检索结果-南通市图书馆

沿黄城市蓝绿空间时空演变及驱动力分析——以泰安市为例

在线全文

学校读者我要写书评

暂无评论

西北林学院学报 2024年第2期39卷 148-155页

作者：张芳源贾艳艳郑海燕山东农业大学林学院山东泰安271018 淄博市周村区园林绿化服务中心山东淄博255300

基于2000-2020年土地利用类型数据,采用景观指数、景观动态度、地理探测器等方法,分析沿黄城市泰安市蓝绿空间时空演变特征及其驱动因素。结果表明,1)近20 a泰安市蓝绿空间规模整体呈减少趋势,动态度为-0.41%,面积减少131.24 km 2,但呈... 详细信息

基于2000-2020年土地利用类型数据,采用景观指数、景观动态度、地理探测器等方法,分析沿黄城市泰安市蓝绿空间时空演变特征及其驱动因素。结果表明,1)近20 a泰安市蓝绿空间规模整体呈减少趋势,动态度为-0.41%,面积减少131.24 km 2,但呈现明显的阶段性特征,前10 a变化剧烈,动态度为-0.82%,后10 a动态度仅为0.005%。2)2000-2020年,蓝绿空间景观格局指数发生了显著变化,且各指数在前10 a的变化程度更大;类型水平上,绿色空间和蓝色空间的景观形状整体趋于规则、均有连片发展趋势,但绿色空间的景观形状更复杂、分布离散度更大;景观水平上,蓝绿空间破碎度呈减弱趋势,但景观连通性下降、景观异质性增强。3)地理探测分析表明,社会经济因素是蓝绿空间分异的主导因子,生产总值、人口密度、第一与第二产业产值等社会经济因素对蓝绿空间变化的解释力显著大于高程等自然因素。研究认为城镇化进程中需要加强对国土空间的科学管控,应加强泰安市蓝绿空间的完整性、连通性保护。该研究为泰安市蓝绿空间优化与管理、区域可持续发展提供一定参考。

关键词：蓝绿空间景观格局时空演变地理探测器黄河沿线城市

维普期刊数据库博看期刊

基于形态标记和ISSR分子标记的长瓣铁线莲遗传多样性分析

在线全文

学校读者我要写书评

暂无评论

草地学报 2024年第1期32卷 75-86页

作者：贾艳艳邱玉鹏周欣莹耿宇航孙浩男刘冬云河北农业大学河北保定071000

为快速区分鉴定市场上繁多的长瓣铁线莲(Clematis macropetala)品种,了解长瓣铁线莲间的遗传多样性水平及亲缘关系,本试验利用形态标记结合ISSR分子标记对25个长瓣铁线莲品种和1个野生种进行遗传多样性研究。结果表明:14个数量形状的变... 详细信息

为快速区分鉴定市场上繁多的长瓣铁线莲(Clematis macropetala)品种,了解长瓣铁线莲间的遗传多样性水平及亲缘关系,本试验利用形态标记结合ISSR分子标记对25个长瓣铁线莲品种和1个野生种进行遗传多样性研究。结果表明:14个数量形状的变异系数在0.24%~2.32%之间;15个假质量性状的信息多样性指数H在0~2.29%之间,遗传多样性指数D在0~0.94%之间;在欧式距离为15时,可将29个表型性状划分为七类,在欧式距离为15时,可将26个长瓣铁线莲划分为五类。12条引物共扩增出144个条带,多态性条带占比为100%。利用引物UBC815、UBC824和UBC836构建26个长瓣铁线莲的指纹图谱,可快速区分鉴定26个长瓣铁线莲。UPGMA聚类结果显示,在遗传相似系数为0.68时,可将26个长瓣铁线莲划分为八大类。形态标记结合ISSR分子标记可有效鉴别长瓣铁线莲种质资源,以期为长瓣铁线莲种质资源收集保存、创制新品种等提供理论基础。

关键词：长瓣铁线莲形态标记 ISSR分子标记遗传多样性

“智慧+”背景下畜牧兽医新农科人才培养与实施路径

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

安徽农业科学 2024年第5期52卷 273-275页

作者：贾艳艳余祖华丁轲河南科技大学动物科技学院河南洛阳471023

随着“互联网+”、人工智能时代的到来,新农科建设“三部曲”等国家重大战略部署的落地实施,越来越多的先进技术推动着畜牧业的发展,促进畜牧业生产力的变革,这对涉农院校畜牧兽医人才培养提出了深层次的要求。阐述了当前畜牧兽医人才... 详细信息

