检索结果-南通市图书馆

Nickel-catalyzed carbonylative four-component 1,4-dicarbofunctionalization of 1,3-enynes

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 Chemistry 2024年第6期67卷 2029-2038页

作者： Yan Zhao Qi-chao Shan Hong Xin Pin Gao Xu yang Xin-Hua Duan li-Na Guo Department of Chemistry School of ChemistryXi’an Key Laboratory of Sustainable Energy Material Chemistry and Engineering Research Center of Energy StorageMaterials and DevicesMinistry of EducationXi’an Jiaotong UniversityXi’an710049China School of Electrical Engineering Xi’an Jiaotong UniversityXi’an710049China

An efficient Ni-catalyzed four-component 1,4-carbocarbonylation of 1,3-enynes with activated alkyl halides and arylboronic acids under atmospheric pressure of CO is *** tuning the electronic and steric effects of alkyl radicals,both electronrich and electron-deficient 1,3-enynes were compatible with this *** protocol features mild conditions,broad substrate scope,excellent functional group compatibility and facile gram-scale synthesis,providing a practical approach to the quaternary carbon center-containing allenyl *** study revealed that the acyl-NiIIspecies plays an important role in both the coupling and the alkyl radical generation processes.

关键词： Ni catalysis four-component 1 4-carbocarbonylation 1 3-enynes

Uncovering the largest negative carbon isotope excursion in Earth history

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第3期67卷 885-889页

作者： chao li Haiyang WANG State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Chengdu University of TechnologyChengdu 610059China Institute of Sedimentary Geology Chengdu University of TechnologyChengdu 610059China Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural Resources Chengdu University of TechnologyChengdu 610059China International Center for Sedimentary Geochemistry and Biogeochemistry Research Chengdu University of TechnologyChengdu 610059China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430074China

The carbon cycle plays a pivotal role in regulating Earth’s surface environment through atmospheric-oceanic acid-base and redox processes, functioning as the engine driving the evolution of our planet’s surface. A deep understanding of the carbon cycle’s evolution is thus essential for our understanding of the evolution of our planet’s habitability.

关键词： carbon planet evolution

Effect of micro-Al_(2)O_(3) powders on oxidation and corrosion behaviors of low-carbon MgO-C refractories

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第6期31卷 1522-1534页

作者： yang Chen Zeng-yi li Hao-bo Tan Yu-ran Fu Jun Ding Cheng-ji Deng chao Yu School of Materials Science and Engineering Hunan Institute of TechnologyHengyang 421002HunanChina The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

To solve the problem of poor high-temperature service performance caused by low carbonization of MgO-C refractories,low-carbon MgO–C refractories with excellent thermal shock,oxidation and corrosion resistances were successfully designed by using SiC whiskers as reinforcing phases and introducing micro-Al_(2)O_(3) powders as *** results indicated that the addition of micro-Al_(2)O_(3) powders optimized the internal structure of the material,like the columnar β-Si_(3)N_(4) with a stepped distribution and the mosaic structure formed between granular and flaky Mg_(2)SiO_(4),which synergistically strengthened and toughened the material and gave the material excellent mechanical properties and thermal shock ***,the cold modulus of rupture and cold crushing strength after thermal shock were increased by 4.1 and 20.3 MPa,***,the addition of micro-Al_(2)O_(3) powders promoted the formation of fine particles of Mg_(2)SiO_(4),MgAl_(2)O_(4) and MgO,as well as a dense protective layer of Mg_(2)SiO_(4) in the material under high-temperature ***,spinel and high-temperature solid solution were formed in the corrosion *** oxidation and corrosion resistances were greatly improved by 41%and 15%,respectively.

关键词： Low-carbon MgO-C refractory Oxidation resistance Corrosion resistance Thermal shock resistance Micro-Al_(2)O_(3)powder

Alignment efficient image-sentence retrieval considering transferable cross-modal representation learning

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2024年第1期18卷 77-91页

作者： yang yang Jinyi GUO Guangyu li Lanyu li Wenjie li Jian yang School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China Department of Computing Hong Kong Polytechnic UniversityHong Kong 100872China State Key Lab.for Novel Software Technology Nanjing UniversityNanjing 210094China 14th Research Institute of China Electronics Technology Group Corporation Nanjing 210094China guangyu.li2017@***

