检索结果-南通市图书馆

Controlled Radical Polymerization:from Oxygen Inhibition and Tolerance to Oxygen Initiation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2021年第9期39卷 1084-1092页

作者： Ning Li xiang-cheng Pan State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai 200438China

Molecular oxygen is a radical scavenger in both conventional and controlled radical polymerization(CRP),resulting in many time-consuming methods for physically removing oxygen before the *** approaches have been developed to have oxygen toleranee by chemically consuming or converting molecular oxygen into non-initiating species to address this ***,we propose another approach called oxygen initiation that directly transforms molecular oxygen into the initiating carbon radical in *** feature article summarizes our rece nt developments in this *** n-initiated reversible additi on-fragmentation transfer(RAFT)polymerization has been successfully conducted using oxygen and trialkylborane as co-initiators under the ambient conditions and atmosphere without any prior degassed *** gas-triggered initiation provides the opportunity for spatiotemporal control of the polymerization by molecular oxygen or *** synthesized alkylborane compounds could derive the predesigned structure of the initiating alkyl radical to minimize the side reacti ons and free polymer chai ns,achievi ng the synthesis of ultra-high molecular weight *** challe nges and perspectives are also discussed in the end.

关键词： Oxygen Radical polymerization Controlled Alkylborane RAFT

Channel Measurements and Models for 6G

在线全文

学校读者我要写书评

暂无评论

China Communications 2022年第11期19卷 I0002-I0004页

作者： Jianhua Zhang Bo ai chengxiang Wang xiang cheng Mansoor Shafi Wei Fan BUPT China Inst Commun Beijing Peoples R China BUPT CMCC Joint Res Ctr Beijing Peoples R China Beijing Jiaotong Univ Beijing Peoples R China State Key Lab Rail Traff Control & Safety Beijing Peoples R China Chinese Inst Elect Beijing Peoples R China Acad Europaea Aalborg Denmark Peking Univ Beijing Peoples R China Victoria Univ Wellington Sch Engn Wellington New Zealand Aalborg Univ Antennas Propagat & Millimeter Wave Syst APMS Sec Aalborg Denmark

In the early stage of 6G research,carrying out research on channel measurements and models is one of the fundamental and prerequisite works,as well as full of the *** by the demand for multiple frequency bands,versatile scenarios,and various new technologies in the future,6G channels are expanding in multiple dimensions such as the space-time-frequency *** all make 6G channel measurement and modeling research face a series of new challenges,e.g.,non-stationarity in multiple dimensions,the obvious increase in modeling complexity,and changes in theoretical premises and *** is therefore clear that more efforts are needed to understand propagation characteristics,especially in the new scenes and applications,and to develop a new paradigm for 6G channel modeling.

关键词： channel dimensions versatile

Disk evolution of the M87’s nucleus observed in 2008

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

Research in Astronomy and Astrophysics 2020年第7期20卷 103-111页

作者： Fei xiang cheng cheng Department of Astronomy Yunnan UniversityKunming 650091China Chinese Academy of Sciences South America Center for Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China

We report the discovery of year-scale X-ray variation in the nuclear region of the M87 by reanalyze the eight Chandra observations from 2007 to 2008. The X-ray spectra are fitted and decomposed into disk and flaring components. This year-scale X-ray variability can be explained quite well by a simple clumpy accretion model. We conclude that the central super-massive black hole of M87 was accreting a cloud of ~ 0.5 M⊙at that time.

关键词： galaxies:active X-ray:individual:M87

Pushing the Boundaries of Molecular Property Prediction for Drug Discovery with Multitask Learning BERT Enhanced by SMILES Enumeration

在线全文

学校读者我要写书评

暂无评论

Research 2023年第3期2022卷 157-170页

作者： Xiao-Chen Zhang cheng-Kun Wu Jia-Cai Yi xiang-xiang Zeng Can-Qun Yang ai-Ping Lu Ting-Jun Hou Dong-Sheng Cao xiangya School of Pharmaceutical Sciences Central South UniversityChangsha 410013Hunan P.R.China Shangqiu Normal University School of Information TechnologyShangqiu 476000HenanP.R.China College of Computer National University of Defense TechnologyChangsha 410005HunanP.R.China Department of Computer Science Hunan UniversityChangsha 410082.HunanP.R.China institute for Advancing Translational Medicine in Bone and Joint Diseases School of Chinese MedicineHong Kong Baptist UniversityHong Kong SAR 999077P.R.China Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University.College of Pharmaceutical Sciences Zhejiang UniversityHangzhou 310058ZhejiangP.R.China

