检索结果-南通市图书馆

Stakeholder Perspectives on Use,Trade,and conservation of Medicinal Plants in the Rasuwa District of central Nepal

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 2011年第1期8卷 75-86页

作者： Yadav UPRETY Ram c.POUDEL Hugo ASSELIN Emmanuel K.BOON krishna K.shrestha Human Ecology Department Vrije Universiteit BrusselLaarbeeklaan 109B-1090 BrusselsBelgium canada Research chair in Aboriginal Forestry Université du Québec en Abitibi-Témiscamingue445Boulevard de l'UniversitéRouyn-NorandaQuébecJ9X 5E4Canada Kunming Institute of Botany Chinese Academy of Sciences central Department of Botany Tribhuvan University

People's livelihood in several Himalayan regions largely depends on collection,use,and trade of medicinal *** use is generally not a problem,but commercial gathering of selected species to meet increasing national and international demand can result in *** management of medicinal plants requires a clear understanding of the respective roles,responsibilities and viewpoints of the various stakeholders *** personal interviews and group discussions,this study aimed at investigating the views of two stakeholder groups on use,trade and conservation of medicinal plants in the Rasuwa district of *** people and district and national organizations agreed that medicinal plants are collected for a combination of commercial and personal *** on market availability differed significantly:100 % of the respondents from district and national organizations saw markets as easily available,against only 36 % for local *** could explain why medicinal plants were perceived by local people to contribute less to income generation than to livelihood *** viewpoints were also expressed concerning the status of medicinal plants in the district:81 % of the respondents from district and national organizationsconsidered that medicinal plants were threatened,compared to only 28 % for local *** this disparity,both stakeholder groups agreed upon potential threats to medicinal plants:over-harvesting;habitat loss due to land-use change and deforestation;and over-grazing by *** challenges were identified regarding sustainable management of medicinal plants,such as ambiguous policies;lack of resources,information and infrastructures;habitat degradation;and *** these challenges,respondents agreed that the medicinal plants sector offers huge opportunities in the Rasuwa district,given resource availability,community awareness and motivation,and the priority given

关键词： Medicinal plants Livelihood improvement Income generation Himalaya Local people conservation Policy

Modification of B3 Model for Sealed concrete with Additives Based on Experimental Observations

在线全文

学校读者我要写书评

暂无评论

Journal of Donghua University(English Edition) 2011年第1期28卷 79-84页

作者：陈宝春 shrestha krishna Man 李生勇 college of civil Engineering Fuzhou University

Thirteen specimens were tested out of which nine were for creep of sealed concrete and four for shrinkage test,for a period of 700 d under controlled temperature *** experimental results for creep and shrinkage were compared with creep and shrinkage computation model B3 and distinct discrepancies between observed and calculated creep and shrinkage strains were *** on regression analysis,modification on B3 model has been formulated which will be applicable at least for concrete of characteristics strength of c40 and c50 with ***,on the basis of observation on identical specimens with varied stress strength ratio,a function is generated which accounts effect of stress strength ratio on ***,civil Engineering community is suggested not to follow the creep prediction models without correction at least for modern concrete,as they do not account the effect of additives on its compliance function.

关键词： stress strength ratio creep test experimental study B3 model regression analysis

Adjustment of B3 model for drying concrete with additives based on experimental data

在线全文

学校读者我要写书评

暂无评论

Journal of chongqing University 2010年第2期9卷 63-71页

作者： krishna Man shrestha college of civil Engineering Fuzhou University

All currently avalable concrete creep predicting models cannot describe well the creep of a concrete structure because they all leave the effects of additives out of consideration. The purpose of this work was to modify model B3 for overcoming this deficiency. We tested thirteen specimens of c40 and c50 concrete with additives, out of which nine were for creep and four for shrinkage tests over a 700 d period under controlled temperature. We compared the experimental results for creep and shrinkage with those obtained by using model B3, and derived modification terms through regression analysis. Based on the experimental results of identical specimens under varied stress levels, we also derived a function considering the effect of stress level on creep. It is suggested that the creep prediction models without adjustment should not be used for modem concrete with a variety of additives.

关键词： stress strength ratio creep test B3 model regression analysis

Broadband achromatic dielectric metalenses

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2018年第1期7卷 236-246页

作者： Sajan shrestha Adam c.Overvig Ming Lu Aaron Stein Nanfang Yu Department of Applied Physics and Applied Mathematics Columbia UniversityNew YorkNY 10027USA Brookhaven National Laboratory Center for Functional NanomaterialsUptonNY 11973USA

Metasurfaces offer a unique platform to precisely control optical wavefronts and enable the realization of flat lenses,or metalenses,which have the potential to substantially reduce the size and complexity of imaging systems and to realize new imaging ***,it is a major challenge to create achromatic metalenses that produce a single focal length over a broad wavelength range because of the difficulty in simultaneously engineering phase profiles at distinct wavelengths on a single *** practical applications,there is a further challenge to create broadband achromatic metalenses that work in the transmission mode for incident light waves with any arbitrary polarization *** developed a design methodology and created libraries of meta-units—building blocks of metasurfaces—with complex cross-sectional geometries to provide diverse phase dispersions(phase as a function of wavelength),which is crucial for creating broadband achromatic *** elucidated the fundamental limitations of achromatic metalens performance by deriving mathematical equations that govern the tradeoffs between phase dispersion and achievable lens parameters,including the lens diameter,numerical aperture(NA),and bandwidth of achromatic *** experimentally demonstrated several dielectric achromatic metalenses reaching the fundamental *** metalenses work in the transmission mode with polarization-independent focusing efficiencies up to 50%and continuously provide a near-constant focal length over λ=1200–1650 *** unprecedented properties represent a major advance compared to the state of the art and a major step toward practical implementations of metalenses.

