关键词： Bacterial Proteins/chemistry   Bacterial Proteins/genetics   Bacterial Proteins/metabolism   Carbon Dioxide/metabolism   Cell Division   Cytoplasmic Structures/chemistry   Cytoplasmic Structures/enzymology   Cytoplasmic Structures/ultrastructure   Cytoskeleton/physiology   Diffusion   Gene Deletion   Genes, Bacterial   Genes, Bacterial   Recombinant Fusion Proteins/chemistry   Recombinant Fusion Proteins/metabolism   Ribulose-Bisphosphate Carboxylase/chemistry   Ribulose-Bisphosphate Carboxylase/chemistry   Ribulose-Bisphosphate Carboxylase/metabolism   Ribulose-Bisphosphate Carboxylase/metabolism   Synechococcus/genetics   Synechococcus/growth & development   Synechococcus/metabolism   Synechococcus/ultrastructure  

摘要： Cyanobacterial carbon fixation is a major component of the global carbon cycle. This process requires the carboxysome, an organelle-like proteinaceous microcompartment that sequesters the enzymes of carbon fixation from the cytoplasm. Here, fluorescently tagged carboxysomes were found to be spatially ordered in a linear fashion. As a consequence, cells undergoing division evenly segregated carboxysomes in a nonrandom process. Mutation of the cytoskeletal protein ParA specifically disrupted carboxysome order, promoted random carboxysome segregation during cell division, and impaired carbon fixation after disparate partitioning. Thus, cyanobacteria use the cytoskeleton to control the spatial arrangement of carboxysomes and to optimize the metabolic process of carbon fixation.

关键词： 动力传动装置   模块化   风机   机械   齿轮箱   接触模式   可靠性   应力和  

摘要： 时下模块化风机齿轮箱的可靠性是一个普遍存在的问题。为此，Maag开发和试制了一种新型Maag DPPV-7-79齿轮箱，在平衡刚度和柔性的基础上能更好地实现载荷的分配均匀，具有较小的应力和最佳齿轮接触模式。

关键词： 机械化   农村剩余劳动力转移   边际技术替代率  

摘要： 采用超越函数代表农业生产函数,从理论上推导了农业机械对劳动力的边际技术替代率;以湖北省为例,实证分析了农业产出对劳动力和机械的弹性、半弹性,计算了近30年湖北省农业机械对劳动力的边际技术替代率,据此分析了农业机械与劳动力的配置效率;同时,应用回归分析方法得出了劳动力转移对农业机械化的影响程度。

关键词： 履带车辆   大功率液力机械综合传动装置   动力传动一体化   换挡品质  

摘要： 通过对大功率液力机械综合传动装置的履带车辆动力传动一体化控制策略的研究和其控制方式的理论分析,提出了一种针对行星变速机构换挡过程中状态的分析方法,并针对某型履带车辆进行仿真验证.通过仿真分析验证了一体化控制策略的正确性和可行性,为履带车辆动力传动一体化控制的进一步研究提供了研究思路.

关键词： 混合动力系统   设计   仿真   工程机械   MATLAB/Simulink  

摘要： 阐述了工程机械混合动力系统设计原理,介绍了混合动力系统结构及设计方法,利用MATLAB/Simulink软件建立了整机动力学及发动机、电动机模型,并对传统动力系统和混合动力系统进行了仿真。仿真试验的对比结果表明,混合动力系统不仅能提高工作效率和降低燃油消耗,还可有效地减少环境污染,延长机械的使用寿命。

关键词： Glass transition   Hydrodynamic interactions   Intermediate scattering function   Mode-coupling equations   Molecular systems   Projection operator method   Self-diffusion   Suspensions of colloids  

摘要： A statistical-mechanical theory of slow dynamics near the glass transition in two kinds of glass-forming systems, (M) molecular systems and (S) suspensions of colloids, is presented from a unified point of view based on the Tokuyama-Mori projection operator method. The exact diffusion equations for the coherent- and the incoherent-intermediate scattering functions are first derived, whose memory functions are convolutionless in time and contain the correlation effects due to the hydrodynamic interactions in (S). The analytic expressions of the memory functions are then calculated within the mode-coupling theory (MCT) approximation and are shown to coincide with the conventional ones obtained by MCT. Alternative mode-coupling equations are thus obtained in (M) and (S) separately. Self-diffusion is also discussed. Alternative equations for the mean-square displacement and the non-Gaussian parameter are also derived within MCT approximation. All results in both the systems are compared with those obtained by MCT. (C) 2009 Elsevier B.V. All rights reserved.

关键词： 劳动力   转移   发展   农机化  

摘要： 劳务输出作为农民增收的重要手段之一，各级政府加大了对劳务输出的组织力度，拉动农民收入呈较快增长态势。随着留在农村的青壮劳动力减少，迫切需要加快发展农业机械化，促进农艺农机结合，降低劳动强度，不断提高农业劳动生产率。积极培育多种形式的农机服务组织和农机专业户，推动农机服务的市场化、专业化和产业化进程。

关键词： ANTIMONY   QUANTUM theory   ELECTRON distribution   SOLVATION   LIGAND binding (Biochemistry)   HYDROGEN bonding  

摘要： An ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulation was performed to investigate the behavior of the Sb3+ ion in aqueous solution. The simulation reveals a significant influence of the residual valence shell electron density on the solvation structure and dynamics of Sb3+. A strong hemidirectional behavior of the ligand binding pattern is observed for the first hydration shell extending up to the second hydration layer. The apparent domain partitioned structural behavior was probed by solvent reorientational kinetics and three-body distribution functions. The three-dimensional hydration space was conveniently segmented such that domains having different properties were properly resolved. The approach afforded a fair isolation of localized solvent structural and dynamical motifs that Sb3+ seems to induce to a remarkable degree. Most intriguing is the apparent impact of the lone pair electrons on the second hydration shell, which offers insight into the mechanistic aspects of hydrogen bonding networks in water. Such electronic effects observed in the hydration of Sb3+ can only be studied by applying a suitable quantum mechanical treatment including first and second hydration shell as provided by the QMCF ansatz.

关键词： 变速箱   控制分析   大型养路机械  

摘要： 德国ZF公司生产的4WG-65B2型变速箱配以完善的控制系统,应用于大型养路机械,具有操作简便、作业及运行安全系数高等优点,针对其挡位控制复杂、联锁精细、故障处理难度大的特点,从其挡位实现、挡位闭锁、性能联锁等方面进行了分析。

关键词： 单自由度   动力学   动态静力法   连杆机构  

摘要： 单自由度机械在生产实践中经常遇到,对于其动力学分析方法中的动态静力法进行了系统的介绍。给出了使用该方法进行动力学分析的详细步骤。通过用该方法来解决典型的反正弦连杆机械系统动力学问题,进一步阐述了该方法在进行机械动力学分析过程中的运用。