Accurate prediction of pharmacological properties of small molecules is becoming increasingly important in drug *** feature-engineering approaches heavily rely on handcrafted descriptors and/or fingerprints,which need extensive human expert *** the rapid progress of artificial intelligence technology,data-driven deep learning methods have shown unparalleled advantages over feature-engineering-based ***,existing deep learning methods usually suffer from the scarcity of labeled data and the inability to share information between different tasks when applied to predicting molecular properties,thus resulting in poor generalization ***,we proposed a novel multitask learning BERT(Bidirectional Encoder Representations from Transformer)framework,named MTL-BERT,which leverages large-scale pre-training,multitask learning,and SMILES(simplified molecular input line entry specification)enumeration to alleviate the data scarcity ***-BERT first exploits a large amount of unlabeled data through self-supervised pretraining to mine the rich contextual information in SMILES strings and then fine-tunes the pretrained model for multiple downstream tasks simultaneously by leveraging their shared ***,SMILES enumeration is used as a data enhancement strategy during the pretraining,fine-tuning,and test phases to substantially increase data diversity and help to learn the key relevant patterns from complex SMILES *** experimental results showed that the pretrained MTL-BERT model with few additional fine-tuning can achieve much better performance than the state-of-the-art methods on most of the 60 practical molecular ***,the MTL-BERT model leverages attention mechanisms to focus on SMILES character features essential to target properties for model interpretability.

关键词： simplified generalization tuning

On the Cellular Indecomposable Property of Semi-Fredholm Operators

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 Annals of Mathematics,Series B 2012年第6期33卷 903-908页

作者： Guozheng cheng xiang FANG School of Mathematics Wenzhou University Department of Mathematics Kansas State University

The authors prove that an operator with the cellular indecomposable property has no singular points in the semi-Fredholm domain, by applying the 4 x 4 matrix model of semi-Fredholm operators due to Fang in 2004. This ... 详细信息

关键词： Cellular indecomposable property Semi-Fredholm operator Singular point

Optically Controlled Extraordinary Terahertz Transmission of Bi2Se3 Film Modulator

在线全文

学校读者我要写书评

暂无评论

Photonic Sensors 2019年第3期9卷 268-276页

作者： Junhu ZHOU Tong ZHOU Dongsheng YANG Zhenyu WANG Zhen ZHANG Jie YOU Zhongjie XU Xin ZHENG xiang-ai cheng College of Advanced Interdisciplinary Studies National University of Defense Technology Changsha 410073 China State Key Laboratory of High Performance Computing National University of Defense Technology Changsha 410073 China National Innovation Institute of Defense Technology Academy of Military Sciences PLA China Beijing 100010 China State Key Laboratory of Laser Interaction with Matter Northwest Insti tute of Nuclear Technology Xi'an 710024 China

Standing on the potential for high-speed modulation and switching in the terahertz (THz) regime, all-optical approaches whose response speeds mainly depend on the lifetime of nonequilibrium free carriers have attracted a tremendous attention. Here, we establish a novel bi-direction THz modulation experiment controlled by femtosecond laser for new functional devices. Specifically, time-resolved transmission measurements are conducted on a series of thin layers Bi2Se3 films fabricated straightforwardly on ai2O3 substrates, with the pump fluence range from 25(iJ/cm2 to 200 |iJ/cm2 per pulse. After photoexcitation, an ultrafast switching of THz wave with a full recovery time of ?1 Ops is observed. For a longer timescale, a photoinduced increase in the transmitted THz amplitude is found in the 8 and 10 quintuple layers (QL) BizSR, which shows a thickness-dependent topological phase transition. Additionally, the broadband modulation effect of the 8 QL Bi2Se3 film is presented at the time delays of 2.2ps and 12.5ps which have a maximum modulation depth of 6.4% and 1.3% under the pump fluence of 200(iJ/cm2, respectively. Furthermore, the absorption of a optical phonon at 1.9 THz shows a time-dependent evolution which is consistent with the cooling of lattice temperature.

关键词： Ultrafast optics topological insulator ultrafast photonic devices

Saturated absorption of different layered Bi_2Se_3 films in the resonance zone

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

Photonics Research 2018年第10期6卷 I0010-I0016页

作者： JUN ZHANG TIAN JIANG TONG ZHOU HAO OUYANG CHENXI ZHANG ZHENG XIN ZHENYU WANG xiang’ai cheng College of Advanced Interdisciplinary Studies National University of Defense Technology State Key Laboratory of High Performance Computing National University of Defense Technology College of Computer National Institute of Defense Technology Innovation Academy of Military Sciences PLA China

Here, we used the micro P-scan method to investigate the saturated absorption(SA) of different layered Bi_2Se_3 continuous films. Through resonance excitation, first, we studied the influence of the second surface state(SS) on SA. The second SS resonance excitation(～2.07 e V) resulted in a free carrier cross section that was 4 orders of magnitude larger than usual. At the same time, we found that the fast relaxation process of the massless Dirac electrons is much shorter than that of electrons in bulk states. Moreover, the second SS excitation resonance reduced the saturation intensity. Second, we studied the effect of the thickness on the SA properties of *** results showed that the saturation intensity was positively correlated to the thickness, the same as the modulation depth, and the thicker the Bi_2Se_3 film was, the less the second SS would influence it. This work demonstrated that by using Bi_2Se_3 as a saturable absorber through changing the thickness or excitation wavelength, a controllable SA could be achieved.

