检索结果-南通市图书馆

THE GENERALIZED(NONLINEAR)POISSON PROBLEM:A DUAL VARIATIONAL APPROACH

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 1994年第3期10卷 227-236页

作者： hans Bufler Institute for Mechanics Stuttgart UniversityD-70550 StuttgartGermany

A series of problems in mechanics and physics are governed by the ordinary Poisson equation which demands linearity,isotropy,and material homo- *** this paper a generalization with respect to nonlinearity,anisotropy,and inhomogeneity is *** from the canonical basic equations in the primal and dual formulation respectively we derive systematically the corresponding generalized variational principles;under certain conditions they can be extended to so called complementary extremum principles allowing for global *** simplicity a restriction to two dimensional problems is made,including twice-connected domains.

关键词： Generalized Poisson problem dual and complementary variational principles

Morphological properties and residual strain along the small intestine in rats

在线全文

学校读者我要写书评

暂无评论

World journal of Gastroenterology 2002年第2期8卷 312-317页

作者： hans Gregersen Biomechanics Lab Centre for Sensory-Motor InteractionAalborg University and Department of surgery AAalborg HospitalDenmark

AIM: Residual stress and strain are important for gastrointestinal function and relate to the geometric configuration, the loading conditions and the zero-stress state of the gastrointestinal tract. The purpose of this project is to provide morphometric data and residual strains for the rat small intestine ( n =11). METHODS: To approach the no-load state, the intestine was surgically excised, transferred to an organ bath and cut transversely into short ring-shaped segments. Each ring was cut radially for obtaining the zero-stress state. The residual stress can be characterised by an opening angle. The strain difference between the zero-stress state and the no-load state is called residual strain. RESULTS: Large morphometric variations were found along the small intestine. The wall thickness was highest in the proximal duodenum and decreased in distal direction along the axis of the small intestine (P<0.001). The circumferential length of the inner and outer surfaces decreased rapidly along the length of duodenum by 30-50% (P<0.001). The wall area and lumen area showed a similar pattern (P<0.001). In zero-stress state the rings always opened up after making the cut. The experiments resulted in larger inner circumferential length and smaller outer circumferential length when compared to the no-load state. The wall thickness and wall area did not differ between the no-load and zero-stress state. The opening angle and tangent rotation angle increased along the length of the duodenum and had its highest value 30% down the intestine. Further down the intestine it decreased again (P<0.001). The serosal residual strain was tensile with the highest value close to the ligament of Treitz (P<0.001). The mucosal residual strain was compressive in all segments of the small intestine with average values between -0.25 and -0.4 and with the lowest values close to the ligament of Treitz (P<0.001). CONCLUSION: Axial variation in morphometric properties and residual s

关键词： Animals In Vitro Intestine, Small histology Male Rats Rats, Sprague-Dawley Research Support, Non-U.S. Gov't Stress, Mechanical

CALCULATION OF THE YOUNG'S MODULUS OF AN ADSORBED POLYMER LAYER

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese journal of Polymer Science 2007年第1期25卷 95-105页

作者： Rüdiger Stark Michael Kappl hans-jürgen Butt Max-Planck-Institute for Polymer Research Ackermannweg 1055128 MainzGermany

Polymer layers adsorbed to a surface or in a confined environment often change their mechanical properties. There is even the possibility of solidification of the confined layer. To judge the stiffness of such a layer, we used the Hertz model to calculate the Young＇s modulus of the polymer layer in the confinement of AFM experiments with silicon nitride tip with a radius of curvature ofR ≈ 50 nm and a glass sphere attached to the cantilever R =5 μm. Since there is no visible indentation of the layer in the AFM experiments, the layer is either penetrated very easily, or the indentation is too small to be seen in a force curve. The latter would be the case for a polymer layer with a Young＇s modulus above 4 × 10^8 Pa in case of an experiment with a silicon nitride tip and 4×10^5 Pa in case of a glass sphere.

关键词： AFM PDMS PI Confined polymer Young's modulus Solidification.

