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Black Hole Clusters: The Dark Matter 预览
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作者 Kenneth Dalton 《高能物理(英文)》 2019年第4期989-991,共3页
Supermassive black holes were created during the Big Bang. As such, they were available for clustering in the early Universe. This paper describes the role these clusters could play in explaining dark matter, and it a... Supermassive black holes were created during the Big Bang. As such, they were available for clustering in the early Universe. This paper describes the role these clusters could play in explaining dark matter, and it answers the following question: What is the energy source for the extremely hot gas found in galactic clusters? 展开更多
关键词 DARK MATTER GALAXIES CLUSTERS
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A New Analytical Solution for the Distance Modulus in Flat Cosmology 预览
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作者 Lorenzo Zaninetti 《天文学与天体物理学国际期刊(英文)》 2019年第1期51-62,共12页
A new analytical solution for the luminosity distance in flat ΛCDM cosmology is derived in terms of elliptical integrals of first kind with real argument. The consequent derivation of the distance modulus allows eval... A new analytical solution for the luminosity distance in flat ΛCDM cosmology is derived in terms of elliptical integrals of first kind with real argument. The consequent derivation of the distance modulus allows evaluating the Hubble constant, H0=69.77&plusmn;0.33, &Omega;M=0.295&plusmn;0.008, and the cosmological constant, . 展开更多
关键词 Galaxy GROUPS CLUSTERS and Superclusters Large Scale Structure of the UNIVERSE COSMOLOGY
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Strategy for efficient cloning of biosynthetic gene clusters from fungi
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作者 Ruixin Li ZiXin Li +6 位作者 Ke Ma Gang Wang Wei Li Hong-Wei Liu Wen-Bing Yin Peng Zhang Xing-Zhong Liu 《中国科学:生命科学英文版》 SCIE CAS CSCD 2019年第8期1087-1095,共9页
Filamentous fungi are excellent sources for the production of a group of bioactive small molecules which are often called secondary metabolites(SMs). The advanced genome sequencing technology combined with bioinformat... Filamentous fungi are excellent sources for the production of a group of bioactive small molecules which are often called secondary metabolites(SMs). The advanced genome sequencing technology combined with bioinformatics analysis reveals a large number of unexplored biosynthetic gene clusters(BGCs) in the fungal genomes. To unlock this fungal SM treasure, many approaches including heterologous expression are being developed and efficient cloning of the BGCs is a crucial step to do this.Here, we present an efficient strategy for the direct cloning of fungal BGCs. This strategy consisted of Splicing by Overlapping Extension(SOE)-PCR and yeast assembly in vivo. By testing 14 BGCs DNA fragments ranging from 7 kb to 52 kb, the average positive rate was over 80%. The maximal insertion size for fungal BGC assembly was 52 kb. Those constructs could be used conveniently for the heterologous expression leading to the discovery of novel natural products. Thus, our results provide an efficient and quick method for the low cost direct cloning of fungal BGCs. 展开更多
关键词 biosynthetic gene CLUSTERS SACCHAROMYCES CEREVISIAE HOMOLOGOUS recombination DNA assembly
激光溅射下四唑环的簇合行为 预览
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作者 丁可伟 李陶琦 +4 位作者 许洪光 刘愆 屈晨曦 郑卫军 葛忠学 《火炸药学报》 CAS CSCD 北大核心 2019年第3期247-250,I0002共5页
