期刊文献+
共找到1,997篇文章
< 1 2 100 >
每页显示 20 50 100
A Two-Stage Method for an Approximate Calculation of Statically Indeterminate Trusses 被引量:2
1
作者 Janusz Rebielak 《Journal of Civil Engineering and Architecture》 2014年第5期567-572,共6页
The paper presents the principles of a method, which in two simple stages makes possible to carry out the statically calculation of values of forces acting in the fiat static indeterminate trusses. In each stage, it i... The paper presents the principles of a method, which in two simple stages makes possible to carry out the statically calculation of values of forces acting in the fiat static indeterminate trusses. In each stage, it is considered the static determinate truss, scheme of which is obtained after remove the suitable number of members from the basic static indeterminate truss. The both intermediate statically determinate trusses are of the same clear span and they are loaded by forces of half values applied to the corresponding truss nodes. The method applies one of the typical procedures of calculation of the statically determinate trusses and then it is applied in an appropriate way the rule of superposition for obtaining the final values of forces acting in particular members of the basic truss. The values of forces calculated in this way are of a very close approximation to the force values determined in the special and complex ways being considered as the exact calculation methods. The proposed method can be useful mostly but not only for the initial structural design of such systems. The simplicity of the two-stage method justifies an assumption that it can be relatively easy and worthy to adjust to the requirements of the computer aided technology of statically calculation of the complex forms of trusses. 展开更多
关键词 Method of static calculation truss structure static indeterminate truss static determinate truss rule of superposition.
下载PDF
Homeostatic Determinate Systems and Thermodynamics of Selforganization and Evolution of Material World 被引量:1
2
作者 Lev E. Panin 《Journal of Modern Physics》 2011年第5期354-369,共16页
The paper considers new approaches to system analysis of natural phenomena in physics, chemistry and bi- ology. It lays the foundation of the homeostatic determinate systems theory that allows revealing the mecha- nis... The paper considers new approaches to system analysis of natural phenomena in physics, chemistry and bi- ology. It lays the foundation of the homeostatic determinate systems theory that allows revealing the mecha- nism by which the basic principle of natural science, determinism, is being realized. Evolution of the mate- rial world is represented as inevitable and continuous growth of orderliness (negentropy) based on transition from one type of determinate systems to another. Increasing negentropy is shown to be closely associated with continuous accumulation of information, which determines the natural diversity in physics, chemistry and biology. 展开更多
关键词 Homeostatic determinate System THERMODYNAMICS EVOLUTION
下载PDF
Statically Determinate Equations of Equilibrium in Particulate Mechanics
3
作者 Wu Bingkun Center of Rock and Soil Mechanics, Southwest Jiaotong University, Chengdu 610031, China 《Journal of Modern Transportation》 1996年第1期2-15,共14页
Based on a model of two stress tensors possessing high fluidity, a statically determinate system of partial difference equations of equilibrium has been derived for use to particulate media... Based on a model of two stress tensors possessing high fluidity, a statically determinate system of partial difference equations of equilibrium has been derived for use to particulate media of such nature. Through non dimensionalization of independent and dependent variables, the system passes into that of partial differential equations. Although the statically determinate system of partial differential equations is non linear, yet the two dimensional one falls apart into three separate groups which can be solved easily one after another. 展开更多
关键词 particulate mechanics statically determinate system stress tensor
下载PDF
Influence of the Interaction of the Mutant Inl Gene and the Type of Fruiting Branches ss on the Anatomical Features of the Stem in the Indeterminate and Determinant Forms of <i>G. hirsutum</i>L.
