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991.
Through the use of reliable AMS dating of high resolution (15–30 years) peat and the establishment of monsoon climate proxies sequence, we have been able to recognize several cold, dry events in the Tibetan Plateau during the Holocene. The more obvious ones occurred around 12800, 11300, 10200, 9580, 8900, 6400, 4400, 3700, 2800 and 1500 cal. aBP. These events correlate well with both ice rafting events recorded in high latitude North Atlantic Ocean sediment cores and cooling events in the low latitude SST. Spectral analysis indicates high frequency climate variation on centennial-millennial time scale during the Holocene. This further reflects Holocene climate instability and the existence of centennial-millenium scale rhythm in mid latitude areas as well.  相似文献   
992.
介绍《桂东明珠-梧州》多媒体光盘的设计与制作的技术方案及实施措施。  相似文献   
993.
Coupling between electrons and phonons (lattice vibrations) drives the formation of the electron pairs responsible for conventional superconductivity. The lack of direct evidence for electron-phonon coupling in the electron dynamics of the high-transition-temperature superconductors has driven an intensive search for an alternative mechanism. A coupling of an electron with a phonon would result in an abrupt change of its velocity and scattering rate near the phonon energy. Here we use angle-resolved photoemission spectroscopy to probe electron dynamics-velocity and scattering rate-for three different families of copper oxide superconductors. We see in all of these materials an abrupt change of electron velocity at 50-80 meV, which we cannot explain by any known process other than to invoke coupling with the phonons associated with the movement of the oxygen atoms. This suggests that electron-phonon coupling strongly influences the electron dynamics in the high-temperature superconductors, and must therefore be included in any microscopic theory of superconductivity.  相似文献   
994.
Atomic-beam alignment of inorganic materials for liquid-crystal displays   总被引:1,自引:0,他引:1  
The technique used to align liquid crystals-rubbing the surface of a substrate on which a liquid crystal is subsequently deposited-has been perfected by the multibillion-dollar liquid-crystal display industry. However, it is widely recognized that a non-contact alignment technique would be highly desirable for future generations of large, high-resolution liquid-crystal displays. A number of alternative alignment techniques have been reported, but none of these have so far been implemented in large-scale manufacturing. Here, we report a non-contact alignment process, which uses low-energy ion beams impinging at a glancing angle on amorphous inorganic films, such as diamond-like carbon. Using this approach, we have produced both laptop and desktop displays in pilot-line manufacturing, and found that displays of higher quality and reliability could be made at a lower cost than the rubbing technique. The mechanism of alignment is explained by adopting a random network model of atomic arrangement in the inorganic films. Order is induced by exposure to an ion beam because unfavourably oriented rings of atoms are selectively destroyed. The planes of the remaining rings are predominantly parallel to the direction of the ion beam.  相似文献   
995.
Liou YC  Sun A  Ryo A  Zhou XZ  Yu ZX  Huang HK  Uchida T  Bronson R  Bing G  Li X  Hunter T  Lu KP 《Nature》2003,424(6948):556-561
The neuropathological hallmarks of Alzheimer's disease and other tauopathies include senile plaques and/or neurofibrillary tangles. Although mouse models have been created by overexpressing specific proteins including beta-amyloid precursor protein, presenilin and tau, no model has been generated by gene knockout. Phosphorylation of tau and other proteins on serine or threonine residues preceding proline seems to precede tangle formation and neurodegeneration in Alzheimer's disease. Notably, these phospho(Ser/Thr)-Pro motifs exist in two distinct conformations, whose conversion in some proteins is catalysed by the Pin1 prolyl isomerase. Pin1 activity can directly restore the conformation and function of phosphorylated tau or it can do so indirectly by promoting its dephosphorylation, which suggests that Pin1 is involved in neurodegeneration; however, genetic evidence is lacking. Here we show that Pin1 expression is inversely correlated with predicted neuronal vulnerability and actual neurofibrillary degeneration in Alzheimer's disease. Pin1 knockout in mice causes progressive age-dependent neuropathy characterized by motor and behavioural deficits, tau hyperphosphorylation, tau filament formation and neuronal degeneration. Thus, Pin1 is pivotal in protecting against age-dependent neurodegeneration, providing insight into the pathogenesis and treatment of Alzheimer's disease and other tauopathies.  相似文献   
996.
