检索结果-南通市图书馆

Chinese Chemical Letters 2024年第1期35卷 528-532页

作者： haiming wu Gaya NAndrew Rajini Anumula Zhixun Luo Beijing National Laboratory for Molecular Sciences(BNLMS) State Key Laboratory for Structural Chemistry of Unstable and Stable SpeciesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemistry University of Chinese Academy of SciencesBeijing 100049China

We have synthesized two copper nanoclusters(NCs)with a protection of the same ligand diphenylphosphino-2-pyridine(C_(17)H_(14)NP,dppy for short),formulated as Cu_(4)(dppy)_(4)Cl_(2)and Cu21(dppy)10,*** former one bears a distorted tetrahedron Cu4 core with its six edges fully protected by chlorine and dppy ligands,while the latter presents a symmetric Cu_(21)core on which ten dppy molecules function as monolayer protection via well-organized monodentate or bidentate ***,the Cu_(4)(dppy)_(4)Cl_(2)cluster exhibits a strong yellow emission at∼577 nm,while Cu_(21)(dppy)_(10)displays dual emissions in purple(∼368 nm)and green(∼516 nm)regions *** combination with TD-DFT calculations,we demonstrate the origin of altered emissions and unique stability of the two copper nanoclusters pertaining to the ligand coordination and metallic superatomic states.

关键词： Copper nanocluster Yellow emission Dual emission Superatomic states Ligand dppy

银离子促进神经传导素分子内氢原子转移和C-C键解离反应

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2024年第2期37卷 341-350,I0104页

作者：易秋浩吴海铭骆智训中国科学院化学研究所分子动态与稳态结构国家重点实验室北京100190 中国科学院大学化学科学学院北京100049

色氨酸、酪氨酸和组氨酸是三种基本的氨基酸,也是大脑营养代谢中重要神经传导素的前驱体。本文利用自制的反射式时间飞行质谱仪结合磁控溅射束源和下联管式反应器,在气相条件下研究了这三个氨基酸与银离子的相互作用,揭示了这些有机小... 详细信息

色氨酸、酪氨酸和组氨酸是三种基本的氨基酸,也是大脑营养代谢中重要神经传导素的前驱体。本文利用自制的反射式时间飞行质谱仪结合磁控溅射束源和下联管式反应器,在气相条件下研究了这三个氨基酸与银离子的相互作用,揭示了这些有机小分子在银离子的存在下容易解离并产生碎片和产物重组的现象,并利用密度泛函理论计算,阐明了其中的反应机制。研究发现,银离子能促进氢原子转移,进而影响竞争性的C_(α)-C_(β)和C_(β)-C_(γ)键解离反应。本研究丰富了对这类神经传导素分子基本规律与性质的精准认识,从而有助于深入理解生物体内类似生理过程的化学机制。

关键词：神经传导素色氨酸金属-有机相互作用 C-C键解离质谱

科技金融赋能农业生产效率提升--来自科技金融试点政策的经验证据

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国农村经济 2024年第5期 81-105页

作者：郭进杨琦吴海明南京师范大学商学院中国人民大学农业与农村发展学院江苏银行股份有限公司丹阳苏银村镇银行

中国农业发展既存在科技投入不足的短板,也面临金融支持不充分的约束。在这一背景下,促进科技和金融在农业生产活动中的结合,对于中国农业现代化建设至关重要。本文将“促进科技和金融结合试点”政策视为一项准自然实验,考察科技金融赋... 详细信息

中国农业发展既存在科技投入不足的短板,也面临金融支持不充分的约束。在这一背景下,促进科技和金融在农业生产活动中的结合,对于中国农业现代化建设至关重要。本文将“促进科技和金融结合试点”政策视为一项准自然实验,考察科技金融赋能农业生产效率提升的政策效果和作用渠道。研究发现:相对于非试点地区,科技金融试点政策实施显著推动了试点地区农业生产效率的提升,且在政策实施后的较长时期内,这一效应持续存在并不断放大。异质性分析结果发现:科技金融试点政策实施对农业生产效率的提升作用,在科技创新能力较弱、金融深化程度较低和农业生产规模较大的试点地区表现得更强,且受政策实施强度和地理区位的影响,对中心城市农业生产效率提升的“锦上添花”效应小于对非中心城市的“雪中送炭”效应。机制分析结果显示:科技金融试点政策实施通过推进农业机械化进程、提升农民人力资本水平和促进农村现代产业发展等渠道,对“三农”工作产生积极影响,构筑起政策多点生效、持续发力的长效机制,最终促进农业生产效率的提升。

关键词：科技金融农业生产效率多时点双重差分模型农业现代化

Chlorine-passivated superatom Al37clusters for nonlinear optics

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2018年第12期61卷 1619-1623页

作者： haiming wu Zhixun Luo State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing J 00049 China