4
作者 Akmal A.Yuldashev Guljan M.Duschanova +1 位作者 Miradkham F.Abzalov Gayrat N.Jurakulov 《American Journal of Plant Sciences》 2020年第4期538-548,共11页
For the first time, a comparative analysis of the structure of the apical meristem and the node of the main shoot of two forms of the indeterminate kind Namangan-77 and the determinant line of Determinant-2 and Determ... For the first time, a comparative analysis of the structure of the apical meristem and the node of the main shoot of two forms of the indeterminate kind Namangan-77 and the determinant line of Determinant-2 and Determinant-3 of G. hirsutum in the kidney ding phase was carried out. In the apical meristem of the indeterminate form Namangan-77 is characterized by the recessive homozygous state of the mutant gene (inlinl) and the dominant homozygous, heterozygous state of the fruiting branch gene S-s: inlinlSS, inlinlSs, inlinlss—more pronounced vegetative, vegetative, with this, this form is predominated by the continuation of first-order shoots and the monopodial branching type with unlimited apical growth, accompanied by a uniform elongation of the internodes. In the apical meristem, in the forms of the determinant lines, Determinant-2 and Determinant-3 are characterized by the dominant homozygous state of the mutant gene (InlInl) and the recessive homozygous state of the allelic gene (ss)—InlInlss—there is a generative collateral kidney in the axillary leaf axial sinus, which is why these forms of the vegetative apex of the shoot when they transit to the reproductive state turn into a floral apical meristem and a sympodial branching type what happens through the development of inflorescences. Obviously, this is a consequence of a change in the phytohormonal status in the apical part of the stem as a result of the interaction of the mutant gene Inl and gene S. The node of the main stem in all forms was also studied, and a three-beam-three-lacuna type of structure was revealed, which is a fairly persistent characterizing feature of large taxa and can be used in their taxonomy. 展开更多
关键词 MUTANT GENE Allele Anatomy STEM INdeterminate DETERMINANT Monopodial Sympodial
下载PDF
Determinates of Childhood Pneumonia and Diarrhea with Special Emphasis to Exclusive Breastfeeding in North Achefer District, Northwest Ethiopia: A Case Control Study
5
作者 Molla Gedefaw Resom Berhe 《Open Journal of Epidemiology》 2015年第2期107-112,共6页
Studies showed that exclusive breast feeding reduced infant morbidity and mortality. In low income countries such as Ethiopia where under-five mortality is very high, the role of exclusively breastfeeding could be eve... Studies showed that exclusive breast feeding reduced infant morbidity and mortality. In low income countries such as Ethiopia where under-five mortality is very high, the role of exclusively breastfeeding could be even more critical. However, studies assessing the place of exclusive breast freeing in the prevention of childhood illnesses in our area are scarce. The aim of the study was to identify determinant factors of childhood pneumonia and diarrhoea. An institution based case control study was conducted in Achefer District in July, 2012. The cases were 122 children of 7 - 24 months old who had repeated attack of diarrhoea or pneumonia over three months prior to the survey while controls were 122 children who visited well baby clinic for vaccination. Data were collected by using pre-tested and structured questionnaire, and analysed using SPSS version 16 for windows. Logistic regression was performed, and strength of associations was estimated using odds ratio and 95% confidence interval. About 83% of the controls and only 12.3% of the cases were exclusively breast fed. Children who were exclusively breast fed were 83 times less likely to develop pneumonia or diarrhea than those who were not exclusively fed. Marital status, monthly income, prelacteal feeding, and late initiation of breast feeding were found to have statistically significant association with childhood diarrhea and pneumonia. This study brought local evidence that exclusive breast feeding had a protective effect against common childhood infectious diseases—pneumonia and diarrhoea—in the study area. Therefore, culture sensitive and plausible health education is recommended to strengthen exclusive breast feeding practices in order to decrease mortality and morbidity of infants and children from pneumonia and diarrhoea. 展开更多
关键词 EXCLUSIVE Breast Feeding DETERMINANT Factors CHILDHOOD Pneumonia DIARRHEA Ethiopia
下载PDF
DETERMINE评分与急性心肌梗死PCI术预后关系的分析
6
作者 李加乐 刘泽岩 程景林 《中文科技期刊数据库(引文版)医药卫生》 2024年第5期0051-0054,共4页