Liver surgery in cirrhosis and portal hypertension

在线全文

学校读者我要写书评

暂无评论

World journal of Gastroenterology 2016年第9期22卷 2725-2735页

作者： Christina Hackl hans j Schlitt Philipp Renner Sven A Lang Department of Surgery University Medical Center Regensburg

The prevalence of hepatic cirrhosis in Europe and the United States, currently 250 patients per 100000 inhabitants, is steadily increasing. Thus, we observe a significant increase in patients with cirrhosis and portal hypertension needing liver resections for primary ormetastatic lesions. However, extended liver resections in patients with underlying hepatic cirrhosis and portal hypertension still represent a medical challenge in regard to perioperative morbidity, surgical management and postoperative outcome. The Barcelona Clinic Liver Cancer classification recommends to restrict curative liver resections for hepatocellular carcinoma in cirrhotic patients to early tumor stages in patients with Child A cirrhosis not showing portal hypertension. However, during the last two decades, relevant improvements in preoperative diagnostic, perioperative hepatologic and intensive care management as well as in surgical techniques during hepatic resections have rendered even extended liver resections in higher-degree cirrhotic patients with portal hypertension possible. However, there are few standard indications for hepatic resections in cirrhotic patients and risk stratifications have to be performed in an interdisciplinary setting for each individual patient. We here review the indications, the preoperative risk-stratifications, the morbidity and the mortality of extended resections for primary and metastatic lesions in cirrhotic livers. Furthermore, we provide a review of literature on perioperative management in cirrhotic patients needing extrahepatic abdominal surgery and an overview of surgical options in the treatment of hepatic cirrhosis.

关键词： Liver resection Hepatocellular carcinoma Liver metastases Portal hypertension Cholangiocellular carcinoma Cirrhosis

Progastrin-releasing peptide and gastrin-releasing peptide receptor mRNA expression in non-tumor tissues of the human gastrointestinal tract

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 2006年第16期12卷 2574-2578页

作者： hans-jürg Monstein Niclas Grahn Mikael Truedsson Bodil Ohisson Molecular Biology Laboratory-LMC University HospitalDepartment of Biomedicine and SurgeryFaculty of Health SciencesS-581 85 LinkpingSweden Department of Clinical Sciences University Hospital MalmS-205 02 MalmSweden

AIM： To investigate the expression of gastrin-releasing peptide （GRP） and GRP-receptor mRNA in non-tumor tissues of the human esophagus, gastrointestinal tract, pancreas and gallbladder using molecular biology techniques. METHODS： Poly A^＋ mRNA was isolated from total RNA extracts using an automated nucleic acid extractor and, subsequently, converted into single-stranded cDNA （sscDNA）. PCR amplifications were carried out using genespecific GRP and GRP-receptor primers. The specificity of the PCR amplicons was further confirmed by Southern blot analyses using gene-specific GRP and GRP-receptor hybridization probes. RESULTS： Expression of GRP and GRP-receptor mRNA was detected at various levels in nearly all segments of the non-tumor specimens analysed, except the gallbladder. In most of the biopsy specimens, coexpression of both GRP and GRP-receptor mRNA appeared to take place. However, expression of GRP mRNA was more prominent than was GRP-receptor mRNA. CONCLUSION： GRP and GRP-receptor mRNAs are expressed throughout the gastrointestinal tract and provides information for the future mapping and determination of its physiological importance in normal and tumor cells.

关键词： Gastrin releasing peptide (GRP) Gastrinreleasing peptide receptor (GRPR) mRNA expression Morphogenesis Gastrointestinal tract

The Dichotomy Between Traces on d-sets Г in R^n and the Density of D(R^n\Г) in Function Spaces

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2008年第4期24卷 539-554页

作者： hans TRIEBEL Mathematisches Institut Fakultt fr Mathematik und InformatikFriedrich-Schiller-Universitt JenaD-07737 JenaGermany

A space Apq^s （R^n） with A ： B or A = F and s ∈R, 0 〈 p, q 〈 ∞ either has a trace in Lp（Г）, where Г is a compact d-set in R^n with 0 〈 d 〈 n, or D（R^n／Г） is dense in it. Related dichotomy numbers are ... 详细信息

A space Apq^s （R^n） with A ： B or A = F and s ∈R, 0 〈 p, q 〈 ∞ either has a trace in Lp（Г）, where Г is a compact d-set in R^n with 0 〈 d 〈 n, or D（R^n／Г） is dense in it. Related dichotomy numbers are introduced and calculated.

关键词： function spaces d-sets fractals traces

Linking monitoring and modelling for river basin management:Danish experience with combating nutrient loadings to the aquatic environment from point and non-point sources

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第11期52卷 3335-3347页

作者： KRONVANG Brian WINDOLF jФrgen GRANT Ruth ANDERSEN hans E THODSEN hans OVESEN Niels B LARSEN SФren E National Environmental Research Institute Aarhus University VejlsФvej 25 DK-8600 Silkeborg Denmark

Nationwide monitoring of the aquatic environment was initiated in 1988 in Denmark as a means to follow the outcome of the Action Plans for nutrient pollution of the aquatic environment. Five Action Plans have been adopted by the Danish Parliament since 1985 and the nationwide monitoring programme can be used to quantify the outcome as shown by reductions in nutrient discharges from both point and non-point sources. Moreover, the empirical experience gathered from nearly 20 years of monitoring is assisting the development and calibration of models for simulation of nitrogen leaching, nitrogen removal in groundwater and surface waters and the establishment of a P-index all covering the entire land area of Denmark.

