检索结果-南通市图书馆

Catalytic Asymmetric Diastereodivergent Synthesis of 2-Alkenylindoles Bearing both Axial and Central Chirality

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Precision Chemistry 2024年第5期2卷 208-220页

作者： Shuang Yang jia-Bo huang Da-hua Wang Ning-Yi Wang yu-yu Chen Xin-Yan Ke Hao Chen Shao-Fei Ni yu-Chen Zhang Feng Shi Research Center of Chiral Functional Heterocycles School of Chemistry and Materials ScienceJiangsu Normal UniversityXuzhou 221116China Department of Chemistry Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong ProvinceShantou UniversityShantou 515063China Department of Otolaryngology Xuzhou First People’s HospitalAffiliated Xuzhou Municipal Hospital of Xuzhou Medical UniversityXuzhou 221002China School of Petrochemical Engineering Changzhou UniversityChangzhou 213164China

The catalytic asymmetric diastereodivergent synthesis of axially chiral 2-alkenylindoles was established via chiral phosphoric acid-catalyzed addition reactions of C3-unsubstituted 2-alkenylindoles with o-hydroxybenzyl alcohols under different reaction *** this strategy,two series of 2-alkenylindoles bearing both axial and central chirality were synthesized in a diastereodivergent fashion with moderate to high yields and good stereoselectivities(up to 99%yield,95:5 er,>95:5 dr).Moreover,theoretical calculations were performed on the key transition states leading to different stereoisomers,which provided an in-depth understanding of the origin of the observed stereoselectivity and diastereodivergence of the products under different reaction *** importantly,these 2-alkenylindoles were utilized in asymmetric catalysis as chiral organocatalysts and in medicinal chemistry for evaluation of their cytotoxicity,which demonstrated their potential *** study has not only established the catalytic atroposelective synthesis of axially chiral 2-alkenylindoles,but also provided an efficient strategy for catalytic asymmetric diastereodivergent construction of indole-based scaffolds bearing both axial and central chirality.

关键词： 2-Alkenylindole Axial chirality Central chirality Diastereodivergent synthesis Chiral phosphoric acid

The pseudospectrum and spectrum (in)stability of quantum corrected Schwarzschild black hole

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(Physics,Mechanics & Astronomy) 2024年第10期Mechanics & Astronomy) .卷 59-79页

作者： Li-Ming Cao jia-Ning Chen Liang-Bi Wu Libo Xie yu-Sen Zhou Peng huanwu Center for Fundamental Theory Interdisciplinary Center for Theoretical Study and Department of Modern Physics University of Science and Technology of China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCAS

In this study, we investigate the pseudospectrum and spectrum(in)stability of quantum corrected Schwarzschild black ***, we use the hyperboloidal framework to cast the quasinormal mode(QNM) problem into an eigenvalue problem associated with a non-selfadjoint operator, and then the spectrum and pseudospectrum are depicted. Besides, the invariant subspace method is exploited to improve the computational efficiency for pseudospectrum. The investigation into the spectrum(in)stability entails two main aspects. On the one hand, we calculate the spectra of the quantum corrected black hole, then by the means of the migration ratio, the impact of the quantum correction effect on the Schwarzschild black hole has been *** results indicate that the so-called “migration ratio instability” will occur for small black holes with small angular momentum number l. In the eikonal limit, the migration ratios remain the same for each overtone. On the other hand, we study the spectrum(in)stability of the quantum corrected black hole by directly adding some particular perturbations into the effective potential,where perturbations are located at the event horizon and null infinity, respectively. There are two interesting observations under the same perturbation energy norm. First, perturbations at infinity are more capable of generating spectrum instability than those at the event horizon. Second, we find that the peak distribution can lead to the instability of QNM spectrum more efficiently than the average distribution.

