检索结果-南通市图书馆

Spatial patterns of distribution and abundance of Harrisia portoricensis,an endangered Caribbean cactus

在线全文

学校读者我要写书评

暂无评论

journal of Plant Ecology 2013年第6期6卷 489-498页

作者： julissa Rojas-Sandoval Elvia j.Meléndez-Ackerman Department of Biology University of Puerto RicoRío Piedras CampusPO Box 23360San JuanPuerto Rico 00931-3360USA Center for Applied Tropical Ecology and Conservation University of Puerto RicoPO Box 70377San JuanPuerto Rico 00936-8377USA Department of Environmental Sciences College of Natural SciencesUniversity of Puerto RicoPO Box 70377San JuanPuerto Rico 00936-8377USA

Aims The spatial distribution of biotic and abiotic factors may play a dominant role in determining the distribution and abundance of plants in arid and semiarid *** this study,we evaluated how spatial patterns of microhabitat variables and the degree of spatial dependence of these variables influence the distribution and abundance of the endangered cactus Harrisia *** We used geostatistical analyses of five microhabitat variables(*** cover,soil cover and light incidence)and recorded the abundance of *** in 50 permanent plots established across Mona Island,Puerto Rico,by the United States Department of Agriculture Forest Service as part of the Forest Inventory and Analysis(USDA–FIA).We also used partial Mantel tests to evaluate the relationships between microhabitat variables and abundance of ***,controlling for spatial *** findings Abundance of *** showed strong affinities with microhabitat variables related to canopy structure,soil cover and light *** distribution of this cactus species throughout the island was consistent with the spatial variation patterns of these *** general,landscape-level analyses suggested a predictive value of microhabitat traits for the distribution and abundance of this endangered *** sensitive cacti species,wherein abundance may be influenced by similar variables,these types of analyses may be helpful in developing management plans and identifying critical habitats for conservation.

关键词： abundance Caribbean cactus geostatistics Harrisia portoricensis Mona Island spatial correlation spatial distribution

Efficiency of a Grass Buffer Strip for Limiting Diuron Losses from an Uphill Vineyard Towards Surface and Subsurface Waters

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2012年第4期22卷 580-592页

作者： j.-G. LACAS N. CARLUER M. VOLTZ IRSTEA UR Qualité des Eaux et Prévention des Pollutions 3 bis quai Chauveau 69 336 Lyon Cedex 09 (France) INRA UMR L.I.S.A.H. INRA-IRD-SupAgro 2 place Viala 34060 Montpellier Cedex 1 (France)

Grass buffer strips limit the transfer of pesticides from cultivated fields to rivers. These solutions are generally efficient at reducing polluted surface flows, mainly by infiltration of the soil, raising the question of the fate of the infiltrated pollutants. An environmental evaluation was conducted on the efficiency of a grass strip receiving diuron-contaminated water from an uphill vineyard in France. During two runoff events, the following measurements were taken: surface inflow and outflow with Venturi flumes, vertical percolated flow below the root layer (0-50 cm), and variations in water and solute content of the root layer. One runoff event occurred under natural rainfall conditions, while the other runoff event was artificially provoked with water doped by diuron and bromide. For the natural runoff event, representative of medium intensity events, 94% of the diuron was retained in the root layer, whereas 2% left the grass strip by surface runoff and 4% left the grass strip in the water percolating under the root zone. For the artificial event, representative of intense runoff events, more than half of the incoming diuron was retained by the grass strip, whereas 24% and 18% of it were transferred by surface runoff and percolation, respectively. These results showed that the capacity of the root layer to retain diuron was highly significant despite a large percolation flux. However, for large runoff events, surface and subsurface losses can still be considerable, up to 40% of the pesticide load entering the strip.

关键词： infiltration percolation pesticide sorption surface runoff

Diagnosis of bile duct hepatocellular carcinoma thrombus without obvious intrahepatic mass

在线全文

学校读者我要写书评

暂无评论

World journal of Gastroenterology 2010年第39期16卷 4998-5004页

作者： Long XY Li YX Wu W Li L Cao j. Department of General Surgery Xiangya Hospital Central South University Changsha 410008 Hunan Province China. liyixiong6@***

AIM:To study the diagnosis of hepatocellular carcinoma(HCC)presenting as bile duct tumor thrombus with no detectable intrahepatic ***:Six patients with pathologically proven bile duct HCC thrombi but no intrahepatic mass demonstrated on the preoperative imaging or palpated intrahepatic mass during operative exploration,were *** clinical and imaging data were retrospectively *** major findings or signs on comprehensive imaging were correlated with the surgical and pathologic ***:jaundice was the major clinical symptom of the *** elevated serum total bilirubin,direct bilirubin and alanine aminotransferase levels were in concordance with obstructive jaundice and the underlying liver *** the 6 patients showing evidence of viral hepatitis,5 were positive for serum alpha fetoprotein and carbohydrate antigen 19-9,and 1 was positive for serum carcinoembryonic *** patient was correctly diagnosed by *** main features of patients on comprehensive imaging were filling defects with cup-shaped ends of the bile duct,with large filling defects presenting as casting moulds in the expanded bile duct,hypervascular intraluminal nodules,debris or blood clots in the bile *** obvious circular thickening of the bile duct walls was ***:Even with no detectable intrahepatic tumor,bile duct HCC thrombus should be considered in patients predisposed to HCC,and some imaging signs are indicative of its diagnosis.