探讨DETERMINE评分(病理性Q波导联数*2+碎裂QRS波导联数+T波倒置导联数)与急性心肌梗死患者经皮冠状动脉介入(PCI)术后预后的关系。方法 选择2021.1-2022.12在我院住院接受PCI治疗的急性心肌梗死患者206例,根据预后情况分为预后良好组(... 探讨DETERMINE评分(病理性Q波导联数*2+碎裂QRS波导联数+T波倒置导联数)与急性心肌梗死患者经皮冠状动脉介入(PCI)术后预后的关系。方法 选择2021.1-2022.12在我院住院接受PCI治疗的急性心肌梗死患者206例,根据预后情况分为预后良好组(165例)和预后不良组(41例)。比较两组患者的临床资料及DETERMINE评分,采用多因素Logistic回归法分析影响急性心肌梗死PCI术后预后的相关因素;创建受试者工作特征曲线(ROC),分析DETERMINE评分对急性心肌梗死PCI术后预后的预测价值。分析急性心肌梗死PCI术预后不良的影响因素。结果 与预后良好组比较,预后不良组糖尿病史、心律失常史比例及DETERMINE评分、年龄、体重指数、左室射血分数、糖化血红蛋白、低密度脂蛋白胆固醇、总胆固醇水平均显著升高,差异具有统计学意义;二元Logistic回归分析显示DETERMINE评分、心律失常史、体重指数、糖化血红蛋白、低密度脂蛋白胆固醇是冠心病患者PCI手术预后不良的独立危险因素(OR=1.443~15.658,P<0.05)。结论 DETERMINE评分与冠心病PCI术预后相关,需引起临床关注。 展开更多
关键词 DETERMINE评分 急性心肌梗死 PCI术后 预后
下载PDF
An Improved Test Method and Numerical Analysis for Crack Opening Resistance of FRC Round Determinate Panels 被引量:2
7
作者 GU Qian XU Hanfeng MINDESS Sidney 《Wuhan University Journal of Natural Sciences》 CAS 2009年第1期47-52,共6页
This paper presents a numerical analysis of a material test program investigating the crack opening properties of fibre reinforced concrete (FRC) round determinate panels (RDP). The objective of this research is t... This paper presents a numerical analysis of a material test program investigating the crack opening properties of fibre reinforced concrete (FRC) round determinate panels (RDP). The objective of this research is to set up a modified RDP test method to improve the current ASTM C1550 test method for FRC and fibre reinforced shotcrete (FRS) composite. By this test method, light small-diameter panels are applied and more crack information can be obtained by a new rotation angle measuring technique. It is shown that this modified test method can be used to effectively evaluate the crack opening resistance of FRC. The finite element analysis was then performed to clarify the crack propaga- tions and failure mode of FRC RDP panels. It helps establish a reasonable theoretical method to predict the structural response of RDP. combining with this modified testing technioue. 展开更多
关键词 fibre reinforced concrete test method round determinate panel finite element analysis crack opening
原文传递
A Coordinate-Free Approach to the Design of Generalized Griffis-Duffy Platforms
8
作者 Chengwei Shen Xu Pei +1 位作者 Lubin Hang Jingjun Yu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第3期95-103,共9页
Architectural singularity belongs to the Type II singularity,in which a parallel manipulator(PM)gains one or more degrees of freedom and becomes uncontrollable.PMs remaining permanently in a singularity are beneficial... Architectural singularity belongs to the Type II singularity,in which a parallel manipulator(PM)gains one or more degrees of freedom and becomes uncontrollable.PMs remaining permanently in a singularity are beneficial for linearto-rotary motion conversion.Griffis-Duffy(GD)platform is a mobile structure admitting a Bricard motion.In this paper,we present a coordinate-free approach to the design of generalized GD platforms,which consists in determining the shape and attachment of both the moving platform and the fixed base.The generalized GD platform is treated as a combination of six coaxial single-loop mechanisms under the same constraints.Owing to the inversion,hidden in the geometric structure of these single-loop mechanisms,the mapping from a line to a circle establishes the geometric transformation between the fixed base and the moving platform based on the center of inversion,and describes the shape and attachment of the generalized GD platform.Moreover,the center of inversion not only identifies the location of rotation axis,but also affects the shape of the platform mechanism.A graphical construction of generalized GD platforms using inversion,proposed in the paper,provides geometrically feasible solutions of the manipulator design for the requirement of the location of rotation axis. 展开更多
关键词 Generalized Griffis-Duffy platforms SELF-MOTION INVERSION Coordinate-free determination Manipulator design
下载PDF
Silencing transformer and transformer-2 in Zeugodacus cucurbitae causes defective sex determination with inviability of most pseudomales
9
作者 Qin Ma Zizhen Fan +5 位作者 Ping Wang Siya Ma Jian Wen Fengqin Cao Xianwu Lin Rihui Yan 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2024年第3期938-947,共10页
