期刊文献+
共找到1,258篇文章
< 1 2 63 >
每页显示 20 50 100
Comparative Study of Genetic Structure and Genetic Diversity betweenWild and Cultivated Populations of Taxus cuspidata,Northeast China
1
作者 Dandan Wang Xiaohong Li Yanwen Zhang 《Phyton-International Journal of Experimental Botany》 SCIE 2024年第2期355-369,共15页
Taxus cuspidata is a rare plant with important medicinal and ornamental value.Aiming at the obvious differences between wild and cultivated populations of T.cuspidata from Northeast China,a total of 61 samples,that is... Taxus cuspidata is a rare plant with important medicinal and ornamental value.Aiming at the obvious differences between wild and cultivated populations of T.cuspidata from Northeast China,a total of 61 samples,that is,33 wild yews and 28 cultivated yews were used to analyze the differences and correlations of the kinship,genetic diversity,and genetic structure between them by specific length amplified fragment sequencing(SLAF-seq).Finally,470725 polymorphic SLAF tags and 58622 valid SNP markers were obtained.Phylogenetic analysis showed that 61 samples were classified into 2 clusters:wild populations and cultivated populations,and some wild yews were categorized into the cultivated populations;the genetic diversity analysis showed that the Nei diversity index of wild populations(0.4068)was smaller than that of cultivated populations(0.4414),and the polymorphic information content(PIC)of wild populations(0.2861)was smaller than that of cultivated populations(0.3309).The genetic differentiation analysis showed that the total populations of gene diversity(H_(t))of cultivated and wild populations were respectively 0.8159 and 0.5685,the coefficient of gene differentiation(G_(st))of cultivated and wild populations was respectively 0.3021 and 0.1068,and the gene flow(N_(m))(2.4967)of wild populations was larger than cultivated populations(0.8199).The molecular variance(AMOVA)revealed that inter-population variation accounted for 29.57%of the total genetic variation,while intra-population variation accounted for 70.42% of the total genetic variation(p<0.001),this suggested that the genetic variation in the T.cuspidata is mainly attributed to within-population factors.In conclusion,the genetic distance between geographical ecological groups of wild populations was generally smaller than that of cultivated populations,and the degree of genetic diversity and genetic differentiation was smaller than that of cultivated populations.As evident,the utilization of SLAF-seq technology enables efficient and accurate development of SNP markers suitable for genetic analysis of T.cuspidata species.These developed SNP markers can provide a molecular foundation for T.cuspidata breeding,construction of genetic maps,variety identification,and association analysis of agronomic traits. 展开更多
关键词 t.cuspidata slAF-seq SNP wild population cultivated population genetic structure
下载PDF
Systematic Review of Community Type 2 Diabetes Structured Health Education (CT2DSHE)
2
作者 Gift Phiri 《Open Journal of Nursing》 2024年第8期377-400,共24页