关键词： chromatic dielectric limitations

Dielectric metasurfaces for complete and independent control of the optical amplitude and phase

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2019年第1期8卷 318-329页

作者： Adam c.Overvig Sajan shrestha Stephanie c.Malek Ming Lu Aaron Stein changxi Zheng Nanfang Yu Department of Applied Physics and Applied Mathematics Columbia UniversityNew YorkNY 10027USA center for Functional Nanomaterials Brookhaven National LaboratoryUptonNY 11973USA Department of computer Science Columbia UniversityNew YorkNY 10027USA

Metasurfaces are optically thin metamaterials that promise complete control of the wavefront of light but are primarily used to control only the phase of ***,we present an approach,simple in concept and in practice,that uses meta-atoms with a varying degree of form birefringence and rotation angles to create high-efficiency dielectric metasurfaces that control both the optical amplitude and phase at one or two *** opens up applications in computer-generated holography,allowing faithful reproduction of both the phase and amplitude of a target holographic scene without the iterative algorithms required in phase-only *** demonstrate all-dielectric metasurface holograms with independent and complete control of the amplitude and phase at up to two optical frequencies simultaneously to generate two-and three-dimensional holographic *** show that phaseamplitude metasurfaces enable a few features not attainable in phase-only holography;these include creating artifactfree two-dimensional holographic images,encoding phase and amplitude profiles separately at the object plane,encoding intensity profiles at the metasurface and object planes separately,and controlling the surface textures of three-dimensional holographic objects.

关键词： holographic phase complete

Habitat Range of two Alpine Medicinal Plants in a Trans-Himalayan Dry Valley,central Nepal

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 2009年第1期6卷 66-77页

作者： Bharat Babu shrestha Pramod Kumar JHA central Department of Botany Tribhuvan UniversityKathmanduNepal

Understanding of the habitat range of threatened Himalayan medicinal plants which are declining in their abundance due to high anthropogenic disturbances is essential for developing conservation strategies and agrotechnologies for cultivation. In this communication, we have discussed the habitat range of two alpine medicinal plants, Aconitum naviculare （Bruehl） Stapf and Neopicrorhiza scrophulariiflora （Pennel） Hong in a trans-Himalayan dry valley of central Nepal, Manang district. They are the most prioritized medicinal plants of the study area in terms of ethnomedicinal uses. A. naviculare occurs on warm and dry south facing slopes between 4090-4650 m asl along with sclerophyllous and thorny alpine scrubs, while N. scrophulariiflora is exclusively found on cool and moist north facing slope between 4000 and 4400 m asl where adequate water is available from snow melt to create a suitable habitat for this wetland dependent species. The soil in rooting zone of the two plants differs significantly in organic carbon （Oc）, organic matter （OM）, total nitrogen （N） and carbon to nitrogen （c/N） ratio. Due to cool and moist condition of N. scrophulariiflora habitat, accumulation of soil Oc is higher, but soil N content is lower probably due to slow release from litter, higher leaching loss and greater retention in perennial live biomass of the plant. The c/N ratio of soil is more suitable in A. navuculare habitat than that of N scrophulariiflora for N supply. Warm and sunny site with N rich soil can be suitable for cultivation ofA. naviculare, while moist and cool site with organic soil for N. scrophulariiflora. The populations of both the plants are fragmented and small. Due to collection by human and trampling damage by livestock, the population of A. naviculare was found absent in open areas in five of the six sampling sites and it was confined only within the bushes of alpine scrubs. For N. serophulariiflora, high probability of complete receding of small glaeiers may be

关键词： Aconitum naviculare Neopicrorhizascrophulariiflora habitat degradation nitrogen organic carbon radiation Manang Nepal

Floristic Diversity and Important Value Indices of Tree Species in Lower Kanchenjunga Singhalila Ridge Eastern Nepal

在线全文

学校读者我要写书评

暂无评论

American Journal of Plant Sciences 2019年第1期10卷 248-263页

作者： Nar Bahadur Khatri chhetri krishna Kumar shrestha Golden Gate International college Battisputali Kathmandu Nepal central Department of Botany Tribhuvan University Kirtipur Kathmandu Nepal

