合力学模型.利用ansys研究电子封装热失效问题,得到温度场、应力场和变彤场的分布规律.温度和应力的主要规律包括两点,一是温度和应力都在角点处变化明显,应力比较集中.温度从上到下逐层变化,逐渐减小,并且层与层之间温度变化不大,模型中间部分温度层厚度几乎相同,下半部分同一温度层有规律的变化.二是当温度较高时,在受约束面上和角点处应力值较大,并且在模型的角点和中部出现应力集中现象.     

Eyelid closure causes myopia in humans

Humans with unilateral ptosis are more myopic in the closed eye than in the normal eye. The effect seems unrelated to visual loss. In pairs of humans ranked for sleep and myopia, the more myopic tends to sleep the more. We conclude that eyelid closure causes myopia.     

Sexually dimorphic response of the mouse submandibular gland to fasting.

The submandibular gland of male mice contained 18% more DNA, 34% more RNA and 63% more protein than that of female mice. After a 48-h fasting, the percent loss of gland weight, protein, RNA and DNA was greater in the female than in the male.     

Differences between drosophila melanogaster and its sibling species D. simulans in sensitivity to acridine orange treatment

Larvae and adults of D. melanogaster and D. simulans were fed with acridine orange, in order to test sensitivity differences between the species. Our results show that, of the two species, D. simulans is more resistant in the larval stages, and D. melanogaster is more resistant in the adult stage. Furthermore, adult males of both species are more sensitive than adult females.     

Eyelid closure causes myopia in humans

Summary Humans with unilateral ptosis are more myopic in the closed eye than in the normal eye. The effect seems unrelated to visual loss. In pairs of humans ranked for sleep and myopia, the more myopic tends to slepp the more. We conculude that eylid closure causes myopia.We are grateful to Mr J.C. Dean Hart, Bristol Eye Hospital. for providing us with some case histories.     

Maternal behavior in two rat lines selected for differences in the acquisition of two-way avoidance.

The maternal behavior of Roman high- and low-avoidance (RHA/Verh and RLA/Verh) rats was studied, using a time-sampling method. It was concluded that: a)RLA/Verh mothers spent more time with their young, b) RHA/Verh mothers were more active, and c) the mothers of both lines mostly "blanketed' their young during nursing, although the RHA/Verh mothers assumed the side-nursing position more often than their counterparts.     

21世纪我国农药发展的若干思考

农药自问世以来虽然带来过一些负面效应,但为人类作出了巨大贡献。通过多年的努力农药的负面效应已经降至一个可以接受的水平。随着科技的发展,有害生物控制手段将越来越多,但未来可持续农业中仍将有农药的一席之地。为了我国农药的更好友展,应该加强农药管理、改善使用技术、开发更多的绿色农药制剂。     

Sexually dimorphic response of the mouse submandibular gland to fasting

Summary The submandibular gland of male mice contained 18% more DNA, 34% more RNA and 63% more protein than that of female mice. After a 48-h fasting, the percent loss of gland weight, protein, RNA and DNA was greater in the female than in the male.This study was supported by the U.S. Public Health Service Research Grant CA 17038. The authors are indebted to Mr I. Borcsanyi for his technical assistance.     

On Mach on time

Mach's views on the nature of time have been unduly neglected. They are both more defensible in their own historical context and more relevant to our own contemporary context than has been appreciated. This essay provides an extended and comprehensive discussion of Mach's writings on time offering novel analysis and interpretation. Contra the prevailing current in the secondary literature, Mach's views on time are shown to be largely vindicated in the context of late nineteenth century physics. Then, building upon this more historical project, we conclude with a critical evaluation of the modern Machian view of time due to Barbour within the context of relativistic chronometry as instantiated via pulsar clocks and atomic clocks. Once more, considered analysis serves to support the Machian view. About time we go back to Mach.     

Possible mechanism of rubidium-induced hyperactivity in the rat

Summary This study suggests that replacement of intracellular potassium by rubidium ions might lower the resting membrane potential. Thus rubidium-treated rats were more responsive to depolarizing influences and generated more cyclic AMP in the brainstem and consequently the behavioral changes.     