关键词： quasinormal modes pseudospectrum hyperboloidal coordinate

同方期刊数据库

Nomogram predicting the cardiovascular disease mortality for older patients with colorectal cancer:A real-world population-based study

在线全文

学校读者我要写书评

暂无评论

World Journal of Cardiology 2024年第8期16卷 458-468页

作者： jia-yu Tan Shuo-Hao Shen Department of Medical Ultrasound The First Affiliated Hospital of Shandong First Medical University&Shandong Provincial Qianfoshan HospitalJinan 250000Shandong ProvinceChina Department of General Surgery Qilu Hospital of Shandong UniversityJinan 250000Shandong ProvinceChina

BACKGROUND Cardio-oncology has received increasing attention especially among older patients with colorectal cancer(CRC).Cardiovascular disease(CVD)-specific mortality is the second-most frequent cause of *** risk factors for CVDspecific mortality among older patients with CRC are still poorly *** To identify the prognostic factors and construct a nomogram-based model to predict the CVD-specific mortality among older patients with *** The data on older patients diagnosed with CRC were retrieved from The Surveillance,Epidemiology,and End Results database from 2004 to *** prognostic factors and a nomogram-based model predicting the CVD-specific mortality were assessed using least absolute shrinkage and selection operator and Cox *** A total of 141251 eligible patients with CRC were enrolled,of which 41459 patients died of CRC and 12651 patients died of *** age at diagnosis,sex,marital status,year of diagnosis,surgery,and chemotherapy were independent prognostic factors associated with CVD-specific mortality among older patients with *** used these variables to develop a model to predict CVD-specific *** calibration curves for CVD-specific mortality probabilities showed that the model was in good agreement with actual *** C-index value of the model in the training cohort and testing cohort for predicting CVD-specific mortality was 0.728 and 0.734,*** The proposed nomogram-based model for CVD-specific mortality can be used for accurate prognostic prediction among older patients with *** model is a potentially useful tool for clinicians to identify high-risk patients and develop personalized treatment plans.

关键词： Older patients Colorectal cancer Cardio-oncology Nomogram Outcome

Spherical Polyelectrolyte Brush Nanoreactor:Preparation of Hollow TiO_(2) Nanospheres and Characterization by Small Angle X-Ray Scattering

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 Polymer Science 2024年第9期42卷 1393-1400,I0009页

作者： yu-hua Zhang Zi-yu Zhang Xin Liu En-Guang Ma jiang-Tao Guo Li Li Xu-Hong Guo State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai200237China Shandong Provincial Key Laboratory of Monocrystalline Silicon Semiconductor Materials and Technology College of Chemistry and Chemical EngineeringDezhou UniversityDezhou253023China Institute of Bast Fiber Crops&Center of Southern Economic Crops Chinese Academy of Agricultural SciencesChangsha410205China

Titanium dioxide(TiO_(2))hollow nanoparticles present significant potential for photocatalytic applications while their straightforward preparation with precise structure control is still *** work reports the approach to preparing tunable hollow TiO_(2) nanospheres by utilization of spherical polyelectrolyte brushes(SPB)as nanoreactors and *** the preparation,the evolution of the structure was characterized by small angle X-ray scattering(SAXS),and in combination with dynamic light scattering and transmission electron *** formation of TiO_(2) shell within the brush(SPB@TiO_(2))is confirmed by the significant increase of the electron density,and its internal structure has been analyzed by fitting SAXS data,which can be influenced by Titanium precursors and ammonia *** calcining SPB@TiO_(2) in a muffle furnace,hollow TiO_(2) nanospheres are produced,and their transition to the anatase crystal form is triggered,as confirmed by X-ray diffraction *** the advantages of their hollow structure,these TiO_(2) nanospheres exhibit exceptional catalytic degradation efficiency of methylene blue(MB),tetracycline(TC),and 2,4-dichlorophenoxyacetic acid(2,4-D),and also demonstrate excellent recyclability.

关键词： Spherical polyelectrolyte brush Nanoreactor Hollow titanium dioxide X-ray scattering

维普期刊数据库

LAMDA-SSL:a comprehensive semi-supervised learning toolkit

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第1期67卷 306-307页

作者： Lin-Han jia Lan-Zhe GUO Zhi ZHOU yu-Feng LI National Key Laboratory for Novel Software Technology Nanjing University

Machine learning, particularly deep learning, has achieved remarkable success across a wide range of tasks. However,most of these tasks demand a substantial amount of labeled training data, which can be challenging to obtain in many real-world applications due to difficulties, costs, or time constraints associated with labeling. In this context,semi-supervised learning (SSL) has emerged as a promising paradigm to alleviate the dependency on large labeled datasets by harnessing the power of unlabeled data [1–3].

