检索结果-南通市图书馆

Reforestation Programs in Southwest china:Reported Success,Observed Failure, and the Reasons Why

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 Mountain Science 2007年第4期4卷 275-292页

作者： christine Jane Trac Stevan Harrell thomas M. Hinckley Amanda c. Henck Department of Biology University of Washington Department of Anthropology Box 353010 University of Washington Seattle WA 98195 USA college of Forest Resources University of Washington Department of Earth and Space Sciences University of Washington

Ever since the disastrous floods of 1998, the chinese government has used the Natural Forest Protection and Sloping Land conversion Programs to promote afforestation and reforestation as means to reduce runoff, control erosion, and stabilize local livelihoods. These two ambitious programs have been reported as large-scale successes, contributing to an overall increase in china’s forest cover and to the stated goals of environmental stabilization. A small-scale field study at the project level of the implementation of these two programs in Baiwu Township, Yanyuan county, Sichuan, casts doubt upon the accuracy and reliability of these claims of success; ground observations revealed utter failure in some sites and only marginal success in others. Reasons for this discrepancy are posited as involving ecological, economic, and bureaucratic factors. Further research is suggested to determine whether these discrepancies are merely local aberrations or represent larger-scale failures in reforestation programs.

关键词： Forests afforestation reforestation grain-to-green natural forest protection plan china Sichuan Liangshan

Influence of La3+ ion in the yttria matrix in improving the microhardness of infrared transparent nano LaxY2-xO3 sintered via hybrid heating

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced ceramics 2017年第3期6卷 240-250页

作者： Jijimon K. thomas Mathew c. T. Jacob KOSHY Sam SOLOMON Electronic Materials Research Laboratory Department of Physics Mar Ivanios College Thiruvananthapuram 695015 Kerala India

In the present work, hybrid sintering technique which couples the resistive heating and microwave heating is employed to sinter infrared transparent La0.15Y1.85O3 to 99.2% of the theoretical density for the first time to the best of our knowledge. The presence of La3+ in the yttria matrix improves the hardness properties to a greater extent without affecting the transmittance properties, but there is a deterioration in the thermal properties of the sample. So we have limited our studies to La0.15Y1.85O3 which shows better optical, thermal, and hardness properties. The pellets fabricated from the ultra-fine nano powder with average particle size of ~12 nm synthesized by combustion technique and sintered at 1430 ℃ with an average grain size of 0.22 μm show ~80.1% transmittance in the UV–visible region and 81% in mid infrared region. For a comparative study of the optical, mechanical, and thermal properties, two other variants of sintering strategies namely conventional sintering and microwave sintering are also employed. A comprehensive analysis on the hardness reveals that the hardness of the pellets sintered via hybrid heating is 9.73 GPa and is superior to the pellets sintered using the other two techniques. The thermal conductivity of the sample is also analyzed in detail. The results clearly indicate that the La0.15Y1.85O3 ultra-fine nano powder synthesised by the single-step combustion method and sintered via microwave hybrid heating shows better transmittance properties without compromising the mechanical properties, and can be used very effectively for the fabrication of infrared transparent windows and domes.

关键词： La3+ concentration microhardness hybrid sintering infrared transparent ceramics thermal conductivity

current role of palliative interventions in advanced pancreatic cancer

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 Gastrointestinal Surgery 2018年第7期10卷 75-83页

作者： chelsey c ciambella Rachel E Beard thomas J Miner Department of Surgical Oncology Warren Alpert Medical School Brown University

Pancreatic adenocarcinoma is the third leading cause of cancer death in the United States. Unfortunately, at diagnosis, most patients are not candidates for curative resection. Surgical palliation, a procedure performed with the intention of relieving symptoms or improving quality of life, comes to the forefront of management. This article reviews the palliative management of unresectable pancreatic cancer, including obstructive jaundice, duodenal obstruction and pain control with celiac plexus block. Although surgical bypasses for both biliary and duodenal obstructions usually achieve good technical success, they result in considerable perioperative morbidity and mortality, even when performed laparoscopically. The effectiveness of selfexpanding metal stents for biliary drainage is excellent with low morbidity. Surgical gastrojejunostomy for duodenal obstruction appears to be best for patients with a life expectancy of greater than 2 mo while endoscopic stenting has been shown to be feasible with good symptom relief in those with a shorter life expectancy. Regardless of the palliative procedure performed, all physicians involved must be adequately trained in end of life management to ensure the best possible care for patients.