为了解四唑环在激光作用下的分解和簇合行为,在高真空条件下,以高纯氮气为载气,用纳秒激光分别溅射四唑、5-氨基四唑以及四唑与氮化锆、钒和铬形成的混合样品,并用反射式飞行时间质谱分析了生成的产物。结果表明,在532nm的激光轰击条件... 为了解四唑环在激光作用下的分解和簇合行为,在高真空条件下,以高纯氮气为载气,用纳秒激光分别溅射四唑、5-氨基四唑以及四唑与氮化锆、钒和铬形成的混合样品,并用反射式飞行时间质谱分析了生成的产物。结果表明,在532nm的激光轰击条件下,大量四唑、5-氨基四唑分子骨架保持完整,易脱去一个氢原子而形成高丰度的负离子,该负离子进一步与1~3个四唑、5-氨基四唑分子形成簇合物;在氮化锆、钒和铬存在下,激光轰击四唑后形成了四唑正离子及四唑分子数不超过2个的簇合物,正离子质谱未发现锆、钒和铬参与四唑簇合物的形成。研究结果表明,激光溅射含氮有机物主要是蒸发作用,可用该方法表征有机物并研究其相互作用特性。 展开更多
关键词 有机化学 四唑类含能化合物 5-氨基四唑 富氮含能化合物 簇合物 激光溅射 簇合行为
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广西柳州1998-2018年新发现HIV阳性者基因亚型亚簇变化
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作者 康瑞华 罗柳红 +12 位作者 陈欢欢 李剑军 梁淑家 朱秋映 蓝光华 沈智勇 唐振柱 杨文敏 廖玲洁 冯毅 邵一鸣 邢辉 阮玉华 《中国热带医学》 CAS 2019年第9期818-822,828共6页
目的了解广西柳州1998—2018年新发现HIV阳性者基因亚型亚簇变化情况。方法选取HIV阳性者,采集全血标本进行DNA提取、pol基因区扩增、测序和判定亚型。采用趋势卡方检验分析不同时间段亚型亚簇变化情况。结果自2007年起检测发现CRF01AE... 目的了解广西柳州1998—2018年新发现HIV阳性者基因亚型亚簇变化情况。方法选取HIV阳性者,采集全血标本进行DNA提取、pol基因区扩增、测序和判定亚型。采用趋势卡方检验分析不同时间段亚型亚簇变化情况。结果自2007年起检测发现CRF01AE的cluster 3和cluster 4两个亚簇,自2010年起检测发现CRF5501B亚型。广西柳州地区流行的亚型、亚簇种类在增加。1998—2006年、2007—2009年、2010—2014年和2015—2018年这四个时间段,CRF01AE亚型的构成比分别为95.3%(346/363)、96.7%(734/759)、94.8%(1 536/1 620)和88.0%(499/567);CRF01AE亚型cluster 1的构成比分别为93.4%(339/363)、91.8%(697/759)、89.3%(1 447/1 620)和79.5%(451/567),趋势卡方检验表明CRF01AE亚型和cluster 1感染者的构成比呈下降趋势(P<0.01)。CRF5501B亚型在2010—2014年和2015—2018年分别发现为7和12人。结论CRF01AE为广西柳州市的主要流行亚型,但该亚型感染者的构成比有下降趋势;该地区CRF01AE亚型中亚簇和HIV亚型种类的增加,提示可能存在新的HIV毒株传入。 展开更多
关键词 艾滋病病毒 基因亚型 亚簇
Palladium nanoclusters immobilized on defective nanodiamond-graphene core-shell supports for semihydrogenation of phenylacetylene 预览
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作者 Fei Huang Zhimin Jia +3 位作者 Jiangyong Diao Hua Yuan Dangsheng Su Hongyang Liu 《能源化学:英文版》 SCIE EI CAS CSCD 2019年第6期31-36,共6页
We report a nanocarbon material with nanodiamond(ND) core and graphene shell(ND@G) as a support for Pd nanocatalysts. The designed catalyst performed good selectivity of styrene(85.2%) at full conversion of phenylacet... We report a nanocarbon material with nanodiamond(ND) core and graphene shell(ND@G) as a support for Pd nanocatalysts. The designed catalyst performed good selectivity of styrene(85.2%) at full conversion of phenylacetylene and superior stability under mild conditions. Supported Pd catalysts are characterized by means of high resolution transmission electron microscopy(HRTEM), Raman, X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and H2 temperature-programmed reduction(H2-TPR).The results clearly show that formation of the strong metal-support interaction(SMSI) between Pd nanoclusters and the defective graphene shell helpfully modifies the selectivity and stability of the Pd-based catalysts. 展开更多
关键词 Selective HYDROGENATION PALLADIUM nano clusters NANOCARBON support Liquid-phase HYDROGENATION
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Growth behavior and electronic properties of Gen+1 and AsGen(n = 1–20) clusters: a DFT study 预览
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作者 M.Benaida K.E.Aiadi +3 位作者 S.Mahtout S.Djaadi W.Rammal M.Harb 《半导体学报:英文版》 EI CAS CSCD 2019年第3期9-17,共9页