Aim: This paper aims to evaluate disparities of type 2 diabetes structured health education programmes that is utilised within the communities. Design: systematic review, (a type of secondary research design) aiming t... Aim: This paper aims to evaluate disparities of type 2 diabetes structured health education programmes that is utilised within the communities. Design: systematic review, (a type of secondary research design) aiming to summarize the results of prior primary research studies on available evidence Community type 2 diabetes structured education (CT2DSHE). Methods: Research question: Type 2 diabetic structured health education within a community how effective is it? Qualitative Systematic review, defined as a way to get reliable and objective picture of current available evidence on the specific topic—(CT2DSHE), (Denscombe, 2021) through reflexivity synthesis of available data as an example. This is valuable in time constraints such as project assignments that must be met within specific time and also to bring together available evidence together [1]. Results: This review has shown that CT2DSHE is effective with seven out of the eleven authors supporting, three authors against and one was neutral, further showed that knowledge and skills acquired can last longer with patient activation improved among T2DM patients ideal for sustaining their self-management of T2DM. Conclusion: This research provides suggestive answers to the research question: “Type 2 diabetic structured health education within a community how effective is it?”, This has demonstrated CT2DSHE effectiveness in knowledge acquisition and improving T2DM awareness among T2DM patients, whilst evidencing long effects beyond the study times of 3 - 9 months period in relation to patient activation. Also Identified diabetes education self-management on newly diagnosed (DESMOND) patient as CT2DSHE program for recommendation. Patient or Public Contribution: This work aspires to contribute to CT2DSHE in these areas;Influencing policy decision-making for community diabetes care within the UK and world at large., Contributing to already vast knowledge on diabetes self-management and reasons why?, Influencing educators on how CT2DSHEP are designed, delivered by putting the patient at the Centre and bringing different perspectives on CT2DSHEP in one place that is serving users time of having to consult several resources especially busy clinicians [2] [3]. 展开更多
关键词 Community Health EDUCAtION EFFECtIVENESS Impact structured and Planned type 2 Diabetes (t2DM)
下载PDF
Probing microstructure of solid-state synthesized LiCoO_(2)with MAS NMR spectroscopy
3
作者 Suyu Gu Guozhong Lu +4 位作者 Nianrui Guo Juncheng Xu Yu Jiang Ming Shen Bingwen Hu 《Magnetic Resonance Letters》 2023年第4期298-305,共8页
LiCoO_(2)is an important category of active cathode materials in lithium-ion batteries due to its high compacted electrode density,good thermal stability,and stable voltage platform.Recent works on LiCoO_(2)have focus... LiCoO_(2)is an important category of active cathode materials in lithium-ion batteries due to its high compacted electrode density,good thermal stability,and stable voltage platform.Recent works on LiCoO_(2)have focused on the realization of higher charging voltages to fully utilize its high theoretical capacity.However,an unambiguous atomic-level local probe is essential for the