检索结果-南通市图书馆

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

吉林陨石的宇宙成因核素与两阶段辐照历史

中国科学(B辑化学生物学农学医学地学) 1983年第11期 1039-1049页

作者：欧阳自远 G.heusser m.h.bner T.Kirsten 中国科学院地球化学研究所西德max-Planck核物理研究所西德max-Planck核物理研究所贵阳 heidelberg

本文根据测定了的吉林陨石中44个样品的散裂、捕获和放射成因稀有气体的含量和35个样品的放射性宇宙成因核素,论述了并提出了吉林陨石两阶段辐照的新模式,又根据样品中21Ne-60Co的含量提出了一种恢复各样品在两阶段母体中相对位置的图式。

关键词：吉林陨石宇宙成因核素辐照

Decline and dieback of cork oak(Quercus suber L.)forests in the mediterranean basin:a case study of Kroumirie,Northwest Tunisia

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Forestry Research 2020年第5期31卷 1461-1477页

作者： Issam Touhami E.Chirino h.Aouinti A.El Khorchani m.T.Elaieb A.Khaldi Z.Nasr The National Research Institute of Rural Engineering Waterand ForestryINRGREFLaboratory of Management and Valorization of Forest ResourcesUniversity of CarthageBP 102080 ArianaTunisia Faculty of Agricultural Sciences Lay University Eloy Alfaro de Manabı´Ciudadela Universitariaav.Circunvalacio´n vı´a San Mateo s/nMantaManabı´Ecuador

Assessing the vulnerability of forest ecosystems in the climate change context is a challenging task as the mechanisms that determine this vulnerability cannot be directly *** on the ecological interrelationships between forests and climate,the present review focused on providing current information about vulnerability assessments of cork oak(Quercus suber L.)forests in the mediterranean basin,especially,in the Kroumirie region(northwest Tunisia),currently under historic extreme drought *** comparing recent findings in this region,we synthesized data on cork oak decline and mortality collected during the historic drought years 1988–1995 *** change impacts cork forest decline,with special interest shown in elevated temperatures and drought;cork oak forest regeneration,and the adaptation of the Kroumirie forest to climate change,are reviewed *** studied region has been influenced largely by frequent prolonged drought periods,especially from 1988 to *** were found to consistently have a more detrimental impact on the growth and mortality rates of cork oak *** oak mortality was recorded for up to 63,622 *** the future,more research studies and observational data will be needed,which could represent an important key to understand ecosystem processes,and to facilitate the development of better models that project climate change impacts and *** study is useful for researchers and forestry decision makers to develop the appropriate strategies to restore and protect ecosystems,and to help anticipate potential future droughts and climate change.

关键词： Climate change Drought effect Forest decline Tree mortality mediterranean forest

Immanant positivity for Catalan-Stieltjes matrices

在线全文

学校读者我要写书评

暂无评论

Frontiers of mathematics in China 2022年第5期17卷 887-903页

作者： Ethan Y.h.LI Grace m.X.LI Arthur L.B.YANG Candice X.T.ZhANG Center for Combinatorics LPMCNankai UniversityTianjin 300071China

We give some sufficient conditions for the nonnegativity of immanants of square submatrices of Catalan-Stieltjes matrices and their corresponding hankel *** obtain these sufficient conditions,we construct new planar networks with a recursive nature for Catalan-Stieltjes *** applications,we provide a unified way to produce inequalities for many combinatorial polynomials,such as the Eulerian polynomials,Schröder polynomials,and Narayana polynomials.

关键词： Immanant character Catalan-Stieltjes matrices hankel matrices planar network

添加不同水平高纤维葵粕在商品来航鸡日粮中应用效果研究

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

饲料与畜牧（新饲料） 2011年第5期 19-21页

作者： Rezaei m.h.fezian h 王继强(译) 李爱琴(译) 张波(校) 北京市营养源研究所北京桑普生物化学技术有限公司不详

试验旨在研究日粮中添加不同水平葵粕在商品蛋鸡日粮中的应用效果。蛋鸡随机分为4组,每组8个重复,每个重复4只。除代谢能外,各试验组营养组分完全相同,日粮中分别添加0%、5%、10%和15%水平的葵粕。在试验期间,每周统计饲料采食量、产蛋... 详细信息