关键词：薄膜饱和强度通讯技术发展现状

混合植物蛋白添加晶体氨基酸替代鱼粉的饲料对花鱼种生长和免疫指标的影响

在线全文

学校读者我要写书评

暂无评论

水产学杂志 2010年第1期23卷 15-23页

作者：王吉桥程爱香闫有利李文宽闫彦春祁彩霞大连水产学院生命科学与技术学院辽宁大连116023 辽宁省淡水水产科学研究院辽宁辽阳111000

在水温25.0±3.0℃下,在以不同比例的玉米蛋白、棉籽粕和豆粕为蛋白源、部分替代鱼粉的饲料中,按鱼粉的必需基酸组成添加晶体赖氨酸、蛋氨酸和精氨酸,配制成5种等蛋白(37.0%)和等脂类(11.0%)的饲料,在60cm×60cm×120cm的微流水网箱中... 详细信息

在水温25.0±3.0℃下,在以不同比例的玉米蛋白、棉籽粕和豆粕为蛋白源、部分替代鱼粉的饲料中,按鱼粉的必需基酸组成添加晶体赖氨酸、蛋氨酸和精氨酸,配制成5种等蛋白(37.0%)和等脂类(11.0%)的饲料,在60cm×60cm×120cm的微流水网箱中饲养平均体质量14.84g,平均体长12.06cm的花鱼种。实验饲料分别含鱼粉28.0%(F0,对照)、21.0%(F1)、14.0%(F2)、7.0%(F3)和0%(F4)。100d的饲养中,花成活率变化在98.67%-100%之间,各组之间差异不显著(P>0.05),但对生长和饲料利用率却有显著影响。花特殊增重率随饲料中鱼粉替代比例的增加而降低,用植物蛋白替代25%(F1)的鱼粉,添加晶体氨基酸,鱼特殊增重率、免疫力和消化率最高,显著高于对照组(P0.05),但用植物蛋白全部替代(F4,100%)鱼粉,鱼的特殊增重率显著低于F2和F3组(P0.05),但蛋白质、总氨基酸、必需氨基酸和脂肪的含量高于对照鱼。

关键词：植物蛋白花鱼鱼粉氨基酸

黄芪、熟地和山楂等中草药对黄颡鱼生长和消化的影响

在线全文

学校读者我要写书评

暂无评论

水产学杂志 2008年第1期21卷 34-41页

作者：王吉桥祁彩霞程爱香闫彦春李文宽闫有利大连水产学院生命科学与技术学院辽宁大连116023 辽宁省淡水水产科学研究院辽宁辽阳111000

水温20.0-30.0℃下,鱼粉和豆饼为蛋白源的含粗蛋白42.0%的饲料中分别加入黄芪、党参等(F1);熟地、当归等(F2);山楂、麦芽等(F3)中草药,在60 cm×60 cm×120cm的流水网箱中饲养平均体重15.5g的黄颡鱼(Pelteobagrus fulvidraco Richardso... 详细信息

水温20.0-30.0℃下,鱼粉和豆饼为蛋白源的含粗蛋白42.0%的饲料中分别加入黄芪、党参等(F1);熟地、当归等(F2);山楂、麦芽等(F3)中草药,在60 cm×60 cm×120cm的流水网箱中饲养平均体重15.5g的黄颡鱼(Pelteobagrus fulvidraco Richardson),对照(F0)组不添加任何中草药,研究了中草药对1冬龄黄颡鱼生长与消化率的影响。结果表明,摄食中草药饲料的鱼特殊增重率分别比对照组提高了58.33%、8.33%和79.17%(P<0.01)。F1和F2组鱼肠道中蛋白酶和脂肪酶的活性分别比对照组高77.61%、47.52%和94.51%,67.07%(p<0.01),而淀粉酶的活性则降低,对饲料干物质、粗蛋白和粗脂肪的表观消化率增高。F1、F2和F3组实验黄肌肉中氨基酸的含量分别比F0组高7.67%、6.60%和6.23%,其中必需氨基酸含量高10.30%、7.52%和8.65%,蛋氨酸的增加量最大。

关键词：黄颡鱼中草药生长消化