understanding of structure-function correlation.Here we employ highresolution solid-state nuclear magnetic resonance(NMR)spectroscopy to study the local atomic environments in LiCoO_(2)synthesized with three common sintering methods.While one-dimensional 7Li NMR shows distinct linewidth and subtle dependence on lithium over-stoichiometry,both 7Li and 59Co relaxation times are highly dependent on the sintering method.We prove that the two-step sintering method favors the elimination of unreacted Co3O4,thereby enabling the best discharge capacity in all-solid-state lithium batteries assembled with LiCoO_(2)/LGPS/LiIn,which is in accordance with its narrowest 7Li linewidth and the longest 7Li/59Co T1. 展开更多
关键词 LiCoO_(2) Solid-state NMR t1 relaxation Local structure
下载PDF
The Meaning of Surface Structure and Deep Structure to Translation
4
作者 罗源 《海外英语》 2014年第23期151-152,共2页
Surface structure and deep structure first come up with by Chomsky is an innovative action in linguistics. Despite the arguments involved around surface structure and deep structure, it is instructional to English-Chi... Surface structure and deep structure first come up with by Chomsky is an innovative action in linguistics. Despite the arguments involved around surface structure and deep structure, it is instructional to English-Chinese translation to some degree and its scientific connotation is meaningful to deepen language study and construct related disciplinary both in theory and practice. 展开更多
关键词 SURFACE structure DEEP structure ENGLISH-CHINESE t
下载PDF
Numerical simulation of rock pore-throat structure effects on NMR T_2 distribution 被引量:4
5
作者 王克文 李宁 《Applied Geophysics》 SCIE CSCD 2008年第2期86-91,共6页
We built a three-dimensional irregular network model which can adequately describe reservoir rock pore-throat structures. We carried out numerical simulations to study the NMR T2 distribution of water-saturated rocks.... We built a three-dimensional irregular network model which can adequately describe reservoir rock pore-throat structures. We carried out numerical simulations to study the NMR T2 distribution of water-saturated rocks. The results indicate that there is a good correlation between T2 distribution and the pore radius frequency histogram. The total T2 distribution can be partitioned into pore body and pore throat parts. The effect of parameters including throat radius, pore-throat ratio, and coordination number of the micro- pore structure on the T2 distribution can be evaluated individually. The result indicates that: 1 ) with the increase of the pore throat radius, the T2 distribution moves toward longer relaxation times and its peak intensity increases; 2) with the increase of the pore-throat ratio, the T2 distribution moves towards longer T2 with the peak intensity increasing and the overlap between pore body T2 and pore throat T2 decreasing; 3) With the increase of connectivity, the short T2 component increases and peak signal intensity decreases slightly. 展开更多
关键词 Network model NMR t2 distribution Pore structure Microstructure modeling
下载PDF
Allozyme Diversity and Population Genetic Structure of Three Medicinal Epimedium Species from Hubei 被引量:4
6