关键词：

Carbon dots-derived three-dimensional-ordered macroporous host with high penetrability and catalytic activity for LSBs under lean electrolyte

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第6期43卷 2560-2573页

作者： jiao-Zi Duan hua-yu Pei Quan Yang Xue Li Xin Ba Xue Yong Jun-Ling Guo Si-yu Lu Green Catalysis Center College of ChemistryZhengzhou UniversityZhengzhou 450001China Country State Center for International Cooperation On Designer Low-Carbon&Environmental Materials School of Materials Science and EngineeringZhengzhou UniversityZhengzhou 450001China Hubei Institute of Quality Supervision Inspection Wuhan 430061China Department of Chemistry University of SheffieldSheffeld S37HFUK

The practical energy density of lithium-sulfur batteries(LSBs)is seriously limited by the high electrolyte-to-sulfur ratios(E/S).The E/S can be reduced by employing hosts with easy-to-infiltrate structure that ensures the uniform distribution of a lean electrolyte and high catalytic activity that can suppress"shuttle effect"via accelerating the slow conversion of soluble poly sulfides to insoluble *** the easy-to-infiltrate structures,the three-dimensional-ordered macroporous(3DOM)structure is easier to scale preparation and more suitable for the existing industrial ***,it is difficult to obtain the 3DOM with(1)high penetrability due to the high viscosity of frequently-used organic polymer precursors and(2)high catalytic activity due to the low confinement effect,meaning that uniformly dispersed small-sized catalytic materials are difficult to load on ***,using carbon dots(CDs)with both organic and inorganic properties as a precursor and aggregation limiting agent,a 3DOM host with high penetrability and homodispersed Ni particles of small sizes(Ni-CDs-3DOM)was *** this host:(1)CDs precursor with suitable viscosity can improve the penetrability.(2)CDs can effectively inhibit the agglomeration of Ni particles.(3)Uniformly dispersed small-size Ni particles offer high-efficiency catalytic activity toward sulfur ***,the Ni-CDs-3DOM/sulfur cathode exhibits high sulfur utilization and stable cycling performance even under high sulfur loading(5.5 mg·cm^(-2))and low E/S(6.5μl·mg^(-1)).This work indicates the usefulness of CDs in constructing hosts for LSBs with high energy density.

关键词： Lithium-sulfur batteries Carbon dots Catalytic action Easy-to-infiltrate structure Lean electrolyte

维普期刊数据库

N6-methyladenosine methylation regulates the tumor microenvironment of Epstein-Barr virus-associated gastric cancer

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal Oncology 2024年第6期16卷 2555-2570页

作者： yu Zhang Fang Zhou Ming-yu Zhang Li-Na Feng jia-Lun Guan Ruo-Nan Dong yu-Jie huang Su-Hong Xia jia-Zhi Liao Kai Zhao Department of Gastroenterology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030Hubei ProvinceChina Institute of Liver and Gastrointestinal Diseases Hubei Key Laboratory of Hepato-Pancreato-Biliary DiseasesTongji Hospital of Tongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030Hubei ProvinceChina Department of Pharmacy Wuhan Fourth HospitalWuhan 430030Hubei ProvinceChina

BACKGROUND N6-methyladenosine(m6A)methylation modification exists in Epstein-Barr virus(EBV)primary infection,latency,and lytic *** also modifies EBV latent genes and lytic ***-associated gastric cancer(EBVaGC)is a distinctive molecular subtype of *** hypothesized EBV and m6A methylation regulators interact with each other in EBVaGC to differentiate it from other types of *** To investigate the mechanisms of m6A methylation regulators in EBVaGC to determine the differentiating factors from other types of *** First,The Cancer Gene Atlas and Gene Expression Omnibus databases were used to analyze the expression pattern of m6A methylation regulators between EBVaGC and EBV-negative GC(EBVnGC).Second,we identified Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)functional enrichment of m6A-related differentially expressed *** quantified the relative abundance of immune cells and inflammatory factors in the tumor microenvironment(TME).Finally,cell counting kit-8 cell proliferation test,transwell test,and flow cytometry were used to verify the effect of insulin-like growth factor binding protein 1(IGFBP1)in EBVaGC cell *** m6A methylation regulators were involved in the occurrence and development of *** with EBVnGC,the expression levels of m6A methylation regulators Wilms tumor 1-associated protein,RNA binding motif protein 15B,CBL proto-oncogene like 1,leucine rich pentatricopeptide repeat containing,heterogeneous nuclear ribonucleoprotein A2B1,IGFBP1,and insulin-like growth factor 2 binding protein 1 were significantly downregulated in EBVaGC(P<0.05).The overall survival rate of EBVaGC patients with a lower expression level of IGFBP1 was significantly higher(P=0.046).GO and KEGG functional enrichment analyses showed that the immunity pathways were significantly activated and rich in immune cell infiltration in *** with EBVnGC,the infiltration of activated CD4+T cells,activated CD8+T cel

