Changes in physical features of Glacier No. 1 of the Tianshan Mountains in response to climate change

This study analyzes the changes in glacier zones and snow composition of Glacier No.1 in the Tianshan Mountains of China since 1961,and their possible relations with climate.It is found that precipitation dominated the snow composition and that air temperature and precipitation controlled the distribution of glacier zones,but interannual change in precipitation had a relatively large effect on glacier zones and snow composition during 1963–1981 (P10) and 1963–1989 (P11).However,during 1982–2007 (P20) and 19...     

Ti-MCM-41分子筛对苯酚羟化反应的催化性能研究

本文用自合成的Ti-MCM-41分子筛为催化剂,苯酚和H2O2直接氧化法合成苯二酚。用化学分析和色谱分析来确定H2O2的分解率、利用率、苯酚的转化率、苯二酚的选择性。反应温度70℃、反应时间7h、进料比：n（苯酚）In（H2OM2）=3：1;n（苯酚）／n（Ti-MCM-41）=10：1是较为理想的条件。     

MCP-1在子痫前期患者胎盘组织及血清中的表达及意义

通过比较单核细胞趋化蛋白-1（MCP-1）在正常孕妇和子痫前期患者胎盘及血清中的表达,探讨MCP-1在子痫前期发病机制中的作用。选取30例正常晚孕妇女、30例轻度子痫前期患者和30例重度子痫前期患者进行研究。采用免疫组织化学S P法检测MCP-1在胎盘组织中的表达;采用酶联免疫吸附法（ELISA）检测血清MCP-1水平。结果：子痫前期患者胎盘组织和血清中MCP-1的表达均高于正常妊娠组,差异有统计学意义（P〈0.01）,且随着病情加重而递增;子痫前期患者胎盘组织MCP-1表达与血清MCP-1水平呈显著正相关（r=0.725,P〈0.01）。结果表明,MCP-1在子痫前期患者胎盘与血清中的表达均升高,提示MCP-1在子痫前期的发生、发展中可能起着重要的作用。     

芳香单氮氧化物与丙烯酸稀土配合物的合成及荧光性质

合成了８种稀土（Ｌａ－Ｔｂ）丙烯酸盐与邻菲罗啉单氮氧化物（ＰｈｅｎＮＯ）的三元固体配合物,通过元素分析确定其组成式为ＲＥ（Ｃ２Ｈ３ＣＯ２）３·（ＰｈｅｎＮＯ）,研究了它们的红外光谱、紫外光谱及荧光光谱,探讨了配体对该配合物荧光性质及稳定性质的影响。     

A major metabolite of Δ1-tetrahydrocannabinol reduces its cataleptic effect in mice

Summary The results described here demonstrate that THC-induced catalepsy in mice can be substantially inhibited by the prior administration of ¹-THC-7-oic acid, the major metabolite of THC in most species including humans. This raises the possibility that the intensity and duration of action of THC may depend to a large degree on the levels of this metabolite at the sites of action.We thank the National Institute on Drug Abuse for supporting this project by grants DA-02043 and DA-02052 and for supplying all of the cannabinoids. One of us (S.B.) is also the recipient of a Research Scientist Award from NIDA. We are grateful to Kristen Carlson and Thomas Honeyman for helpful suggestions in preparing this report.     

CD1d and natural T cells: how their properties jump-start the immune system

Cellular and humoral immune mechanisms recruited to defend the host from infectious agents depend upon the early immune events triggered by antigen. The cytokine milieu within which the immune response matures is the most important of many factors that govern the nature of the immune response. Natural T cells, whose function is controlled by CD1d molecules, are an early source of cytokines that can bestow type 1 or type 2 differentiative potential upon helper T lymphocytes. This review attempts to illuminate the glycolipid antigen presentation properties of CD1d, how CD1d controls the function of natural T cells and how CD1d and natural T cells interact to jump start the immune system. CD1d is postulated to function as a sensor, sensing alterations in cellular lipid content by virtue of its affinity for such ligands. The presentation of a neo-self glycolipid, presumably by infectious assault of antigen-presenting cells, activates natural T cells, which promptly release pro-inflammatory and anti-inflammatory cytokines and jumpstart the immune system. Received 10 July 2000; received after revision 16 October 2000, accepted 16 November 2000     

Sphingolipids in mammalian cell signalling

Sphingolipids and their metabolites, ceramide, sphingosine and sphingosine-1-phosphate, are involved in a variety of cellular processes including differentiation, cellular senescence, apoptosis and proliferation. Ceramide is the main second messenger, and is produced by sphingomyelinase-induced hydrolysis of sphingomyelin and by de novo synthesis. Many stimuli, e.g. growth factors, cytokines, G protein-coupled receptor agonists and stress (UV irradiation) increase cellular ceramide levels. Sphingomyelin in the plasma membrane is located primarily in the outer (extracellular) leaflet of the bilayer, whilst sphingomyelinases are found at the inner (cytosolic) face and within lysosomes/endosomes. Such cellular compartmentalisation restricts the site of ceramide production and subsequent interaction with target proteins. Glycosphingolipids and sphingomyelin together with cholesterol are major components of specialised membrane microdomains known as lipid rafts, which are involved in receptor aggregation and immune responses. Many signalling molecules, for example Src family tyrosine kinases and glycosylinositolphosphate-anchored proteins, are associated with rafts, and disruption of these domains affects cellular responses such as apoptosis. Sphingosine and sphingosine-1-phosphate derived from ceramide are also signalling molecules. In particular, sphingosine-1-phosphate is involved in proliferation, differentiation and apoptosis. Sphingosine-1-phosphate can act both extracellularly through endothelial-differentiating gene (EDG) family G protein-coupled receptors and intracellularly through direct interactions with target proteins. The importance of sphingolipid signalling in cardiovascular development has been reinforced by recent reports implicating EDG receptors in the regulation of embryonic cardiac and vascular morphogenesis. Received 16 May 2001; received after revision 29 June 2001; accepted 3 July 2001     

2010年高性能计算机排行榜对比分析

为了更好地掌握全球高性能计算机技术的发展态势,从而为政府决策提供有力支撑,有必要对国内外高性能计算机领域的主要动向进行总结.在综合相关文献资料的基础上,对比世界超级计算机TOP500排行榜与中国高性能计算机TOP100排行榜,可以发现,由于系统性能的快速提高,排行榜中的高性能计算机更新很快.中国的“天河一号”荣登TOP500排行榜榜首,表明中国高性能计算技术进入世界先进行列.本文从总体性能、技术演进、能效、国家分布、制造商格局等角度,对国内外高性能计算机的发展现状进行对比分析,并对其发展趋势进行预测,以图对我国高性能计算科学技术的发展提供借鉴.     

系统解耦的一种设计方法

本文给出了在多输入多输出的非解耦系统中,采用单位输出负反馈的系统结构,并且系统前向通路串入解耦补偿器组.可实现系统解耦的一种方法.并分析了系统的解耦条件和解耦补偿器的作用原理,给出了解耦补偿器传递矩阵 G,(s)的计算公式和设计方法.     

玉米发芽、初期生育期生长发育分析

本文利用干物质生产与幼苗形态特征相结合的研究方法,对王米发芽、初期生育期进行了生长发育分析。按营养方式,将该期划分成异养、异养和自养并进及完全自养三个生长阶段。干物质的分配有中心从地上部向根系转移的过程。地上部与根系生长之间存在着明显的相互影响。对各器官干物质变化的过程给出最优方程形式予以模拟。这一时期农业生产应以如何促进幼苗自养能力的尽快建立为中心。