t-Haplotypes of the mouse may involve a change in intercalary DNA.

The naturally occurring t-haplotypes of the mouse exhibit a set of peculiar genetic properties, including strong suppression of crossing over in the segment of chromosome 17 between the loci of T and H--2. Study of the genetics of mutant haplotypes suggests that the observed effects on meiosis and embryonic development may be due to an altered form of intercalary DNA (iDNA) in the relevant chromosomal region (band 17B).     

Identity of cells that imprint H-2-restricted T-cell specificity in the thymus

The thymus has two important roles in controlling the specificity of T lymphocytes. First, T cells differentiating in the thymus are rendered tolerant of 'self' antigens, particularly antigens encoded by the major histocompatibility complex, the H-2 complex in mice. Second, the thymus imbues T cells with the property of H-2-restricted recognition of antigen, that is, the capacity of T cells to react with foreign antigens presented in association with self H-2 gene products. Until recently it has generally been assumed that self-tolerance and H-2-restricted specificity both reflect early T-cell contact with self H-2 determinants expressed on thymic epithelial cells. Recent evidence suggests, however, that intrathymic cells of the macrophage/dendritic cell (Mphi/DC) lineage also have a role in shaping T-cell specificity. In particular, it has been found that the tolerance to graft-type H-2 determinants which normally ensues when T cells differentiate in an H-2-different thymus fails to occur when the thymus is pretreated with deoxyguanosine (dGuo), a procedure that selectively destroys Mphi/DC but spares epithelial cells. In contrast to these findings on tolerance induction, evidence is presented here that dGuo-treated thymus grafts do imprint T cells with H--2-restricted specificity for antigen. It appears, therefore, that induction of tolerance and H--2 restriction are controlled by different cells in the thymus.     

锅炉摆动式喷燃器的炉膛传热数学模型和仿真

以ＤＧ－１０００Ｔ／Ｈ－１７０ａｔａ－Ｉ型锅炉为研究对象，建立了喷燃器摆角变动时锅炉炉膛的数学模型，探讨了喷燃器角度变化时炉膛热负荷分配对主汽温的影响，此外，在数字计算机上进行了仿真，同时验证了模型的合理性。     

带电的希格斯玻色子与W玻色子在ILC上的联合产生

带有单个电荷和双电荷的希格斯玻色子(H±和H±±)是希格斯三重态模型中的特征粒子.主要研究在高能直线对撞机上带电的希格斯玻色子与W玻色子的联合产生过程:e+e-→W+H+H--.计算了该过程的产生截面、末态粒子的横动量和快度的分布,并分析了标准模型的背景.结果表明,产生截面在一定的参数空间内可以达到几个飞靶的量级.只要带电希格斯玻色子的质量不是很大,在未来的高能直线对撞机上实验中可以通过该过程探测到这些带电希格斯玻色子的信号.     

氯桥联镉（Ⅱ）一维配位聚合物的合成及晶体结构研究

通过N,N-二甲基甲酰胺（L）配体与二氯化镉反应合成了一种新的一维的以氯原子为桥的桥连一维聚合物：{CdC l2[（CH3）2NCHO]2}n,并通过X射线单晶衍射对其进行了表征,配合物1属于单斜晶系,C2/c空间群,其晶胞参数为a=12.9073（14）,b=13.5631（15）,c=6.8759（12）,α=90°,β=91.9650（10）,°γ=90,°Z=4,V=1203.0（3）3,Dc=1.821g/cm3,μ=2.234mm-1,F（000）=648,R1=0.0210,wR2=0.0563.该配合物是中心对称的以氯原子为桥的一维聚合物,镉离子与分别来自2个氯原子和2个L配体的2个氧原子发生配位作用,形成一个六配位的以金属镉原子为配位中心的八面体几何构型,而且,一维聚合链之间还通过分子间的C-H…C l弱作用形成了一个二维的网状结构.     