关键词： N6-methyladenosine methylation Tumor microenvironment Epstein-Barr virus Gastric cancer Insulin-like growth factor binding protein 1

Study on Catalytic Behavior of Iron-based Catalyst with IITP as Electron Donor in the Polymerization of Butadiene

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 Polymer Science 2024年第5期42卷 612-619,I0007页

作者： Shi-Liang Xu Ying-Nan Zhao Yao yu Qi Yang Li-hua Na Heng Liu Chun-yu Zhang Xue-Quan Zhang Key Laboratory of Advanced Rubber Material Ministry of EducationSchool of Polymer Science and EngineeringQingdao University of Science&TechnologyQingdao266042China Shandong Provincial College Laboratory of Rubber Material and Engineering School of Polymer Science and EngineeringQingdao University of Science&TechnologyQingdao266042China Key Lab of Rubber-Plastics Ministry of Education/Shandong Provincial Key Lab of Rubber-plasticsSchool of Polymer Science and EngineeringQingdao University of Science&TechnologyQingdao266042China

In this study,a novel iron-based catalyst system,Fe(acac)3/(isocyanoimino)triptenylphosphorane(IITP)/AlR3,was employed for the synthesis of syndiotactic 1,2-polybutadiene in *** catalyst system exhibits remarkably high catalytic activity,achieving a polymerization activity of 762 kgpolymer·molcatalyst^(-1)·h^(-1)at 50℃with a[BD]/[Fe]molar ratio of ***,living polymerization characteristic were observed during the investigation of the polymerization kinetics of 1,3-butadiene *** characteristics were well demonstrated by a narrow molecular weight distribution(PDI≈2.0)of the resulting polybutadiene and a linear relationship between-ln(1-c)and polymerization time as well as number average molecular weight and polymer *** resultant polymer showed a 1,2-selectivity of approximately 76%and stereoregularity ranging from 62%to 73%(rrrr).Additionally,through kinetic studies on polymerization reaction,an apparent activation energy Ea value of this catalytic system was calculated to be 84.98 kJ·mol^(-1),which suggests that high polymerization temperature favors efficient polymerization.

关键词： Iron catalyst Syndiotactic 1,2-polybutadiene Elastomers Donor Selectivity

维普期刊数据库

Rate transient analysis methods for water-producing gas wells in tight reservoirs with mobile water

在线全文

学校读者我要写书评

暂无评论

Energy Geoscience 2024年第1期5卷 311-320页

作者： Qingyan yu Ying jia Pengcheng Liu Xiangyang Hu Shengye Hao Research Institute of Petroleum Exploration and Development of SINOPEC Beijing100083China School of Energy Resources China University of GeosciencesBeijing100083China

Tight gas reservoirs with mobile water exhibit multi-phase flow and high stress *** analyzing the reservoir and well parameters using conventional single-phase rate transient analysis methods proves *** study introduces novel rate transient analysis methods incorporating evaluation processes based on the conventional flowing material balance method and the Blasingame type-curve method to examine fractured gas wells producing *** positing a gas-water two-phase equivalent homogenous phase that considers characteristics of mobile water,gas,and high stress sensitivity,the conventional single-phase rate transient analysis methods can be applied by integrating the phase's characteristics and defining the phase's normalized parameters and material balance *** rate transient analysis methods based on the equivalent homogenous phase can be used to quantitatively assess the parameters of wells and gas reservoirs,such as original gas-in-place,fracture half-length,reservoir permeability,and well drainage *** facilitates the analysis of production dynamics of fractured wells and well-controlled areas,subsequently aiding in locating residual gas and guiding the configuration of well *** specific evaluation processes are ***,a numerical simulation mechanism model was constructed to verify the reliability of the developed *** methods introduced have been successfully implemented in field water-producing gas wells within tight gas reservoirs containing mobile water.

关键词： Gas reservoirs with mobile water Gas-water two phase flow High stress sensitivity Equivalent homogenous phase Rate transient analysis