关键词： nitrogen phosphorus monitoring data point sources non-point sources models Action Plans Danish experience

Preface: Metamorphism and Orogenic Belts——Response from Micro-to Macro-Scale

在线全文

学校读者我要写书评

暂无评论

journal of Earth Science 2019年第6期30卷 1075-1083页

作者： Xu-Ping Li hans-Peter Schertl jürgen Reinhardt Shandong Key Laboratory of Depositional Mineralization and Sedimentary Minerals Shandong University of Science and TechnologyQingdao 266590China Ruhr-University Bochum Institute of GeologyMineralogy and GeophysicsD-44780 BochumGermany College of Earth Science and Engineering Shandong University of Science and TechnologyQingdao 266590China Department of Earth Sciences University of the Western CapeBellville 7535South Africa

The geological toolbox for the analysis of orogenic processes has seen substantial additions over the recent *** advances have been made in the ability to simulate geological conditions and processes by computer modeling,we have a much improved knowledge of geochemical processes(trace elements and isotopes in particular),and,last but not least,the range and versatility of micro-analytical methods and instrumentation available to us has been expanded *** latter aspect has had a particular impact on metamorphic petrology as the conventional tools to determine pressure-temperaturetime paths via rock and mineral analysis combined with isotope geochronology have generally gained in precision and accuracy through a much improved *** has moved from whole-grain analysis to spot analyses on zoned single grains while analyzing trace elements and isotopes at the same *** is therefore possible to recognize complex multi-stage orogenic events in single samples or single *** profiles in minerals provide us with time-scales of metamorphic and magmatic *** and trace elements as well as isotope profiles of mineral grains give us insight into changing ambient conditions during mineral *** special issue focuses on pressure-temperature conditions and geochronology of metamorphic rocks,isotope studies of magmatic rocks,partial melting and metasomatic processes,all with a view at tectonic implications and *** of the evidence has been gained from small-scale observation and *** field work and detailed microscopic examination remain indispensable,though,as demonstrated clearly by the"expansion"of the P-T space as applicable to crustal metamorphic processes towards extreme pressures and *** a consequence,much interest has thus focused on UHP and UHT rocks and the orogenic processes that generate *** is petrological evidence for subduction to,and subsequent exhumation fr

关键词： orogeny metasomatism UHP metamorphism UHT metamorphism geochemistry geochronology

Interference from HONO in the measurement of ambient air NO2 via photolytic conversion and quantification of NO

在线全文

学校读者我要写书评

暂无评论

journal of Environmental Sciences 2021年第9期33卷 184-193页

作者： Nicholas j.Gingerysty Charles A.Odame-Ankrah Nick jordan hans D.Osthoff Department of Chemistry University of CalgaryCalgary AB T2N 1N4Canada Global Analyzer Systems Ltd. Calgary AB T2E 7L6Canada

The reference method to quantify mixing ratios of the criteria air pollutant nitrogen dioxide(NO_(2)) is NO-O_(3) chemiluminescence(CL), in which mixing ratios of nitric oxide(NO) are measured by sampling ambient air directly, and mixing ratios of NO_(x)(= sum of NO and NO_(2))are measured by converting NO_(2) to NO using, for example, heated molybdenum catalyst or,more selectively, photolytic conversion(P-CL).In this work, the nitrous acid(HONO) interference in the measurement of NO_(2) by P-CL was *** with two photolytic NO2 converters are *** first used radiation centered at 395 nm, a wavelength region commonly utilized in *** second used light at 415 nm, where the overlap with the HONO absorption spectrum and hence its photolysis rate are *** ratios of NO_(2),NO_(x) and HONO entering and exiting the converters were quantified by Thermal Dissociation Cavity Ring-down Spectroscopy(TD-CRDS).Both converters exhibited high NO_(2) conversion efficiency(CF_(NO2);> 90%) and partial conversion of *** of CF against flow rate were consistent with photolysis frequencies of 4.2 s^(-1) and 2.9 s^(-1) for NO_(2) and 0.25 s^(-1) and 0.10 s^(-1) for HONO at 395 nm and 415 nm, *** larger than predicted from the overlap of the emission and HONO absorption *** results imply that measurements of NO2 by P-CL marginally but systematically overestimate true NO_(2) concentrations,and that this interference should be considered in environments with high HONO:NO_(2) ratios such as the marine boundary layer or in biomass burning plumes.

关键词： Photolytic conversion of NO_(2) HONO interference