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941.
Kinetic Alfven waves (KAWs) driven by the diamagnetic drift instability that is excited by the density inhomogeneity in low-β plasmas, such as plasmas in the auroral region, are investigated by adopting the particle aspect analysis and loss-cone distribution function. The results obtained in this paper indicate that the propagation and evolution of kinetic Alfven waves decrease and the kinetic Alfven wave excitation becomes not easier with increasing loss-cone index J. But the spatial scales of the perpendicular perturbation driving kinetic Alfven waves have a decreasing tendency with the larger values of J, which perhaps is in relation with the decreasing width of loss-cone. A single hump appears in the plots of the growth rate of the instability when J=2. But the hump cannot emerge when J=0 or J=1. The density inhomogeneity of ions plays an important role in driving KAWs and it cannot be ignored. KAWs can be easier driven and KAWs can propagate and evolve faster with the increasing level of density inhomogeneity. However, the range of the perpendicular wave number of the wave instability decreases, namely, the longer the scale of perpendicular disturbance the easier the excitation of KAW. As the density inhomogeneity increases, the tendency of numerical solutions of the dispersion relation is similar to that obtained by the kinetic theory and Maxwellian distribution function (Duan and Li, 2004). But the profiles of the plots of numerical solutions are different. This means that the velocity distribution function of particles is important for KAW driven in magnetoplasmas, especially in the active regions of the magnetosphere, such as auroral region, and plasma sheet boundary. 相似文献
942.
B.Y. Duan Y.Y. Qiu Y.X. Su W.L. Wang R.D. Nan B. Peng 《Astrophysics and Space Science》2001,278(1-2):237-242
An innovative design for a feed support structure for the next generation large radio telescope, based on the idea of integrating
mechanical, electronic and optical technologies(OPTOMECHATRONICS), is considered. Theoretical analyses and simulations are
carried out. A 5 m experimental model is built to demonstrate the idea.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
943.
Based on DNA extraction and optimization of random amplified reaction (RAPD) to the gametophytes and sporophytes of Kelp “901”
strain, genetic study on variation was conducted to its parents and offsprings of F6, F7, F8, and F9 generation. RAPD results have shown that among 30 selected primers for gametophytes, 297 loci ranging from 200 to 3 000 bp
were obtained in the average of 9.9 loci for each primer. This indicated a high polymorphic rate with RAPD detection. UPGMA
(unweighted pair-group method arithmetic average) analysis showed that each male and female gametophyte of a generation could
be clustered into one pair separately. The genetic distances of the Kelp 901 generation were 0.3212–0.4767, and the maximum
was between F7 and F8 (0.4767). Identity analysis showed that F6 generation was more close to the female parent (0.6593), and F7 generation was more close to the male parent (0.578 8). To the sporophytes study in 24 selected primers for RAPD amplification,
191 loci ranging from 230–2800 bp were obtained, in the average to each primer of 8.0 loci. The heterozygosity to six populations
were male parent (0.2239), female parent (0.1072), F6 (0.2164), F7(0.2286), F8(0.2296) and F9(0.3172). The nearest genetic distance was 0.083 5(F8, F9). Total heterozygosity (HT) of F6, F7, F8 and F9 generations was 0.3186, the average heterozygosity (HS) for F6, F7, F8 and F9 generations was 0.2480, and deduced coefficient of population differentiation (Gst) was 22.2%. Six sequence characterized amplified regions (SCAR) were preliminary screened through RAPD analysis. It needed
to be verified in detail as they are significant for molecular marker assistance in breeding and selectingLaminaria. 相似文献
944.
945.
MULTI-SCALE DECOMPOSITION OF BOUGUER GRAVITY ANOMALY AND SEISMIC ACTIVITY IN NORTH CHINA 总被引:1,自引:0,他引:1
Fang Shengming Zhang Xiankang Jia Shixu Duan Yonghong Yang Zhuoxin Qiu Shuyan 《大地测量与地球动力学》2003,23(Z1)
1 IntroductionThecrustalstructureofNorthChinahasbeenstudiedalotwithgravitymethod[1 ,2 ] .Theresultsareundoubtedlyofgreatsignificancetoabetterun derstandingofthecrustalstructureofthisregion .Butsofar,neithervertical/lateraldistributionscalesnorcharacteristicsofanomalousdensitybodiesofrockmediaintheregionhavebeenrevealedsystem aticallyintermsofrockdensity .Assurfacegravityanomalyreflectstheoveralleffectofgravityanoma liesofsubsurfaceanomalousgeologicalbodiesatdif ferentdepths,ondifferentscales… 相似文献
946.
