检索结果-南通市图书馆

维普期刊数据库

高强度轴承钢滚动接触疲劳的Ⅱ型裂纹扩展驱动力

在线全文

学校读者我要写书评

暂无评论

河南科技大学学报(自然科学版) 1988年第2期 29-40页

作者：陈菁 hahn g t Rubin C A Bhargava V

本文探讨了滚动接触产生的残余应力对Ⅱ型应力强度因子幅度(ΔK)的影响,此ΔK是指承受重复滚动接触轴承圈的次表层裂纹扩展驱动力。对于高强度轴承钢,分别在短寿命(N=2—10~7),产生较小周向残余应力的情况下及在长寿命(N=10~8—10)产生... 详细信息

本文探讨了滚动接触产生的残余应力对Ⅱ型应力强度因子幅度(ΔK)的影响,此ΔK是指承受重复滚动接触轴承圈的次表层裂纹扩展驱动力。对于高强度轴承钢,分别在短寿命(N=2—10~7),产生较小周向残余应力的情况下及在长寿命(N=10~8—10)产生较大周向残余应力的情况下进行了计算。在计算时还把赫芝应力、裂纹相对深度、裂纹倾斜角度及裂纹表面间的摩擦力等作为变量。在下列前提下进行计算:二维的、重复的、无摩擦的纯滚动接触;符合线弹性断裂力学条件;存在的是平面的、小的次表面裂纹。最后将计算结果与实际观察的裂纹生长剥落情况对比。研究结果表明:除裂纹倾角极小的特殊情况外,一般说在较长寿命下所形成较大的残余压应力能明显地使次表层粗糙裂纹的扩展驱动力(ΔK)减小。

关键词：裂纹实际观察高倍缺陷(金属) 应力强度因子力学因子残余应力残余内应力滚动接触疲劳轴承钢周向驱动力相对深度纯滚动接触线弹性断裂力学脆性断裂力学高强度

Detailed derivation of the ^(3)P_(0) strong decay model applied to baryons

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics C 2025年第1期49卷 139-153页

作者： t.Aguilar A.Capelo-Astudillo M.Conde-Correa A.Duenas-Vidal P.g.Ortega J.Segovia Departamento de Física Escuela Politécnica NacionalQuito 170143Ecuador Departamento de Física Fundamental Universidad de SalamancaE-37008 SalamancaSpain Instituto Universitario de Física Fundamental y Matemáticas(IUFFyM) Universidad de SalamancaE-37008 SalamancaSpain Departamento de Sistemas Físicos Químicos y NaturalesUniversidad Pablo de OlavideE-41013 SevillaSpain

By using the ^(3)P_(0) pair creation model,we provide a detailed derivation of the transition matrix for a baryon decaying into a meson-baryon *** analysis was successfully conducted for a meson in[***,***,and ***,***.B 715,322(2012),and we extend the same formalism to the baryon sector,focusing on the △(1232)→πN strong decay width because all hadrons involved in the reaction are very well established,the two hadrons in the final state are stable and require no further analysis,all quarks are light and thus equivalent,and the decay width of the process is relatively well *** a very common Rayleigh-Ritz variational method to solve the 2-and 3-body Schodinger bound-state equation in which the hadron's radial wave functions are expanded in terms of a gaussian basis,we can relate the expression of the invariant matrix element with the mean-square radii of hadrons involved in the *** use their experimental measures in such a way that only the strength of the quark-antiquark pair creation from the vacuum is a free *** is then taken from our previous study on strong decay widths in the meson sector[***,***,and ***,***.B 715,322(2012),and the obtained results are compatible with the experimental results for the calculated △(1232)→πN decay *** requiring the calculation of additional baryon strong decays,a feasible avenue towards a unified description of both baryon and meson strong decay widths within a single constituent quark model framework may be ***,this research has been developed to lay the foundation for a novel raft of applications to exotic hadrons,i.e.,the description of the baryon's coupling to meson-baryon thresholds,one of the mechanisms that is considered to be responsible for providing either a large renormalization to naive states or genuine dynamicallygenerated meson-baryon molecules.

