我国博士生合理学制探讨

博士生学习年限长短是管理者、教育者和受教育者所共同关心的问题。研究发现,我国的博士生学制规定具有较为明显的历史阶段性特征;实行弹性学制、自行确定博士生修业年限已成为高校的共识和普遍性做法;博士生获得学位的平均学习年限已从十年前的三年半左右延长到目前的四年半左右,博士生的实际修业年限已经普遍延长。据此,将博士生基本学制调整为4年,进而完善博士生管理规定、合理配置教育资源,符合当前我国博士生培养和管理的实际,是促进博士生培养质量的有效策略。     

比利时IMEC等开发出60μm厚的柔性三维封装技术

比利时研究机构IMEC开发出了厚度不足60μm的柔性三维封装“ultra—thin chip package（UTCP）”，并在2009年3月10-11日于比利时举行的“SMART SYSTEMS INTEGRATION 2009”上发布。     

拓展领域规划未来

在第五届中国CAE工程分析技术年会上,我刊记者采访了LMS国际公司北京代表处的石银明博士. LMS国际公司1980年成立于比利时鲁文市(Leuven),源于世界模态分析技术研究的中心-比利时鲁文大学,是汽车、航天、航空领域及其它先进制造领域的工程创新的强力合作伙伴.     

天一药业生物品出口比利时

日前，比利时驻华使馆商务参赞呼伯特来哈出席了中国天一医药集团与比利时生物医药企业签订战略合作框架协议签字仪式。这是哈尔滨市生物制药领域企业首次将生物高科技产品出口到比利时，并将进一步扩大到其他欧盟国家。     

天一药业生物品出口比利时

日前,比利时驻华使馆商务参赞呼伯特来哈出席了中国天一医药集团与比利时生物医药企业签订战略合作框架协议签字仪式。这是哈尔滨市生物制药领域企业     

人物

Hans Bijl先生西门子自动化和驱动集团比利时Antwerp制药技术中心市场经理Hans Bijl先生负责西门子自动化和驱动集团位于比利时Antwerp的制药技术中心在中国大陆的业务拓展。     

明确方向 攻克难关——访南京航空航天大学刘志东教授

正刘志东:工学博士,教授,博士生导师。现任南京航空航天大学教授、博士生导师,担任中国机械工程学会全国特种加工分会常务理事,全国特种加工分会电火花线切割专业委员会副主任委员,江苏省第六届特种加工学会理事长。研究领域:电火花加工、激光表面处理、电化学沉积等特种加工技术研究,以及高阻半导体材料的电火花加工,钛合金电火花高效、高精成形加工方面的研究工作。研究成果:在特种加工领域30余年的工作和实践中先后研制出:封闭式电火花线切割机床、六连杆摇动大锥度电     

自组生长新纳米材料

湖南大学博士生导师唐元洪教授课题组率先合成自组生长的硅纳米管，标志着我国在纳米材料研究方面取得重大突破。     

本刊特邀编委名单

(以姓氏笔画为序)万遇良王,志新方明伦李京平齐智平蒋晓华蔡建国缪其浩中国科学院电工技术研究所机电控制工程研究发展中心研究员上海交通大学电气工程系教授上海大学常务副校长,教授,博士生导师上海市机械自动化及机器人重点实验室主任北京联合大学信息工程学院副教授中国科学院电工技术研究所研究员,博士生导师中国电工技术学会机电一体化专业委员会主任清华大学教授,博导上海交通大学机械工程系教授,博士生导师上海图书馆上海科学技术情报研究所副馆所长本刊特邀编委名单     

第三届机械工程博士论坛在长沙召开

中国工程机械学会于2011年10月14日-16日在湖南长沙举办了机械工程学科第三届博士生论坛，原定参会人员在50人内，由于各校博士生踊跃投稿，根据投稿情况，经审定挑选了60篇编入《第三届机械工程博士论坛论文集》，到会宣读论文的有22所大学的博士生56人，内容涉及机械设计、制造、材料、表面工程及运行状态监测等。     