详细介绍了自1993年开始以来《中日亚洲季风机制合作研究计划》在青藏高原上观测研究的一些基本情况。包括三个部分:观测仪器的特点、观测环境的气候特征和观测项目(要素);观测资料的特点;部分观测资料的初步分析结果介绍 相似文献
947.
Jiu-Ning Han Wen-Shan Duan Jun-Xiu Li Guang-Xing Dong Su-Hong Ge 《Astrophysics and Space Science》2014,351(2):525-531
A theoretical investigation has been made on the head-on collision of cylindrical and spherical electron-acoustic solitary waves in a non-Maxwellian plasma composed of stationary ions, cold fluid electrons, and superthermal electrons obeying κ velocity distribution. By using the extended Poincaré-Lighthill-Kuo perturbation method, the effects of plasma parameters, especially the superthermal effect on the interaction of colliding solitary waves are studied. It is found that there are both positive and negative colliding phase shifts for each colliding wave in its traveling direction. Also, it is shown that the solitary waves received the largest colliding phase shifts in spherical geometry, followed by the cylindrical and planar geometries. 相似文献
948.
????????????????????????????в??????????????????У??????????????о??????????????????????仯??????????????????????????????в??????????????仯??????????£??????????????????????????????????????????????????ζ????????????????????????????????????????????ж???????????????????- ?????????????????????????????????????????????????????????? 相似文献
949.
In order to find out whether long interspersed elements (LINEs) existed in macro-algae ge- nomes or not, we tested the LINE homologues in representative families (species): Gracilaria (G. eucheumoides Harv., G. tenuistipitata Chang et Xia, and G. textorii (Sur) De-Toni), Laminaria (L. longis- sima Miyabe and L. japonica Aresch.), and Ulva (U. lactuca L. and U. pertusa Kjellm.) during 2004 to 2005. Polymerase Chain Reaction (PCR) was carried out with degenerate oligonucleotide primers de- signed from LINEs of rice homologues and Cin4 of maize. Cloning and nucleotide sequencing of the PCR products revealed that 4 clones that derived from 3 species of Gracilaria have LINE homologues. The nucleotide sequences of the 4 LINE homologues diverged greatly, but the amino acid sequences deduced from them were relatively conserved. The endonuclease regions of the LINE homologues greatly di- verged from that of other plants, but they had closer phylogenetic relationship to Zepp elements in Chlor- ella sp., which indicated that sequence divergence by vertical transmission has been a major influence on the evolution of algal LINEs. 相似文献
950.
Patrick Louchouarn Rainer M.W. Amon Shuiwang Duan Christina Pondell Shaya M. Seward Noah White 《Marine Chemistry》2010,118(1-2):85-97
A series of reference materials are proposed for intercomparison and quality control purposes during the quantification of lignin oxidation products (LOP) from diverse environmental matrices. These materials are all easily accessible and certified for diverse organic constituents (NIST and IHSS). They represent a suite of natural environmental matrices (from solids to aqueous) and are characterized by a wide range of organic carbon and lignin concentrations with abundant proportions of all major LOP. The variability of LOP concentrations and signatures for all these materials averages 3–5% and does not exceed 10%. Using these standards, a new quantification method was developed and validated for the determination of low-level CuO oxidation products using capillary gas chromatography–tandem mass spectrometry (GC/MS–MS). Tandem mass spectrometry provides both the high sensitivity and selectivity required for the identification and quantification of trace levels of dissolved lignin. The method is particularly useful for removing interference from co-eluting isotopes generated from the DOM matrix and during glucose amendment procedures of low-carbon samples. Such glucose amendment is not necessary, however, when the CuO to organic carbon weight-to-weight ratio can be kept at a value < 200–300. 相似文献