希格斯三重态模型中三体希格斯玻色子在ILC上的产生

在希格斯三重态模型(HTM)的理论框架下,研究了带电希格斯玻色子对(H~±,H~(±±))与中性的希格斯玻色子h在国际线性对撞机(ILC)上的两个协同产生过程:e-e+→h H~+H~-和e-e+→hH~(++)H~(--),并计算了它们的产生截面,讨论了相关的标准模型背景.结果表明,在合理的参数空间内,这两个过程的产生截面分别达到几个fb和数十fb的量级,在未来的ILC实验上可能通过这些过程探测到HTM中带电标量粒子H~±和H~(±±)的信号.     

Crystal structure of the phosphotyrosine recognition domain SH2 of v-src complexed with tyrosine-phosphorylated peptides.

Three-dimensional structures of complexes of the SH2 domain of the v-src oncogene product with two phosphotyrosyl peptides have been determined by X-ray crystallography at resolutions of 1.5 and 2.0 A, respectively. A central antiparallel beta-sheet in the structure is flanked by two alpha-helices, with peptide binding mediated by the sheet, intervening loops and one of the helices. The specific recognition of phosphotyrosine involves amino-aromatic interactions between lysine and arginine side chains and the ring system in addition to hydrogen-bonding interactions with the phosphate.     

牛血清白蛋白-羟基磷灰石难溶性复合物的FT-IR光谱研究

利用富立叶变换红外光谱(FT-IR)法对牛血清白蛋白(BSA)-羟基磷灰石［Ca₁₀(OH)₂(PO₄)₆］难溶性复合物的组成及BSA与羟基磷灰石的作用方式进行了研究。结果表明,复合物中BSA与羟基磷灰石之间存在着强烈的相互作用,这种相互作用使水溶性的BSA进入固体羟基磷灰石的结构形成难溶性BSA-羟基磷灰石复合物。复合物具有非化学计量的性质,体现了生物矿化的特征。正是这种蛋白质与羟基磷灰石间的复杂相互作用,形成高级自组装结构,使矿化产物具有高强度和韧性。     

应用RE_SAF_phen_CTMAB显色反应分光光度测定希土总量

本文报导测定希土总量的一种新的分光光度方法.利用形成四元配合物[希土(RE)—水杨基莹光酮(SAF)—邻菲啰啉(phen)—溴化十六烷基三甲铵(CTMAB)〕测定希土总量,测定的pH值为9.5;测定的波长为570—58nm;各种希土配合物的表观摩尔吸光系数为(1.0 5—1.51)×10~5升·摩尔·厘米.在特定的条件下,不同希土配合物显色反应的强度近乎相同,配合物组成RE:SAF=1:2.本文还叙述了外来离子干扰情况及其消除办法.此法已用于测定土壤、岩石和矿石样品的希土总量.     

Newly replicated DNA is associated with DNA topoisomerase II in cultured rat prostatic adenocarcinoma cells

DNA topoisomerases have been proposed to function in a variety of genetic processes in both prokaryotes and eukaryotes. Here, we have assessed the role of DNA topoisomerase II in mammalian DNA replication by determining the proximity of newly synthesized DNA to covalent enzyme-DNA complexes generated by treating cultured rat prostatic adenocarcinoma cells with teniposide. Teniposide (VM-26), an epipodophyllotoxin, is known to interact with mammalian DNA topoisomerase II so as to trap the enzyme in a covalent complex with DNA. We have found that the teniposide-induced trapping of such complexes requires MgCl2, is stimulated by ATP and is inhibited by novobiocin. The formation of covalent complexes seems to be reversible on removal of teniposide. Furthermore, analysis of the covalent complexes formed between 3H-thymidine pulse-labelled DNA and topoisomerase II following teniposide treatment reveals a direct association of the enzyme with nascent DNA fragments. Our results suggest that DNA topoisomerase II may interact with newly replicated daughter DNA molecules near DNA replication forks in mammalian cells.     

