稳定性核素~(15)N在农业研究中的应用

稳定性核素示踪是现代农业研究中一门新兴技术。稳定性核素15N作为一种有效手段在农业施肥研究、氮素循环研究中发挥着极为重要的作用。本文介绍了15N的相关概念,列举了20世纪80年代以来15N在氮肥研究、氮素转化研究以及农业环境保护中的应用进展,阐明了应用15N的新技术已解决的问题,以及将要解决的问题,并展望了性核素示踪技术的应用前景。

一氧化氮是脱落酸诱导杨树叶片气孔关闭的信号分子

研究了外源NO和ABA对杨树气孔运动调节作用 .结果表明 ,外源NO和ABA都能诱导杨树离体叶片气孔关闭 ,且具有剂量效应 ,NO可加强ABA诱导气孔关闭的作用 .NO清除剂 (c PTIO)可大大减弱NO和ABA对气孔关闭的诱导作用 .证实了NO参与ABA调控气孔开闭运动过程 ,不同浓度NO供体SNP和ABA处理杨树离体叶片 ,SOD活性变化不明显 ,POD活性受到显著抑制 .杨树叶片粗酶液的体外实验表明 ,不同浓度SNP对POD活性的抑制呈明显的浓度及时间效应 ;而ABA对POD活性则几乎没有影响 .本研究证明 ,NO调节ABA诱导的树木气孔关闭作用 ,是ABA诱导树木气孔关闭的一种重要信号分子 .

用拉格朗日反演模型模拟长白山森林蒸散

该文以长白山阔叶红松林为研究对象,以Raupach提出的Localized Near Field(LNF)理论为依据,耦合垂直速度标准差σw(z)和拉格朗日时间尺度TL(z),建立林冠内水汽源/汇强度和平均浓度廓线之间的关系;利用拉格朗日反演模型提出了通过林冠水汽浓度梯度计算林冠内的水汽源/汇强度进而推算森林蒸散的方法.模拟结果与开路涡动相关系统的观测数据比较显示:白天水汽累积通量的模拟精度达到81%,模拟值高出实测值约15%~25%;夜间模拟值比实测值高出2~4倍,其原因尚不清楚.观测期内全天水汽总量模拟值298.91 mm,观测值为240.33 mm.最后,讨论了水汽源/汇强度及其通量随时间和高度的演变过程.

Synthesis and characterization of magnetite dodecahedron nanostructure by hydrothermal method

Magnetite dodecahedral nanocrystals were fabricated using ethlenediamine tetraacetic acid (EDTA)-mediated hydrothermal route. Scanning electron microscopy images displayed that the products were almost dodecahedrons. The length of two different ribs were about 300 and 200 nm, respectively. X-ray diffraction patterns showed that the products were the cubic inverse spinel structure. Fourier transform infrared spectrum directly provided evidence of the EDTA bound to a specific surface of the precipitated magnetic nanocrystal.

Macroscopic single-crystal tubes assembled with porous supramolecular architecture of water-soluble calixarene and phenanthroline

Single-crystal tubular products on the millimetre scale have been synthesized from water-soluble calixarene and phenanthroline in the presence of lanthanides by a hydrothermal method, in which the extended structures contain some 1D infinite channels.

Magnetic Mesoporous Silica Spheres for Drug Targeting and Controlled Release

Magnetically functionalized mesoporous silica spheres with different size (average diameter, A.D.) from 150 nm to 2 mu m and pore size distribution were synthesized by generating magnetic FexOy nanoparticles onto the mesoporous silica hosts using the sol-gel method. The X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), N-2 adsorption/desorption results show that these composites conserved regular sphere morphology and ordered mesoporous structure after the formation of FexOy nanoparticles. XRD and X-ray photoelectron spectroscopy (XPS) analysis confirmed that the FexOy generated in these mesoporous silica hosts is mainly composed of gamma-Fe2O3. Magnetic measurements reveal that these composites with different gamma-Fe2O3 loading amounts possess super-paramagnetic properties at 300 K, and the saturation magnetization increases with increasing Fe ratio loaded.