作者 徐艳琴 李作洲 +1 位作者 王瑛 黄宏文 《Journal of Genetics and Genomics》 SCIE CAS CSCD 北大核心 2007年第1期56-71,共16页
Three Epimedium species, E. pubescens Maxim., E. sagittatum (Sieb. & Zucc.) Maxim., and E. wushanense T. S. Ying, which are sympatrically distributed in the western Hubei Province, have been used in traditional Chi... Three Epimedium species, E. pubescens Maxim., E. sagittatum (Sieb. & Zucc.) Maxim., and E. wushanense T. S. Ying, which are sympatrically distributed in the western Hubei Province, have been used in traditional Chinese medicine (TCM) for about 2,000 years. Genetic variability and population genetic structure of 11 natural populations of these Epimedium species were investigated using isoelectric focusing in thin-layer polyacrylamide slab gels. Of the 22 enzyme systems prescreened, six coding for 13 loci and 45 alleles were resolved, which were used for analyzing genetic diversity and population structure at both intraspecific and interspecific levels. The results showed that: l) high levels of genetic diversity were observed in all three species (A = 2.6-3.2, P = 69.2%-84.6%, Ho= 0.274-0.377, HE= 0.282-0.369), which were higher than that of other herbaceous and aulmal-pollinated species with similar life-history characteristics; 2) there was significant deviation from Hardy-Weinberg Equilibrium, with one half of the loci showing heterozygote excess and the other homozygote excess, in all populations, suggesting the complicated breeding system of Epimedium species; 3) the low level of intraspecific and interspecific genetic differentiation (GST= 0.0246-0.0409 and 0.0495-0.1213, respectively) indicated a high level of gene flow among populations and close genetic relationship among the three species; and 4) UPGMA cluster analysis further showed that E. pubescens was more closely related to E. sagittatum than to E. wushanense, which was in good agreement with the morphological characters and the recent phylogenetic analysis of these species. On the basis of these results, it was concluded that the mixed breeding system, long-lived perennial life form, ancient evolutionary history, and seed dispersal by ants in Epimedium are responsible for the genetic variation and population structure of these species. 展开更多
关键词 Epimedium pubescens Maxim. E. sagittatum (Sieb. Zucc.) Maxim. E. wushanense t. S. Ying ALLOZYME genetic diversity population structure
下载PDF
A Rhetorical Structure Theory Based Approach to Texture Coherence in Chinese EFL Learners' Argumentative Writing
7
作者 李洪坤 廖志华 《海外英语》 2015年第16期201-204,共4页
Based on Rhetorical Structure Theory(RST),this study intends to investigate into the typical features of rhetorical relations in Chinese EFL learners’argumentative writing and their relationship with writing quality.... Based on Rhetorical Structure Theory(RST),this study intends to investigate into the typical features of rhetorical relations in Chinese EFL learners’argumentative writing and their relationship with writing quality.A set of 60 essays(30 with the highest scores and another 30 with the lowest scores)were drawn from SWECCL(Spoken and Written English Corpus of Chinese Learners).These essays were then cut into elementary discourse units and manually annotated with rhetorical relations.Research findings show that there is no significant difference in terms of the total numbers and types of rhetorical relations between the two proficiency groups.However,comparisons of the rhetorical relations both at the intra-paragraph and at the inter-paragraph level indicate statistical differences between the two groups. 展开更多