Utilizing a facile top-down synthetic procedure, here we report the finding of a chlorine-passivated Al_(37) superatom cluster. It is demonstrated that the presence of electrophilic groups, severing as protecting ligands, alters the valence electron count of the metallic core and stabilize the as-prepared aluminum clusters especially when even-numbered chlorine atoms are located at equilibrium positions. Following the discussion regarding their reasonable stabilities, we illustrate the feasible reaction pathways in forming such chlorine-passivated Al_(37) superatom clusters which bear delocalized superatomic orbitals with five valence 3P^5 electrons shifting to the chlorine ligands indicative of a closed electron shell 2F^(14) of the metal core. The successful synthesis of such chlorine-protected aluminum clusters evidences the compatibility of general theory of cluster chemistry in both gas phase and wet chemistry. Such simple-ligand-protected aluminum clusters exhibit reverse-saturated-absorption(RSA) nonlinear optical property pertaining to electronic transitions within the discrete energy states of cluster materials.

关键词： chlorine-passivated superatom Al37cluster nonlinear optics laser ablation in liquid

Increased Uterine NK-Derived IFN-γand TNF-αin C57BL/6J Mice during Early Gestation

在线全文

学校读者我要写书评

暂无评论

Cellular & Molecular Immunology 2006年第2期3卷 131-137页

作者： Xiaoyan wu haiming Wei Jianhong Zhang Zhigang Tian Hefei National Laboratory for Physical Sciences at Microscale School of Life Sciences University of Science and Technology of China Hefei 230027 Anhui China

Natural killer （NK） cells are bone marrow-derived lymphocytes. They produce cytokines that regulate the development of acquired immunity. In view of their accumulation at the maternal-fetal interface, uterine natural killer （uNK） cells are also thought to play essential roles during pregnancy. Our results compared the differences of cytokine secretion profile by NK cells in uterine endometrium, liver, spleen and peripheral blood, and focused on the cytokines secretion by uNK cells. It was demonstrated that the expression of IFN-γ and TNF-α in uterine endometrium of pregnant mice are lower than those in liver, but they increase significantly during pregnancy. Our study showed that the number of uNK cells was increased significantly during pregnancy. They produced more IFN-γ and TNF-α than other organ-derived NK cells, and they also secreted minor amount of IL-4 and IL-5. The results indicated that the IFN-γ and TNF-α produced by uNK cells ensured a successful pregnancy progress.

关键词： uNK IFN-γ TNF-α IL-4 IL-5 pregnancy

Ligand accommodation causes altered reactivity of silver clusters with iodomethane:superatomic stability of Ag_(9)I_(2)^(+)in mimicking XeF_(2)

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2022年第8期65卷 1594-1600页

作者： haiming wu Mengzhou Yang Benben Huang Wen Gan Zhixun Luo Beijing National Laboratory for Molecular Sciences(BNLMS) State Key Laboratory for Structural Chemistry of Unstable and Stable SpeciesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Exploring metal cluster reactivity with alkyl halides enables to understand the related chemical mechanism of metal surfaces in terms of active *** we report a study of Ag_(n)^(+)(n=1-27)clusters reacting with iodomethane by a flow tube apparatus in tandem with a customized triple quadrupole mass *** even/odd alternation of the Ag_(n)^(+)is observed in their reactions with CH_(3)I,where silver clusters with even-number,Ag_(2n)^(+),find favorable products of Ag_(2n)I_(1,3)^(+)series,while the Ag_(2n−1)^(+)clusters form Ag_(2n−1)I_(2,4)^(+)***,Ag_(9)^(+)shows up with prominent mass abundance but allows for the formation of Ag_(9)I_(2)^(+),which finds an echo with the formation of Ag_(10)I_(3)^(+).We illustrate the enhanced stability of Ag_(9)I_(2)^(+)and Ag_(10)I_(3)^(+)by showing their significantly enlarged highest occupied molecular orbital(HOMO)-lowest unoccupied molecular orbital(LUMO)gaps and balanced charge distribution compared with the bare metal clusters,*** elucidated,is the superatomic nature of these bare and iodinated silver clusters,especially Ag_(9)I_(2)^(+)which mimics the rare-gas compound XeF_(2).This study expands a vivid example of special and general superatoms,and enriches the general knowledge on how a ligand stabilizes a metal cluster.

