精密与超精密磨削的发展现状

介绍了精密磨削与超精密磨削的机理,阐述了精密磨床以及精密磨削与超精密磨削技术的研究现状,并分析了精密磨削与超精密磨削的发展趋势.     

大理百合的离体快繁研究

以大理百合的鳞片为外植体进行离体培养,获得再生植株,并初步建立起快速繁殖体系．结果表明：大理百合鳞片适宜诱导芽和愈伤组织的培养基MS＋0．5mg／LBA＋0．1～0．5mg／LNAA＋3％蔗糖;增殖培养基为MS＋0．5mg／LBA＋0．05～0．1mg／LNAA＋4．5％蔗糖;生根结鳞茎培养基为1／4MS＋0．01mg／LNAA＋6％蔗糖＋10mg／LCCC．     

BAX activation is initiated at a novel interaction site

BAX is a pro-apoptotic protein of the BCL-2 family that is stationed in the cytosol until activated by a diversity of stress stimuli to induce cell death. Anti-apoptotic proteins such as BCL-2 counteract BAX-mediated cell death. Although an interaction site that confers survival functionality has been defined for anti-apoptotic proteins, an activation site has not been identified for BAX, rendering its explicit trigger mechanism unknown. We previously developed stabilized alpha-helix of BCL-2 domains (SAHBs) that directly initiate BAX-mediated mitochondrial apoptosis. Here we demonstrate by NMR analysis that BIM SAHB binds BAX at an interaction site that is distinct from the canonical binding groove characterized for anti-apoptotic proteins. The specificity of the human BIM-SAHB-BAX interaction is highlighted by point mutagenesis that disrupts functional activity, confirming that BAX activation is initiated at this novel structural location. Thus, we have now defined a BAX interaction site for direct activation, establishing a new target for therapeutic modulation of apoptosis.     

辽西化石研究大事纪

以辽西朝阳为中心发源地的热河生物群,迄今为止,已知的化石种类包括约100多种脊椎动物、300多种无脊椎动物、60多种植物．种类繁多、数量之大,世界罕见．发现表明：该地区极有可能既是鸟类起源和早期演化区域,也是某些哺乳类、鱼类和昆虫类群的起源和演化中心．此研究成果涉及现代生物界许多重要生物门类的起源和早期演化问题,为探讨地球陆相生态系统的演变过程和规律也提供了难得的线索和例证．     

The methylated component of the Neurospora crassa genome

Cytosine methylation is common, but not ubiquitous, in eukaryotes. Mammals and the fungus Neurospora crassa have about 2-3% of cytosines methylated. In mammals, methylation is almost exclusively in the under-represented CpG dinucleotides, and most CpGs are methylated whereas in Neurospora, methylation is not preferentially in CpG dinucleotides and the bulk of the genome is unmethylated. DNA methylation is essential in mammals but is dispensable in Neurospora, making this simple eukaryote a favoured organism in which to study methylation. Recent studies indicate that DNA methylation in Neurospora depends on one DNA methyltransferase, DIM-2 (ref. 6), directed by a histone H3 methyltransferase, DIM-5 (ref. 7), but little is known about its cellular and evolutionary functions. As only four methylated sequences have been reported previously in N. crassa, we used methyl-binding-domain agarose chromatography to isolate the methylated component of the genome. DNA sequence analysis shows that the methylated component of the genome consists almost exclusively of relics of transposons that were subject to repeat-induced point mutation--a genome defence system that mutates duplicated sequences.     

体育游戏在田径术课教学中的应用

针对我国在田径术课的教学中内容枯燥、形式单一、教学方法落后的现状,对体育游戏在田径术课中的作用、特点、方法及组织教法进行综合分析。结果发现:体育游戏能够有效地改变传统的体育教学模式,丰富教学内容,完善教学方法,提高教学质量,以及实现健身和娱乐等功能。     

贵阳市乌当区将军滩果园场含硒水果生产的初步分析

对将军滩果园示范场的含硒水果的自然条件、生产现状等作初步分析 ,论述该场种植含硒产品的适宜性及可行性 ,找出存在的问题及提出解决问题的建议。     

高师教育实习与基础教育课程改革的对接

《基础教育课程改革纲要（试行）》不仅对基础教育课程改革提出了新的思路,而且对高等师范教育的教育理念、教学实践提出了新的挑战。面对基础教育课程改革,高师教育实习必须在教育价值观、教学观、课程观、学生评价观等方面更新理念,采取有效模式,突出主体性、过程性、职业性,尽快实现与基础教育课程改革的对接。     

地下水流对冻结壁形成影响的数学模型建立

采用多孔介质热运移理论建立了考虑地下水流时冻结壁发展的数学模型,可用于数值模拟研究地下水流对冻结壁形成的影响。     

基于MATLAB的机构位置问题的牛顿法数值求解

四连杆机构的位置问题涉及非线性超越方程组的建立与求解,介绍了四连杆机构位置方程的建立,提出了利用牛顿数值法求解该问题的一种方法,编制了MATLAB求解程序,较好地解决了这个问题．