关键词 RHEtORICAL structure tHEORY RHEtORICAL RELAtIONS t
下载PDF
衍生T形槽干气密封稳态性能研究
8
作者 丁雪兴 江安迪 +2 位作者 王世鹏 丁俊华 蒋海涛 《装备环境工程》 CAS 2024年第3期105-112,共8页
目的 设计具备双向旋转特点的动压型干气密封端面结构,并展现良好的开启性能,以T形槽为优化对象,衍生出一种新型槽型结构。方法 借助有限元软件,计算并对比经典T形槽与衍生槽型在流场特性和稳态性能方面的差异,探讨不同参数对2种槽型干... 目的 设计具备双向旋转特点的动压型干气密封端面结构,并展现良好的开启性能,以T形槽为优化对象,衍生出一种新型槽型结构。方法 借助有限元软件,计算并对比经典T形槽与衍生槽型在流场特性和稳态性能方面的差异,探讨不同参数对2种槽型干气密封稳态性能的影响规律,揭示衍生槽型的密封机理。结果 衍生槽型的开启力高于经典T形槽,泄漏率也会增加。随着工况参数的升高,2种槽型的稳态性能参数近似线性增加,且差异逐渐增大,最小差异达到6.6%。随着槽深的增加,泄漏率方面的差距在逐渐减小,为扩大衍生槽型的控漏效果,槽深应>5μm。开设有引流槽型结构的衍生槽型稳态性能顺序为发散型>直口型>收敛型,但在文中的工况下,数值差别较小,最大仅为1.2%。结论 相比于经典T形槽,衍生槽型具有更强的动压效应,开启性能明显提升。另外,通过开设不同形式的引流槽可以改变气膜的流动特性和干气密封性能。 展开更多
关键词 t形槽干气密封 微槽流动 衍生结构 仿真计算 增压效应
下载PDF
翼缘尺寸对地聚物混凝土T形梁抗弯性能的影响 被引量:1
9
作者 徐勇 毛宇光 +3 位作者 刘翼玮 苏捷 杜运兴 史才军 《重庆交通大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第2期1-9,23,共10页
通过对5根不同翼缘尺寸的地聚物混凝土T形梁和1根普通混凝土T形梁进行四点弯曲试验,研究了翼缘宽度和厚度对地聚物混凝土T形梁抗弯性能的影响,以及与普通混凝土T形梁的差异。研究结果表明:地聚物混凝土T形梁的抗弯极限荷载、屈服荷载、... 通过对5根不同翼缘尺寸的地聚物混凝土T形梁和1根普通混凝土T形梁进行四点弯曲试验,研究了翼缘宽度和厚度对地聚物混凝土T形梁抗弯性能的影响,以及与普通混凝土T形梁的差异。研究结果表明:地聚物混凝土T形梁的抗弯极限荷载、屈服荷载、裂缝行为及失效模式与普通混凝土T形梁相似,且延性更优,但其跨中受拉纵筋应变较大,刚度、开裂荷载和最大裂缝宽度限值下的承载力较低。随着翼缘宽度从200 mm增大到500 mm,地聚物混凝土T形梁的刚度、屈服荷载、抗弯极限荷载、延性和在最大裂缝宽度限值下的承载力均增大,跨中受拉纵筋应变减小,开裂荷载无明显变化,但越宽的翼缘宽度能有效承担荷载的也只是靠近腹板的一部分宽度。增大翼缘厚度对地聚物混凝土T形梁抗弯性能的影响与增大翼缘宽度基本一致,但其对最大裂缝宽度限值下的承载力提高效果显著。规范GB 50010—2010和ACI 318—19的正截面受弯承载力设计公式适用地聚物混凝土T形梁,GB 50010—2010的预测更精确,ACI 318—19的安全储备更高。 展开更多
关键词 桥梁工程 结构工程 地聚物混凝土 t形梁 翼缘宽度 翼缘厚度 抗弯性能
下载PDF
Nuclear magnetic resonance T_2 spectrum:multifractal characteristics and pore structure evaluation 被引量:20
10
作者 Yan Jian-Ping He Xu +4 位作者 Geng Bin Hu Qin-Hong Feng Chun-Zhen Kou Xiao-Pan Li Xing-Wen 《Applied Geophysics》 SCIE CSCD 2017年第2期205-215,322,共12页
Pore structure characteristics are important to oil and gas exploration in complex low-permeability reservoirs. Using multifractal theory and nuclear magnetic resonance (NMR), we studied the pore structure of low-pe... Pore structure characteristics are important to oil and gas exploration in complex low-permeability reservoirs. Using multifractal theory and nuclear magnetic resonance (NMR), we studied the pore structure of low-permeability sandstone rocks from the 4th Member (Es4) of the Shahejie Formation in the south slope of the Dongying Sag. We used the existing pore structure data from petrophysics, core slices, and mercury injection tests to classify the pore structure into three categories and five subcategories. Then, the T2 spectra of samples with different pore structures were interpolated, and the one- and three-dimensional fractal dimensions and the multifractal spectrum were obtained. Parameters a (intensity of singularity) andf(a) (density of distribution) were extracted from the multifractal spectra. The differences in the three fractal dimensions suggest that the pore structure types correlate with a andf(a). The results calculated based on the multifractal spectrum is consistent with that of the core slices and mercury injection. Finally, the proposed method was applied to an actual logging profile to evaluate the pore structure of low-permeability sandstone reservoirs. 展开更多