关键词： Hepatocellular carcinoma Obstructive jaundice Bile duct tumor thrombus Diagnosis Diagnostic imaging

Next generation of power electronic-converter application for energy-conversion and storage units and 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

Clean Energy 2019年第4期3卷 307-315页

作者： Kasper Luthje jørgensen Zhe Zhang Michael A.EAndersen Department of Electrical Engineering Technical University of DenmarkElektrovej 325DK-2800 Kongens LyngbyDenmark

By a rearrangement of the traditional supply-converter-load system connection,partial-power-processing-based converters can be used to achieve a reduction in size and cost,increase in system efficiency and lower device power *** concept is promising for different applications such as photovoltaic arrays,electric vehicles and *** photovoltaic applications,it can drive each cell in the array to its maximum power point with a relatively smaller converter;for electric-vehicle applications,both an onboard charger with reduced weight and improved efficiency as well as a fast charger station handling higher power can be *** showing different examples of partial-power-processing application for energy-conversion and storage units and systems,this paper discusses key limitations of partial-power-processing and related improvements from different perspectives to show the potential in future power electronic systems.

关键词： batteries DC-DC converter differential power processing fuel cells hydrogen production partial-power processing wide band-gap devices fractional power processing

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

Switching O-O bond formation mechanism between WNA and I2M pathways by modifying the Ru-bda backbone ligands of water-oxidation catalysts

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 Energy Chemistry 2021年第3期30卷 815-821页

作者： Biaobiao Zhang Shaoqi Zhan Tianqi Liu Linqin Wang A.Ken Inge Lele Duan Brian j.j.Timmer Oleksandr Kravchenko Fei Li Marten S.G.Ahlquist Licheng Sun Department of Chemistry KTH Royal Institute of Technology10044 StockholmSweden Department of Theoretical Chemistry&Biology School of Engineering Sciences in Chemistry Biotechnology and HealthKTH Royal Institute of Technology10691 StockholmSweden Department of Materials and Environmental Chemistry Stockholm University10691 StockholmSweden Department of Chemistry Southern University of Science and Technology(SUSTech)Shenzhen 518055GuangdongChina State Key Laboratory of Fine Chemicals Institute of Artificial PhotosynthesisDUT–KTH Joint Education and Research Center on Molecular DevicesDalian University of Technology(DUT)Dalian 116024LiaoningChina

Understanding the seven coordination and O-O coupling pathway of the distinguished Ru-bda catalysts is essential for the development of next generation efficient water-oxidation catalysts based on earthabundant *** work reports the synthesis,characterization and catalytic properties of a monomeric ruthenium catalyst Ru-bnda(H2 bnda=2,2’-bi(nicotinic acid)-6,6’-dicarboxylic acid)featuring steric hindrance and enhanced hydrophilicity on the *** experimental evidence with systematic density functional theory calculations on the Ru-bnda and related catalysts Ru-bda(H_(2)bda=2,2’-bipyridine-6,6’-dicarboxylic acid),Ru-pda(H_(2)pda=1,10-phenanthroline-2,9-dicarboxylic acid),and Ru-biqa(H_(2)biqa=(1,1’-biisoquinoline)-3,3’-dicarboxylic acid),we emphasized that seven coordination clearly determines presence of Ru^(Ⅴ)=O with high spin density on the ORu^(Ⅴ)=O atom,*** with radical properties,which is one of the necessary conditions for reacting through the O-O coupling ***,an additional factor to make the condition sufficient is the favorable intermolecular faceto-face interaction for the generation of the pre-reactive[Ru^(Ⅴ)=O…O=Ru^(Ⅴ)],which may be significantly influenced by the secondary coordination *** work provides a new understanding of the structure-activity relationship of water-oxidation catalysts and their potential to adopt I2M pathway for O-O bond formation.

