检索结果-南通市图书馆

Local Uniqueness of Weak Solutions for a Class of Quasilinear Subelliptic Equations

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 Mathematical Research and Exposition 2011年第2期31卷 295-302页

作者： Xue Wei cui yong Zhong wang Department of Applied Mathematics Northwestern Polytechnical University Shaanxi 710072 P. R. China

In this note,we obtain some a-priori estimates for gradient of weak solutions to a class of subelliptic quasilinear equations constructed by Ho¨rmander’s vector fields,and then prove local uniqueness of weak solutio... 详细信息

关键词： Hrmander’s vector fields subelliptic weak solution uniqueness

Three Types of Isocoumarins with Unusual Carbon Skeletons from Artemisia dubia var. subdigitata and Their Antihepatoma Activity

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2024年第16期42卷 1901-1912页

作者： Ke-Xin Yang Tian-Ze Li Yun-Bao Ma yong-cui wang Feng-Jiao Li Ji-Jun Chen State Key Laboratory of Phytochemistry and Plant Resources in West China Kunming Institute of BotanyChinese Academy of SciencesKunmingYunnan 650201China University of Chinese Academy of Sciences Beijing 100049China

Ten novel isocoumarins,including four pairs of enantiomers,were isolated from Artemisia dubia ***(Asteraceae).Compounds 1,2 and 3a/3b possessed a unique 6/6/6-tricyclic system comprising an unusual 1-(2-methylcyclohexyl)propan-1-one moiety fused with isocoumarin core *** 4a/4b were characterized as an unexpected 2,5-dimethylcyclohexan-1-one scaffold,and compounds 5a/5b and 6a/6b were rare 1,*** structures and absolute configurations were elucidated through spectroscopic data,X-ray crystallography,ECD and NMR calculations with DP4+*** biosynthetic pathways were proposed from the naturally occurring *** pharmacological analysis suggested that the targets of compound 1 were significantly enriched in the cell cycle and Pl3K-Akt signaling *** molecular docking revealed that compound 1 had high binding affinity with CDK2(total score:6.8717).Furthermore,compounds 1 and 2 exhibited inhibitory activity on three human hepatoma cell lines,with inhibitory ratios of 85.1% and 84.5%(HepG2),88.2% and 87.3%(Huh7),and 69.2% and 69.1%(SK-Hep-1)at 200μmol·L^(-1),respectively.

关键词： Artemisia dubia var.subdigitata Isocoumarins Antihepatoma activity Cancer Natural products X-ray diffraction

Guaiane-type Sesquiterpenoid Dimers from Artemisia zhongdianensis and Antihepatoma Carcinoma Activity via the p38MAPK Pathway

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2023年第19期41卷 2453-2468页

作者： Wei Dong Wen-Jing Ma Yun-Bao Ma Feng-Jiao Li Tian-Ze Li yong-cui wang Xiao-Feng He Chang-An Geng Xue-Mei Zhang Ji-Jun Chen State Key Laboratory of Phytochemistry and Plant Resources in West China Kunming Institute of BotanyChinese Academy of SciencesKunmingYunnan650201 China University of Chinese Academy of Sciences Beijing100049 China

17 new guaiane-type sesquiterpenoid dimers(GSDs),artemzhongdianolides B1—B17(1—17),were isolated from Artemisia zhongdianensis under the guidance of bioassay,and elucidated by spectral analyses(HRESIMS,1D and 2D NMR,IR,ECD).The absolute configuration of compounds 1,3,7,9,10,and 13 was determined by single-crystal X-ray diffraction ***,artemzhongdianolides B1(1)and B2(2)were the first example of the GSDs fused via a C-13/C-13'single bond,and artemzhongdianolides B3—B17 were[4+2]Diels–Alder adducts of two monomeric *** of the compounds showed antihepatoma cytotoxicity with IC_(50) values ranging from 9.9 to 170.1μmol/***,artemzhongdianolide B9(9)was the most active one against three hepatoma cell lines with IC_(50) values of 13.1μmol/L(HepG2),19.5μmol/L(Huh7),and 19.5μmol/L(SK-Hep-1),and dose-dependently inhibited cell migration and invasion,induced G1 cell cycle arrest and cell apoptosis in HepG2 *** 9 might suppress HepG2 cells via affecting the p38MAPK signaling pathway suggested by machine learning approach,and significantly upregulated expression of phosphorylated p38 validated by Western blot assay.