关键词 NMR t2 spectrum MULtIFRACtAL INtERPOLAtION pore structure PERMEABILItY SANDStONE
下载PDF
Method of reverberation ray matrix for static analysis of planar framed structures composed of anisotropic Timoshenko beam members 被引量:2
11
作者 Jiao ZHANG Guohua NIE 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2015年第2期233-242,共10页
Based on the method of reverberation ray matrix(MRRM), a reverberation matrix for planar framed structures composed of anisotropic Timoshenko(T) beam members containing completely hinged joints is developed for st... Based on the method of reverberation ray matrix(MRRM), a reverberation matrix for planar framed structures composed of anisotropic Timoshenko(T) beam members containing completely hinged joints is developed for static analysis of such structures.In the MRRM for dynamic analysis, amplitudes of arriving and departing waves for joints are chosen as unknown quantities. However, for the present case of static analysis, displacements and rotational angles at the ends of each beam member are directly considered as unknown quantities. The expressions for stiffness matrices for anisotropic beam members are developed. A corresponding reverberation matrix is derived analytically for exact and unified determination on the displacements and internal forces at both ends of each member and arbitrary cross sectional locations in the structure. Numerical examples are given and compared with the finite element method(FEM) results to validate the present model. The characteristic parameter analysis is performed to demonstrate accuracy of the present model with the T beam theory in contrast with errors in the usual model based on the Euler-Bernoulli(EB) beam theory. The resulting reverberation matrix can be used for exact calculation of anisotropic framed structures as well as for parameter analysis of geometrical and material properties of the framed structures. 展开更多
关键词 planar framed structure ANISOtROPIC timenshenko(t beam stiffness matrix method of reverberation ray matrix(MRRM) static analysis
下载PDF
Insights into tertiary lymphoid structures in the solid tumor microenvironment: anti-tumor mechanism, functional regulation, and immunotherapeutic strategies 被引量:3
12
作者 Hua Zhao Hao Wang +1 位作者 Qiuru Zhou Xiubao Ren 《Cancer Biology & Medicine》 SCIE CAS CSCD 2021年第4期981-991,共11页
Tertiary lymphoid structures(TLSs)are ectopic immune cell aggregations that develop in peripheral tissues in response to a wide range of chronic inflammatory conditions,including infection,autoimmune disease,and cance... Tertiary lymphoid structures(TLSs)are ectopic immune cell aggregations that develop in peripheral tissues in response to a wide range of chronic inflammatory conditions,including infection,autoimmune disease,and cancer.In the tumor microenvironment(TME),the structures of TLSs,including B-cell-and T-cell-enriched areas indicate that the TLSs might be the local site during the initiation and maintenance of humoral and cellular immune responses against cancers.Numerous