关键词： Water oxidation Oxygen evolution Ruthenium O-O bond formation

RESTful implementation of geospatial services for Earth and Space Science applications

在线全文

学校读者我要写书评

暂无评论

International journal of Digital Earth 2009年第S1期2卷 40-61页

作者： P.Mazzetti S.Nativi j.Caron Institute of Methodologies for Environmental Analysis(IMAA) Italian National Research Council(CNR)Tito ScaloItaly PIN University of FlorencePratoItaly UNIDATAUCAR P.O.Box 3000 Boulder CO 80307-3000USA

In recent years,Representational State Transfer(REST)has been proposed as the architectural style for the World Wide *** promises of scalability and simple deployment of Web Services seem to be particularly appealing for Earth and Space Science(ESS)*** fact,most of the available solutions for geospatial data sharing,applying standard interoperability specifications,require complex service-oriented infrastructures;these are powerful and extensible environments,but they usually result in difficult to deploy and manage for ESS research ***,ESS researchers would gain great benefit from an easy way of sharing geo-information using the international interoperability *** variety and complexity of geo-information sharing services poses several architectural issues;in fact these services encompass sensor planning and observation,coverages and features publication and retrieving,models and simulations running,data citation and ***,the adoption of a specific architectural style must be carefully evaluated against these specific *** this work we analyse the existing geospatial services from an architectural perspective and investigate their possible RESTful *** attention is paid to the OGC Web Coverage Service(WCS).Possible benefits and drawbacks,along with open issues and possible solutions are *** investigation suggests that REST may fit well to the typical ESS research usage ***,the architectural choice(*** Object Access Protocol(SOAP)vs REST)will depend on a case-by-case *** important factors must be considered,such as the application context:a valuable example in point are the e-Business and e-Government application scenarios which require message based solutions-like those implemented by *** any case,there is a clear need for harmonization and reconciliation of these two approaches.

关键词： geospatial web services ROA REST WCS SOA e-Science

HOMOTOPY PERTURBATION SOLUTION AND PERIODICITY ANALYSIS OF NONLINEAR VIBRATION OF THIN RECTANGULAR FUNCTIONALLY GRADED PLATES

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 Solida Sinica 2014年第2期27卷 210-220页

作者： A.Allahverdizadeh R.Oftadeh M.j.Mahjoob M.H.Naei School of Engineering - Emerging Technologies University of Tabriz School of Mechanical Engineering College of Engineering University of Tehran Department of Mechanical and Industrial Engineering Northeastern University

In this paper nonlinear analysis of a thin rectangular functionally graded piate is formulated in terms of von-Karman＇s dynamic equations. Functionaily Graded Material （FGM） properties vary through the constant thickness of the plate at ambient temperature. By expansion of the solution as a series of mode functions, we reduce the governing equations of motion to a Duffing＇s equation. The homotopy perturbation solution of generated Duffing＇s equation is also obtained and compared with numerical solutions. The sufficient conditions for the existence of periodic oscillatory behavior of the plate are established by using Green＇s function and Schauder＇s fixed point theorem.

关键词： nonlinear vibration FGM rectangular plate Schauder's fixed point theorem homotopy perturbation method

Theoretical potential for low energy consumption phase change memory utilizing electrostatically-induced structural phase transitions in 2D materials

在线全文

学校读者我要写书评

暂无评论

npj Computational Materials 2018年第1期4卷 653-661页

作者： Daniel A.Rehn Yao Li Eric Pop Evan j.Reed Department of Mechanical Engineering Stanford UniversityStanfordCA 94305USA Department of Applied Physics Stanford UniversityStanfordCA 94305USA Department of Electrical Engineering Stanford UniversityStanfordCA 94305USA Department of Materials Science and Engineering Stanford UniversityStanfordCA 94305USA

Structural phase-change materials are of great importance for applications in information storage *** driven structural phase transitions are employed in phase-change memory to achieve lower programming voltages and potentially lower energy consumption than mainstream nonvolatile memory ***,the waste heat generated by such thermal mechanisms is often not optimized,and could present a limiting factor to widespread *** potential for electrostatically driven structural phase transitions has recently been predicted and subsequently reported in some two-dimensional materials,providing an athermal mechanism to dynamically control properties of these materials in a nonvolatile fashion while achieving potentially lower energy *** this work,we employ DFT-based calculations to make theoretical comparisons of the energy required to drive electrostatically-induced and thermally-induced phase *** theoretical limits in monolayer MoTe2 and thin films of Ge_(2)Sb_(2)Te_(5),we find that the energy consumption per unit volume of the electrostatically driven phase transition in monolayer MoTe2 at room temperature is 9% of the adiabatic lower limit of the thermally driven phase transition in Ge_(2)Sb_(2)Te_(5).Furthermore,experimentally reported phase change energy consumption of Ge_(2)Sb_(2)Te_(5) is 100–10,000 times larger than the adiabatic lower limit due to waste heat flow out of the material,leaving the possibility for energy consumption in monolayer MoTe2-based devices to be orders of magnitude smaller than Ge_(2)Sb_(2)Te_(5)-based devices.

关键词： transitions phase structural