Traditional image-sentence cross-modal retrieval methods usually aim to learn consistent representations of heterogeneous modalities,thereby to search similar instances in one modality according to the query from another modality in *** basic assumption behind these methods is that parallel multi-modal data(i.e.,different modalities of the same example are aligned)can be obtained in *** other words,the image-sentence cross-modal retrieval task is a supervised task with the alignments as ***,in many real-world applications,it is difficult to realign a large amount of parallel data for new scenarios due to the substantial labor costs,leading the non-parallel multi-modal data and existing methods cannot be used *** the other hand,there actually exists auxiliary parallel multi-modal data with similar semantics,which can assist the non-parallel data to learn the consistent ***,in this paper,we aim at“Alignment Efficient Image-Sentence Retrieval”(AEIR),which recurs to the auxiliary parallel image-sentence data as the source domain data,and takes the non-parallel data as the target domain *** single-modal transfer learning,AEIR learns consistent image-sentence cross-modal representations of target domain by transferring the alignments of existing parallel ***,AEIR learns the image-sentence consistent representations in source domain with parallel data,while transferring the alignment knowledge across domains by jointly optimizing a novel designed cross-domain cross-modal metric learning based constraint with intra-modal domain adversarial ***,we can effectively learn the consistent representations for target domain considering both the structure and semantic ***,extensive experiments on different transfer scenarios validate that AEIR can achieve better retrieval results comparing with the baselines.

关键词： image-sentence retrieval transfer learning semantic transfer structure transfer

Characteristics of Bi-2223 HTS Tapes Under Short-Circuit Current Impacts in Hybrid Energy Transmission Pipelines

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2024年第2期10卷 736-745页

作者： Yuguang Sun chao Yin Weizhen li Xinyang li Xiaohua Jiang Department of Electric Engineering Tsinghua UniversityBeijing 100084China

A hybrid energy transmission pipeline is proposed with the aim of long-distance cooperative transmission of electricity and chemical fuels, which is composed of an inner high-temperature superconducting (HTS) power cable and outer liquefied natural gas (LNG) pipeline. The flowing LNG could maintain the operating temperature of the inner HTS power cable within the range of 85 K-90 K, thus the Bi-2223 superconductors in the HTS power cable produce little Joule loss with the transmission current below the critical current. Owing to the advantages of high power density, low transmission losses and economical manufacturing costs, the hybrid energy transmission pipeline is expected to be widely utilized in the near future. In order to ensure the safety of the HTS power cable and explosive LNG in case of short-circuit faults, this paper tests and analyzes the characteristics of Bi-2223 HTS tapes of the Type HT-CA, Type HT-SS and Type H models under short-circuit current impacts at the LNG cooling temperature (85 K-90 K). An experimental platform is designed and established for the ampacity tests of HTS tapes above LN2 cooling temperature (77 K). The AC over-current impact tests at 85 K-90 K are carried out on each sample of Bi-2223 tapes respectively, and the experimental results are analyzed and compared to evaluate their performances under different operating conditions. The results indicate that the Type HT-CA tape can withstand 50 Hz short-circuit current impact with the amplitude of 1108 A (10 times of critical current Ic ) for 100 ms at 90 K, and its resistance is the smallest of the three tested samples under similar current impacts. Therefore, the Type HT-CA Bi-2223 tape is the optimal superconductor of the HTS power cable in the hybrid energy transmission pipeline.

关键词： Bi-2223 high-temperature superconducting(HTS)tape critical current hybrid energy transmission pipeline liquefied natural gas(LNG)cooling temperature short-circuit current impact characteristics

Current status and future development of aortic stent fenestration-assisted techniques

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 Medical Journal 2024年第6期137卷 752-754页

作者： Gezheng Chen Xiaoyu Qi Wanying Wu Dongsheng Fu li Qin chao yang Department of Vascular Surgery Union HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanHubei 430022China Department of Vascular Surgery Nanjing Drum Tower HospitalAffiliate Hospital of Nanjing University Medical SchoolNanjingJiangsu 210008China

To the Editor:In 1996,Parodi et al^([1])introduced the technique of fenestrated endovascular aneurysm repair(f-EVAR)for treatment of pararenal abdominal aortic *** use physician modified stent grafts(PMSGs)for fenestration,which allows for stent grafts to gain sufficient proximal sealing zones and maintain the blood perfusion of visceral arteries.^([2])Stent grafts used in the f-EVAR technique developed from PMSGs to Company Modified Devices(CMDs)and off-the-shelf devices.^([3])To improve the precision of PMSGs and shorten the time of stent graft modification,various techniques that assist in the process of fenestration have been researched and developed,including 3-dimensional(3D)printing technique,the Mixed Reality(MR)technique,and the 3D parametric surface planar topological guide *** article describes the current status and future development of these techniques.