studies have evaluated the expression of TLSs in different cancer patients and their association with prognoses of cancer patients.It was shown that welldeveloped TLSs characterized by mature B cells synthesized tumor specific antibodies,which were considered as specific markers for a good prognosis.However,there are still some immunosuppressive factors existing in the TLSs that may affect anti-tumor responses.These factors include dysfunctional B cells,regulatory T cells,and T follicular regulatory cells.The complexity and heterogeneity of the TLS composition may affect the function and activity of TLSs;it is therefore essential to fully understand the function and influencing factors in TLSs.It has been reported that checkpoint inhibitors and vaccines are currently being developed to reprogram the TME by establishing mature TLSs to improve cancer immunotherapies.In this review,we focused on recent advances in TLSs in human solid tumors,including structural characteristics and classes,antitumor mechanisms,immunosuppressive factors,and TLSbased therapeutic approaches. 展开更多
关键词 tertiary lymphoid structure tumor microenvironment IMMUNOtHERAPY B cells t cells
下载PDF
具有宇称-时间反演对称性的虚势能对T-型石墨烯结构能谱和边缘态的影响
13
作者 江翠 李家锐 +1 位作者 亓迪 张莲莲 《物理学报》 SCIE EI CAS CSCD 北大核心 2024年第20期253-265,共13页
本文通过T-型石墨烯结构的条带两侧分别施加单层或者双层具有宇称-时间(parity-time,PT)对称性的虚势能,考察了非厄米机制对能谱和边缘态的调控作用.结果发现,当对条带最外侧单层格点施加虚势能时,边缘态的能量出现虚部,并且从局域在系... 本文通过T-型石墨烯结构的条带两侧分别施加单层或者双层具有宇称-时间(parity-time,PT)对称性的虚势能,考察了非厄米机制对能谱和边缘态的调控作用.结果发现,当对条带最外侧单层格点施加虚势能时,边缘态的能量出现虚部,并且从局域在系统两侧变为一侧.而拓扑平庸区出现PT对称相转变.当虚势能达到临界值时,体态的能隙中会有新的虚能边缘态.另一方面,当施加双层虚势能时,体系中会出现两种不同的边缘态.一种是出现在顶带和底带、局域在系统一侧的边缘态,另一种是出现在第2条和第3条能带中间、局域性相对较弱的边缘态,且不会进入能隙中.本工作有助于理解PT对称的边缘虚势能对T-型石墨烯结构物性的调控作用. 展开更多
关键词 t-型石墨烯结构 宇称-时间对称 能谱 边缘态
下载PDF
激光-电弧复合增材制造Al-Cu合金T型结构微观组织演变与熔池流动行为分析
14
作者 王儒政 马广义 +3 位作者 吴胜男 刘德华 牛方勇 吴东江 《航空制造技术》 CSCD 北大核心 2024年第9期62-69,77,共9页
在T型结构增材制造过程中,交叉节点处易出现冶金结合不良及重熔缺陷等问题,制约该结构性能的提升。采用激光-电弧复合增材制造技术制备了Al-Cu合金T型结构,对交叉节点处的组织形貌进行了表征,并通过数值模拟分析了节点处熔池内的温度分... 在T型结构增材制造过程中,交叉节点处易出现冶金结合不良及重熔缺陷等问题,制约该结构性能的提升。采用激光-电弧复合增材制造技术制备了Al-Cu合金T型结构,对交叉节点处的组织形貌进行了表征,并通过数值模拟分析了节点处熔池内的温度分布以及流动特征。结果表明,在T型结构节点处能够观察到重熔作用所导致的弧形条纹特征,该区域的模拟形貌与实际结果具有良好的一致性;熔池边界处等温线分布较为密集,内部Marangoni对流导致逆时针涡流的形成,最高流速可达0.16 m/s。依据顶层晶粒形态差异,分为顶层节点重熔区(RZI)和顶层热影响区(HAZ)。其中RZI内主要为细小的树枝晶,平均晶粒尺寸相比于HAZ降低了20.8%,内部析出相主要为与α-Al基体呈非共格界面的大尺寸θ(Al_(2)Cu)相;平均显微硬度可达(98.4±6.4)HV_(0.1),相比于未重熔区最高提升约14.0%。 展开更多
关键词 激光-电弧复合增材制造 AL-CU合金 t型结构 组织形貌 熔池流动
下载PDF
翼缘尺寸对地聚物混凝土T形梁抗剪性能的影响
15
作者 宋建雄 毛宇光 +3 位作者 刘翼玮 苏捷 杜运兴 史才军 《重庆交通大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第1期1-9,共9页
为探究翼缘尺寸对地聚物混凝土T形梁抗剪性能的影响,对1根普通混凝土和4根不同翼缘尺寸的地聚物混凝土T形梁进行了集中荷载下的抗剪试验;试验获得了T形梁试件的承载力、挠度、钢筋应变、破坏模式及裂缝的开展等相关参数。研究结果表明:... 为探究翼缘尺寸对地聚物混凝土T形梁抗剪性能的影响,对1根普通混凝土和4根不同翼缘尺寸的地聚物混凝土T形梁进行了集中荷载下的抗剪试验;试验获得了T形梁试件的承载力、挠度、钢筋应变、破坏模式及裂缝的开展等相关参数。研究结果表明:地聚物混凝土T形梁具有与普通混凝土T形梁相似的裂缝扩展、破坏模式及抗剪承载力,但其刚度和斜截面开裂荷载较低,跨中纵筋和箍筋的应变较大;将翼缘厚度与截面有效高度比值从0.24增大到0.48时,地聚物混凝土T形梁的刚度增大、跨中纵筋应变减小,抗剪承载力提高了12.7%,地聚物混凝土的归一化抗剪强度增大了25.3%;当翼缘宽度超过两倍腹板宽度时,继续增大能减小跨中纵筋应变,但地聚物混凝土T形梁的刚度、抗剪承载力及地聚物混凝土归一化抗剪强度不再增大。规范ACI 318—19和Eurocode 2的计算结果明显低估了地聚物混凝土T形梁的抗剪承载力,GB 50010—2010较接近试验值。为更好预测地聚物混凝土T形梁的计算抗剪承载力,建议在抗剪承载力计算公式中增加翼缘有效受剪面积所提供的剪力。 展开更多
关键词 桥梁工程 建筑结构工程 建筑材料工程 地聚物混凝土 t形梁 翼缘尺寸 抗剪性能
下载PDF
不锈钢复合钢材焊接方管T形管节点试验研究
16