关键词： Surgical palliation Duodenal obstruction Hepatojejunostomy Gastrojejunostomy Endoscopic stenting Malignant ascites celiac block Palliative triangle Pancreatic cancer Obstructive jaundice

Reduced non-cpG methylation is a potential epigenetic target after spinal cord injury

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2023年第11期18卷 2489-2496页

作者： Zhourui Wu chen Li Ran Zhu Yiqiu cao thomas c.chen Liming cheng Key Laboratory of Spine and Spinal cord Injury Repair and Regeneration(Tongji University) Ministry of EducationShanghaiChina Division of Spine Department of OrthopedicsTongji HospitalTongji University School of MedicineShanghaiChina Institute of Spinal and Spinal cord Injury Tongji University School of MedicineShanghaiChina Department of Neurosurgery Keck School of MedicalUniversity of Southern CaliforniaLos AngelesCAUSA

DNA methylation is a critical epigenetic regulator in the occurrence and development of diseases and is closely related to various functional responses in relation to spinal cord *** investigate the role of DNA methylation in spinal cord injury,we constructed a library with reduced-representation bisulfite sequencing data obtained at various time points(day 0-42)after spinal cord injury in *** DNA methylation levels,specifically non-cpG(cHG and cHH)methylation levels,decreased modestly following spinal cord *** post-spinal cord injury were classified as early(day 0-3),intermediate(day7-14),and late(day 28-42)based on similarity and hie rarchical cluste ring of global DNA methylation *** non-cpG methylation level,which included cHG and cHH methylation levels,was markedly reduced despite accounting for a minor proportion of total methylation *** multiple genomic sites,including the 5’untranslated regions,promoter,exon,intron,and 3’untranslated regions,the non-cpG methylation level was markedly decreased following spinal cord injury,whereas the cpG methylation level remained unchanged at these *** one-half of the differentially methylated regions were located in intergenic areas;the other differentially methylated regions in both cpG and non-cpG regions were cluste red in intron regions,where the DNA methylation level was *** function of genes associated with differentially methylated regions in promoter regions was also *** Gene Ontology analysis results,DNA methylation was implicated in a number of essential functional responses to spinal cord injury,including neuronal synaptic connection creation and axon ***,neither cpG methylation nor non-cpG methylation was implicated in the functional response of glial or inflammatory *** summary,our work elucidated the dynamic pattern of DNA methylation in the spinal co rd following injury and identified reduced noncpG meth

关键词： cpG methylation cytosine fraction differentially methylated regions DNA methylation DNA methyltransferases dynamic signatures Gene Ontology non-cpG methylation single-cell RNA-Seq spinal cord injury

Investigations of ZnO thin films deposited by a reactive pulsed laser ablation

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2009年第1期52卷 99-103页

作者： Y. c. SOO H. KANDEL M. A. thomas c. P. DAGHLIAN Department of Physics and Astronomy University of Arkansas at Little Rock Little Rock E. M. Facilities Dartmouth College Hanover

Highly transparent ZnO thin films were deposited at different substrate temperatures by pulsed laser deposition in an oxygen atmosphere. The thin films were characterized by various techniques including X-ray diffraction, scanning electron microscopy, optical absorption, and photoluminescence. We demonstrated that oriented wurtzite ZnO thin films could be deposited at room temperature using a high purity zinc target. Variable temperature photoluminescence revealed new characteristics in the band edge emission. The underlying mechanism for the observed phenomena was also discussed.