关键词： Artemzhongdianolides B1-B17 Artemisia zhongdianensis Guaiane-type sesquiter penoid dimers Antihepatoma activity p38MAPK pathway Cancer NMR spectroscopy X-ray diffraction

Delaying wheat sowing date and increasing sowing rate promotes lignin synthesis and reduces lodging

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Crop Journal 2025年第1期13卷 269-280页

作者： Li, Chunhui cui, Haixing Jin, Min Sun, Shufang wang, Jiayu Luo, yongli Li, yong wang, Zhenlin State Key Laboratory of Wheat Improvement Agronomy College of Shandong Agricultural University Shandong Tai'an 271000 China

Population size plays a crucial role in determining wheat yields. Altered carbohydrate accumulation resulting from increased competition between populations and individuals leads to poor-quality stems. The sowing date can mitigate competition in densely planted populations. However, the underlying mechanism by which it confers resistance to wheat lodging remains elusive. In this study, Zimai 28 (lodging-sensitive variety) and Shannong 28 (lodging-resistant variety) were used with three sowing treatments on October 22 (S1), October 28 (S2), and November 3 (S3). The sowing rate was adjusted to ensure adequate population size and consistency in the overwintering populations across sowing dates (300 plant m−2 for S1, 375 plant m−2 for S2, and 525 plant m−2 for S3). The lodging resistance in winter wheat was increased by delayed sowing and increased sowing rate, which led to a reduction in tiller numbers and fostered primary stem development. A reduction in the overwinter cumulative temperature from 500 to 450 °C, coupled with an elevation in sowing rates from 300 to 375 plant m−2 (transition from S1 to S2), corresponded with a notable increase in structural carbohydrates (lignin, cellulose, hemicellulose, and pectin) by 175.07 mg g−1. Additionally, there was a moderate increase in non-structural carbohydrates, including soluble sugars and starch, by 15.54 mg g−1. Delayed sowing and increased sowing rate elevated the precursor contents of lignin synthesis. Enhanced metabolic activity of related pathways ultimately increased dimer/trimer content. In summary, this study highlights the pivotal role of lignin metabolites and cross-linked structures in determining the stem stiffness breaking strength. © 2024

关键词： Carbohydrates Lignin metabolism Lodging Stem quality Wheat

Spatiotemporal evolution of wildfire activity during the Paleocene-Eocene Thermal Maximum in China

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2025年第2期68卷 509-522页

作者： Xue-Ting wang Zuoling CHEN Linlin cui Xu wang State Key Laboratory of Lithospheric and Environmental Coevolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences College of Earth and Planetary SciencesBeijing 100049China Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China

The Paleocene-Eocene Thermal Maximum(PETM)was the most prominent warming event in the Cenozoic and serves as a geological analog for the current global warming driven by anthropogenic CO_(2)emissions from burning fossil *** a primary disruptor of Earth's ecosystems,wildfire activity affects the balance of ecosystems,the global carbon cycle,and climate ***,studying the evolution and driving mechanisms of wildfires during the PETM is essential for predicting wildfire activity under global warming scenarios and for understanding the carbon cycle in the context of wildfire *** research on wildfires during the PETM has mainly focused on the Northern Hemisphere,particularly Europe and North America,whereas studies on Chinese mainland remain *** this study,we analyzed black carbon(BC)concentration and carbon isotope(δ13C)in the Beigou section of the Nanyang Basin and the Xilutian section of the Fushun Basin to reconstruct the spatiotemporal evolution of wildfires in arid/semi-arid and humid *** integrated these findings with those of previous studies on the paleoclimate of the research area to elucidate the driving mechanisms behind wildfire *** results indicate that wildfire activity weakened at the onset of the PETM,with the negative carbon isotope period characterized by low wildfire activity,except for a brief resurgence in the Nanyang *** the recovery phase of the PETM,wildfire activity gradually increased,returning to the pre-PETM *** prolonged low wildfire state was likely caused by extremely high temperatures and precipitation as well as the resulting vegetation *** the PETM recovery phase,increased wildfire activity transformed“short-term carbon sinks”of the biological-atmospheric carbon cycle into“long-term carbon sinks”through the burial of *** process of carbon sink conversion may have acted as a negative feedback mechanism,contributing to carbon sequestration and the e

关键词： PETM Wildfire Carbon cycle Nanyang Basin Fushun Basin

同方期刊数据库

Advancing gravitational theory through the tetrahedral constellation gravitational wave observatory

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第2期68卷 197-198页

作者： Yun-yong wang Zhou-Jian Cao Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing102206China

The Tetrahedral Constellation Gravitational Wave Observatory(TEGO)[1]represents a significant leap forward in gravitational wave detection,advancing our understanding of gravitational *** introducing a fourth spacecraft to form a tetrahedral configuration,TEGO enhances traditional triangular setups,enabling the simultaneous sensitivity to all six gravitational wave polarization modes,including those not predicted by general relativity.