Distribution of sex steroid hormone receptors in the avian brain: functional implications for neural sex differences and sexual behaviors

Developmental and seasonal changes in the production of androgens, estrogens, and progestins seem to control sex-specific differentiation and seasonal changes in appetitive and consummatory sexual behaviors of birds. This results in profound sex differences in the quality (sex-specific) or quantity (sex-typical) of behaviors such as courtship, territoriality, or copulation. Steroids affect the brain by binding to intracellularly located receptors. The same brain areas express androgen, estrogen, and progesterone receptors in male and female brains. Sex differences in these genetically determined patterns occur in the size of neuron populations that intrinsically express sex steroid receptors. Further permanent sex differences are subsequent to degenerative fates of receptor expressing neuron populations during ontogeny. Transient sex differences in receptor expression appear to be due to area-specific up- and down-regulation of receptor levels, reflecting transient changes in the level of circulating steroids, changes in environmental conditions, or in the physiological status of the individuals. In particular, intrinsic sex differences in the expression pattern of sex steroid receptors and steroid-independent regulation of the expression level of these receptors in the brain are limiting mechanisms for gonad-dependent sexual development and activities.     

牛顿流体和非牛顿流体教学演示仪器的开发研究

牛顿流体和非牛顿流体存在着较大的差异,有关牛顿流体和非牛顿流体特性差异方面的教学演示仪器还较少,有些还处于空白。为了加强学生对牛顿流体和非牛顿流体的认识,本文根据牛顿流体与非牛顿流体流动特性差异,设计制作了表现牛顿流体和非牛顿流体层流流速分布差异的演示仪器;利用自行研制的示踪液体演示了非牛顿流体和牛顿流体运动过程,直观的展示了牛顿流体与非牛顿流体层流流速分布的差异。     

南昌自动站和人工站温度观测结果差异分析

新旧两种观测体制造成两种观测方法的观测结果差异是必然的。为确保历史观测资料的均一性,本文对自动站和人工站的温度观测结果进行了比对和质量评估。从统计学角度,对南昌站2008年的623组观测资料进行了分类比较,得出了不同天气状况下两者差异的变化规律、频率分布规律和日年变化规律。同时,从气象学角度,分析了产生差异的原因。     

旋涡风机前向和后向叶轮特性对比研究

利用CFD软件分别对前向和后向叶轮旋涡风机的单个叶道进行流场分析,得到前向和后向叶轮单个叶道的压力性能差异.然后进行试验研究,得到前向和后向叶轮整体的压力性能差异.     

液化天然气商用车与柴油商用车生命周期能耗差异评价

从生命周期视角,研究了液化天然气（liquefied natural gas,LNG）商用车与柴油商用车在材料制备、零部件加工制造、整车装配、使用、回收利用等整个生命周期各阶段的能源消耗差异,建立了LNG商用车与柴油商用车能耗差异评价模型,并利用该模型对某LNG搅拌车和柴油搅拌车的直接能耗差异和生命周期总能耗差异进行了实证研究。结果表明,LNG搅拌车具有节能优势。     

Sex differences in songbirds 25 years later: What have we learned and where do we go?

About 25 years ago, Nottebohm and Arnold reported that there are profound male-biased sex differences in volume in selected nuclei in telencephalic portions of the song control system. This review focuses on issues related to the cellular bases of these sex differences in volume and comparative studies that might elucidate the function of this variation between the sexes. Studies utilizing a variety of neurohistological methods in several different species to define the boundaries of two key telencephalic song nuclei HVc and the robust nucleus of the archistriatum (RA) all tend to find a sex difference in volume in agreement with Nissl-defined boundaries. Sex differences in volume in nuclei such as HVc and RA are associated with differences in cell size and cell number. Other attributes of the phenotype of cells in these nuclei are also different in males and females such as the number of cells expressing androgen receptors. Comparative studies have been employed to understand the function of these sex differences in the brain. In some songbird species, females sing rarely or not at all, and the brain nuclei that control song are many times larger volume in males than females. In other species, males and females sing approximately equally, and the brain nuclei that control song are approximately equal between the sexes. Recently, statistical methods have been employed to control for phylogenetic effects while comparing the co-evolution of traits. This analysis indicates that the evolution of sex differences in song has co-evolved with the evolution of sex differences in singing behavior in songbird species. Future studies should focus on the function of the smaller song control nuclei of females and investigate the role these nuclei might play in perception as well as in production. Microsc. Res. Tech. 54:327–334, 2001. © 2001 Wiley-Liss, Inc.     