0 IntroductionTheneedforintegrationofdifferentdatabasemanagementsystems (DBMSs) ,makingdifferencesbetweenthesesystemsinvisibleandprovidinguserswithauniformaccesstoallthedatabaseshasgrownrapidlyduringthelastdecade .However,databaseautonomyandheterogeneity…  相似文献   
997.
Inclusion complex of Orange II with β-Cyclodextrin (β-CD) and the anti-photolysis effect under UV-light were investigated. The molar ratio of inclusion complex of β-Cyclodextrin and Orange II is 1∶1. The formation constantK = 1.236×103 L/mol was determined by the UV and Fluorescence spectra respectively, which was quite in accordance with the calculation with a modified Benesi-Hildbrand equation. The inclusion complex was characterized by the IR spectra and the molar ratio of inclusion complex is 1∶1 too. The formation constantK = 1.266×103 L/mol was determined by1H NMR analysis and was nearly the same by UV and fluorescence spectra. The photocatalytic decolorization rate of Orange II solutions containing β-CD and TiO2 was smaller by 51.9% than that of the Orange II solutions only containing TiO2, while in the case of direct photolysis of Orange II solutions, β-CD can lower the photolysis rate by 48.1% under UV-light. This result indicates β-CD can inhibit the photolysis and photocatalytic decolorization of Orange II under UV-light. The β-CD inclusion complex was found to be persistent to UV-light photolysis. Foundation item: Supported by the National Natural Science Foundation of China (20177017) Biography: Lu Ping (1958), male. Associate professor, research direction: environmental photochemistry.  相似文献   
998.
0 IntroductionArtificialarthrosiseshavebeenwidelyusedintheoperatorsclinicalsurgeriesforthepatientswhosearthrosiseswerese riouslyseverelydamaged.Butmostofartificialarthrosisescanon lybeusedforabouttenyearslongduetotheseriousabrasion .Forthisreason ,theimprovementofthelongevityofartificialarthrosisbecomesanimportantsubjectofstudy .TheartificialarthrosisesbeingmadeupofTialloyTC4(Ti 6Al 4V)andthepolythenewithultrahighmolecularweighthavegreatpotentialitiesonim provinglongevitybecauseTC4canreac…  相似文献   
999.
Several proteins implicated in the pathogenesis of polycystic kidney disease (PKD) localize to cilia. Furthermore, cilia are malformed in mice with PKD with mutations in TgN737Rpw (encoding polaris). It is not known, however, whether ciliary dysfunction occurs or is relevant to cyst formation in PKD. Here, we show that polycystin-1 (PC1) and polycystin-2 (PC2), proteins respectively encoded by Pkd1 and Pkd2, mouse orthologs of genes mutated in human autosomal dominant PKD, co-distribute in the primary cilia of kidney epithelium. Cells isolated from transgenic mice that lack functional PC1 formed cilia but did not increase Ca(2+) influx in response to physiological fluid flow. Blocking antibodies directed against PC2 similarly abolished the flow response in wild-type cells as did inhibitors of the ryanodine receptor, whereas inhibitors of G-proteins, phospholipase C and InsP(3) receptors had no effect. These data suggest that PC1 and PC2 contribute to fluid-flow sensation by the primary cilium in renal epithelium and that they both function in the same mechanotransduction pathway. Loss or dysfunction of PC1 or PC2 may therefore lead to PKD owing to the inability of cells to sense mechanical cues that normally regulate tissue morphogenesis.  相似文献   
1000.
In this paper, the Life Cycle of Urban Development was firstly analyzed, and the phases of Life Cycle Assessment applied to Urban Development (ULCA) were described. As a case study, ULCA was applied in the environmental impact assessment of the land readjustment project of Hyogo District of Saga, Japan. In addition, mitigation proposals for reducing CO2 were also presented and the relevant environmental ef-fects were simulated.  相似文献   
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