Inhibition of mRNA binding to ribosomes by localized activation of dsRNA-dependent protein kinase

The initiation of protein synthesis can be regulated in mammalian cells by protein kinases which phosphorylate the alpha subunit of initiation factor eIF-2. This phosphorylation results in a block in the recycling of eIF-2 and in the inhibition of messenger RNA binding to 80S initiation complexes. After eIF-2 alpha is phosphorylated, the mRNA becomes associated with 48S complexes consisting of a 40S ribosomal subunit, eIF-2 (alpha P), GDP and Met-tRNAf. One of the eIF-2 alpha kinases is activated by low concentrations of double-stranded RNA (dsRNA). This kinase (PKds) is present at a basal level in all mammalian cells investigated and its synthesis is induced in cells treated with interferon. The PKds may be involved in the inhibition of translation of viral mRNA in interferon-treated cells infected with RNA viruses, as it is activated by viral replicative complexes. It is not known, however, if the activated PKds preferentially inhibits the translation of viral mRNA when cellular protein synthesis proceeds at a normal rate in infected cells. We now report that mRNA covalently linked to dsRNA is preferentially inhibited from binding to 80S complexes by a localized activation of PKds. This suggests that in interferon-treated cells the binding of some nascent viral mRNAs to functional initiation complexes may be preferentially inhibited by a similar mechanism.     

钴多吡啶配合物[Co（phen）3]3+和[Co（bpy）3]3+电子吸收光谱的理论研究

采用密度泛函理论,在B3LYP/LanL2DZ水平上,在真空和溶液中对两个钴多吡啶配合物的几何结构进行了优化.结果表明在溶液中优化的几何结构和实验结果吻合较好.以在溶液中优化的几何结构为基础,用含时密度泛函(TDDFT)方法计算配合物的电子吸收光谱,并模拟配合物的电子吸收光谱图.模拟结果和实验结果吻合较好,说明溶剂效应对带有较多正电荷的钴(III)多吡啶配合物的电子吸收光谱影响较大,同时对实验测得的强的吸收带进行了详细解释.     

Synthesis and Characterization of Quaternary Complexes Ln ( CH2 ClCO0 ) 2 ( NO3 ) ( phen)

Many trinary lanthanide complexes have been studied. However, few mixed anion complexes with bidentate heterocyclic amines were synthesized. We synthesized mixed anion complexes Ln ( CHi CICO0 )2 (NO3) (phen) which was determined by elemental analyses. The IR spectra analyses indicate that NO3 ,CH2 C1CO0- and phen are coordinated with Ln. The molar conductances of the complexes at 10-3 mol. L-1 were founded to be between 32.4 and 35.8 S. cma@mol- 1 , suggesting the nonelectrolytes in N Dimethylformamide. And we determined the fluorescent spectra Eu(CH2C1COO)2(NO3) ( phen ) and ESR spectra of Gd( CH2 ClC00 )2 ( NOs ) ( phen ) .     

北京油松天然林和人工林乔木层生产力与气候因子的关系

以北京松山国家自然保护区内油松天然林和人工林为研究对象,根据冀北地区的油松生物量与胸径的关系,利用树木年轮宽度计算出过去33年中两种林分的生物量和生产力动态,并用当地的气候因子(温度与降雨)与生产力做相关分析,经多元逐步回归,得到了气候因子与生产力的回归方程。结果显示:①该地区油松天然林和人工林生物量分别从1980年的50.52 t/hm²和7.74 t/hm²增长到2013年的173.23 t/hm²和114.49 t/hm²,33 a中平均年净生产力分别为3.72 t/(hm²·a)和3.23 t/(hm²·a); ②气候分析表明两种林分乔木层生产力与气候因子均有密切关系:单月气候因子中上年8月温度、当年2月温度和当年6月降雨与油松天然林乔木层净生产力显著正相关; 当年5月降雨和当年1、2月温度与人工林显著正相关。研究表明,松山地区油松天然林乔木层生产力年际变化主要受5—7月降雨和年均气温的综合影响,人工林则更多受1—4月平均气温的影响。     

金属离子与壳聚糖配位氧原子相互作用的密度泛函理论研究

采用DMol3密度泛函理论方法研究了Cu2+,Fe2+,Mn2+与壳聚糖中3种不同化学环境氧原子的相互作用.初始结构采用悬式模型(pendantmodel),利用竞争配位法设计了H2O和OH-分别与Cu2+相互作用形成六配位、与Fe2+和Mn2+相互作用形成七配位的中性络合物.9个初始结构在GGA水平上,利用非对称限制法、自旋非限制法及BLYP/DND法进行了全优化和频率分析.研究结果表明,对于Cu2+,由于Jahn-Teller效应,其络合物为四配位;Fe2+和Mn2+主要形成五配位或四配位的络合物;壳聚糖中只有C3位上的羟基O3′能与3种金属离子发生配位作用.     

