Metabolically blocked analogs of housefly sex pheromone: I. Synthesis of alternative substrates for the cuticular monooxygenases

Cuticular monooxygenases in the cuticle of the female houseflyMusca domestica oxidize (Z)-9-tricosene to m-9,10-epoxytricosane and to (Z)-9-tricosen-14-one. One possible explanation for these two products is that a single monooxygenase accepts the alkene substrate in two different orientations. Eleven analogs of (Z)-9-tricosene bearing methyl substituents, cyclopropyl groups, fluorine substituents, deuterium substituents, and additional double bonds were synthesized to probe the substrate requirements of this monooxygenase system. In addition, the 11 corresponding epoxides were prepared to aid in identification of the metabolites of each modified alkene.     

钻井风险评价方法与模型建立

提出了钻井风险的多因素多层次综合评价方法，以层次分析法建立模型，并求得了该模型的解。介绍了层次分析法，阐明了多因素多层次与风险的关系。通过实例分析，说明该方法可行，有助于钻井风险评价与防范，并提供了一个便于计算的风险定量化模型。     

The evolution of the U.S. industrial landscape, 1969–1995

The industrial landscape of the U.S. has undergone major changes in the last three decades, which have affected the location of the work-force as much as sector location. This paper adopts a dynamic approach in order to analyse the principal characteristics of this process in the time-period 1969–1995 among the twenty two-digit SIC industries. Two main conclusions have emerged. First, we find that, in general, industries are tending to reduce their degree of concentration. Secondly, the classification of industries according to different economic criteria allows us to test the degree of compliance with various theoretical propositions and to detect relevant empirical regularities. Received: July 2001/Accepted: August 2002 The authors would like to express their thanks to two anonymous referees for their valuable comments and observations on an earlier version of this work. Similarly, they are grateful for the financial support provided by the University of Zaragoza under Project UZ2001-SOC-09.     

14MnNbq钢板在4200mm轧机的轧制工艺

本文依据含铌钢的特性，结合舞钢轧钢厂的生产实际，对加热，轧制，热处理工艺进行优化，生产出机械性能，表面质量均达到技术条件要求的１４ＭｎＮｂｑ钢板，现已用于目前我国跨度最大的芜湖长江大桥。     

Exchange and Crystalline Electric Field Interactions in Tm_2Fe_(14)B Compound

A series of magnetic properties of Tm_2Fe_(14)B are explained quantitatively by the calculations based on thesingle ion model. The magnetic properties include the temperature dependence of the spontaneous magnetization,the spin reorientation temperature and the magnetization curves along the principal crystal axes at 4.2, 100, 150and 200 K. The values of the exchange field and the crystalline electric field parameters used in the calculationsare μ_BH_(ex)(T=0 K)=135, B_2~0=1.77, B_2~2=±2.97, B_4~0=-3.06×10~(-3), B_4~(-2)=0, B_4~4=-6.82×10~(-3), B_6~0=1.05×10~(-5), B_6~(-2)=±7.40×10~(-5), B_6~4=1.96×10~(-4), and B_6~(-6)=0 all in K unit. The magnetization processes of the Fe-andTm-sublattices at different temperatures are analysed. The processes are characterized by the non-collinearitybetween the magnetic moments of the Fe-and Tm-sublattices.     

Eingangsportal; Änderung des äußeren Ansehens; baubewilligungspflichtige Maßnahmen

Die Errichtung eines Flugdaches im Umfang von 8 m × 4 m und 2,90 m H?he (hier: aufgebaut auf eine bestehende Pergola) ist ein baubewilligungspflichtige Ma?nahme.     

AI、Nb在Nd_2Fe_(14)B晶体中的价态及对其磁性的影响

本文研究了Al、Nb在Nd_2Fe_(14)B晶体中的价态及对其磁性的影响。结果表明:在Nd_2Fe_(14)B晶体中,具有较大结构体积的j_2晶位Fe原子[Fe(j_2)],由于受到近邻Nd的f电子的强烈作用,其d电子可以被“诱发”为磁电子,原子磁矩达3.4μ_B,比纯铁的2.4μ_B大得多;Nb原子在晶体中置换j_2、k_1、k_2晶位上Fe原子时,它的d电子也可能成为磁电子;Al和Nb原子在Nd_2Fe_(14)B晶体价电子结构中,以无晶格电子的价态置换有晶格电子的Fe原子价态,导致硬磁性相各向异性的增强;Nb的两个4d价电子参加晶体的键合,增强了材料的磁温度稳定性。     

NMR Studies of the Dynamic Motion of Encapsulated Ions and Clusters in Fullerene Cages: A Wheel Within a Wheel

Nuclear magnetic resonance (NMR) has provided an important approach to investigate the structure and dynamics of encapsulated metal ions and clusters in endohedral metallofullerenes (EMFs). In this paper, we review NMR studies of the environment and dynamics of dimetallic, trimetallic nitride, metal carbide and metal cyanide clusters encapsulated in EMFs. The NMR chemical shielding parameter is a sensitive probe for monitoring the carbon cage (¹³C) and encapsulated clusters (¹³C, ¹⁴N, ¹³⁹La, ⁴⁵Sc, and ⁸⁹Y). Future NMR EMF studies could be very fruitful and help elucidate coupled motion between the carbon cage and encapsulated cluster or other “wheel within a wheel” motional processes.     

秦山核电基地外围水体环境中~(14)C水平和分布

为了解和评价运行20余年的秦山核电基地外围环境水体中14 C的水平和分布,本文研制了水体中溶解态无机碳提取装置,并结合加速器质谱法对秦山核电基地外围环境中采集的水体样品进行了14 C活度的测量。测量结果表明,距排放口5km内的海水样品14 C比活度为(203.4±5.6)Bq/kg,分布范围为196.8~206.5Bq/kg,与参照点(本底)处于同一水平,未观察到显著的浓度分布规律。另外,也未观察到地表水、井水及地下水样品中14 C浓度与参照点相比有显著增高。本次水体采样调查结果表明,核电站排放的冷却水未引起近海岸海水中14 C浓度增高,无14 C富集现象。