随着“互联网+”、人工智能时代的到来,新农科建设“三部曲”等国家重大战略部署的落地实施,越来越多的先进技术推动着畜牧业的发展,促进畜牧业生产力的变革,这对涉农院校畜牧兽医人才培养提出了深层次的要求。阐述了当前畜牧兽医人才培养模式中存在的问题,“智慧+”背景下畜牧兽医新农科人才跨学科培养的紧迫性,并提出了构建“智慧+”背景下多学科融合的畜牧兽医新农科人才培养模式的路径与措施。

关键词： “智慧+” 新农科畜牧兽医人才培养模式跨学科教育

Correlation power analysis of DECIM～v2

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2011年第5期18卷 118-123页

作者： jia yan-yan HU Yu-pu ZHAO Yong-bin GAO Jun-tao Key Laboratory of Computer Networks and Information Security Xidian University Xi＇an 710071 China State Key Laboratory of Information Security Graduate University of Chinese Academy of Sciences Beijing 100049 China

Power analysis has been a powerful and thoroughly studied threat for implementations of block ciphers and public key algorithms but not yet for stream ciphers. Based on the consumed power differences between two neighboring clock cycles, this paper presents a correlation power analysis （CPA） attack on the synchronous stream cipher DECIM^v2 （the tweaked version of the original submission DECIM）. This attack resynchronizes the cryptographic device ceaselessly with many different initialization values （IVs） to obtain enough power traces. Then by modeling the statistical properties of the differential power traces with the correlation coefficients, the proposed attack algorithm can completely reveal the secret key of DECIM^v2. Furthermore, a simulation attack is mounted to confirm the validity of the algorithm. The results show that the entire secret key of DECIM^v2 can be restored within several minutes by performing 12 CPA attacks. It seems that there are still some defects in the design of DECIM^v2 and thus some further improvements should be made to resist the proposed attack.

关键词： cryptography cryptanalysis side channel attacks (SCA) CPA DECIM^v2

Three New Polyoxometalates Derivatives Decorated by Phenanthroline and Transition-metal Cations(M=Zn~ⅡI , Co~Ⅱ , Ni~Ⅱ)

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2010年第5期26卷 683-686页

作者： ZHANG Yong-feng jia yan-yan NIE Hai-liang yan Xing-juan WANG Li HUANG Ru-dan Department of Chemistry Beijing Institute of Technology Beijing 100081 P. R. China

Three new Keggin polyoxometalates, [Zn（phen）3]2[SiW12O40]＇5H2O（1）, [Co（phen）3]2[SiW12O40]（2） and [Ni（phen）3]2[SiW12O40].2H2O（3）（phen=1,10＇-phenanthroline） have been hydrothermally synthesized and characterized by elemental analysis, IR, crystal X-ray diffraction, thermogravimetric analyses（TGA） and fluorescence tech- niques. Complex 1, crystallized in the triclinic space group Pi, consists of one [SiW12O40]4 anion, two discrete [Zn（phen）3]^2＋ cations and five crystal water molecules. Complexes 2 and 3 have the similar configuration to complex 1, but they crystallized in the monoclinic space group C2/c. Variable-temperature magnetic susceptibilities of complexess 2 and 3 reveal antiferromagnetism and ferromagnetism, respectively.

关键词： Polyoxometalate Phen Organic-inorganic compound Hydrothermal synthesis

Extending Structures for Gel'fand-Dorfman Bialgebras

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第2期40卷 619-638页

作者： jia jia WEN yan Yong HONG School of Mathematics Hangzhou Normal UniversityHangzhou 311121P.R.China

Gel'fand-Dorfman bialgebra,which is both a Lie algebra and a Novikov algebra with some compatibility condition,appeared in the study of Hamiltonian pairs in completely integrable *** also emerged in the description of a class special Lie conformal algebras called quadratic Lie conformal *** this paper,we investigate the extending structures problem for Gel'fand-Dorfman bialgebras,which is equivalent to some extending structures problem of quadratic Lie conformal ***,given a Gel'fand-Dorfman bialgebra(A,o,[.,.]),this problem is how to describe and classify all Gel'fand-Dorfman bialgebra structures on a vector space E(A⊂E)such that(A,o,[.,.])is a subalgebra of E up to an isomorphism whose restriction on A is the identity *** by the theories of extending structures for Lie algebras and Novikov algebras,we construct an object gH2(V,A)to answer the extending structures problem by introducing the notion of a unified product for Gel'fand-Dorfman bialgebras,where V is a complement of A in *** particular,we investigate the special case when dim(V)=1 in detail.