关键词： thin films pulsed laser deposition optical property zinc oxide

comparison of carbon-stock changes, eddycovariance carbon fluxes and model estimates in coastal Douglas-fir stands in British columbia

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2015年第2期2卷 104-122页

作者： colin J Ferster JA (Tony) Trofymow Nicholas c coops Baozhang chen thomas Andrew Black Department of Forest Resources Management University of British Columbia canadian Forest Service (Pacific Forestry centre) Natural Resources Canada Department of Biology University of Victoria Faculty of Land and Food Systems University of British Columbia

Background： The global network of eddy-covariance （Ec） flux-towers has improved the understanding of the terrestrial carbon （c） cycle, however, the network has a relatively limited spatial extent compared to forest inventory data and plots. Developing methods to use inventory-based and Ec flux measurements together with modeling approaches is necessary evaluate forest c dynamics across broad spatial extents. Methods： changes in c stock change （Ac） were computed based on repeated measurements of forest inventory plots and compared with separate measurements of cumulative net ecosystem productivity （~NEP） over four years （2003 - 2006） for Douglas-fir （Pseudotsuga menzies# var menziesil} dominated regeneration （HDF00）, juvenile （HDF88 and HDF90） and near-rotation （DF49） aged stands （6, 18, 20, 57 years old in 2006, respectively） in coastal British columbia. Ac was determined from forest inventory plot data alone, and in a hybrid approach using inventory data along with litter fall data and published decay equations to determine the change in detrital pools. These Ac-based estimates were then compared with Y_NEP measured at an eddy-covariance flux-tower （Ec-flux） and modelled by the carbon Budget Model - canadian Forest Sector （cBM-cFS3） using historic forest inventory and forest disturbance data. Footprint analysis was used with remote sensing, soils and topography data to evaluate how well the inventory plots represented the range of stand conditions within the area of the flux-tower footprint and to spatially scale the plot data to the area of the Ec-flux and model based estimates, Results： The closest convergence among methods was for the juvenile stands while the largest divergences were for the regenerating clearcut, followed by the near-rotation stand. At the regenerating clearcut, footprint weighting of cBM-cFS3 TNEP increased convergence with Ec flux Z_NEP, but not for Ac. While spatial scaling and footprint weighting did not increase convergence for Ac, they d

关键词： Forest carbon Micrometeorology Blometry Remote sensing Geographic information systems

Genetic algorithms for computational materials discovery accelerated by machine learning

在线全文

学校读者我要写书评

暂无评论

npj computational Materials 2019年第1期5卷 746-751页

作者： Paul c.Jennings Steen Lysgaard Jens Strabo Hummelshøj Tejs Vegge thomas Bligaard SUNcAT center for Interface Science and catalysis Department of Chemical EngineeringStanford UniversityStanfordCA 94305USA SLAc National Accelerator Laboratory 2575 Sand Hill RoadMenlo ParkCA 94025USA Department of Energy conversion and Storage Technical University of DenmarkLyngbyDenmark Toyota Research Institute Los AltosCA 94022USA

Materials discovery is increasingly being impelled by machine learning methods that rely on pre-existing *** datasets are lacking,unbiased data generation can be achieved with genetic *** a machine learning model is trained on-the-fly as a computationally inexpensive energy predictor before analyzing how to augment convergence in genetic algorithm-based approaches by using the model as a *** leads to a machine learning accelerated genetic algorithm combining robust qualities of the genetic algorithm with rapid machine *** approach is used to search for stable,compositionally variant,geometrically similar nanoparticle alloys to illustrate its capability for accelerated materials discovery,e.g.,nanoalloy *** machine learning accelerated approach,in this case,yields a 50-fold reduction in the number of required energy calculations compared to a traditional“brute force”genetic *** makes searching through the space of all homotops and compositions of a binary alloy particle in a given structure feasible,using density functional theory calculations.