关键词： metal cluster superatom halide superatomic complex gas-phase reaction

Enhancement of Organic Electrolum Inescent Intensity by Doping Hole-Property Polymers

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1995年第9期12卷 569-572页

作者： WANG Guangming wu haiming YUAN Chunwei WEI Yu National Laboratory of Molecular and Bioelectronics Southeast UniversityNanjing 210096

Organic electroluminescent(EL)diodes with one-layer poly(3-octylthiophene)(P3OT)and P3OT doped with poly(N-vinylcarbazole)(PVK)(P3OT/PVK)as EL emitting layer sandwiched between indium/tin oxide(lTO)and aluminium electrodes have been fabricated by spin coating onto IT0 *** P3OT/PVK EL diode starts to emit red-orange light at 5 V in our experiment,the luminance and the current for the P3OT/PVK EL diode at bias voltage was compared with those for the only P3OT EL diode,indicating that the PVK dopant has power over the P3OT electroluminescence.

关键词： diode dopant diodes

Small gold clusters catalyzing oxidant-free dehydrogenation of glycerol initiated by methene hydrogen atom transfer

维普期刊数据库评论

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 Chemical Letters 2019年第5期30卷 1000-1004页

作者： Anthony M.S.Pembere Chaonan Cui haiming wu Zhixun Luo State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences

Developing oxygen-free methodology for the conversion of alcohols to carbonyls is essentially important because it suppresses the over-oxidation of alcohols to carboxylic acids and enables the production of energetic *** we report a finding of feasible oxidant-free dehydrogenation of glycerol over chemically-pure Au clusters synthesized by a green chemistry method named as laser ablation in liquid(LAL).As results,glycerol is dehydrogenated to form glyceraldehyde which undergoes subsequent dehydrogenation to hydroxymethyl *** this,reaction dynamics calculations find interesting dehydrogenation reaction pathways with a low-energy barrier of transition state initiated by hydrogen atom transfer from methene,which differs from the general reaction mechanism based on ***,it is interesting that the presence of additionalààOH group molecules especially H2O can effectively lower the energy barrier in the activation of the OààH and CààH bonds in *** principle is also applicable to the oxidant-free dehydrogenation of methanol and ethanol,helping to fully understand the catalytic mechanism of alcohols conversion chemistry.

关键词： Density functional theory Alcohols Bond activation Reaction path Energy barrier

Effects of iron and humic acid on competition between Microcystis aeruginosa and Scenedesmus obliquus revealed by HPLC analysis of pigments

在线全文

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2021年第2期39卷 525-535页

作者： Miaomiao ZHAO Qiang HE Chongtai CHEN Yaqi TIAN Jing WEI Pengfei DUAN haiming wu Ming LI College of Natural Resources and Environment Northwest A&F UniversityYangling 712100China Collaborative Innovation Center of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province Nanyang Normal UniversityNanyang 473061China Scientific Laboratory of Heyang Agricultural Environment and Farmland Cultivation Ministry of Agriculture and Rural Aff airsHeyang 715300China

Iron is a vital micronutrient for growth of bloom-forming Microcystis aeruginosa and competition with other algae,and its availability is affected by humic *** effect of iron and humic acid on growth and competition between *** and Scenedesmus obliquus was *** results showed the growth of *** and *** in mono-cultures was inhibited by humic acid at low iron concentrations(0.01 mg/L);the maximum inhibition ratios were 67.84%and 38.31%,*** inhibition of humic acid on the two species was significantly alleviated when iron concentrations were 1.00 mg/L,with the maximum inhibition rate reduced to 5.82%for *** and to 23.06%for *** was the dominant species in mixed cultures,and the mutual inhibition between *** and *** at low iron concentration was greater than that at high iron *** inhibition of *** on *** was reduced at low iron concentrations;it increased at high iron concentrations,as concentrations of humic acid rose.

关键词： Microcystis Scenedesmus iron humic acid competition pigment

一种应用探地雷达进行早期人防工程回填治理的方法

在线全文

学校读者我要写书评

暂无评论

北京测绘 2024年第3期38卷 441-446页

作者：杜朋卫周芳玲吴海明田文静同创数字空间(北京)有限公司北京100048

早期人防工程由于建设年代久远,处于长期闲置状态,且防护标准低、结构安全性差、安全隐患较多,不利于城市的规划发展、地下空间的整体利用以及地面的安全。在对人防工程回填治理工作中,对回填质量的评价缺少科学、准确的数据依据。本文... 详细信息

早期人防工程由于建设年代久远,处于长期闲置状态,且防护标准低、结构安全性差、安全隐患较多,不利于城市的规划发展、地下空间的整体利用以及地面的安全。在对人防工程回填治理工作中,对回填质量的评价缺少科学、准确的数据依据。本文以人防治理回填项目为研究对象,结合早期人防的回填治理特点,研究通过使用探地雷达法,采用适宜的探测方法获取回填后的影像资料并对其进行解译,发现施工回填过程中存在的质量问题,为回填工程质量评价提供依据,为类似工程提供应用参考。

关键词：早期人防探地雷达洞内探测地面探测