检索结果-南通市图书馆

Birhodomolleins D and e, two new dimeric grayanane diterpenes with a 3-O-2＇ linkage from the fruits of Rhododendron pumilum

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2018年第1期29卷 123-126页

作者： RuiZhang Chunping Tang Chang-Qiang ke Sheng yao Ge Lin yang ye State key Laboratory of Drug Research and Natural Products Chemistry Department Shanghai Institute of Materia Medica Chinese Academy of Sciences Shanghai 201203 China University of Chinese Academy of Sciences Beijing 100049 China SIMM-CUHK Joint Research Laboratory for Promoting Globalization of Traditional Chinese Medicines between Shanghai Institute of Materia Medica Chinese Academy of Sciences and The Chinese University of Hang Kong Hang Kong SAR China School of Biomedical Sciences The Chinese University of Hang Kong Hang Kong SAR China School of Life Science and Technology ShanghaiTech University Shanghai 201210 China

Two new dimeric diterpenes, birhodomolleins D （1） and e （2）, were characterized from the fruits of Rhododendron pumilum. Their structures featured two grayanane diterpenes dimerized through an oxygen bridge locating at C-3 and C-2＇. They are the first examples of dimeric grayanane diterpenes with a 3-O-2＇ linkage from the ericaceae family. Their structures were elucidated on the basis of comprehensive analysis of spectroscopic data.

关键词： Rhododendron pumilumericaceaeDimeric diterpeneGrayananeBirhodomollein DBirhodomollein e

Giant magnetocaloric effect in Tb_5Ge_(2-x)Si_(2-x)Mn_(2x) compounds

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第5期19卷 542-548页

作者： e.yzak B.emre y.elerman A.ycel department of engineering Physics Faculty of EngineeringAnkara University06100 BesevlerAnkaraTurkey Faculty of Science and Letters Physics DepartmentMugla UniversityKtekli 48000 MuglaTurkey

The crystal structure, magnetic and magnetocaloric characteristics of the pseduo ternary compounds of TbsGe2-xSi2-xMn2x （0 ≤ 2x ≤ 0.1） were investigated by x-ray powder diffraction and magnetization measurements. The x-ray powder diffraction results show that all compounds preserve the monoclinic phase as the majority phase and all the synthesized compounds were observed to be ferromagnetic from magnetization measurements. Magnetic phase transitions were interpreted in terms of Landau theory. Maximum isothermal magnetic entropy change value （20.84 J-kg-1 -K-1） was found for Tb5Ge1.95Si1.95Mn0.1 at around 123 K in the magnetic field change of 5T.

关键词： magnetic properties magnetocaloric effect isothermal magnetic entropy change

ANALySIS OF OSCILLATORy BLOOD FLOW IN VARyING-AReA eLASTIC VeSSeL

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2003年第6期15卷 16-24页

作者： Gong ke-qin Biomechanics Laboratory Fudan University Shanghai 200433 Chinae-mail:jxegong 1981

In this paper, by solving the fundamental e-qualions of periodicallyoscillatory blood flow, the distributions of pressure gradient and blood velocity in varying-areae-lastic vessel were obtained, and then the wall shear stress and its gradient were calculated. Asan example, the pulsatile blood flow in human carotid was analyzed and the effects of vessel taperangle on the distribution of wall shear stress and its gradient were discussed in detail. Numercialresults show that the wall shear stress will enlarge when the taper angle increases. Meantime, nomatter whether the vessel is converging or diverging, with the increase of the absolute value oftaper angle, the amplitude of wall shear stress gradient will enlarge significantly.