作者 杨晓峰 班慧勇 石永久 《工程力学》 EI CSCD 北大核心 2024年第S01期50-56,共7页
不锈钢复合钢材是一种成本低、强度高、耐腐蚀性能优异的高性能钢材,其在对耐腐蚀要求高的工程结构应用中尤其具有竞争力。该文旨在通过试验,研究不锈钢复合钢材焊接方管T形节点在静力和低周往复荷载作用下的力学性能,设计、制作了4个... 不锈钢复合钢材是一种成本低、强度高、耐腐蚀性能优异的高性能钢材,其在对耐腐蚀要求高的工程结构应用中尤其具有竞争力。该文旨在通过试验,研究不锈钢复合钢材焊接方管T形节点在静力和低周往复荷载作用下的力学性能,设计、制作了4个管节点试件并完成了加载,基于试验结果重点研究了各管节点试件的试验过程、破坏模式、荷载-位移响应和应变发展等;按中国规范GB 50017和欧洲规范EN 1993-1-8进行了节点承载力计算,并与试验值进行了对比。研究结果表明,对于支管承受轴向压力的管节点试件,以主管上表面塑性破坏为主;对于支管承受水平低周往复荷载的管节点试件,以主管上表面塑性变形和主管与支管之间连接焊缝断裂破坏为主;当管节点破坏模式符合现行规范GB 50017和EN 1993-1-8中规定时,相关承载力计算公式仍适用于此类不锈钢复合钢材焊接方管T形管节点的设计计算。 展开更多
关键词 不锈钢复合钢材 焊接t形管节点 力学性能 试验研究 设计方法
下载PDF
基于多综眼的纬向T型结构多筋机织物的设计与织造
17
作者 鄢梦麟 林富生 +2 位作者 刘泠杉 宋志峰 龚小舟 《毛纺科技》 CAS 北大核心 2024年第10期16-21,共6页
为了解决传统织机织造效率低下以及异型织物织造难度大的问题,设计了一种基于多综眼的纬向T型结构多筋机织物的织造工艺。通过研究整体T型结构机织物的成形技术,采用多层角联锁结构为基础,结合多综眼织机的特性,设计经向截面图并绘制纹... 为了解决传统织机织造效率低下以及异型织物织造难度大的问题,设计了一种基于多综眼的纬向T型结构多筋机织物的织造工艺。通过研究整体T型结构机织物的成形技术,采用多层角联锁结构为基础,结合多综眼织机的特性,设计经向截面图并绘制纹版图,通过机织方法织造了梁高和基座厚度相同的纬向T型结构多筋机织物。结果表明:采用五综眼织机相较于单综眼织机织造效率提升了5倍,织造基于多综眼的纬向T型结构多筋机织物是可行的。 展开更多
关键词 t 三维机织物 多综眼 多筋 预制体 角联锁结构
下载PDF
复合材料T型节点强度直接计算模型研究
18
作者 石宝松 严仁军 《舰船科学技术》 北大核心 2024年第7期52-56,共5页
针对T型节点强度预测大多是通过试验进行,但试验测试存在周期长、成本高等问题,特别是对节点进行尺寸优化后再次进行试验效率较低,有必要针对复合材料T型节点直接计算模型进行研究,实现对T型节点强度的快速校核。因此以复合材料T型节点... 针对T型节点强度预测大多是通过试验进行,但试验测试存在周期长、成本高等问题,特别是对节点进行尺寸优化后再次进行试验效率较低,有必要针对复合材料T型节点直接计算模型进行研究,实现对T型节点强度的快速校核。因此以复合材料T型节点作为研究对象,参考相关规范确定节点直接计算模型的边界条件、尺寸以及强度校核标准,得到一个用于T型节点强度校核的直接计算模型。 展开更多
关键词 夹芯复合材料结构 t型节点 直接计算
下载PDF
LOCAL INFLUENCE ASSESSMENT IN A MULTIVARIATE t-MODEL WITH RAO'S SIMPLE STRUCTURE 被引量:3
19
作者 邹清明 张怀雄 《Acta Mathematica Scientia》 SCIE CSCD 2005年第1期179-192,共14页
The local influence analysis is an important problem in statistical inference and some models have been discussed in many literatures This paper deals with the problem of assessing local influences in a multivariate t... The local influence analysis is an important problem in statistical inference and some models have been discussed in many literatures This paper deals with the problem of assessing local influences in a multivariate t-model with Rao's simple struc-ture(RSS). Based on Cook's likelihood displacement, the effects of some minor perturbation on the statistical inference is assessed. As an application, a common covariance-weighted perturbation is thoroughly discussed. 展开更多
关键词 Multivariate t-model Rao's simple structure ω-model likelihood displacement MLE
下载PDF
Stable t-structures and Homotopy Category of Strongly Copure Projective Modules 被引量:1
20
作者 ma xin zhao you-yi du xian-kun 《Communications in Mathematical Research》 CSCD 2017年第3期281-288,共8页
In this paper, we study the homotopy category of unbounded complexes of strongly copure projective modules with bounded relative homologies K;(SCP).We show that the existence of a right recollement of K;(SCP) with... In this paper, we study the homotopy category of unbounded complexes of strongly copure projective modules with bounded relative homologies K;(SCP).We show that the existence of a right recollement of K;(SCP) with respect to K;(SCP), K;(SCP) and K;(SCP) has the homotopy category of strongly copure projective acyclic complexes as a triangulated subcategory in some case. 展开更多
关键词 homotopy category RECOLLEMENt stable t-structure
下载PDF
上一页 1 2 63 下一页 到第
使用帮助 返回顶部