transformer is a switch gene for sex determination in many insects, which cooperates with transformer-2 that is expressed in both sexes to regulate female differentiation, particularly in dipterans. Zeugodacus cucurbi... transformer is a switch gene for sex determination in many insects, which cooperates with transformer-2 that is expressed in both sexes to regulate female differentiation, particularly in dipterans. Zeugodacus cucurbitae(Coquillett) is a very destructive pest worldwide, however, its sex determination pathway remains largely uncharacterized. Here, we show that the female sex ratio is sharply reduced with knockdown of either transformer or transformer-2 by RNA interference in early embryos of Z. cucurbitae. Most of the males grown from the embryos with transient transformer and transformer-2 suppression mated with wild-type females and produced mixed sex progeny, with one exception that produced only female progeny, and all of the few remaining males failed to mate with wild-type females and produced no progeny. The exceptional male and those males with mating failure were XX pseudomales as determined by the detection of Y chromosome-linked Maleness-on-the-Y, indicating that most XX pseudomales are not viable. The phenotypes of transformer and transformer-2 suggest that they play a key role in regulating sex determination and are required for female sexual development of Z. cucurbitae. Our results will be beneficial to the understanding of sex determination in Z. cucurbitae and can facilitate the development of genetic sexing strains for its biological control. 展开更多
关键词 Zeugodacus cucurbitae TRANSFORMER transformer-2 sex determination RNA interference biological control
下载PDF
Review of the Low-Lying Excited Baryons∑*(1/2-)
10
作者 En Wang Li-Sheng Geng +2 位作者 Jia-Jun Wu Ju-Jun Xie and Bing-Song Zou 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第10期31-37,共7页
Strong empirical and phenomenological indications exist for large sea-quark admixtures in the low-lying excited baryons.Investigating the low-lying excited baryon∑*(1/2-)is important for determining the nature of the... Strong empirical and phenomenological indications exist for large sea-quark admixtures in the low-lying excited baryons.Investigating the low-lying excited baryon∑*(1/2-)is important for determining the nature of the low-lying excited baryons.We review the experimental and theoretical progress on the studies of the∑*(1/2-). 展开更多
关键词 EXCITED QUARK DETERMINING
下载PDF
foxl2l is a germ cell-intrinsic gatekeeper of oogenesis in zebrafish
11
作者 Zhiqin Ren Ding Ye +5 位作者 Naike Su Chaofan Wang Lijia He Houpeng Wang Mudan He Yonghua Sun 《Zoological Research》 SCIE CSCD 2024年第5期1116-1130,共15页
Zebrafish serve as a valuable model organism for studying germ cell biology and reproductive processes.The AB strain of zebrafish is proposed to exhibit a polygenic sex determination system,where most males initially ... Zebrafish serve as a valuable model organism for studying germ cell biology and reproductive processes.The AB strain of zebrafish is proposed to exhibit a polygenic sex determination system,where most males initially develop juvenile ovaries before committing to male fate.In species with chromosomal sex determination,gonadal somatic cells are recognized as key determinants of germ cell fate.Notably,the loss of germ cells in zebrafish leads to masculinization,implying that germ cells harbor an intrinsic feminization signal.However,the specific signal triggering oogenesis in zebrafish remains unclear.In the present study,we identified foxl2l as an oocyte progenitor-specific gene essential for initiating oogenesis in germ cells.Results showed that foxl2l-knockout zebrafish bypassed the juvenile ovary stage and exclusively developed into fertile males.Further analysis revealed that loss of foxl2l hindered the initiation of oocyte-specific meiosis and prevented entry into oogenesis,leading to premature spermatogenesis during early gonadal development.Furthermore,while mutation of the pro-male gene dmrt1 led to fertile female differentiation,simultaneous disruption of foxl2l in dmrt1 mutants completely blocked oogenesis,with a large proportion of germ cells arrested as germline stem cells,highlighting the crucial role of foxl2l in oogenesis.Overall,this study highlights the unique function of foxl2l as a germ cell-intrinsic gatekeeper of oogenesis in zebrafish. 展开更多
关键词 foxl2l DMRT1 OOGENESIS Sex determination MEIOSIS
下载PDF
Ionization Potential Depression Model for Warm/Hot and Dense Plasmas
12
作者 Chensheng Wu Fuyang Zhou +4 位作者 Jun Yan Xiang Gao Yong Wu Chunhua Zeng Jianguo Wang 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第8期45-57,共13页
