奶牛过瘤胃液中氨基酸的研究进展

本文综述了奶牛过瘤胃液氨基酸的概念、分类、检测方法、应用效果、影响因素及存在的问题和应用前景     

Quantitative measurements in in situ straining experiments in transmission electron microscopy

Several examples of recent studies by in situ straining experiments in a transmission electron microscope performed in the Toulouse group (France) are presented. In particular, quantitative measurements of the features of the dislocation motion are described. These examples deal with individual or collective propagation of dislocations, which are submitted to various types of obstacle. Different metallic materials are investigated: magnesium, intermetallics, aluminium alloys and γ phase of a superalloy.     

“中国制造”的发展趋势

<正>"中国制造"成为了眼下一大热门话题。近期相关媒体采访了几位我国著名的品牌问题研究专家,聆听专家们对我国目前品牌产品发展现状和未来发展的看法与建议。本刊将专家的观点经整理提供给大家,希望能对企业有所帮助。     

有限元分析网格划分的关键技巧

从灵活确定网格参数、有机把握网格质量和及时进行网格质量检查等3方面说明有限元分析中网格划分的关键技巧,网格参数包括单元格长度、网格数量和网格疏密程度,灵活确定网格参数是达到有限元分析精度和效率结合最佳化的关键因素.     

中国创造与工业设计

本文通过对“中国制造”现象的分析,阐述了设计作为一项基本国策的紧迫性,并认为工业设计是提升企业国际竞争力的主要途径之一。21世纪的国际竞争实质是设计和创新的竞争。只有实现由“中国制造”向“中国创造”的跨越,才能使我国在国际经济竞争中赢得主动权和市场份额。     

罗红霉素大鼠体内消除过程中的立体选择性

罗红霉素(Roxithromycin,RXM)化学名为(9E)-{O-[(2-甲氧基乙氧基)甲基]肟基}红霉素,是1990年代初投入使用的新型大环内酯类抗生素.与红霉素相比,虽有相似的体外抗菌谱,但其耐酸稳定性、胃肠道吸收、组织和体液中药物浓度均较高,因而具有更好的抗菌效能.     

我国拖拉机标准回顾与展望

我国的拖拉机生产从20世纪50年代后期引进国外样机开始。经历了前期仿制、自行研制、技术引进和自主开发几个阶段。拖拉机标准也随之蓬勃发展。经过50多年的发展,我国拖拉机行业已形成以全国拖拉机标准化技术委员会为基本活动单元的行业标准化工作体系。目前我国有关拖拉机的各类标准总计210项。其中国家标准114项,机械行业标准93项。其他行业标准三项。在与拖拉机有关的88项国际标准中。修改或等同采用国际标准及国外先进标准58项。国际标准的转化率达65．9％。本期,我们特邀全国拖拉机标准化技术委员会秘书长尚项绳、中国农业机械学会拖拉机学会陈英超、江苏常发集团农业装备公司品质部长廖汉平、常州东风农机集团有限公司质量总师苏东林对拖拉机行业及标准发展．以及企业自身建设做详细介绍。     

Some recent progress in microtribology in Japan

The micro in the word of microtribology is defined as science and engineering supported by modern physics and chemistry. In the engineering area, the ultimate goal of microtribology is to create practical zero-wear devices. The importance of microtribology was recognized by Japanese scientists and engineers in the latter half of the 1980s, and much progress has been made in microtribological studies of mechanisms of friction, lubrication with very thin liquid films, and microwear processes.     

Lubrication in steel strip rolling in Japan

Research into, and the state of technology for, lubrication in steel strip rolling in Japan are reviewed. Both cold and hot strip rolling are discussed. Subjects covered include coefficient of friction and oil film thickness, friction pick-up, and roll wear.     