关键词： baryon strong decays ^(3)P_(0)decay model quark model

On Sawada-Kotera and Kaup-Kuperschmidt integrable systems

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in theoretical Physics 2025年第2期77卷 23-31页

作者： Metin gürses Asl| Pekcan Department of Mathematics Faculty of Science Bilkent University Department of Mathematics Faculty of Science Hacettepe University

to obtain new integrable nonlinear differential equations there are some well-known methods such as Lax equations with different Lax representations. there are also some other methods that are based on integrable scalar nonlinear partial differential equations. We show that some systems of integrable equations published recently are the M2-extension of integrable such scalar equations. For illustration, we give Korteweg–de Vries, Kaup-Kupershmidt, and SawadaKotera equations as examples. By the use of such an extension of integrable scalar equations, we obtain some new integrable systems with recursion operators. We also give the soliton solutions of the systems and integrable standard nonlocal and shifted nonlocal reductions of these systems.

关键词： recursion operator nonlocal reductions Hirota bilinear form soliton solutions .M2-extension recursion operator nonlocal reductions Hirota bilinear form soliton solutions

Solvation Effects on the Dielectric Constant of 1 M LiPF6 in Ethylene Carbonate:Ethyl Methyl Carbonate 3:7

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Energy & Environmental Materials 2024年第1期7卷 253-256页

作者： Julian Self Nathan t.hahn Kristin A.Persson Department of Chemical Engineering Polytechnique MontrealMontrealQC H3T 1J4Canada Department of Materials Science and Engineering University of CaliforniaBerkeleyCA 94720USA Energy technologies Area Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA Material Physical and Chemical Sciences CenterSandia National LaboratoriesAlbuquerqueNM 87185USA

We report the dielectric constant of 1 M LiPF_(6)in EC:EMC 3∶7 w/w(ethylene carbonate/ethyl methyl carbonate)in addition to neat EC:EMC 3∶7 w/*** three Debye relaxations,the static permittivity value,or dielectric constant,is extrapolated to 18.5,which is compared to 18.7 for the neat solvent *** EC solvent is found to strongly coordinate with the Li^(+)cations of the salt,which results in a loss of dielectric contribution to the ***,the small amplitude and large uncertainty in relaxation frequency for EMC cloud definitive identification of the Li^(+)solvation ***,the loss of the free EC permittivity contribution due to Li^(+)solvation is almost completely balanced by the positive contribution of the associated LiPF_(6)salt,demonstrating that a significant quantity of dipolar ion pairs exists in 1 M LiPF_(6)in EC:EMC 3∶7.

关键词： batteries dielectric relaxation spectroscopy electrolytes

维普期刊数据库

the Root Cap Determines Ethylene-Dependent growth and Development in Maize Roots

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2008年第2期1卷 359-367页

作者： Achim hahn Roman Zimmermann Dierk Wanke Klaus Harter Hans g. Edelmann Botanisches Institut Universitfit zu Koin Gyrhofstr. 15 D-50931 Koin Germany Present address: ZMBP Pflanzenphysiologie University TQbingen Auf der Morgenstelle 1 D-72076 TQbingen Germany Institut fur Entwicklungsbiologie Universitat zu Koin Gyrhofstr. 17 D-50931 Koin Germany Institut fur Entwicklungsbiologie Universitat zu Koin Gyrhofstr. 17 D-50931 Koln Germany ZMBP Pflanzenphysiologie Universitat Tubingen Auf der Morgenstelle 1 D-72076 Tubingen Germany Present address: Biologie und ihre Didaktik Universitat Siegen D-57068 Siegen Germany

Besides providing protection against mechanical damage to the root tip, the root cap is involved in the perception and processing of diverse external and internal stimuli resulting in altered growth and development, the transduction of these stimuli includes hormonal signaling pathways such as those of auxin, ethylene and cytokinin. Here, we show that the root cap is essential for the ethylene-induced regulation of elongation growth and root hair formation in maize. Exogenously applied ethylene is no longer able to inhibit elongation growth when the root cap has been surgically removed prior to hormone treatment. Reconstitution of the cap positively correlates with the developing capacity of the roots to respond to ethylene again. In contrast, the removal of the root cap does not per se affect growth inhibition controlled by auxin and cytokinin. Furthermore, our semi-quantitative Rt-PCR results support earlier findings that the maize root cap is a site of high gene expression activity with respect to sensing and responding to hormones such as ethylene, From these data, we propose a novel function of the root cap which is the establishment of competence to respond to ethylene in the distal zones of the root.