Glutathione-capped CdTe quantum dots for the sensitive detection of glucose

A simple and sensitive assay system for glucose based on the glutathione (GSH)-capped CdTe quantum dots (QDs) was developed. GSH-capped CdTe QDs exhibit higher sensitivity to H2O2 produced from the glucose oxidase catalyzed oxidation Of glucose, and are also more biocompatible than other thiols-capped QDs. Based on the quenching of H2O2 on GSH-capped QDs, glucose can be detected. The detection conditions containing reaction time, the concentration of glucose oxidase and the sizes of QDs were optimized and the detection limits for glucose was determined to be 0.1 mu M; two detection ranges of glucose from 1.0 mu M to 0.5 mM and from 1.0 mM to 20 mM, respectively Were obtained. The detection limit was almost a 1000 times lower than other QDs-based optical glucose sensing systems. The developed glucose detection system was simple and facile with no need of complicated enzyme immobilization and modification of QDs.

White electroluminescence from a single polymer system: Improved performance by means of enhanced efficiency and red-shifted luminescence of the blue-light-emitting species

High-efficiency white electrolurninescence from a single polymer is achieved by enhancing the electroluminescence efficiency and effecting a red-shift in the emission spectrum of the blue emissive species. A single-layer device of the resultant polymer exhibits a higher luminous efficiency than the nonmodified species (12.8 cd A(-1), see figure) and an external quantum efficiency of 5.4 % with CIE coordinates of (0.31,0.36), exemplifying the success of the reported methodology.

Morphological, thermal, and mechanical properties of polypropylene/polycarbonate blend

This work deals with the effect of compatibilizer on the morphological, thermal, rheological, and mechanical properties of polypropylene/polycarbonate (PP/ PC) blends. The blends, containing between 0 to 30 vol % of polycarbonate and a compatibilizer, were prepared by means of a twin-screw extruder. The compatibilizer was produced by grafting glycidyl methacrylate (GMA) onto polypropylene in the molten state. Blend morphologies were controlled by adding PP-g-GMA as compatibilizer during melt processing, thus changing dispersion and interfacial adhesion of the polycarbonate phase. With PP-g-GMA, volume fractions increased from 2.5 to 20, and much finer dispersions of discrete polycarbonate phase with average domain sizes decreased from 35 to 3 mu m were obtained. The WAXD spectra showed that the crystal structure of neat PP was different from that in blends. The DSC results suggested that the degree of crystallization of PP in blends decreased as PC content and compatibilizer increased. The mechanical properties significantly changed after addition of PP-g-GMA. (C) 1997 John Wiley & Sons, Inc.

CONFORMATION OF PHENYL RINGS IN THE HELICAL CHAIN POLYMER POLY(TRIPHENYLMETHYL METHACRYLATE)

The conformation of phenyl rings in the side groups of the helical chain polymer poly(tripenyl-methyl methacrylate) (1) in solution was studied by spectroscopic methods. According to the Raman spectrum the phenyl rings of 1 and triphenylmethyl methacrylate in solution have the same depolarization ratio at 1002 cm-1. The electronic spectra (ultraviolet and fluorescence) of 1 are similar to those of model substances, except for the "red shift" of the spectra of about 5 nm. It was concluded that the phenyl rings can rotate around the phenyl-C bond.

Ship-board measurements and estimations of air-sea fluxes in the western tropical Pacific during TOGA COARE

Direct air-sea flux measurements were made on RN Kexue #1 at 40 degrees S, 156 degrees E during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean-Atmospheric Response Experiment (COARE) Intensive Observation Period (IOP). An array of six accelerometers was used to measure the motion of the anchored ship, and a sonic anemometer and Lyman-alpha hygrometer were used to measure the turbulent wind vector and specific humidity. The contamination of the turbulent wind components by ship motion was largely removed by an improvement of a procedure due to Shao based on the acceleration signals. The scheme of the wind correction for ship motion is briefly outlined. Results are presented from data for the best wind direction relative to the ship to minimize flow distortion effects. Both the time series and the power spectra of the sonic-measured wind components show swell-induced ship motion contamination, which is largely removed by the accelerometer correction scheme, There was less contamination in the longitudinal wind component than in the vertical and transverse components. The spectral characteristics of the surface-layer turbulence properties are compared with those from previous land and ocean results, Momentum and latent heat fluxes were calculated by eddy correlation and compared to those estimated by the inertial dissipation method and the TOGA COARE bulk formula. The estimations of wind stress determined by eddy correlation are smaller than those from the TOGA COARE bulk formula, especially for higher wind speeds, while those from the bulk formula and inertial dissipation technique are generally in agreement. The estimations of latent heal flux from the three different methods are in reasonable agreement. The effect of the correction for ship motion on latent heat fluxes is not as large as on momentum fluxes.