在多元中融通 在理解中共生——多元文化背景下的国际理解教育

多元文化的态势随着全球化的加剧日趋明显,各类文化的共生共荣需要通过国际理解教育的推动而实现。国际理解教育的要义在于培养国际理解精神、创建和平文化、推动和平、人权和民主以及促进理解、尊重及共同发展。在多元文化背景下,学校实施国际理解教育不仅有助于培养学生的世界公民意识、文化多元意识,而且有助于激发学生的民族认同感和民族自豪感、形成学生的平等观和关爱心并促进学生道德水准的实质提升。国际理解的达成需要在知识掌握、视野扩展、充分了解中,在扩大开放、增进交流、平等对话中,在环境浸淫、生活体验及实际行动中实现。     

Bielayev's point in poroelastic bodies in contact

In two elastic bodies in contact the point of the maximum stressing is found at some depth below the surface of contact. This point, called Bielayev's point, is examined in the case when the extremities of the bodies in contact are spherically shaped and the material is poroelastic. Such a viscoelastic model can simulate bone articulation. It is found that the location of Bielayev's point, evaluated on the basis of the energy strength hypothesis, changes insignificantly with time. However, the stressing to which the material is subjected is the most intense at the moment of the (sudden) application of load.     

我国泵CAD发展中的几个问题

综述了我国泵CAD的发展过程和技术特点，以及起步，发展和完善等三个发展阶段，泵CAD技术有人机交互设计，功能模块化和数据管理等内容，分析了泵CAD技术存在的不足，提出了新世纪泵CAD的发展方向。     

地球科学中热电离质谱法的进展

对应用于地球科学领域的几种热电离质谱新方法的进展进行了综述,包括Sr、Nd同位素稀释分析的分馏校正、Re—Os负离子质谱法、热电离质谱铀系法、B、Cl稳定同位素测定及La—Ce法。     

Light transport in single-crystal scintillation detectors in SEM

A Monte Carlo simulation method was developed to determine the efficiency of photon transport through a modified rotationally symmetric Everhart-Thornley detector. The method makes use of the random generation of photon emission from a luminescent centre and describes the trajectory of photons and the efficiency of their transport toward the photocathode of the photomultiplier tube. The model includes photon generation in a point source, mirror reflection by a metal-coated surface, Fresnel reflection by a metal-uncoated surface, Fresnel passage through the boundary of different materials, diffusion reflection, and passage through a matted surface and optical absorption in material. For the simulation, an IBM-PC-compatible program was written and applied to detection systems with disc, conical, and hemispherical YAG:Ce single-crystal scintillators with cylindrical or tapered light guides or without any light guide. The model was verified by measuring the efficiency of detection systems excited by the primary electron beam in the line-scan SEM mode.     

2005年美国市场投资预测

由中国机床工具工业协会事先组织安排，在IMTS2004期间，美国GARDNER出版公司为机床协会组织的由用户和会员企业领导组成的代表团作了有关美国市场方面的报告，内容包括美国2005年投资预测、推进媒体在当今社会中起到的重要作用以及如何在美国选择经销商三个主题。     

Podocyte electrophysiology,in vivo and in vitro

Podocytes are the most differentiated cell types in the glomerulus, which have been assumed to participate in the regulation of the ultrafiltration coefficient K(f). In podocytes in vivo and in vitro vasoactive agonists, such as angiotensin II and acetylcholine, increase the free cytosolic Ca(2+) concentration via a release of Ca(2+) from intracellular stores and an influx of Ca(2+) from the extracellular space. An increase of the cytosolic Ca(2+) in podocytes activates Cl(-) channels in podocytes in vivo and in vitro, resulting in a depolarization of podocytes. In vitro studies have shown that in addition to Ca(2+)-activated Cl(-) channels, cAMP-activated Cl(-) channels and Ca(2+)-activated K(+) channels are present in cultured podocytes. The characterization of the signaling pathways that regulate ion channels in podocytes may be important in the understanding of the regulation of the ultrafiltration coefficient K(f). This review summarizes the currently known electrophysiological properties of podocytes.