For warm/hot and dense plasmas(WDPs),ionization potential depression(IPD)plays a crucial role in determining its ionization balance and understanding the resultant microscopic plasma properties.A sophisticated and uni... For warm/hot and dense plasmas(WDPs),ionization potential depression(IPD)plays a crucial role in determining its ionization balance and understanding the resultant microscopic plasma properties.A sophisticated and unified IPD model is necessary to resolve those existing discrepancies between theoretical and experimental results.However,the applicability of those widely used IPD models nowadays is limited,especially for the nonlocal thermodynamic equilibrium(non-LTE)dense plasma produced by short-pulse laser.In this work,we propose an IPD model that considers inelastic atomic processes,in which three-body recombination and collision ionization processes are found to play a crucial role in determining the electron distribution and IPD for a WDP.This IPD model is validated by reproducing latest experimental results of Al plasmas with a wide-range condition of 70 eV–700 eV temperature and 0.2–3 times solid density,as well as a typical non-LTE system of hollow Al ions.It is demonstrated that the present IPD model has a significant temperature dependence due to the consideration of the inelastic collision processes.With a lower computational cost and wider application range of plasma conditions,the proposed model is expected to provide a promising tool to study the ionization balance and the atomic processes,as well as the related radiation and particle transports properties of the WDP. 展开更多
关键词 properties. COLLISION DETERMINING
下载PDF
DSAS:A new macromolecular substructure solution program based on the modified phase-retrieval algorithm
13
作者 付兴科 谭振希 +2 位作者 耿直 刘茜 丁玮 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期125-132,共8页
Considering the pivotal role of single-wavelength anomalous diffraction(SAD) in macromolecular crystallography,our objective was to introduce DSAS,a novel program designed for efficient anomalous scattering substructu... Considering the pivotal role of single-wavelength anomalous diffraction(SAD) in macromolecular crystallography,our objective was to introduce DSAS,a novel program designed for efficient anomalous scattering substructure determination.DSAS stands out with its core components:a modified phase-retrieval algorithm and automated parameter tuning.The software boasts an intuitive graphical user interface(GUI),facilitating seamless input of essential data and real-time monitoring.Extensive testing on DSAS has involved diverse datasets,encompassing proteins,nucleic acids,and various anomalous scatters such as sulfur(S),selenium(Se),metals,and halogens.The results confirm DSAS’s exceptional performance in accurately determining heavy atom positions,making it a highly effective tool in the field. 展开更多
关键词 DSAS single-wavelength anomalous diffraction automated parameters settings phase-retrieval algorithm substructure determination
下载PDF
STARLIKENESS ASSOCIATED WITH THE SINE HYPERBOLIC FUNCTION
14
作者 Mohsan RAZA Hadiqa ZAHID Jinlin LIU 《Acta Mathematica Scientia》 SCIE CSCD 2024年第4期1244-1270,共27页
Let q_(λ)(z)=1+λsinh(ζ),0<λ<1/sinh(1)be a non-vanishing analytic function in the open unit disk.We introduce a subclass S^(*)(q_(λ))of starlike functions which contains the functions f such that zf'/f i... Let q_(λ)(z)=1+λsinh(ζ),0<λ<1/sinh(1)be a non-vanishing analytic function in the open unit disk.We introduce a subclass S^(*)(q_(λ))of starlike functions which contains the functions f such that zf'/f is subordinated by q_(λ).We establish inclusion and radii results for the class S^(*)(q_(λ))for several known classes of starlike functions.Furthermore,we obtain sharp coefficient bounds and sharp Hankel determinants of order two for the class S^(*)(q_(λ)).We also find a sharp bound for the third Hankel determinant for the caseλ=1/2. 展开更多
关键词 starlike functions sine hyperbolic functions radii problems coefficient bounds Hankel determinants
下载PDF
TOEPLITZ DETERMINANTS IN ONE AND HIGHER DIMENSIONS
15
作者 Surya GIRI S.Sivaprasad KUMAR 《Acta Mathematica Scientia》 SCIE CSCD 2024年第5期1931-1944,共14页
In this study,we derive the sharp bounds of certain Toeplitz determinants whose entries are the coefficients of holomorphic functions belonging to a class defined on the unit disk U.Furthermore,these results are exten... In this study,we derive the sharp bounds of certain Toeplitz determinants whose entries are the coefficients of holomorphic functions belonging to a class defined on the unit disk U.Furthermore,these results are extended to a class of holomorphic functions on the unit ball in a complex Banach space and on the unit polydisc inℂn.The obtained results provide the bounds of Toeplitz determinants in higher dimensions for various subclasses of normalized univalent functions. 展开更多
