排序方式: 共有11条查询结果,搜索用时 15 毫秒
1.
L. A. Bondar L. M. Kustov I. P. Beletsky V. B. Kazansky 《Reaction Kinetics and Catalysis Letters》1993,50(1-2):193-198
Microporous silica gels containing small amounts of titanium ions have been synthesized. Porous structure and surface active sites of silica gels have been studied. It has been found that the titanium ions are distributed uniformly in silica gel matrix, substituting silicon ions isomorphically. 相似文献
2.
Genome sequence and analysis of the tuber crop potato 总被引:11,自引:0,他引:11
Potato Genome Sequencing Consortium Xu X Pan S Cheng S Zhang B Mu D Ni P Zhang G Yang S Li R Wang J Orjeda G Guzman F Torres M Lozano R Ponce O Martinez D De la Cruz G Chakrabarti SK Patil VU Skryabin KG Kuznetsov BB Ravin NV Kolganova TV Beletsky AV Mardanov AV Di Genova A Bolser DM Martin DM Li G Yang Y Kuang H Hu Q Xiong X Bishop GJ Sagredo B Mejía N Zagorski W Gromadka R Gawor J Szczesny P Huang S Zhang Z Liang C He J Li Y He Y Xu J Zhang Y Xie B Du Y Qu D Bonierbale M Ghislain M 《Nature》2011,475(7355):189-195
Potato (Solanum tuberosum L.) is the world's most important non-grain food crop and is central to global food security. It is clonally propagated, highly heterozygous, autotetraploid, and suffers acute inbreeding depression. Here we use a homozygous doubled-monoploid potato clone to sequence and assemble 86% of the 844-megabase genome. We predict 39,031 protein-coding genes and present evidence for at least two genome duplication events indicative of a palaeopolyploid origin. As the first genome sequence of an asterid, the potato genome reveals 2,642 genes specific to this large angiosperm clade. We also sequenced a heterozygous diploid clone and show that gene presence/absence variants and other potentially deleterious mutations occur frequently and are a likely cause of inbreeding depression. Gene family expansion, tissue-specific expression and recruitment of genes to new pathways contributed to the evolution of tuber development. The potato genome sequence provides a platform for genetic improvement of this vital crop. 相似文献
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The rotational motion of a satellite with a magnetic stabilization system is discussed. The motion is described by a nonautonomous differential equation, with the magnetic moment of the satellite as a parameter. The global phase portrait of the problem is investigated in a wide range of magnetic-parameter values, using a numerical realization of the method of Poincare point maps. New periodic solutions of the problem are found, and an analysis is carried out of the evolution of the phase portrait and the bifurcation of periodic solutions with varying magnetic-parameter values. The values of the magnetic parameter that must be avoided in the design of the satellite magnetic stabilization system are discussed. (c) 1999 American Institute of Physics. 相似文献
4.
Yu. Y. Beletsky A. I. Bugrij A. A. Trushevsky 《Zeitschrift fur Physik C Particles and Fields》1981,10(4):317-325
The paper deals with the thermodynamical properties of ultrarelativistic matter described by the Van der Waals equation of state under condition of free creation and annihilation of particles. In such a system phase transitions take place. Near the phase transitions the behaviour of the system radically depends on which of thermodynamical variable—the temperature or the density of energy—is independent. Some astrophysical consequences of the results obtained are discussed. 相似文献
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The dependence of sorption properties on the nature of heteroatoms in substituted five- and six-membered heterocyclic compounds with two heteroatoms (sulfur and oxygen), thiophenes and furans bearing alkyl, formyl, acetyl, and sulfide substituents have been investigated. Equations for calculating the retention indices of analogs have been proposed, and the indices of 35 previously non-investigated substances of these classes have been predicted.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1224–1227, July, 1993. 相似文献
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R Nirmala V Sankaranarayanan K Sethupathi AV Morozkin T Geethakumary Y Hariharan 《Pramana》2002,58(5-6):1101-1104
New R
2Ti3Ge4 (R=Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac
magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize
in the parent, Sm5Ge4-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series.
The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales
with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays
a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects. 相似文献
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Alexander V. Kolobov a) onleavefromA .F .IoffePhysico TechnicalInstitute StPetersburg Russia 《中国科学技术大学学报》2001,31(3):282-288
Thelatticemismatchbetweenthesubstrateandtheovergrownlayerallowstheformationofself as sembledquantumdots (QDs)throughtheStranski Krastanovmechanism[1,2 ] .Thistechniquehasbeensuccessfullyappliedtovarioussemiconductorsystems,andinparticulartoGe/Siquantumdots(Q… 相似文献
10.
Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta0.33V0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV2. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase. 相似文献