试验旨在研究日粮中添加不同水平葵粕在商品蛋鸡日粮中的应用效果。蛋鸡随机分为4组,每组8个重复,每个重复4只。除代谢能外,各试验组营养组分完全相同,日粮中分别添加0%、5%、10%和15%水平的葵粕。在试验期间,每周统计饲料采食量、产蛋率、蛋重、饲料转化率、哈氏单位、蛋比重和死亡率指标。在试验的开始和结束,称量每只蛋鸡的体重。试验结果显示,日粮中添加10%葵粕不影响蛋鸡的采食量和产蛋率;然而当日粮中葵粕的添加量达到15%时,饲料采食量、产蛋率和蛋重分别降低了5.7%、7.06%和5.49%,饲料转化率显著提高(P<0.05)。鸡蛋品质不受葵粕添加比例的影响。试验结果表明,在蛋鸡日粮中添加10%高纤维葵粕对蛋鸡生产性能和蛋品质无负面影响。

关键词：葵粕蛋鸡日粮产蛋率蛋品质

magnetic/magnetostrictive Properties Together with Resistivity and Corrosion Behaviors of CoFe_2 and Its Composite with CoFe_2N

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2017年第7期33卷 744-750页

作者： B.Q.Geng Y.Q.ma m.Wang Z.L.Ding W.h.Song B.C.Zhao Key Laboratory of materials Physics Institute of Solid State Physics Chinese Academy of Sciences Hefei 230031 China

The CoFe_2alloy（CF） was prepared by reducing CoFe_2O_4 in the h_2 ambient. Subsequently the CF sample was nitrided in the Nh_3 atmosphere to produce the composite of CoFe_2N and CoFe_2. The magnetostriction, thermal expansion, resistivity and corrosion resistance of CF sample and the nitrided sample（CFN）at 1000？C were investigated. The saturation magnetostriction coefficiency λ_s and thermal expansion coefficient ？ at 300 K for the nitrided CFN were 50 ppm and 10 ppm/K, respectively, approximately equal to those for the CF sample. however, compared with CF, CFN presents a decrease in temperature coefficient R_λ（300 K） of magnetostriction by 11%. The smaller resistivity and improved corrosion resistance in the h_2SO_4 solution may expand the applications of the CoFe_2 in the fields needing lower resistivity or in the acidic environment.

关键词： CoFe alloy CoFe_2N alloy magnetostriction Resistivity Corrosion resistance

在线全文

学校读者我要写书评

暂无评论

绳系卫星释放阶段的空间姿态非线性稳定控制

西北工业大学学报 2016年第1期34卷 60-66页

作者：王长青杜崇刚李爱军 Z.h.Zhu 西北工业大学陕西西安710072 York University Toronto M3J 1P3

主要考虑绳系卫星释放阶段的姿态运动对空间系绳系统稳定性产生的影响。基于欧拉-牛顿法建立绳系卫星的姿态动力学与运动学方程,研究了释放阶段系绳与卫星之间固定点存在静态不对称性时,卫星姿态的稳定性。为抑制释放阶段卫星姿态运动... 详细信息

主要考虑绳系卫星释放阶段的姿态运动对空间系绳系统稳定性产生的影响。基于欧拉-牛顿法建立绳系卫星的姿态动力学与运动学方程,研究了释放阶段系绳与卫星之间固定点存在静态不对称性时,卫星姿态的稳定性。为抑制释放阶段卫星姿态运动对系绳系统稳定性产生的不利影响,设计了一种基于Lyapunov函数方法的非线性姿态控制器。数值仿真及分析验证了该控制器可实现卫星姿态的稳定。

关键词：绳系卫星释放姿态控制 Lyapunov函数

在线全文

学校读者我要写书评

暂无评论

现代优化气缸变形的新方法

汽车与新动力 2016年第4期48卷 50-55页

作者： m.Berg h.Schultheiβ D.musch T.hilbert 范明强

未来实际行驶排放(RDE)法规要求在目前的行驶循环之外也应具有更好的废气排放可靠性。由于对负荷和动态性能的要求更高,诸如机油窜入燃烧室等现象也会对废气排放特性产生不利的影响,因此活塞-气缸系统和优化气缸变形在发动机整个开发过... 详细信息