We present a systematic computational study based on the density functional theory(DFT) aiming to high light the possible effects of one As doping atom on the structural, energetic, and electronic properties of differ... We present a systematic computational study based on the density functional theory(DFT) aiming to high light the possible effects of one As doping atom on the structural, energetic, and electronic properties of different isomers of Gen+1 clusters with n = 1–20 atoms. By considering a large number of structures for each cluster size, the lowest-energy isomers are determined. The lowest-energy isomers reveal three-dimensional structures starting from n = 5. Their relative stability versus atomic size is examined based on the calculated binding energy, fragmentation energy, and second-order difference of energy. Doping Gen+1 clusters with one As atom does not improve their stability. The electronic properties as a function of the atomic size are also discussed from the calculated HOMO–LUMO energy gap, vertical ionization potential, vertical electron affinity, and chemical hardness. The obtained results are significantly affected by the inclusion of one As atom into a Gen cluster. 展开更多
关键词 DENSITY FUNCTIONAL theory As–Ge CLUSTERS structural PROPERTIES ELECTRONIC PROPERTIES
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Microstructure of NiSO4 Solution:A Combined DFT and EXAFS Study 预览
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作者 LIU Hong-yan ZHU Fa-yan +5 位作者 ZHOU Yong-quan WANG Guang-guo FANG Chun-hui FANG Yan ZHANG Wen-qian HAN Li 《盐湖研究》 CSCD 2019年第2期53-68,共16页
The microhydration structure of nickel sulfate aqueous solution has been determined via density functional theory (DFT) calculation and extended X-ray absorption fine structure (EXAFS) spectroscopy.The geometric optim... The microhydration structure of nickel sulfate aqueous solution has been determined via density functional theory (DFT) calculation and extended X-ray absorption fine structure (EXAFS) spectroscopy.The geometric optimization and energy calculation of nickel sulfate hydrated clusters of the molecular formula [NiSO4(H2O)n ]^0 (n=1-12) were determined via DFT using the B3LYP method.Several possible initial structures were considered for clusters of each size to locate the equilibrium geometry.Based on the DFT calculation,the favorable structure of Ni^2+ includes the six-coordinated form of [NiSO4(H2O)n ]^0 clusters.The results of hydration energy calculation suggest that the six-coordinated contact ion pair (CIP) is the stable configuration for small hydration clusters (n≤5),while the solvent-shared ion pair (SSIP) represents the favorable structure for medium hydration clusters (6≤n≤10).The solvent is separated by x water molecules (xSIP,x≥2 is the number of water molecule between Ni^2+ and SO4^2-) in larger hydration clusters (n≥11).The EXAFS analysis of the NiSO 4 aqueous solutions and NiSO4 ·6H2O solid established that Ni^2+ was surrounded by six water molecules tightly forming an octahedral structure in the first hydration shell,and no CIP was found from 0.70 mol/L to 2.22 mol/L (near saturation).The Ni-O distance and coordinated number were 2.040±0.020 and 6.0±1.0,respectively.These results are consistent with the DFT calculations for [NiSO4(H2O)n ]^0 clusters.DFT and EXAFS are powerful techniques that can be used to enhance the resolution of NiSO 4 solution microstructure. 展开更多
关键词 [NiSO4(H2O)n]^0 CLUSTERS Ion PAIRS Structure Energy HYDRATION
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TM1~2Mn@(BN)48笼团簇的结构与磁性研究 预览
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作者 梁文娟 刘永文 +1 位作者 荆补琴 卢珍 《山西大同大学学报:自然科学版》 2019年第4期1-5,11共6页
在密度泛函理论BPW91/LanL2DZ计算水平下,对TM1~2Mn(TM=Fe,Co,Ni)笼团簇的结构和磁性进行研究。结果显示:Mn掺杂金属小团簇TM1~2,磁性发生显著增强。同时,TM1~2Mn@(BN)48团簇的包含能均为负,与自由态合金团簇比较,笼中的TM1~2Mn合金团... 在密度泛函理论BPW91/LanL2DZ计算水平下,对TM1~2Mn(TM=Fe,Co,Ni)笼团簇的结构和磁性进行研究。结果显示:Mn掺杂金属小团簇TM1~2,磁性发生显著增强。同时,TM1~2Mn@(BN)48团簇的包含能均为负,与自由态合金团簇比较,笼中的TM1~2Mn合金团簇键能明显增加,表明磁性合金团簇与笼发生较强的相互作用,从而使得TM1~2Mn@(BN)48包含物足够稳定。稳定态的TM1~2Mn@(BN)48表明,被包含的合金团簇偏离(BN)48笼中心靠近六元环。CoMn和NiMn合金团簇在包含前后磁性保持不变;其他的合金团簇被包含后,磁性均有所减小。 展开更多