关键词 holomorphic mappings starlike mappings Toeplitz determinants coefficient inequalities
下载PDF
Unraveling the regulatory network of flower coloration in soybean:Insights into roles of GmMYBA3 and GmMYBR1
16
作者 Ruifang Gao Yueqing Li +8 位作者 Yanan Wang Xiaotong Shan Siqi Yang Ye Zhang Saiyu Ma Chunbao Zhang Jianchun Qin Li Wang Xiang Gao 《The Crop Journal》 SCIE CSCD 2024年第2期443-455,共13页
Anthocyanins play crucial roles in pollen protection and pollinator attraction in flowering plants.However,the mechanisms underlying flower color determination and whether floral anthocyanin regulators participate in ... Anthocyanins play crucial roles in pollen protection and pollinator attraction in flowering plants.However,the mechanisms underlying flower color determination and whether floral anthocyanin regulators participate in other processes remain largely unresolved in soybeans(Glycine max).In this study,we investigated the genetic components and mechanisms governing anthocyanin biosynthesis in soybean flowers.Molecular and genetic studies have characterized two antagonistic regulators,the positive activator GmMYBA3 and the negative repressor GmMYBR1,that modulate the gene expression of anthocyanin biosynthesis in soybean flowers.Further findings revealed a regulatory interplay between GmMYBA3 and GmMYBR1 bridged by GmTT8a,highlighting the complexity of anthocyanin regulation in different soybean organs.Exploration of additional soybean cultivars demonstrated the universality of GmMYBA3 and GmMYBR1 in regulating floral anthocyanin biosynthesis-related genes,with GmF3’5’H identified as a crucial determinant of white flower color.This study provides a molecular mechanism underlying soybean flower color determination,paving the way for the molecular modification of soybean flowers to probably enhance their resistance to abiotic stresses and attractiveness to pollinators. 展开更多
关键词 ANTHOCYANIN Flower color determination MBW complex MYB repressor Pleiotropic regulator
下载PDF
Influence of O-O formation pathways and charge transfer mediator on lipid bilayer membrane-like photoanodes for water oxidation
17
作者 Yingzheng Li Shaoqi Zhan +9 位作者 Zijian Deng Meng Chen Yilong Zhao Chang Liu Ziqi Zhao Hongxia Ning Wenlong Li Fei Li Licheng Sun Fusheng Li 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第6期526-537,I0013,共13页
Inspired by the function of crucial components in photosystemⅡ(PSⅡ),electrochemical and dyesensitized photoelectrochemical(DSPEC)water oxidation devices were constructed by the selfassembly of well-designed amphipat... Inspired by the function of crucial components in photosystemⅡ(PSⅡ),electrochemical and dyesensitized photoelectrochemical(DSPEC)water oxidation devices were constructed by the selfassembly of well-designed amphipathic Ru(bda)-based catalysts(bda=2,2'-bipyrdine-6,6'-dicarbonoxyl acid)and aliphatic chain decorated electrode surfaces,forming lipid bilayer membrane(LBM)-like structures.The Ru(bda)catalysts on electrode-supported LBM films demonstrated remarkable water oxidation performance with different O-O formation mechanisms.However,compared to the slow charge transfer process,the O-O formation pathways did not determine the PEC water oxidation efficiency of the dyesensitized photoanodes,and the different reaction rates for similar catalysts with different catalytic paths did not determine the PEC performance of the DSPECs.Instead,charge transfer plays a decisive role in the PEC water oxidation rate.When an indolo[3,2-b]carbazole derivative was introduced between the Ru(bda)catalysts and aliphatic chain-modified photosensitizer in LBM films,serving as a charge transfer mediator for the tyrosine-histidine pair in PSⅡ,the PEC water oxidation performance of the corresponding photoanodes was dramatically enhanced. 展开更多
关键词 Water oxidation Rate determine step Dye-sensitized photoelectrochemical cell Charge transfer Artificial photosynthesis
下载PDF
Cryo-EM combined with image deconvolution to determine ZIF-8 crystal structure
18
作者 吴抗 杨柏松 +3 位作者 薛文华 孙大鹏 葛炳辉 王玉梅 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第7期44-49,共6页