A quantitative interference light microscope study of human first trimester chorionic villi

Using a Jamin-Lebedeff-type interference microscope an analysis of frozen sections of human first trimester chorionic villi reveals regional differences down to subcellular resolution. The evidence indicates compositional differences between villus cell types and shows that the syncytiotrophoblast is differentiated into at least three layers, one of which corresponds positionally to the previously described syncytioskeletal layer. Quantitative measurements have been made of specimen thickness, refractive index and dry mass of regions in the tissue. Local differences in syncytiotrophoblast have been noted with respect to the content of a population of organelles with distinctive optical properties. These may correspond to stored forms of steroid hormone or their precursors.     

Accuracy investigation of height obtained from Classical and Network RTK with ANOVA test

To assess the accuracy of vertical components obtained by Classical RTK and Network Real Time Kinematic positioning with different correction methods with setting of different number of epoch, height differences obtained from precise geometric leveling was used as reference height differences along with those obtained from static GPS only solutions, and combined solutions of GPS and GLONASS on different GNSS days. One-way variance analysis (ANOVA) were applied to the height differences to test them whether they are significantly different or not. The significant differences, if any, were further tested by using Post Hoc test to reveal the effects of the method used, the epoch number, or the measuring time, which is responsible for the significant differences. The results from ANOVA showed that the number of epoch had not much effect on the vertical components but on the correction methods. MAC method presented the most deviated results compared to the other methods with different GNSS days’ solutions. In general, VRS method was found to be the most consistent method among others used. This study is important in both; an accuracy assessment with respect to the most precise method in heights (i.e., precise geometric leveling) was carried. The techniques (ANOVA and Post Hock Test) used in the accuracy assessment.     

Atomic force microscopy analysis of enveloped and non-enveloped viral entry into, and egress from, cultured cells

Since its invention, the atomic force microscope has been used to image a wide variety of biological samples, including viruses. Viral entry into, and egress from, cultured cells has been extensively studied using numerous scientific techniques and to a limited extent using atomic force microscopy. One of the main structural differences that can exist between viruses is the absence, or presence, of an envelope and this factor has consequences for the mode of viral entry and egress. In this study, the entry into, and egress from, cultured cells of enveloped and non-enveloped viruses were investigated using atomic force microscopy. No significant cell surface changes were observed following infection with enveloped or non-enveloped viruses. Although roughness analysis of viral entry revealed cell smoothing post-infection, no differences between the roughness values of enveloped and non-enveloped viral entry were observed. Line analysis of viral entry revealed minor differences between cells infected with an enveloped rather than a non-enveloped virus. These differences may represent a distinction between the uptake processes of enveloped and non-enveloped viruses. Studies of viral egress revealed that infected cells were undergoing cytopathic changes. Whilst topographic, height and roughness differences clearly occurred between virally- and mock-infected cells, no significant differences were elucidated between enveloped and non-enveloped viral egress.     

The wear of diamond tools turning mild steel

Previous experiments on the wear of diamond tools turning mild steel have shown that the very high rates of wear of the diamond arise from the degeneration of the diamond to graphite, the details of the wear mechanisms depending on the cutting conditions. The present experiments on a larger number of tools show much greater differences in the wear rates of different diamonds than have been reported previously. It appears probable that these differences in wear rates arise from differences in the chemical constitution of the diamonds.