关键词 (BN)48笼 团簇 磁性
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Single-doped charged gold cluster with highly selective catalytic activity for the reduction of SO2 by CO: First-principles study
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作者 胡燕玲 祝浩然 韦世豪 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第11期140-149,共10页
It is important for environmental protection to search for catalysts with excellent performance and cost-effective to reduce SO2 by CO. In this work, using first-principles calculation, we have studied the catalytic p... It is important for environmental protection to search for catalysts with excellent performance and cost-effective to reduce SO2 by CO. In this work, using first-principles calculation, we have studied the catalytic performance of Au5M^n(M = Ni, Pd, Pt, Cu, Ag, Au;n = 1, 0,-1) clusters, and showed that, by giving a negative charge to the Au5M(M = Cu,Ag, Au, Pd) clusters, we could improve the selectivity of SO2 and avoid effectively catalyst CO poisoning simultaneously.At the same time, the catalytic reaction rate for the reduction of SO2 by CO with Au5M^-(M = Cu, Ag, Au, Pd) clusters is greatly improved when the Au5M clusters are charged. These advantages can be well explained by the charge transfer between the clusters and adsorbed molecules, which means that we can effectively control the performance of the catalyst.The equilibrium structures of Au5M^n(M = Ni, Pd, Pt, Cu, Ag, Au;n = 1, 0,-1) clusters without or with adsorbed SO2 or CO molecule are also discussed, and the most stable geometrical structures of Aun5 M^n-ML(ML = SO2, CO, SO, and COS)can be explained very well by the match of orbitals symmetry and density of electron cloud through their frontier molecular orbitals. Considering the catalyst cost(Cu is much cheaper than Ag and Au), selectivity of SO2, and effectively avoiding the catalyst CO poisoning, we propose that Au5Cu-is an ideal catalyst for getting rid of SO2 and CO simultaneously. 展开更多
关键词 bimetallic clusters catalyst FIRST-PRINCIPLES electronic structure
CdS magic-size clusters exhibiting one sharp ultraviolet absorption singlet peaking at 361 nm
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作者 Junbin Tang Juan Hui +6 位作者 Meng Zhang Hongsong Fan Nelson Rowell Wen Huang Yingnan Jiang Xiaoqin Chen Kui Yu 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第6期1437-1444,共8页
We report,for the first time,the synthesis of CdS magic-size clusters (MSCs) which exhibit a single sharp absorption peaking at ~ 361 nm,along with sharp band edge photoemission at ~ 377 nm and broad trap emission pea... We report,for the first time,the synthesis of CdS magic-size clusters (MSCs) which exhibit a single sharp absorption peaking at ~ 361 nm,along with sharp band edge photoemission at ~ 377 nm and broad trap emission peaking at ~ 490 nm.These MSCs are produced in a singleensemble form without the contamination of conventional quantum dots (QDs) and/or other-bandgap clusters.They are denoted as MSC-361.We present the details of several controlled syntheses done in oleylamine (OLA),using C,d(NO3)2 or C,d(OAc)2 as a C,d source and thioacetamide (TAA) or elementary sulfur (S) as a S source.A high synthetic reproducibility of the reaction of Cd(NO3)2 and TAA to single-ensemble MSC-361 is achieved,the product of which is not contaminated by other bandgap clusters and/or QDs.In some cases,the reaction product exhibits an additional absorption peak at ~ 322 nm.We demonstrate that the two peaks,at 361 and 322 nm,do not evolve synchronously.Therefore,the 322 nm peak is not a higher order electronic transition of MSC-361,but due to the presence of another ensemble,namely MSC-322.The present study suggests that there is an outstanding need for the development of a physical model to narrow the knowledge gap regarding the electronic structure in these colloidal semiconductor CdS MSCs. 展开更多
