检索结果-南通市图书馆

Instabilities of Rayleigh-Marangoni-Benard Convection in two-layer liquids.

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Instabilities of Rayleigh-Marangoni-Benard Convection in two...

Geomagnetic episodes of the last 1.2 Myr recorded in Chinese loess

5th China-Japan Workshop on Microgravity sciences

作者： q.s.liu B.H.Zhou LNMC Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China LNMC Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

＜正＞ The convections in two or multi-layer liquids system have been paid more attention due to complicate nature phenomena and numerous engineering applications such as in geophysics, atmospheric physics, astrophysics and in industrial processes. The convective instabilities in two or more superposed layers subjected to a thermal gradient parallel or perpendicular to interface were studied theoretically and experimentally by many scientist.

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Geomagnetic episodes of the last 1.2 Myr recorded in Chinese...

GLOBAL sUPERCONVERGENCE EsTIMATEs OF FINITE ELEMENT METHOD FOR sCHRODINGER EqUATION

中国科学院地质与地球物理研究所2002学术年会

作者： Y.X.Pan,~a R.X.Zhu,~a q.s.liu,~b B.Guo,1 L.P.Yue,~c and H.N.Wu~c a.Institute of Geology and Geophysics,Chinese Academy of sciences,Beijing China b.Institute for Rock Magnetism,University of Minnesota,Minneapolis,UsA c.Department of Geology,Northwest University,Xi’an,China.

The Matuyama-Brunhes(M/B) boundary,termination of Jaramillo normal subchron (J/M) as well as three young geomagnetic excursions has been revealed in the Weinan loess section [Zhu et al.,1994,1998,1999].Recently,we carried out further paleomagnetic directional studies on the same section and recovered the onset of the Jaramillo normal subchron(M/J) and four geomagnetic excursions,two in the Brunhes and two in the late *** fact that all seven excursions found in this section are in loess units and expected excursions in paleosols are not found suggests that short-lived geomagnetic signals could be only recorded in loess units,and may have been fully smoothed or wiped out in paleosol units by strong *** by a new astronomical timescale(HLD00),ages of the geomagnetic excursions and reversal boundaries have been *** tentatively correlated these excursions with previous results,indicating that a large lock-in model may not be correct for the whole loess profile,although some apparently big positive age discrepancies were observed for the main boundaries.

关键词： Geomagnetic excursion Chinese loess 1.2 Myr

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1998年第6期16卷 521-526页

作者： Lin, q liu, Xq Acad sinica Inst Syst Sci Beijing 100080 Peoples R China Xiangtan Teachers Coll Dept Math Hunan 411201 Peoples R China

In this paper, we shall study the initial boundary value problem of schrodinger equation. The second order gradient superconvergence estimates for the problem are obtained solving by linear finite elements.

关键词： finite element superconvergence estimates interpolation schrodinger equation

The effects of exercise interventions on brain-derived neurotrophic factor levels in children and adolescents:a meta-analysis

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第5期20卷 1513-1520页

作者： Xueyun shao Longfei He Yangyang liu Physical Education school Shenzhen UniversityShenzhenGuangdong ProvinceChina shenzhen Institute of Neuroscience ShenzhenGuangdong ProvinceChina

Brain-derived neurotrophic factor is a crucial neurotrophic factor that plays a significant role in brain health. Although the vast majority of meta-analyses have confirmed that exercise interventions can increase brain-derived neurotrophic factor levels in children and adolescents, the effects of specific types of exercise on brain-derived neurotrophic factor levels are still controversial. To address this issue, we used meta-analytic methods to quantitatively evaluate, analyze, and integrate relevant studies. Our goals were to formulate general conclusions regarding the use of exercise interventions, explore the physiological mechanisms by which exercise improves brain health and cognitive ability in children and adolescents, and provide a reliable foundation for follow-up research. We used the Pub Med, Web of science, science Direct, springer, Wiley Online Library, Weipu, Wanfang, and China National Knowledge Infrastructure databases to search for randomized controlled trials examining the influences of exercise interventions on brain-derived neurotrophic factor levels in children and adolescents. The extracted data were analyzed using Review Manager 5.3. According to the inclusion criteria, we assessed randomized controlled trials in which the samples were mainly children and adolescents, and the outcome indicators were measured before and after the intervention. We excluded animal experiments, studies that lacked a control group, and those that did not report quantitative results. The mean difference(MD;before versus after intervention) was used to evaluate the effect of exercise on brain-derived neurotrophic factor levels in children and adolescents. Overall, 531 participants(60 children and 471 adolescents, 10.9–16.1 years) were included from 13 randomized controlled trials. Heterogeneity was evaluated using the q statistic and I^(2) test provided by Review Manager software. The meta-analysis showed that there was no heterogeneity among the studies(P = 0.67,

关键词： adolescents brain-derived neurotrophic factor children exercise meta-analysis randomized controlled trials

First-principles Investigation of Bi segregation at the solder Interface of Cu/Cu_3sn(010)

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & Technology 2010年第12期26卷 1057-1062页

作者： X.Y. Pang Z.q. liu s.q. Wang J.K. shang shenyang National Laboratory for Materials science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials science and Engineering University of Illinois at Urbana-Champaign IL 61801 USA