高分子无机锡配合物催化环己酮Baeyer—Villiger氧化性能研究

将聚酰胺一胺树状分子的一到三代通过固相合成担载于纤维素上,分别用2,4-二羟基苯甲醛和邻羟基苯甲醛对其外围的氨基进行了修饰,再与SnCl2·2H2O反应形成两类树状大分子金属锡配合物．用ICP、IR和XPS对此类配合物的结构进行了表征．将此类配合物用于30％双氧水氧化环己酮的Baeyer-Villiger（B-V）反应的非均相催化剂,研究表明,在此类配合物作用下,环己酮高选择性地转化为ε-己内酯．比较不同配体修饰的催化剂作用下的氧化反应情况,发现配体对金属的担载量和催化活性均有不同程度的影响．此类催化剂以天然高分子纤维素为载体,具有原料来源丰富、制备方法简单、催化反应时间短、可重复利用等特点．     

Study of complexes of lanthanum with amino acids by titration calorimeter

The stability constants and thermodynamic functions for complexes of lanthanum with eight kind of amino acids according to 1∶1 and 1∶2 in proportion have been determined by titration calorimeter at 298.15 K. The enthalpy change makes a predominant contribution to the stability of these complexes. The ring in amino acid associated with lanthanum ion helps to enhance the stability of complexes. Steric effects between rings in complexes leads to that the equilibrium constants of reaction of the complexes (1∶2) is much less than that of the complexes (1∶1). Foundation item: Supported by the National Nature Science Foundation of China (29873036) Biography: Ye Gang (1974-), male, M S., research direction: thermochemistry.     

弱光和Tris处理条件下PSⅡ放氧核心复合物的损伤

弱光条件下(120μmol·m-2·s-1)用Tris(0.8mol/L,pH6.5～10.0)处理具有放氧活性的PSⅡ核心复合物,可引起33kD锰稳定蛋白的释放和锰复合物的破坏,并导致核心复合物的结构发生明显的改变.温和电泳、SDS-PAGE和双向电泳分析表明,主要是PSⅡ核心复合物的二聚体和单体减少,并且复合物部分解体;除反应中心D1和D2蛋白外,核心天线CP43和CP7的量也减少,33kD锰稳定蛋白要发生降解.避光时,PSⅡ核心复合物不受影响.     

Eu(Ⅲ)/Gd(Ⅲ)-HTTA-TPA-Phen配合物的共发光研究

为了研究Eu(Ⅲ)-配合物的共发光与其结构的关系,合成了Eu (Ⅲ)/Gd (Ⅲ)与2-噻酚三氟乙酰丙酮(HTTA)、对苯二甲酸(TPA)和邻菲罗啉(Phen)形成的系列配合物,并运用元素分析、红外光谱对这些配合物进行表征.共发光Gd3 离子对Eu(Ⅲ)-配合物的荧光增强效果非常明显,其共发光效果与结构的关系是:网状多核配合物Eu2(1-x)Gd2x(TPA)3Phen2 ＞ 链状多核配合物Eu1-xGdx(TPA)(TTA)Phen ＞单核配合物Eu1-xGdx(TTA)3Phen.荧光增强的机理可从配合物的单核和多核结构获得解释,异多核配合物Eu1-xGdx(TPA)(TTA)Phen与 Eu2(1-x)Gd2x(TPA)3Phen2分子内能量传递比异单核配合物Eu1-xGdx(TTA)3Phen分子间能量传递更有效.