关键词： aortic perfusion arteries

A Review on Flow Boiling of the Fluid with Lower Boiling Point in Micro-Channels

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第1期33卷 1-17页

作者： ZHANG Zhiqiang JIA li DANG chao Beijing Key Laboratory of Flow and Heat Transfer of Phase Changing in Micro and Small Scale School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

With the advancement of micro machining technology,the high-heat-flux removal from miniature electronic devices and components has become an attractive *** boiling in micro-channels is an optimal form of heat transfer and has been widely employed in high-heat-flux cooling *** comprehensively-reviewed article focused on the available recent literatures of experimental investigation regarding the flow boiling heat transfer and unstable behaviors of the fluid with lower boiling point in *** thermal-fluid characteristics and potential heat transfer mechanisms of low-boiling-point fluids flow boiling in different narrow passages were summarized and *** literatures regarding the pressure drop and occurrence of the unstable phenomena existing in two-phase flow boiling process were also *** emphasis was given to the heat transfer enhancement methods as well as instability elimination,and various methods such as modification of surface and channel flow geometries were *** future researches in the field of micro-scale flow boiling were suggested.

关键词： flow boiling lower boiling point fluids mini/micro-channels instabilities enhancement suppression

Polymetamorphism of the ultrahigh-temperature granulites in the Rauer Group,East Antarctica:new evidence from zircon SHRIMP U-Pb ages

在线全文

学校读者我要写书评

暂无评论

Advances in Polar Science 2024年第2期35卷 192-205页

作者： TONG Laixi liU Zhao li chao LU Junsheng yang Wenqiang WANG Yanbin State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi’an 710069China Institute of Geology Chinese Academy of Geological SciencesBejing 100037China

The Rauer Group is located on the eastern margin of the early Paleozoic Prydz Belt in East Antarctica,and the typical ultrahigh-temperature(UHT,>900℃)granulites outcrop on Mather ***,the timing of UHT metamorphism and P–T path of the UHT granulites have long been debated,which is critical to understanding the tectonic nature and evolution history of the Prydz ***,both a sapphirine-bearing UHT metapelitic granulite and a garnet-bearing UHT mafic granulite are selected for zircon SHRIMP U-Pb age *** results show that metamorphic zircon mantles yield weighted mean^(206)Pb/^(238)U ages of 918±29 Ma and 901±29 Ma for the metapelitic and mafic granulites,respectively,while zircon rims and newly grown zircons yield weighted mean^(206)Pb/^(238)U ages of 523±9 Ma and 532±11 Ma,*** new zircon age data suggest that the UHT granulites may have experienced polymetamorphism,in which pre-peak prograde stage occurred in the early Neoproterozoic Grenvillian orogenesis(1000–900 Ma),whereas the UHT metamorphism occurred in the late Neoproterozoic to early Paleozoic Pan-African orogenesis(580–460 Ma).This implies that P–T path of the UHT granulites should consist of two separate high-grade metamorphic events including the Grenvillian and Pan-African events,which are supposed to be related to assembly of Rodinia and Gondwana supercontinents respectively,and hence the overprinting UHT metamorphic event may actually reflect an important intracontinental reworking.

关键词： ultrahigh-temperature granulites zircon SHRIMP U-Pb ages polymetamorphism Rauer Group East Antarctica

Targeting ASIC1a Promotes Neural Progenitor Cell Migration and Neurogenesis in Ischemic Stroke

在线全文

学校读者我要写书评

暂无评论

Research 2024年第1期2023卷 369-387页

作者： Hongfei Ge Tengyuan Zhou chao Zhang Yupeng Cun Weixiang Chen yang yang Qian Zhang Huanhuan li Jun Zhong Xuyang Zhang Hua Feng Rong Hu Department of Neurosurgery and Key Laboratory of Neurotrauma Southwest HospitalThird Military Medical University(Army Medical University)400038 ChongqingChina Medical Research Center Southwest HospitalThird Military Medical University(Army Medical University)400038 ChongqingChina Pediatric Research Institute Ministry of Education Key Laboratory of Child Development and DisordersNational Clinical Research Center for Child Health and DisordersChildren’s Hospital of Chongqing Medical University400014 ChongqingChina

Cell replacement therapy using neural progenitor cells(NPCs)has been shown to be an effective treatment for ischemic ***,the therapeutic effect is unsatisfactory due to the imbalanced homeostasis of the local microenvironment after *** acidosis is a common imbalanced homeostasis in the penumbra and could activate acid-sensing ion channels 1a(ASIC1a),a subunit of proton-gated cation channels following ischemic ***,the role of ASIC1a in NPCs post-ischemia remains ***,our results indicated that ASIC1a was expressed in NPCs with channel functionality,which could be activated by extracellular *** evidence revealed that ASIC1a activation inhibited NPC migration and neurogenesis through RhoA signaling-mediated reorganization of filopodia formation,which could be primarily reversed by pharmacological or genetic disruption of *** vivo data showed that the knockout of the ASIC1a gene facilitated NPC migration and neurogenesis in the penumbra to improve behavioral recovery after stroke.

关键词： ASIC1a homeostasis inhibited