关键词： AUXIN BIOSYNtHESIS INSENSItIVE MUtANtS CELL ELONgAtION

Effect of humic substances on the precipitation of calcium phosphate

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2006年第5期18卷 852-857页

作者： SONg Yong-hui Hermann H. hahn Erhard HOFFMANN Peter g. WEIDLER Chinese Research Academy of Environmental Sciences Beijing 100012 China Institute for Aquatic Environmental Engineering University of Karlsruhe Karlsruhe D-76128 Germaay Institute for technical Chemistry Research Centre of Karlsruhe Eggenstein-Leopoldshafen D-76344 Germany

For phosphorus （P） recovery from wastewater, the effect of humic substances （HS） on the precipitation of calcium phosphate was studied. Batch experiments of calcium phosphate precipitation were undertaken with synthetic water that contained 20 mg/L phosphate （as P） and 20 mg/L HS （as dissolved organic carbon, DOC） at a constant pH value in the range of 8.0-10.0. the concentration variations of phosphate, calcium （Ca） and HS were measured in the precipitation process; the crystalline state and compositions of the precipitates were analysed by powder X-ray diffraction （XRD） and chemical methods, respectively. It showed that at solution pH 8.0, the precipitation rate and removal efficiency of phosphate were greatly reduced by HS, but at solution pH ≥9.0, the effect of HS was very small. the Ca consumption for the precipitation of phosphate increased when HS was added; HS was also removed from solution with the precipitation of calcium phosphate. At solution pH 8.0 and HS concentrations ≤3.5 mg/L, and at pH ≥ 9.0 and HS concentrations ≤ 10 mg/L, the final precipitates were proved to be hydroxyapatite （HAP） by XRD. the increases of solution pH value and initial Ca/P ratio helped reduce the influence of HS on the precipitation of phosphate.

关键词： calcium phosphate phosphorus recovery precipitation humic substances initial CaJP ratio solution pH value

维普期刊数据库

Atmospheric chemistry of trifluorodicarbonyls initiated by Cl atoms:Reactivity trends,mechanism,and acid formation yields

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2025年第5期151卷 12-25页

作者： Pedro L.Lugo Vianni g.Straccia Cynthia B.Rivela Mariano A.teruel María B.Blanco Laboratorio Universitario de Química y Contaminación del Aire(L.U.Q.C.A) Instituto de Investigaciones en Fisicoquímica de Córdoba(I.N.F.I.Q.C.)Dpto.de Fisicoquímica.Facultad de Ciencias QuímicasUniversidad Nacional de Córdoba.Ciudad Universitaria5000 CórdobaArgentina Institute for Atmospheric and Environmental Research University of WuppertalDE-42097 WuppertalGermany

Rate coefficients of the gas-phase reactions of Cl atoms with a series of fluorinated diketones(FDKs):CF_(3)C(O)CH_(2)C(O)CH_(3)(tFP),CF_(3)C(O)CH_(2)C(O)CH_(2)CH_(3)(tFH)and CF_(3)C(O)CH_(2)C(O)CH(CH_(3))2(tFMH),have been measured at(298±2)K and under atmospheric *** experiments were performed using the relative-rate method with a gC-FID detection *** different determinations and references used,the following rate coefficients were obtained(in cm3/(molecule·sec)):k_(4)(tFP+Cl)=(1.75±0.21)×10^(−10),k_(5)(tFH+Cl)=(2.05±0.23)×10^(−10),k_(6)(tFMH+Cl)=(2.71±0.34)×10^(−10).Reactivity trends of FDKs were discussed and Free Energy Relationships analysis was *** expression lgkOH=1.68 lgkCl+5.71 was obtained for the reactivity of the studied FDKs together with similar unsaturated VOCs with Cl and OH radicals Additionally,acetic acid(CH_(3)C(O)OH)and trifluoroacetic acid(CF_(3)C(O)OH)were positively identified and quantified as degradation products using in situ FtIR *** to the identified products,atmospheric chemical mechanisms were *** atmospheric implications of the studied reactions were assessed by the estimation of the tropospheric lifetimes of tFP,tFH,and tFMH concerning their reaction with Cl atoms to be 48,41,and 31 hours,*** relatively short residence in the atmosphere of the fluorocarbons studied will have a local/regional impact with restricted *** warming potential(gWP(20 yr))calculated for the studied fluoro diketones were 0.014,0.003 and 0.001 for tFP,tFH and tFMH,respectively with a negligible contribution to the greenhouse effect.