The present paper is based on the finding of floristic diversity inventory research work conducted in Lower Kanchenjungha Singhalila Ridge, in Nepal side of Eastern Himalaya. Knowledge on floristic diversity of an area can reflect the total resources, their use patterns and conservation status which have a key role for making conservation strategies and policies. Analysis of vegetation helps to develop detailed picture of plant communities of that region. A total of 299 plant species belonging to 184 genera and 86 families were found in the Lower Kanchenjungha Singhalila Ridge. Dicotyledonous flora includes 69 families, 150 genera and 229 species whereas Monocotyledonous flora includes 15 families, 32 genera and 39 species. On the basis of floristic analysis Rosaceae was found to be the largest family with 23 species followed by Ericaceae 17, and Lauraceae 9 species. current study furnishes three new addition to the flora of Nepal viz. Begonia flaviflora H. Hara (Begoniaceae), carex cruciate Wahlenberg var. argocarpa c. B. clarke (cyperaceae), and Strobilanthes helicta Anderson (Acanthaceae). Of this total, 30 woody tree species with 551 individuals and 23 genera were recorded from the altitudinal range of 2100 - 3000 m of study area. The highest relative frequency was recorded by Lithocarpus pachyphylla (18.48%), Symplocos ramosissima (16.30%), Rhododendron falconeri (13.95%), Symplocos dryophylla (10.20%). Eurya acuminate and Symplocos species were found to be dominant in lower elevation whereas Lithocarpus pachyphylla and Rhododendron species were found to be dominant in upper elevation.

关键词： Eastern Himalaya Inventory Plant Specimens Species Richness conservation

Environmentally assisted cracking behavior of U-bend specimens of Mg-RE alloys in chloride containing basic solution

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 Magnesium and Alloys 2020年第3期8卷 731-751页

作者： Jakraphan Ninlachart Nikunja shrestha krishnan S.Raja Department of Marine Engineering Academic BranchRoyal Thai Naval AcademySamut Prakan 10270Thailand chemical and Materials Engineering University of IdahoMoscowID 83844-1021USA

Environmentally assisted cracking(EAc)behavior of two Mg-rare earth(RE)alloys such as Mg-Zn-Gd-Nd-Zr(EV31A)and Mg-Y-Nd(WE43c)alloys was investigated by using U-bend *** circuit potentials(OcP)of the U-bend specimens were monitored during the EAc tests in 0.1 M NaOH solution with different chloride concentrations at room ***31A(as-received,and peak aged)and WE43c(peak aged)specimens failed by Scc in 80 ppm chloride containing 0.1 M NaOH solution at *** the EAc initiation occurred,the OcP decreased *** fluctuations of the OcP were observed in the absence of *** OcP versus time profile could be used for monitoring EAc failure of the Mg-RE alloy components in real life *** potentials did not cause cracking of the EV31A alloy in 80 ppm cl-containing 0.1 M *** cracking was observed on the WE43c alloy in peak-aged condition under the applied potentials in the transpassive region when compared to that of OcP *** decreased the susceptibility to cracking.

关键词： Magnesium rare earth(Mg-RE)alloy Stress corrosion cracking Hydrogen assisted cracking Localized corrosion

Study of Fruit Diversity and Selection of Elite Acid Lime (<i>citrus aurantifolia Swingle</i>) Genotypes in Nepal

在线全文

学校读者我要写书评

暂无评论

American Journal of Plant Sciences 2012年第8期3卷 1098-1104页

作者： Ram Lal shrestha Durga Datta Dhakal Durga Mani Gautum krishna Prasad Paudyal Sangita shrestha Agricultural Research Station (ARS) Dhankuta Nepal Horticulture Research Division (HRD) Lalitpur Nepal Institute of Agriculture and Animal Science (IAAS) Rampur Chitwan Nepal Nepal Academy of Science and Technology (NAST) Lalitpur Nepal

Acid lime (citrus aurantifolia) fruits are cultivated in terai, mid hill and high hill districts of Nepal. It is cross-pollinated crop and has a high variation in fruit characters within the species. Fruit character is the main basis of genotype selection. Study of fruit diversity is of utmost importance to select the elite genotypes for breeding and variety development program. Therefore, total of 620 fruit samples were collected and evaluated in the main production season of the year 2010 and 2011, from 62 bearing trees. Samples were collected from three agro-ecological domains, representing terai, mid hill and high hill areas of eastern Nepal. Elite landraces were selected on the basis of scoring fruit characters. High variation in vitamin c was observed between the terai (57.4 mg) and high hill (72.5 mg) samples. Amount of juice was 36.8% in mid hill and 44.1% in terai samples. Higher percent of juice and total soluble solids (TSS) observed in terai samples but tritable acidity (TA) and vitamin c was low as compare to high hills. There was significantly negative correlation found in fruit weight, fruit diameter, juice percent and seed number, whereas significantly positive correlation was in pulp and vitamin c, with altitude range. Total landraces were separated in five major cluster group. Variation in the level of similarity was observed among the cluster groups. The variability distance of fruit characters was highest in cluster group II (–17.45%) and lowest in cluster group V (58.5%). On the basis of scoring number of fruit characters, total four elite genotypes i.e. LD-49 from mid hills, LD-23 and LT-17 from higher hills and LM-44 from terai were selected for conservation, breeding and variety development purpose.

关键词： Vitamin c TSS TA correlation Elite Genotypes conservation