关键词 COLLOIDAL semiconductor CDS magic-size CLUSTERS (MSCs) MSC-361 quantum dots (QDs) electronic structures
Optimization of well pad design and drilling - well clustering 预览
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作者 ABRAMOV Aleksandr 《石油勘探与开发:英文版》 2019年第3期614-620,共7页
A model accounting for more than 30 parameters of drilling projects, and a computer program to enumerate groupings of the wells of a pad with consequent calculations of technical-economic characteristics, are develope... A model accounting for more than 30 parameters of drilling projects, and a computer program to enumerate groupings of the wells of a pad with consequent calculations of technical-economic characteristics, are developed and tested. Seven drilling scenarios for a 24-well pad with different starting oil flow rates for the wells are studied. Optimal well groupings in terms of Net Present Value (NPV) for three discount rates and five oil production decline rates have been found. The results show that: NPV-maximizing well pad designs with unequal (varying) numbers of wells in groups (clusters) may require only slight alterations of existing designs (changing the configurations of a couple of well clusters);relative NPV gain is inversely proportional to the absolute value of NPV;observed increases in NPV in groupings with varying numbers of wells reach up to 1% with respect to groupings with equal (constant) numbers of wells in groups for conventional projects, and could reach 2% and more for shale formation development projects, and up to 45% for marginal projects. 展开更多
关键词 PAD DRILLING MULTI-WELL PAD WELL groupings BATCH DRILLING clusters of WELLS
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Adsorption of Nin (n=1-4) clusters on perfect and O-defective CuAl2O4 surfaces:A DFT study
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作者 Li Li Liu Shi +5 位作者 Xiaohu Yu Shaojun Qing Zhixian Gao Qiquan Luo Gang Feng Rongbin Zhang 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第6期1147-1152,共6页
The density functional theory was employed to investigate the adsorption of Nin (n=1–4) on the perfect and O-defect CuAl2O4 surfaces. The computational results show that for single Ni atom on the perfect spinel (100)... The density functional theory was employed to investigate the adsorption of Nin (n=1–4) on the perfect and O-defect CuAl2O4 surfaces. The computational results show that for single Ni atom on the perfect spinel (100) surface, the adsorption energy is-5.30 eV, much larger than Ni on other CuAl2O4 surfaces. The adsorption of Nin (n=1–4) absorbed on the O-defect CuAl2O4 (100) surface is less stable than on the perfect CuAl2O4 (100) surface. However, the adsorption energy for Nin (n=1–4) on the O-defect CuAl2O4 (110) surface is close to on the perfect CuAl2O4 (110) surface. Bader charge and partial density of states (PDOS) analysis revel that the adsorption of Ni on the CuAl2O4 spinel surface is accompanied by charge transfer from the metal to the support. The growth and aggregations analysis show that the general growth and aggregation ability for Nin clusters follow the order:gas phase>γ-Al2O3 (110)>CuAl2O4 (110)>CuAl2O4 (100). This result can give reasonable explanations for the experimental phenomenon that Ni supported on the CuAl2O4 spinel performs much better stability than on the γ-Al2O3. 展开更多