关键词： alloy alloys searching

GENERATION OF TRANSGENIc MIcE FOR IN VIVO DETEcTION OF INSULIN-cONTAINING GRANULE EXOcYTOSIS AND QUANTIFIcATION OF INSULIN SEcRETION

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 Innovative Optical Health Sciences 2009年第4期2卷 397-405页

作者： JINLING LU NATALIA GUSTAVSSON QIMING LI GEORGE KRADDA thomas c.SUUDHOF WEIPING HAN Laboratory of Metabolic Medicine Singapore Bioimaging consortium A*STAR Singapore 138667 Department of Molecular and cellular Physiology and Howard Hughes Medical Institute Stanford University School of Medicine Palo Alto CA 94304USA Department of Biochemistry Yong Loo Lin School of Medicine National University of Singapore Singapore 117597

Insulin secretion is a complex and highly regulated *** much progress has been made in understanding the cellular mechanisms of insulin secretion and regulation,it remains unclear how conclusions from these studies apply to living *** few studies have been done to address these issues is largely due to the lack of suitable tools in detecting secretory events at high spatial and temporal resolution in *** combined with genetically encoded biosensor,optical imaging is a powerful tool for visualization of molecular events in *** this study,we generated a DNA construct encoding a secretory granule resident protein that is linked with two spectrally separate fluorescent proteins,a highly pH-sensitive green pHluorin on the intra-granular side and a red mcherry in the *** exocytosis of secretory granules,the dim pHluorin inside the acidic secretory granules became highly fluorescent outside the cells at neutral pH,while mcherry fluorescence remained constant in the process,thus allowing ratiometric quantification of insulin secretory ***,mcherry fluorescence enabled tracking the movement of secretory granules in living *** validated this approach in insulin-secreting cells,and generated a transgenic mouse line expressing the optical sensor specifically in pancreaticβ-*** transgenic mice will be a useful tool for future investigations of molecular mechanism of insulin secretion in vitro and in vivo.

关键词： Insulin secretion diabetes optical imaging secretory granule exocytosis.

A method for groundwater prospect zonation in data poor areas using remote sensing and GIS:a case study in Kalikavu Panchayath of Malappuram district,Kerala,India

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2009年第2期2卷 155-170页

作者： B.c.thomas S.L.Kuriakose S.K.Jayadev School of Geography University of SouthamptonUK United Nations University-ITc School for Disaster Geo-information Management International Institute for Geo-information Science and Earth Observation(ITC)EnschedeThe Netherlands University Library University of KeralaPalayamThiruvananthapuramKeralaIndia

The present study was an attempt to delineate potential groundwater zones in Kalikavu Panchayat of Malappuram district,Kerala,*** geo-spatial database on geomorphology,landuse,geology,slope and drainage network was generated in a geographic information system(GIS)environment from satellite data,Survey of India topographic sheets and field *** understand the movement and occurrence of groundwater,the geology,geomorphology,structural set-up and recharging conditions have to be well *** the present study,the potential recharge areas are delineated in terms of geology,geomorphology,land use,slope,drainage pattern,*** thematic data generated were integrated using a heuristic method in the GIS domain to generate maps showing potential groundwater *** composite output map scores were reclassified into different zones using a decision *** final output map shows different zones of groundwater prospect,viz.,very good(15.57%of the area),good(43.74%),moderate(28.38%)and poor(12.31%).Geomorphic units such as valley plains,valley fills and alluvial terraces were identified as good to excellent prospect zones,while the gently sloping lateritic uplands were identified as good to moderate *** sloping hilly terrains underlain by hard rocks were identified as poor groundwater prospect zones.

关键词： groundwater Kerala GIS satellite images geomorphic units land use heuristic methods prospect zones the Western Ghats