Density functional theory was employed to investigate the bismuth segregation at Cu/Cu3sn（010） interface. Five initial constructions were introduced by adopting the adhesion energy criterion. Among them, the so-called ＂between-Cu＂ construction in which the interface Cu atoms of Cu slab locate along Cu-Cu bond direction in Cu3sn slab was found to be the most energy-favored at an adhesion energy of 1.96 J/m^2. Based on this construction, five possible segregation sites were examined, and the most likely segregation site was determined with adhesion energy as low as 1.06 J/m^2, which was almost half of the initial one. Comparing with other sitest adhesion energies, it was concluded that size effect took a large part in embrittlement. The analyses of atomic structure and electronic density revealed that the slabs shifted away from interfaces due to bismuth segregation, and the atoms around Bi atom were Dressed away. This calculated work agreed aualitativelv with reported experimental results.

关键词： First-principles calculation segregation Bismuth Interface snBi solder

Molecular Arrangement of a Bolaamphiphilic Anthrancene Derivative in Langmuir-Blodgett Film

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2001年第12期12卷 1105-1108页

作者： Lu, q liu, MH Chinese Acad sci Lab Colloid & Interface Sci Ctr Mol Sci Inst Chem Beijing 100080 Peoples R China

This paper reports the molecular assembly in the LB film of a novel bolaamphiphilic anthracene derivative (BIsANs) in comparison with that of one-headed amphiphilic anthracene derivative (ANs). While ANs formed a stretched monolayer at the air/water interface, BIsANs underwent aggregation to form crystal film on the water surface. Both of the H-aggregates and J-aggregates exist in the transferred LB films of bolaamphiphilic BIsANs, only J-aggregates formed in the LB film of ANs.

关键词： bolaamphiphile air/water interface stretched monolayer

THERMAL sTREssEs RELAXATION DEsIGN OF Ni/NiFe_(2)O_(4) sYsTEM FUNCTIONALLY GRADED CERMET INERT ANODE

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica sinica(English Letters) 2005年第5期18卷 635-641页

作者： J. Li q.s. Zhang Y.q. Lai s.L. Ye Y.X. liu school of Metallurgy science and Engineering Central South University Changsha 410083 China

The thermal stresses relaxation of Ni/NiFe2O4 system functionally graded cermet inert anode for aluminum electrolysis was optimally designed. The transient thermal stresses of the inert anode under complex boundary condition during high-temp （955℃） electrolysis were calculated using the finite-element software ANsYs, the influence of different parameters on the distribution of the thermal stresses were analyzed. The results showed that, during the process of thermal shock, the thermal hoop tensile stress on the surface of the anode is very large, which is possibly the major cause of anode crack; when the radius of the anode is between 0.05-0.15m, a range that can be realized by recent manufacturing technology, the optimum composition distribution exponent p is 0.25; The hoop tensile stresses reduce with the decrease of anode scale and also decrease with the decrease of the convection coefficient between the electrolyte and the anode.

关键词： functionally graded material (FGM) transient thermal stresses ANsYs inert anode aluminum electrolysis

Template-free Fabrication and Luminescent Characterization of Highly Uniform and Monodisperse Y_2O_2s:sm^(3+) Hollow submicrospheres

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & Technology 2012年第7期28卷 666-672页

作者： s.q. Deng Z.P. Xue Y.H. Yang q. Yang Y.L. liu Department of Chemistry Jinan University Guangzhou 510632 China

Well dispersed and homogeneous Y2O2s：sm3＋ hollow submicrospheres were successfully achieved by a template- free solvothermal method combining with a postcalcining process. The crystalstructure and particle morphology were investigated by the X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectra, scanning and transmission electron microscopy （sEM and TEM）, respectively. A possible growth mechanism was proposed to reveal the formation process. Luminescence properties of the Y202s：sm3＋ long-lasting phosphor were an- alyzed by measuring the excitation spectra, emission spectra, afterglow decay curve and thermoluminescence curve. The excitation spectra indicated that the phosphor could be excited effectively by the ultraviolet-light emitting diode （UV-LED） or blue LED, and the emission spectra showed that the phosphor could emit red light from 600 to 650 nm.

关键词： Yttrium oxysulfide Hollow submicrosphere Luminescence Long-lasting phosphor

TOTAL ENERGIEs AND ELECTRONIC sTRUCTUREs OF CO_3Ti AND HYDROGENIZED Co_3Ti

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica sinica(English Letters) 1998年第3期11卷 197-201页

作者： s.q.Duan s.J.liu B.K.Ma Beijing Normal Univ Beijing China

Electronic structure calculations using the tighting-binding linear muffin-tin orbital (TB-LMTO) method have been performed for Co3Ti and its hydride CO3Ti. The computed values of lattice constants and bulk moduli agree with the experiment values. The theoritical excess enerpy and lattice staid due to hydrogen absorption consequently obtained hem the ab initio results indicate that H has the tendency to stay in Co3Ti and the ionicities of Co atomic spheres due to hydmpen absorption change from the canons to the ations. On the other hand, the changes of band structures due to hydrogenation are found to be remarkable.

关键词： total enerpy electronic structure hydrogenized Co3Ti