未来实际行驶排放(RDE)法规要求在目前的行驶循环之外也应具有更好的废气排放可靠性。由于对负荷和动态性能的要求更高,诸如机油窜入燃烧室等现象也会对废气排放特性产生不利的影响,因此活塞-气缸系统和优化气缸变形在发动机整个开发过程中越来越成为关注的焦点。介绍了IAV公司应用对此具有重要意义的开发工具和方法的可能性,这些有针对性的步骤有助于减小气缸变形。

关键词：气缸变形设计优化窜气

homozygous mutation in the m.h.S Gene may Contribute to the Development of Cerebral Folate Deficiency Syndrome

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Reproductive and Developmental medicine 2020年第2期4卷 72-77页

作者： Dharaniya Sakthivel Yunping Lei Xuanye Cao Richard h.Finnell Center for Precision Environmental health Baylor College of MedicineHoustonTexas 77030-3411USA Department of molecular and human Genetics Baylor College of MedicineHoustonTexas 77030-3411USA Department of molecular and Cellular Biology Baylor College of MedicineHoustonTexas 77030-3411USA Department of medicine Baylor College of MedicineHoustonTexas 77030-3411USA

Objective:The purpose of this study was to examine the role of rare variants in the one-carbon metabolic pathway in the etiology of the cerebral folate deficiency(CFD)*** CFD syndrome is a neurometabolic syndrome identified by low concentrations of 5-methyltetrahydrofolate(5-m.h.)in the cerebrospinal fluid(CSF)in spite of near-normal peripheral folate levels resulting in neurodevelopmental ***:The localized folate metabolism impairments in CFD are thought to be either the result of mutations in genes responsible for folate transport or folate turnover through *** that have been previously implicated in the etiology of CFD include folate receptor alpha-1(FOLR1),dihydrofolate reductase,proton-coupled folate transporter,and *** performed whole-exome sequencing(WES)analysis of a CFD patient that revealed 99 novel missense mutations,of which 21 were classified as damaging mutations through the Poly-Phen2 prediction *** vitro functional studies were conducted by transient transfection of wild-type and mutant m.h.S into hEK293T cells to determine the impact of the variants on enzyme ***:Of the damaging variants identified in the WES studies,we focused on the gene coding for the enzyme 5,10-methenyl-tetrahydrofolate synthetase(m.h.S).This enzyme catalyzes the production of methenyl ThF which is subsequently converted to *** CFD patient described within was found to carry a homozygous mutation,c.101G>T(p.R34L,rs200058464)in m.h.S,while the parents of the proband are heterozygotes for the m.h.S gene,and the healthy sibling is not a ***:The mutant allele displayed a 50%reduction in luciferase activity(Phat homozygous loss of the m.h.S gene may play a significant role in the development of CFD.

关键词： Cerebral Folate Deficiency Syndrome m.h.S Intellectual Disability

Estimations of primary production and export production in the South China Sea based on sediment trap experiments

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第7期43卷 583-586页

作者： Jianfang Chen Lianfu Zheng m. G. Wiesner Ronghua Chen Yulong Zheng h. K. Wong SOA Inst Oceanog 2 Hangzhou 310012 Peoples R China Univ hamburg Inst Biogeochem & Marine Chem D-20146 Hamburg Germany

The results of time series sediment trap experiments in the South China Sea show that particulate organic carbon (POC) fluxes are influenced by the monsoons. The increase of productivity in the northern South China Sea is mainly due to northeast monsoon while in the central South China Sea the influence of southwest monsoon becomes more prominent. The annual primary production and export production calculated based on POC fluxes are 53 0-63 4 and 10 32-12 93 gC·m -2·a -1, respectively. The enhancement of POC flux during monsoon period suggest that higher palaeoproductivity or organic carbon accumulation rate in glacial age in the South China Sea might be the result of strengthening of the monsoons.

关键词： South China Sea POC flux sediment trap primary production export production