关键词 Ni CLUSTERS CuAl2O4 SPINEL Density functional theory ADSORPTION Growth and AGGREGATION
Determining endemic values of cutaneous leishmaniasis in Iranian Fars province by retrospectively detected clusters and receiver operating characteristic curve analysis
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作者 Marjan Zare Abbas Rezaianzadeh +3 位作者 Hamidreza Tabatabaee Hossain Faramarzi Mohsen Aliakbarpour Mostafa Ebrahimi 《亚太热带生物医学杂志:英文版》 CAS 2019年第9期359-364,共6页
Objective: To determine the endemic values of cutaneous leishmaniasis in different cities of Fars province, Iran. Methods: Totally, 29 201 cases registered from 2010 to 2015 in Iranian Fars province were selected, and... Objective: To determine the endemic values of cutaneous leishmaniasis in different cities of Fars province, Iran. Methods: Totally, 29 201 cases registered from 2010 to 2015 in Iranian Fars province were selected, and the endemic values of cutaneous leishmaniasis were determined by retrospective clusters derived from spatiotemporal permutation modeling on a time-series design. The accuracy of the values was assessed using receiver operating characteristic(ROC) curve. SPSS version 22, Arc GIS, and ITSM 2002 software tools were used for analysis. Results: Nine statistically significant retrospective clusters(P<0.05) resulted in finding seven significant and accurate endemic values(P<0.1). These valid endemic scores were generalized to the other 18 cities based on 6 different climates in the province. Conclusions: Retrospectively detected clusters with the help of ROC curve analysis could help determine cutaneous leishmaniasis endemic values which are essential for future prediction and prevention policies in the area. 展开更多
关键词 CUTANEOUS LEISHMANIASIS Retrospective CLUSTERS Receiver operating characteristic curve ENDEMIC VALUES Fars PROVINCE
A facile method to synthesize water-soluble Pd8 nanoclusters unraveling the catalytic mechanism of p-nitrophenol to p-aminophenol
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作者 Pan An Rajini Anumula +4 位作者 Chaonan Cui Yang Liu Fei Zhan Ye Tao Zhixun Luo 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第10期2589-2596,共8页
Hydroge nation of p-n itrophe nol(PNP)towards the con versi on to p-ami nophe no I(PAP)by metal catalysis is known as a simple and I eco-frie ndly tech nique for the production of corresp on ding in dustrial and pharm... Hydroge nation of p-n itrophe nol(PNP)towards the con versi on to p-ami nophe no I(PAP)by metal catalysis is known as a simple and I eco-frie ndly tech nique for the production of corresp on ding in dustrial and pharmaceutical in termediates.While continu ous efforts are paid for§more sustainable and greener procedures by using transition metal catalysts,atomic-precise reaction mechanism for the PNP-to-PAP is still illusive to be fully un derstood.Utilizi ng a dry-wet com bined strategy,here we have syn thesized water-soluble Pd8 nano clusters(NCs)with mercaptosuccinic acid(H2SMA)as the ligand,and the Pd8 NCs found high catalytic performance for the conversion of PNP-to-PAP,as identified by the electrospray ionization mass spectrometer(ESI-MS)measurement.The gradual changes over time of ultraviolet-visible(UV-vis)spectra of PNP really display