关键词： Gel'fand-Dorfman bialgebra Lie conformal algebra Extending structures problem Novikovalgebra

Pyrolysis of Glucose over Two Amphoteric Metal Oxides

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2009年第2期25卷 234-238页

作者： yanG Yu XIANG Xi LUO jia QI Wei-yan yan Hong-Peng LI Gui-Ying HU Chang-Wei Key Laboratory of Green Chemistry and Technology Ministry of Education College of Chemistry Sichuan University Chengdu 610064 P. R. China

The catalytic pyrolysis of glucose over amphoteric metal oxide, ZnO or γ-l2O3, was studied comparatively with direct pyrolysis. The effects of catalyst to glucose ratio on the yields of pyrolytic products and on the chemical composition of the liquid products were discussed. Compared with the pyrolytic products of direct pyrolysis, the amount of residual char decreased, whereas the gas yield increased in the presence of the catalysts. The highest liquid yield over ZNO（49.5%） was obtained when the ratio of ZnO to glucose was 5%, whereas over γ-Al2O3 the liquid yield increased with increasing the amount of γ-Al2O3 added. The presence of both the catalysts enhanced the selectivity to furans in liquid and reduced that of anhydro sugars. A selectivity of 69.7% to furans was obtained over 1% ZnO with a selectivity of 14.6% to 5-hydroxymethylfurfural（HMF）. The maximum selectivity to furans（74.9%） and that to HMF（25.6%） were obtained in the presence of 10% γ-Al2O3.

关键词： Glucose ZnO γ-Al2O3 Furans 5-Hydroxymethylfurfural

在线全文

学校读者我要写书评

暂无评论

一种轴端挡板用螺栓断裂原因的分析

机械工程与自动化 2024年第2期 188-189,192页

作者：赵振武李庆鹤张晋雨贾艳艳郭晓阳山西航天清华装备有限责任公司山西长治046012

针对某工程中出现的轴端挡板用螺栓断裂的现象,从关节润滑脂不足、螺栓松动等5个方面进行论述,分析了轴端挡板的螺栓受力情况,得出螺栓断裂的真正原因,对轴端挡板进行了改进,并进行了优化设计。

关键词：轴端挡板螺栓断裂原因分析

A robust implicit high-order discontinuous Galerkin method for solving compressible Navier-Stokes equations on arbitrary grids

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2024年第8期40卷 96-119页

作者： jia yan Xiaoquan yang Peifen Weng Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China College of Energy and Mechanical Engineering Shanghai University of Electric PowerShanghai200090China

The primary impediments impeding the implementation of high-order methods in simulating viscous flow over complex configurations are robustness and *** challenges impose significant constraints on computational efficiency,particularly in the domain of engineering *** address these concerns,this paper proposes a robust implicit high-order discontinuous Galerkin(DG)method for solving compressible Navier-Stokes(NS)equations on arbitrary *** method achieves a favorable equilibrium between computational stability and *** solve the linear system,an exact Jacobian matrix solving strategy is employed for preconditioning and matrix-vector generation in the generalized minimal residual(GMRES)*** approach mitigates numerical errors in Jacobian solution during implicit calculations and facilitates the implementation of an adaptive Courant-Friedrichs-Lewy(CFL)number increasing strategy,with the aim of improving convergence and *** further enhance the applicability of the proposed method for intricate grid distortions,all simulations are performed in the reference *** practice significantly improves the reversibility of the mass matrix in implicit calculations.A comprehensive analysis of various parameters influencing computational stability and efficiency is conducted,including CFL number,Krylov subspace size,and GMRES convergence *** computed results from a series of numerical test cases demonstrate the promising results achieved by combining the DG method,GMRES solver,exact Jacobian matrix,adaptive CFL number,and reference domain calculations in terms of robustness,convergence,and *** analysis results can serve as a reference for implicit computation in high-order calculations.

关键词： Discontinuous Galerkin method Exact Jacobian matrix GMRES solver Adaptive CFL number Reference domain High-order