The many faces of unification and pluralism in economics: The case of Paul Samuelson's Foundations of Economic Analysis

The history of modern economics abounds with pleas for more pluralism as well as pleas for more unification. These seem to be contradictory goals, suggesting that pluralism and unification are mutually exclusive, or at least that they involve trade-offs with more of one necessarily being traded off against less of the other. This paper will use the example of Paul Samuelson's Foundations of Economic Analysis (1947) to argue that the relationship between pluralism and unification is often more complex than this simple dichotomy suggests. In particular, Samuelson's Foundations is invariably presented as a key text in the unification of modern economics during the middle of the twentieth century; and in many ways that is entirely correct. But Samuelson's unification was not at the theoretical (causal and explanatory) level, but rather at the purely mathematical derivational level. Although this fact is recognized in the literature on Samuelson, what seems to be less recognized is that for Samuelson, much of the motivation for this unification was pluralist in spirit: not to narrow scientific economics into one single theory, but rather to allow for more than one theory to co-exist under a single unified derivational technique. This hidden pluralism will be discussed in detail. The paper concludes with a discussion of the implications for more recent developments in economics.     

Asymmetric distribution of male and female foetuses in the pregnant rabbit uterus

Summary The sex distribution of foetuses in the uterine horn of the pregnant rabbit was found to be asymmetrical, with more males being present in the left uterine horn and more females in the right (p<0.05).     

GSM无线网络性能测试及优化

GSM网络日渐成熟,规模日趋完善,而移动通信业务却在迅猛发展,无线网络的具体情况也在随着环境改变,如何利用现有的网络资源最大限度的提高网络质量,使得网络性能测试和优化成为一项长期而艰巨的任务。本文首先对网络性能测试方法进行阐述,然后针对可能出现的问题进行网络优化。     

红外物理与技术发展

经过长期探索，人们掌握了红外辐射的基本规律，不断研制出新型，优质红外探测器件，发展了红外光谱和红外成像等重要技术。并使之在当代许多领域，尤其在遥感，军事及其它高科技领域占据突出地位。     

台湾地区SCI论文数在世界中所处的位置及统计分析

台湾的科技发展得到了世界越来越多的关注，本文通过SCI收录台湾地区的科技论文，从发表机构、学科、参考文献以及台湾地区科技论文的被引用等情况，介绍台湾地区的科技论文产出情况，以便了解台湾地区在世界科技中的地位和影响。     

世界植物园的现状与展望

世界植物园的发展史，是一部人类加深认识、进行保护和扩大利用植物的历史。随着植物园数量的增长，植物园可分为综合性、园林和观赏园艺、经济植物及种质保存等类型。当前植物瞻的任务主要为植物多样性的保护、植物资源利用、展示教育与咨询和科学研究。由于植物资源的竞争更加激烈但规范化、管理更加现代化与科学化、植物园更加开放与联合，展望植物园今后的发展，可能将在植物园学和科学植物园、专类园建设及群落建园、植物园信息管理系统、虚拟植物园与科普、植物园网络化、推动植物资源可持续利用等方面不断加强与完善。     

Understanding algorithm aversion: When is advice from automation discounted?

Forecasting advice from human advisors is often utilized more than advice from automation. There is little understanding of why “algorithm aversion” occurs, or specific conditions that may exaggerate it. This paper first reviews literature from two fields—interpersonal advice and human–automation trust—that can inform our understanding of the underlying causes of the phenomenon. Then, an experiment is conducted to search for these underlying causes. We do not replicate the finding that human advice is generally utilized more than automated advice. However, after receiving bad advice, utilization of automated advice decreased significantly more than advice from humans. We also find that decision makers describe themselves as having much more in common with human than automated advisors despite there being no interpersonal relationship in our study. Results are discussed in relation to other findings from the forecasting and human–automation trust fields and provide a new perspective on what causes and exaggerates algorithm aversion.     

分子电子学

作为纳米电子学的一个重要分支，分子电子学在近年来得到了巨大的发展，并成为国际上研究的热点。本文介绍了各种分子器件的制作技术及基本工作原理，回顾了近年来分子电子学的最新进展，展望了分子电子学的未来发展。     

微观纤维增强高分子复合材料研究--分子复合材料的研究现状及展望

分子增强高分子复合材料由于其诱人的潜在工业应用前景而备受重视。本文就“分子复合材料”这一领域国内外的研究现状、存在的主要问题及未来发展的展望进行综述。     

Wall hydroxyproline and growth of georeactive roots (Zea mays L.)

Summary For the growing maize roots the increase of the content of wall hydroxyproline was related to a decrease of the root elongation and vice-versa. For the georeactive roots the wall hydroxyproline level was lower in the upper part which elongates more than the lower part containing more wall hydroxyproline.