the catalytic reduction by NaBH4 in presence of Pd8 NCs.Further,in-depth charge transfer interactions between PNP and the Pd8 clusters at the proton-rich conditions are investigated by natural bond orbital(NBO)analysis and electron density differenee(EDD)analysis.The exothermic and kinetic-favorable reaction pathways are addressed,based on successive PNP hydrogenation and H2O removal processes,clarifying the reaction mechanism of Pd catalysts.It is worth noting that this solid-state synthetic route for such Pd8 clusters enables gram-scale quantity of production in likely practical use. 展开更多
关键词 catalytic CLUSTERS mechanism
Perspective Material for Photoenergetics on the Basis of Silicon with Binary Elementary Cells 预览
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作者 M.K. Bakhadyrhanov U.X. Sodikov +2 位作者 Kh.M. Iliev S.A. Tachilin Tuerdi Wumaier 《材料物理与化学》 2019年第1期89-95,共7页
The paper proposes a scientifically grounded - principally new approach to managing the fundamental parameters of the basic material of electronic engineering as like silicon. The essense of the proposed approach is t... The paper proposes a scientifically grounded - principally new approach to managing the fundamental parameters of the basic material of electronic engineering as like silicon. The essense of the proposed approach is that the formation of binary elementary cells in the silicon lattice involving elements III (B, Al, Ga, Zn) and V (P, As, Sb) groups in the form of Si2GaAs, Si2GaSb, etc., taking into account electrical and chemical parameters of these impurity atoms, as well as their diffusion parameters in Si, are determined by the most suitable pairs of atoms of groups III and V that allow obtaining silicon with the necessary composition and structure of binary elementary cells, as well as their more complex associations, up to the formation of nanocrystals of semiconductor connections AIIIBV. It is shown that by controlling the composition and structure, as well as the concentration of binary elementary cells, it is possible to significantly expand the spectral sensitivity of silicon, both in the IR and hλ> Eg directions. The formation of nanoclusters of AIIIBV semiconductor compounds in the silicon lattice significantly changes the emissivity of the material. It is established that the successive diffusion of elements of groups III and V in silicon and additional low-temperature annealing under certain thermodynamic conditions makes it possible to ensure the maximum participation of the impurity atoms introduced in the formation of binary elementary cells. It is shown that silicon with binary elementary cells involving atoms of groups III and V is a new class of semiconductor material with unique functionality for modern optoelectronics and photoenergetics. 展开更多
关键词 Semiconductor Binary clusters Muticascade PV CELLS Elementary CELLS SELF-ORGANIZATION Self-Structure Nanostructure Nanocrystal Photosensivity Combinations MULTISTAGE PV CELLS
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NO在金属Ben(n=2-12)团簇表面的平行吸附
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作者 李淑萍 孟江 王继刚 《原子与分子物理学报》 CAS 北大核心 2019年第2期240-245,共6页
采用密度泛函理论(DFT)中的广义梯度近似(GGA),对BenNO (n=2-12)团簇进行了构型优化,稳定性和电子性质分析.结果表明:从n=3开始,Be_nNO的基态均为NO分子平行吸附于主团簇Ben某一表面时形成的,此时N-O键自然断裂(N-O键伸长量均超过了100... 采用密度泛函理论(DFT)中的广义梯度近似(GGA),对BenNO (n=2-12)团簇进行了构型优化,稳定性和电子性质分析.结果表明:从n=3开始,Be_nNO的基态均为NO分子平行吸附于主团簇Ben某一表面时形成的,此时N-O键自然断裂(N-O键伸长量均超过了100%),而N端吸附于Be-Be桥位的结构仅是BenNO (n=2-12)团簇的一个亚稳态结构.成键性质分析表明,NO平行吸附时,N,O原子倾向于同时吸附于近邻的三个Be原子面位,相应的Be_n团簇表现出了很好的吸附能力.此时N, O原子的sp^3轨道杂化出现的孤对电子对N-O键的断裂产生了重要影响. 展开更多