关键词： elastic vessel shear stress taper angle carotid oscillatory flow

On M-theory on real toric fibrations

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2021年第8期73卷 67-74页

作者： A Belhaj H Belmahi M Benali S-e ennadifi y Hassouni y Sekhmani equipe des Sciences de la matière et du rayonnement ESMaRDépartement de Physique Facultédes SciencesUniversitéMohammed V de RabatMorocco LHeP-MS Département de PhysiqueFaculte des SciencesUniversitéMohammed V de RabatMorocco

Borrowing ideas from elliptic complex geometry, we approach M-theory compactifications on real fibrations. Precisely, we explore real toric equations rather than complex ones exploited in F-theory and related dual models. These geometries have been built by moving real toric manifolds over real bases. Using topological changing behaviors, we unveil certain data associated with gauge sectors relying on affine lie symmetries.

关键词： real fibrations M-theory toric real manifolds affine lie symmetries

Multi-objective Optimization of the Distributed Permutation Flow Shop Scheduling Problem with Transportation and eligibility Constraints

在线全文

学校读者我要写书评

暂无评论

Journal of the Operations Research Society of China 2018年第3期6卷 391-416页

作者： Shuang Cai ke yang ke Liu Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China key Laboratory of Management Decision and Information SystemsChinese Academy of SciencesBeijing 100190China National Center for Mathematics and Interdisciplinary Sciences Chinese Academy of SciencesBeijing 100190China

In this paper,we consider the distributed permutation flow shop scheduling problem(DPFSSP)with transportation and eligibility *** objectives are taken into account,i.e.,makespan,maximum lateness and total costs(transportation costs and setup costs).To the best of our knowledge,there is no published work on multi-objective optimization of the DPFSSP with transportation and eligibility ***,we present the mathematics model and constructive heuristics for single objective;then,we propose an improved The Nondominated Sorting Genetic Algorithm II(NSGA-II)for the multi-objective DPFSSP to find Pareto optimal solutions,in which a novel solution representation,a new population re-/initialization,effective crossover and mutation operators,as well as local search methods are *** on extensive computational and statistical experiments,the proposed algorithm performs better than the well-known NSGA-II and the Strength Pareto evolutionary Algorithm 2(SPeA2).

关键词： Multi-objective optimization Distributed scheduling Permutation flow shop scheduling Transportation NSGA-II

Dynamic Plastic deformation (DPD):A Novel Technique for Synthesizing Bulk Nanostructured Metals

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

Journal of Materials Science & Technology 2007年第6期23卷 771-774页

作者： Nairong TAO ke LU Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

While some superior properties of nanostructured materials （with structural scales below 100 nm） have attracted numerous interests of material scientists, technique de.e.opment for synthesizing nanostructured metals and alloys in 3-dimensional （3D） bulk forms is still challenging despite of extensive investigations over decades. Here we report a novel synthesis technique for bulk nanostructured metals based on plastic deformation at high Zener-Hollomon parameters （high strain rates or low temperatures）, i.e., dynamic plastic deformation （DPD）. The basic concept behind this approach will be addressed together with a few examples to demonstrate the capability and characteristics of this method. Perspectives and future de.e.opments of this technique will be highlighted.

关键词： Nanostructured materials

Catalytic Hydrogenation of Methanol-Containing effluent from epoxidation of Propylene

在线全文

学校读者我要写书评

暂无评论

China Petroleum Processing & Petrochemical Technology 2015年第3期17卷 94-101页

作者： Cheng ke SINOPeC Luoyang Petrochemical Complex

This paper describes the hydrogenation of impurities in the methanol-containing effluent from the propylene epoxidation process with hydrogen peroxide. The effects of reaction temperature, pressure, weight hourly space velocity(WHSV) and H2/methanol ratio on the concentration of various impurities in methanol solvent were investigated. It was found out that the aldehyde, hydrogen peroxide and nitro compounds in the methanol solvent could be completely hydrogenated over the Ni catalyst under proper reaction conditions. 90% of acetone and up to 50% of acetals(ketals) existing in the methanol solvent could be hydrogenated. No significant change was observed for the rest of the impurities that were present in the methanol solvent(i. e., 1-methoxy-2-propanol, 2-methoxy-1-propanol and 1,2-propanediol). The H2O2 decomposition reaction was enhanced using Ni catalyst, through the formation of NioOH, but no oxygen was found in the off-gas of hydrogenation reaction since NioH could react on NioOH formed via dissociative adsorption of hydrogen peroxide, or on NioO formed via adsorption of oxygen.