关键词： wave polarization theory

同方期刊数据库

Experiments and modeling of microstructural and mechanical behaviors of laser-welded Ni-based superalloy at high temperatures

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2025年第1期38卷 99-114页

作者： Ting HOU yong LI Degang wang Yuelin wang Marko VILOTIC School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Department of Structure Shenyang Aircraft Designand Research InstituteShenyang 110000China Engineering Center Shenyang Aircraft CorporationShenyang 110000China Faculty of Technical Science University of Novi SadNovi Sad 21102Serbia

The performance of welded Ni-based superalloys at high temperatures is essential to be evaluated due to their particular service environment for aero-engines and high-speed *** tensile properties and related microstructural evolutions such as the carbide precipitate and grain of a laser-welded Ni-based alloy were experimentally and numerically investigated at different temperatures(20,300,500,800℃).The results show that at room temperature,the strength of the Base Material(BM)was slightly smaller,with a difference of less than 1%,than the Welded Material(WM),which can be attributed to the more uniformly distributed needle-shaped carbide precipitates in the WM than those nonuniformly coarser spherical ones in the *** at 300℃ and 500℃,the strength of WM decreased more obviously compared with that of BM due to the more apparent growth of grain:13.52%loss in yield strength in WM alloys as compared with BM alloys at 300℃,and 16.57% at 500℃.At 800℃,the strength of BM and WM both decreased to a similar level due to Dynamic Recrystallization(DRX).However,a much higher elongation was observed for the BM than WM(less than 50%of BM),which can be attributed to the enhanced dislocation accumulation capability of the large spherical carbides along grain boundaries on the fracture surface in ***,a unified model considering the welding effects on both microstructures(dislocation,carbides,and grain)and mechanical properties evolutions at different temperatures was developed and *** on this model,the key temperature ranges(20–600℃)where apparent weakening of strength and uniform plasticity occurs for welded structures were identified,providing a direct guidance for potential structure and process design.

关键词： Ni-based superalloy Microstructure Mechanical properties Constitutive model High temperature

The Hilbert expansion of the Boltzmann equation in the incompressible Euler level in a channel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2025年第1期68卷 39-88页

作者： Feimin Huang Weiqiang wang yong wang Feng Xiao Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Computing and Stochastic Mathematics(Ministry of Education) School of Mathematics and StatisticsHunan Normal UniversityChangsha 410081China

The study of the hydrodynamic limit of the Boltzmann equation with physical boundary is a challenging problem due to the appearance of the viscous and Knudsen boundary *** this paper,the hydrodynamic limit from the Boltzmann equation with the specular reflection boundary condition to the incompressible Euler equations in a channel is *** on the multi-scaled Hilbert expansion,the equations with boundary conditions and compatibility conditions for interior solutions,and viscous and Knudsen boundary layers are derived under different scaling,***,some uniform estimates for the interior solutions,and viscous and Knudsen boundary layers are *** the help of the L^(2)-L^(∞) framework and the uniform estimates obtained above,the solutions to the Boltzmann equation are constructed by the truncated Hilbert expansion with multiscales,and hence the hydrodynamic limit in the incompressible Euler level is justified.

关键词： Boltzmann equation incompressible Euler equations hydrodynamic limit Hilbert expansion specular reflection boundary condition viscous boundary layer Knudsen boundary layer

Dative B–N bonds weaven toward two-dimensional purely organic materials for single crystals

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第1期68卷 12-14页

作者： Wei-Lei Zhou Siwei wang yong Chen College of Chemistry and Materials Science Inner Mongolia Key Laboratory of Chemistry for Nature Products and Synthesis for Functional MoleculesInnovation Team of Optical Functional Molecular DevicesInner Mongolia Minzu UniversityTongliao 028000China College of Chemistry Nankai UniversityTianjin 300071China

Molecular topology is one of the important topics to study and understand the relationship between molecular structure and properties^([1]).Particularly,two-dimensional(2D)materials with extremely high surface area and ultra-thin morphology have attracted considerable attention due to their unexpected properties in materials and chemistry^([2,3]).

关键词： bonds purely dimensional