Metal–organic frameworks(MOFs) are crystalline porous materials with tunable properties, exhibiting great potential in gas adsorption, separation and catalysis.[1,2]It is challenging to visualize MOFs with transmissi... Metal–organic frameworks(MOFs) are crystalline porous materials with tunable properties, exhibiting great potential in gas adsorption, separation and catalysis.[1,2]It is challenging to visualize MOFs with transmission electron microscopy(TEM) due to their inherent instability under electron beam irradiation. Here, we employ cryo-electron microscopy(cryoEM) to capture images of MOF ZIF-8, revealing inverted-space structural information at a resolution of up to about 1.7A and enhancing its critical electron dose to around 20 e^(-)/A^(2). In addition, it is confirmed by electron-beam irradiation experiments that the high voltage could effectively mitigate the radiolysis, and the structure of ZIF-8 is more stable along the [100] direction under electron beam irradiation. Meanwhile, since the high-resolution electron microscope images are modulated by contrast transfer function(CTF) and it is difficult to determine the positions corresponding to the atomic columns directly from the images. We employ image deconvolution to eliminate the impact of CTF and obtain the structural images of ZIF-8. As a result, the heavy atom Zn and the organic imidazole ring within the organic framework can be distinguished from structural images. 展开更多
关键词 cryo-electron microscopy(cryo-EM) ZIF-8 image deconvolution crystal structure determination
下载PDF
Relative orbit determination algorithm of space targets with passive observation
19
作者 DAI Chenchao QIANG Hongfu +2 位作者 ZHANG Degang HU Shaolei GONG Baichun 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第3期793-804,共12页
Angles-only relative orbit determination for space non-cooperative targets based on passive sensor is subject to weakly observable problem of the relative state between two spacecraft. Previously, the evidence for ang... Angles-only relative orbit determination for space non-cooperative targets based on passive sensor is subject to weakly observable problem of the relative state between two spacecraft. Previously, the evidence for angles-only observability was found by using cylindrical dynamics, however, the solution of orbit determination is still not provided. This study develops a relative orbit determination algorithm with the cylindrical dynamics based on differential evolution. Firstly, the relative motion dynamics and line-of-sight measurement model for nearcircular orbit are established in cylindrical coordinate system.Secondly, the observability is qualitatively analyzed by using the dynamics and measurement model where the unobservable geometry is found. Then, the angles-only relative orbit determination problem is modeled into an optimal searching frame and an improved differential evolution algorithm is introduced to solve the problem. Finally, the proposed algorithm is verified and tested by a set of numerical simulations in the context of highEarth and low-Earth cases. The results show that initial relative orbit determination(IROD) solution with an appropriate accuracy in a relative short span is achieved, which can be used to initialize the navigation filter. 展开更多
关键词 angles-only measurement relative orbit determination cylindrical coordinate differential evolution
下载PDF
Evaluating the relative importance of predictors in Generalized Additive Models using the gam.hp R package
20
作者 Jiangshan Lai Jing Tang +2 位作者 Tingyuan Li Aiying Zhang Lingfeng Mao 《Plant Diversity》 SCIE CAS CSCD 2024年第4期542-546,共5页
Generalized Additive Models(GAMs)are widely employed in ecological research,serving as a powerful tool for ecologists to explore complex nonlinear relationships between a response variable and predictors.Nevertheless,... Generalized Additive Models(GAMs)are widely employed in ecological research,serving as a powerful tool for ecologists to explore complex nonlinear relationships between a response variable and predictors.Nevertheless,evaluating the relative importance of predictors with concurvity(analogous to collinearity)on response variables in GAMs remains a challenge.To address this challenge,we developed an R package named gam.hp.gam.hp calculates individual R^(2) values for predictors,based on the concept of'average shared variance',a method previously introduced for multiple regression and canonical analyses.Through these individual R^(2)s,which add up to the overall R^(2),researchers can evaluate the relative importance of each predictor within GAMs.We illustrate the utility of the gam.hp package by evaluating the relative importance of emission sources and meteorological factors in explaining ozone concentration variability in air quality data from London,UK.We believe that the gam.hp package will improve the interpretation of results obtained from GAMs. 展开更多
关键词 Average shared variance Coefficient of determination Commonality analysis GAMs Hierarchical partitioning Individual R^(2)
下载PDF
上一页 1 2 100 下一页 到第
使用帮助 返回顶部