关键词： propylene epoxidation methanol hydrogenation

endoscopic dacryocystorhinostomy with bicanalicular silicone tube intubation for treating chronic dacryocystitis secondary to nasolacrimal duct stent incarceration

在线全文

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(english edition) 2023年第8期16卷 1218-1223页

作者： Shan Lan Jin-Qiang yu Feng ke de-Kun Li Bo yu Zhen-Kai Liu department of Radiology Renmin HospitalHubei University of MedicineShiyan 442000Hubei ProvinceChina department of Ophthalmology Renmin HospitalHubei University of MedicineShiyan 442000Hubei ProvinceChina National Clinical Research Center for Ocular Diseases Eye HospitalWenzhou Medical UniversityWenzhou 325027Zhejiang ProvinceChina

AIM:To investigate the feasibility of endoscopic dacryocystorhinostomy(en-DCR)with bicanalicular silicone tube intubation for treating chronic dacryocystitis secondary to nasolacrimal duct stent(NDS)***:en-DCRs were performed on 44 chronic dacryocystitis patients(46 eyes)secondary to NDS incarceration from April 2016 to October *** granuloma and scar tissues were separated,and the removal of NDS incarceration was achieved during the surgery;the flap of the lacrimal sac was trimmed and anastomosed with nasal mucosal,a bicanalicular silicone tube was implanted,and lacrimal size and condition were *** tube was removed 3mo after *** the final follow-up of 12mo when the surgery was completed,the complications and the rates of surgical success were ***:This study covered 40 patients(42 eyes).Intraoperatively,it was found that the lacrimal sac became small,and the sac wall had granulation and scar tissue attached to the incarcerated NDS in all *** 12mo after surgery completed,the rates of the functional and anatomical success reached 80.95%(34/42)and 83.33%(35/42),*** the effect of intranasal ostial closure,seven eyes failed to achieve anatomical *** serious complications(e.g.,visual impairment,sinusitis,and orbital fat prolapse)was ***:With the success rate over 80%and no serious complications,en-DCR with bicanalicular silicone tube implantation is effective in treating chronic dacryocystitis secondary to NDS incarceration.

关键词： endoscopic dacryocystorhinostomy bicanalicular silicone tube nasolacrimal duct stent incarceration

Flare Forecast Model Based on DS-SMOTe and SVM with Optimized Regular Term

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 2023年第6期23卷 38-46页

作者： Jie Wan Jun-Feng Fu Ren-Qing Wen ke Han Meng-yao yu Peng e School of electrical engineering and Automation Harbin Institute of TechnologyHarbin 150001China Laboratory for Space environment and Physical Sciences Harbin Institute of TechnologyHarbin 150001China School of Computer and Information engineering Harbin University of CommerceHarbin 150028China

The research of flare forecast based on the machine learning algorithm is an important content of space *** order to improve the reliability of the data-driven model and weaken the impact of imbalanced data set on its forecast performance,we proposes a resampling method suitable for flare forecasting and a Particle Swarm Optimization(PSO)-based Support Vector Machine(SVM)regular term optimization *** the problem of intra-class imbalance and inter-class imbalance in flare samples,we adopt the density clustering method combined with the Synthetic Minority Over-sampling Technique(SMOTe)oversampling method,and performs the interpolation operation based on euclidean distance on the basis of analyzing the clustering space in the minority *** the same time,for the problem that the objective function used for strong classification in SVM cannot adapt to the sample noise,In this research,on the basis of adding regularization parameters,the PSO algorithm is used to optimize the hyperparameters,which can maximize the performance of the ***,through a comprehensive comparison test,it is proved that the method designed can be well applied to the flare forecast problem,and the effectiveness of the method is proved.

关键词： Sun:flares Sun:magnetic fields Sun:X-rays gamma-rays (Sun:)sunspots