关键词 团簇 NO吸附 基态结构 电子性质
Linux高性能计算集群SSH安全远程登录的研究 预览
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作者 金能智 文洮 +1 位作者 安文婷 杨博超 《现代信息科技》 2019年第13期177-179,共3页
高性能计算集群是当前较为先进的计算体系,高性能计算的快速发展已为其他科学技术的发展提供了越来越广的支撑,其安全性显得非常重要。SSH(Secure Shell)作为一种通用的、基于软件的安全访问远程服务器的网络协议,已广泛应用于Linux高... 高性能计算集群是当前较为先进的计算体系,高性能计算的快速发展已为其他科学技术的发展提供了越来越广的支撑,其安全性显得非常重要。SSH(Secure Shell)作为一种通用的、基于软件的安全访问远程服务器的网络协议,已广泛应用于Linux高性能计算集群,本文以甘肃省计算中心高性能计算集群为实验对象,以OpenSSH为例,介绍了SSH的工作原理,OpenSSH的安装和配置,以及远程登录管理服务器,对于利用SSH远程管理服务器具有一定的指导意义。 展开更多
关键词 LINUX 高性能计算 集群 SSH
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Motif-mediated Au25(SPh)5(PPh3)ioX2 nanorods with conjugated electron delocalization
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作者 Kai Zheng Jiangwei Zhang +3 位作者 Dan Zhao Yong Yang Zhimin Li Gao Li 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第3期501-507,共7页
We developed a general and effective strategy to afford rod-like [Au25(SPh)5(PPh3)10X2]X2 (X = Cl/Br) nanoclusters, capped by conjugated delocalized pπ electron mediated ligands. The detailed atomic structure of thes... We developed a general and effective strategy to afford rod-like [Au25(SPh)5(PPh3)10X2]X2 (X = Cl/Br) nanoclusters, capped by conjugated delocalized pπ electron mediated ligands. The detailed atomic structure of these materials was resolved by synchrotron radiation X-ray diffraction (SRXRD) combined with electrospray ionization mass spectrometry (ESI-MS) and UV–vis analyses. The Au17(SR)3(PPh3)6X2minimum asymmetric unit, with exposed Au atoms at the center, can serve as an important model to understand the transformation of homogold nanoclusters into alloy nanoclusters. The conjugated delocalized pπ electrons of the thiolate ligands can effectively tune the electronic properties of the Au25 kernel, as qualitatively evidenced by the energy gaps measured by UV–vis experiments and density functional theory (DFT) calculations. The delocalized electrons distinctly flow to the orbitals of the Au25 kernel via the S atoms of the aromatic thiolates. The ESI-MS analysis indicates that Au3 clusters are formed during the etching reactions, which provide an opportunity to gain insight into the intriguing conversion pathway of the Aun(PPh3)mXy precursor to the final Au25 nanorods. Finally, the thiophenol-protected Au25 nanorods, immobilized on activated carbon, show good catalytic activity in the aerobic oxidation of glucose to gluconic acid (74% glucose conversion and 100% selectivity for gluconic acid), much higher than that of the aliphatic Au25 analogue. The Au25(SPh)5(PPh3)10X2 catalyst yields a turnover frequency (TOF) of 13.5 s^–1, higher than that of commercial catalysts such as Pd/activated carbon (AC) and Pd-Bi/AC. The insight obtained from this study will support the development and design of efficient nanogold catalysts for special oxidation reactions. 展开更多
关键词 gold clusters AU25 nanorod SYNCHROTRON radiation X-ray diffraction (SRXRD) AEROBIC oxidation
热辐射对热团簇衰变率和丰度的影响 预览
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作者 Klavs Hansen P. Ferrari 《化学物理学报》 SCIE CAS CSCD 2019年第2期167-174,I0002共9页
本文量化了辐射冷却对单分子衰变速率、热簇以及非特定激发能量的分子的影响.检测出两种不同的区域,可以通过发射光子的能量大小进行定义,并根据光子发射速率常数和颗粒的热性质确定它们之间的边界.此外,通过丰度光谱计算了相当于小光... 本文量化了辐射冷却对单分子衰变速率、热簇以及非特定激发能量的分子的影响.检测出两种不同的区域,可以通过发射光子的能量大小进行定义,并根据光子发射速率常数和颗粒的热性质确定它们之间的边界.此外,通过丰度光谱计算了相当于小光子能量的连续冷却情况.两种不同区域分别是连续性冷却和单分子衰变的单光子猝灭.辐射效应通过重新定义每个单独的团簇用于进行蒸发的时间进行参数化,可用有效辐射时间常数来表示. 展开更多
关键词 团簇 热辐射 丰度 衰减率
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