检索结果-南通市图书馆

Changes in peripheral perfusion index within 72h of life in a cohort of very low birth weight infants

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 Medical Journal 2022年第10期135卷 1252-1254页

作者： Xiaojing Hu Conway Niu Ruyi Zheng Li Zhang Hongyan Chen Yun Cao Guoying Huang Neonatal Congenital Heart Disease Screening Office Children's Hospital of Fudan UniversityShanghai 201102China Department of Neonatology King Edward Memorial HospitalSubiacoPerthWestern Australia 6008Australia Department of Neonatology Children's Hospital of Fudan UniversityShanghai 201102China Department of Clinical Epidemiology and Clinical Trial Unit Children's Hospital of Fudan UniversityShanghai 201102China Shanghai Key Laboratory of Birth Defects Shanghai 201102China

To the Editor:The latest generation of pulse oximeters are equipped with technology allowing for monitoring of the peripheral perfusion index(PI),the percentage of the amount of light absorbed by pulsatile tissue(variable arterial blood flow)over non-pulsatile tissue(venous blood,muscle,and other tissues)at a wavelength of 940 nm as a signal.

关键词： index equipped weight

Wellbore stability analysis to determine the safe mud weight window for sandstone layers

在线全文

学校读者我要写书评

暂无评论

Petroleum Exploration and Development 2019年第5期46卷 1031-1038页

作者： DARVISHPOUR Ayoub CHERAGHI SEIFABAD Masoud WOOD David Anthony GHORBANI Hamzeh Department of Mining Engineering Isfahan University of TechnologyIsfahan ***Iran DWA Energy Limited LincolnLN59JPUnited Kingdom Southern Oil Fields National Iranian Oil CompanyTeheran ***Iran

The wellbore stability of a vertical well through the sandstone reservoir layers of the Asmari oil-bearing formation in south-west Iran is *** safe drilling-fluid density range for maintaining wellbore stability is determined and simulated using FLAC3 D software and a finite volume model established with drilled strata geomechanical *** initiation of plastic condition is used to determine the safe mud weight window(SMWW)in specific sandstone *** effects of rock strength parameters,major stresses around the wellbore and pore pressure on the SMWW are investigated for this *** analysis reveals that a reduction in cohesion and internal friction angle values leads to a significant narrowing of the *** the other hand,the reduction of pore pressure and the ratio between maximum and minimum horizontal stresses causes the SMWW to widen *** ability to readily quantify changes in SMWW indicates that the developed model is suitable as a well planning and monitoring tool.

关键词： wellbore stability wellbore geomechanical property safe mud weight window wellbore instability risk factors drilling stress simulation

同方期刊数据库

Molecular weight Dependence of Associative Behavior in Polyimide/DMF Solutions

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第6期38卷 629-637页

作者： Hong-Xiang Chen En-Song Zhang Mei Hong Wei Liu Xue-Min Dai Quan Chen Xue-Peng Qiu Xiang-Ling Ji State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei230026China Laboratory of Polymer Composites and Engineering Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

Eight 6FDA-TFDB polyimide(PI)samples with absolute molecular weights ranging from 1.25 × 10^5 g mol^-1 to 3.11 × 10^5 g mol^-1 are obtained by precipitation *** experiments are conducted to determine the influence of molecular weight on the associating behavior of PI in A/X-dimethylformamide(DMF)solutions in a broad volume fraction,including abnormal steady shear flow,solution heterogeneity,and scaling *** flow behaviors,i.e.,multi-region shear thinning and weak shear thickening,are studied,and these behaviors have not been reported in *** heterogeneity of PI/DMF solutions is examined by dynamic rheological *** plotting qsp versus four concentration regions of l-IV can be distinguished for all PI samples with various molecular *** scaling results in different concentration regions are in good agreement with the associative polymer theory proposed by Rubinstein and *** scaling exponents do not show molecular weight dependence in concentration regions I and *** concentration regions Ⅲ and Ⅳ,the scaling exponents change little when the molecular weight is below 242 k but increase when the molecular weight increases from 242 k to 311 *** work can help us to understand polyimide solution properties from dilute to semidilute entangled solutions,and will guide the polyimide solution preparation for different processing.