中国海蓝子鱼科Family Siganidae分类和动物地理学特点

蓝子鱼科鱼类隶属于鲈形目、刺尾鱼亚目，广泛分布于我国东海、南海及台湾海域。本文根据中国科学院海洋研究所多年来在我国海域采集并收藏的以及部分补充采集的蓝子鱼标本，参考国际最新研究资料，对我国海域蓝子鱼科鱼类进行分类和动物地理学研究，共记录中国海域蓝子鱼科鱼类1属2亚属11种。经研究分析，得到如下结论： 1.中国沿海蓝子鱼科鱼类的多样性问题。国内曾有13种蓝子鱼的分布记录，其中蠕纹蓝子鱼Siganus vermiculatus和暗体蓝子鱼S. punctatissimus仅以前的学者做过名录形式的记载，并无标本收藏，本文中不做介绍。此外尖嘴蓝子鱼Siganus unimaculatus也可能存在于中国海域，有待于进一步研究。目前确定在中国海域有分布的蓝子鱼为11种，约占世界总种数（27）的40％多，种的多样性较高。 2. 形态学比较研究说明，蓝子鱼在体形、体色、牙齿、头骨、椎骨、耳石等特征方面存在种间差异，可作为蓝子鱼科鱼类分类的有效鉴别特征。对于外部形态极其相似的种，可借助内部解剖特征相辅助予以区分。 3．对蓝子鱼动物地理学特点研究分析结论如下：a.中国海域存在的11种蓝子鱼在印度－太平洋海域均有分布，没有地方特有种。b.长鳍蓝子鱼和褐蓝子鱼在我国东海、台湾海域和南海均有分布，褐蓝子鱼在黄海北部亦有分布，种群数量较大；其它9种，除凹吻蓝子鱼仅分布于南海外，均分布于南海及台湾海域，种群数量较小。c.中国海域蓝子鱼种类组成与邻近的菲律宾、马来西亚、印度尼西亚海域比较相似，中国分布的种类在这些海域均有分布，且分布于这一区域而中国没有记录的有5种。与日本相比，种类组成也比较相似，中日共有种达9种，仅分布于中国海域2种，仅分布于日本海域1种。 4. 作者参照国际最新研究结果和较为公认的分类系统Nelson（1994），将蓝子鱼科置于刺尾鱼亚目，而不再使用国内学者长期惯用的蓝子鱼亚目。蓝子鱼科包括一属蓝子鱼属Siganus Forsskål, 1775，两亚属：蓝子鱼亚属Siganus Forsskål, 1775 和罗蓝子鱼亚属 Lo Seale, 1906，同时使全部种名的变动和确定与国际最新研究结果(Woodland, 1990; 2001）取得一致。

Characterization of 12 single nucleotide polymorphisms (SNPs) in Pacific abalone, Haliotis discus hannai

We report here for the first time 12 polymorphic single nucleotide polymorphisms (SNPs) in a commercially important gastropod, Pacific abalone (Haliotis discus hannai) that were identified by searching expressed sequence tag database. These SNP loci (seven nuclear and five mitochondrial SNPs) were polymorphic among 37 wild abalone individuals, based on a four-primer allele-specific polymerase chain reaction analysis. All loci had two alleles and the minor allele frequency ranged from 0.027 to 0.473. For the seven nuclear SNPs, the expected and observed heterozygosities ranged from 0.053 to 0.499 and from 0.054 to 0.811, respectively.

Sensitisation identification of stainless steel to intergranular stress corrosion cracking by atomic force microscopy

A new technique was developed for characterisation of stainless steel to intergramilar stress corrosion cracking by atomic force microscopy. The technique proved to be effective in sensitisation identification of AISI 304 stainless steel and might be promising in sensitisation identification of other stainless steels. (c) 2007 Elsevier B.V. All rights reserved.

21世纪智能机器人发展预测

智能机器人是作为扩大计算机的功能和人工智能的实验床而形成和发展起来的.80年代中期基于感觉控制的智能机器人进入实用阶段.90年代将以装配机器人为先导产品,以电子、电气、精密机械制造为先导应用产业普及,特种机器人也将取得突破性的进展.本文对21世纪的下一代机器人的单元技术,应用领域及其前景作了预测.