3-RPS并联机构奇异位形及工作空间研究

提出一种求解并联机构无奇异位形工作空间的方法。通过分析3-RPS并联机构在奇异位形时动平台的微分运动与结构约束及关节约束的关系，得到机构奇异位形判别方程和奇异位形曲面方程。探索了工作空间边界，综合分析了机构奇异位形与工作空间的关系。合理选择机构结构参数和关节变化范围，得到了无奇异位形的工作空间。     

发展农业机械化,建设社会主义新农村

现代化的农机装备作为先进的劳动工具,推动了生产力和文明社会的快速发展。建设社会主义新农村,农业机械化既是充要条件,又是必要条件;农业机械化是实现生产发展、生活宽裕、村容整洁、环境和谐的手段、条件、保证。没有农业的机械化,不可能有真正意义上的社会主义新农村建设。     

明甪直天王殿松木斗拱振动台试验研究

以甪直保圣寺天王殿斗拱为参考对象,进行无缩尺松木斗拱模型的地震台试验研究。通过对斗拱的加速度与动力放大系数变化趋势、斗拱在振动过程中位移响应变化特征、斗拱变形最大时刻和各构件变形最大时刻的滑移位移和回转位移数值对比分析,得出以下结论：地震加速度用于衡量地震烈度,并不能直接反映斗拱试件的最大变形;振动频率的变化对斗拱回转变形的变化起重要作用,振幅是决定各构件水平滑移的主要因素;各构件变形最大值与斗拱整体变形最大值具有很强相关性,其中栌斗和华拱的回转变形对斗拱的整体变形而言,处于支配地位;斗拱的华拱连下昂部分主要起装饰作用,其榫卯连接节点位置在振动过程中较为薄弱,在对实际文物维护修缮过程中应引起重视并采取相关加固措施。     

Measurements to Protect Owners'' Benefits under the Non-price Bottom Bidding

Investment on construction projects has become an important factor in improving the development of economy in China.The non-price bottom bidding is a representation that the investment on projects is becoming standardized.During the years of trying out the non-price bottom bidding,the colluding in bidding or bidding below the cost has happened several times,which have damaged the benefits of owners.To solve theses problems,this paper firstly studies the reason of these problems-the failure in the normal relationship between principal and agent.Then,some measures have been presented as follows: building systematic and scientific system of qualification prejudication,judging behaviors of colluding in bidding and bidding below the cost with reason and providing a surety mechanism of the project.The authors hope that these measures are beneficial to non-price bottom bidding.     

Analysis on Limitation of Present Urban Planning in China

In urban design, only by continuous and dynamic research work from design to finally putting it into practice, can we made good control on city appearance. This article analyzes nowadays defects in our urban design from two aspects as the result establishment and validated control, and tries to conceive a feasibility plan to solve the problem.     

Current Status of DIMOX in Synthesizing Al/Al2O3 by Aluminum Alloy

The processes, microstructures, properties and mechanisms of DIMOX in synthesizing Al/Al 2O 3 by Al-Mg-Si alloy are reviewed and their problems are considered mainly as following:non_homogeneous oxidation growth of Al/Al 2O 3 at the surface of melts and the porosity of Al/Al 2O 3 limites structural application of Al/Al 2O 3 composite. The mechanisms and models of microchannel,magnesium action,silicon action,and induction are outlined. Several problems which need to be noticed are pointed out,which are diffusion and transfer of oxygen in aluminium melts;the role of MgO and MgAl 2O 4 at outer layer;the reaction feature of solid_gas in the oxidation microstructures of Al_Mg_Si alloy;SiO 2 induction mechanism of silicon and its correlation with the mechanism of magnesium action in Al_Mg_Si alloy.     

Mechanism and Progress About Protein Crystal Growth by Atomic Force Microscopy

Atomic Force Microscopy(AFM) plays a very important role in researching crystal growth mechanism, especially protein crystals. The principle of AFM for protein crystal examination is briefly described as well as the importance of research on protein crystal growth, known growth mechanisms including 2-D steps nucleation, spiral dislocation, normal growth, 3-D nucleation and anisotropic development, and latest progress about eucommia antifungal protein(EAFP) and Trichosanthin(TCS) protein crystal growth mechanism, respectively. Finally, protein growth under microgravity environment is also expounded here and their development tendency and practical prospect.     

建立农产品质量安全市场准入机制的原则及措施分析

随着《中华人民共和国农产品质量安全法》的深入实施,中国农产品质量安全准入制度的建立势在必行,而建立良性的准入机制是各项制度有效运转的根本。该文从建立良性的农产品质量安全市场准入运行机制、建设有效的技术支撑体系、加强财政政策扶持等方面入手,提出了建立农产品质量安全市场准入机制的措施和建议。     

内毒素对肠黏膜微血管内皮细胞内分泌一氧化氮和内皮素的影响

目的是研究内毒素（lipopolysaccharide; LPS）导致肠黏膜微血管内皮细胞损伤的作用机制。将所培养的肠黏膜微血管内皮细胞分为空白对照组和LPS组，每组按时间分为4个亚组：3h、6h、9h、12h。空白对照组加维持培养液，LPS组加1μg/ml LPS培养液，在CO2培养箱内静置培养。结果表明，一氧化氮（NO）分泌明显升高，3h后达到高峰，随后逐渐降低，而内皮素（endothelin; ET）分泌急剧升高，9h后达到高峰，随后又开始逐渐降低，但一直保持在较高的水平。所以引起了NO和ET的升高可能是LPS导致肠黏膜微血管内皮细胞的损伤机制。     

高等院校农业科技推广人员激励模式初探

农业科技推广是实现科技成果转化的重要桥梁,是联系科研、教育、生产的重要纽带,是促进农业技术进步、实现农业现代化的重要手段。以大学为依托的农业推广体系,是对以政府为主体的推广体系的有效补充。通过对高等农业院校推广队伍存在的主要问题进行分析,提出了建立推广人员物质激励与精神激励两种模式,并进行了具体分析。