关键词： Fluorinated diketones Kinetics SPME-gC-FID FtIR in situ SAR Free energy relationships

Jejunitis and brown bowel syndrome with multifocal carcinogenesis of the small bowel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of gastroenterology 2015年第36期21卷 10461-10467页

作者： Martin Raithel tilman t Rau Alexander F Hagel Heinz Albrecht thomas de Rossi thomas Kirchner Eckhart g hahn Department of Medicine 1 Friedrich-Alexander-University Erlangen-Nuremberg Department of Pathology Friedrich-Alexander University Erlangen-Nuremberg Department of Pathology Ludwig-Maximilians-University Munich

this is the first report describing a case where prolonged,severe malabsorption from brown bowel syndrome progressed to multifocally spread small bowel adenocarcinoma. this case involves a female patient who was initially diagnosed with chronic jejunitis associated with primary diffuse lymphangiectasia at the age of 26 years. the course of the disease was clinically,endoscopically,and histologically followed for 21 years until her death at the age 47 due to multifocal,metastasizing adenocarcinoma of the small bowel. Multiple lipofuscin deposits(so-called brown bowel syndrome) and severe jejunitis were observed microscopically,and sections of the small bowel showed dense lymphoplasmacytic infiltration of the lamina propria as well as blocked lymphatic vessels. After several decades,multifocal nests of adenocarcinoma cells and extensive,flat,neoplastic mucosal proliferations were found only in the small bowel,along with a loss of the mismatch repair protein MLH1 as a long-term consequence of chronic jejunitis with malabsorption. No evidence was found for hereditary nonpolyposis colon carcinoma syndrome. this article demonstrates for the first time multifocal carcinogenesis in the small bowel in a malabsorption syndrome in an enteritis-dysplasia-carcinoma sequence.

关键词： Brown bowel syndrome Carcinogenesis of the small b

Helicobacter pylori upregulates prion protein expression in gastric mucosa: A possible link to prion disease

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of gastroenterology 2005年第48期11卷 7651-7656页

作者： Peter C Konturek Karolina Bazela Vitally Kukharskyy Michael Bauer Eckhart g hahn Detlef Schuppan Department of Medicine

AIM： Pathological prion protein （PrP^sc） is responsible for the development of transmissible spongiform encephalopathies （tSE）. While PrPc enters the organism via the oral route, less data is available to know about its uptake and the role of gastrointestinal inflammation on the expression of priori precursor PrPc, which is constitutively expressed in the gastric ***： We studied PrPc expression in the gastric mucosa of 10 Helicobacter pylori-positive patients before and after successful H pylori eradication compared to non-infected controls using Rt-PCR and Western blotting. the effect of central mediators of gastric inflammation, i.e., gastrin, prostaglandin E2 （PgE2）, tumor necrosis factor alpha （tNF-α） and interleukin 1 beta （IL-1β） on PrPc expression was analyzed in gastric cell ***： PrPc expression was increased in H pyloriinfection compared with non-infected controls and decreased to normal after successful eradication. gastrin, PgE2, and IL-1β dose-dependently upregulated PrPc in gastric cells, while tNF-α had no ***： H pylori infection leads to the upregulation of gastric PrPc expression. this can be linked to H pylori induced hypergastrinemia and increased mucosal PgE2 and IL-1β synthesis. H pylori creates a milieu for enhanced propagation of prions in the gastrointestinal tract.

关键词： Prions Helicobacter pylori, gastrin Proinflammatory cytokines