关键词： Soluble polyimide Molecular weight Rheology Associative polymer Scaling behavior

Preparation of Ultralow Molecular weight Poly(vinyl chloride) with Submicrometer Particles via Precipitation Polymerization

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2019年第7期37卷 646-653页

作者： Peng Cui Chang-Tong Song Xian-Hong Zhang Dong Chen Yu-Hong Ma Wan-Tai Yang State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China College of Material Science and Engineering Beijing University of Chemical TechnologyBeijing 100029China

Poly(vinyl chloride), with ultralow molecular weight, produced by free radical polymerization either at high temperature or in the presence of chain transfer agents, is widely used as special resins and polymer process additives. This paper reports a new process, called self-stabilized precipitation polymerization, in which the polymerization of vinyl chloride monomer (VCM) is conducted in hydrocarbon diluents without addition of any suspending agent or emulsifier. The merits of this novel strategy include:(1) PVC resins with ultra-low number-average molecular weight (Mn) from 4000 to 15000, which is much lower than Mn of those prepared by conventional suspension and emulsion polymerizations,(2) sub-micrometer PVC particles with near spherical morphology, and (3) the very simple post-polymerization separation process. Under mild stirring, polymerization proceeds stably and smoothly. The influences of main process factors, such as solvents, initiator and monomer concentrations, polymerization time, and temperature on both particle morphology and Mn of the polymer products are investigated systematically. The molar ratio of-CH2-CHCl-/-CH=CH-CH2CHCl, a good indicator of structural defects, is about 1000/0.1 which means the low molecular weights do not result from chain transfer to the monomers. Then the mechanism of this polymerization is proposed. In summary, this novel polymerization technology provides a straightforward method for preparing PVC particulate products with low Mn.

关键词： Precipitation polymerization Vinyl chloride Ultralow molecular weight Pure product

Complete weight Enumerator for a Class of Linear Codes from Defining Sets and Their Applications

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2019年第3期32卷 947-969页

作者： LIU Haibo LIAO Qunying WANG Xiaofeng 不详 Institute of Mathematics and Software Science Sichuan Normal University College of Mathematics and Statistics Shenzhen University

Recently, linear codes over finite fields with a few weights have been extensively studied due to their applications in secret sharing schemes, authentication codes, constant composition codes. In this paper, for an odd prime p,the complete weight enumerator of a class of p-ary linear codes based on defining sets are determined. Furthermore, from the explicit complete weight enumerator of linear codes, a new class of optimal constant composition codes and several classes of asymptotically optimal systematic authentication codes are obtained.

关键词： Authentication codes complete weight enumerator constant composition codes exponential sums linear codes secret sharing schemes weight distributions

Construction mechanism of whitenization weight function and its application in grey clustering evaluation

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2019年第1期30卷 121-131页

作者： XIE Naiming SU Bentao CHEN Nanlei College of Economics and Management Nanjing University of Aeronautics and Astronautics

The clustering evaluation can be used to scientifically classify the objects to be evaluated according to the information aggregation of various evaluation rules. In grey weighted clustering evaluation, the index clustering rule relies on the construction of the whitenization weight function, while the existing construction method of the linear function lacks the construction mechanism analysis and validity explanation. A normative construction principle is put forward by analyzing the construction mechanism of the function. Through proving the normative principle of the function,the basic modal function(BMF) is proposed and characterized by different function forms. Then, a new type of the whitenization weight function and its grey clustering evaluation model algorithm are given by studying the mechanism and nature of the construction of different forms of the function. Finally, the comparative study for self-innovation capability of defense science and technology industry(DSTI) is taken as an example. The results show that the different construction ways of the function have an effect on the clustering result. The proposed construction mechanism can better explain the index clustering rules and evaluation effectiveness,which will perfect the theoretical system of grey clustering evaluation and be applied to practice effectively.

关键词： whitenization weight function grey system theory grey clustering evaluation.

weight strings and weight sets of modules over generalized Kac-Moody algebras

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1996年第4期41卷 281-286页

作者：靳一东张知学 Department of Mathematics Hebei University Baoding 071002 ChinaDepartment of Mathematics Hebei University Baoding 071002 China

Borcherds first introduced the so-called generalized Kac-Moody (GKM) algebras. Most of the results about ordinary Kac-Moody algebras can be generalized to these new algebras (cf. ref. [1] and §11.13 in ref. [2]). In the present note we discuss some properties about weight strings and weight sets of the module L(Λ) over a generalized Kac-Moody algebra.

关键词： generalized Kac-Moody algebra weight string weight set.

Controlling Heat Transfer for the Manufacturing of High Molecular weight Polyisobutylene via Formation of Micelles

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2019年第9期37卷 898-902页

作者： Szilard Csihony Nicole Janssen Klaus Mühlbach Advanced Materials & Systems

An alternative cationic polymerization method is developed to produce high molecular weight polyisobutylene (HM-PIB) with molecular weights above 5×10^5g/mol. The method involves micelle formation via functionalized low molecular weight polyisobutylene (LM-PIB) in non-polar solvent. One end of LM-PIB is modified with an imidazolium-containing ionic group, which together with the anion (eg. Al2Cl7) works as Lewis acid. While the monomer isobutylene dissolves readily in non-polar solvent, polymerization can occur only within the micelle, which affords stable HM-PIB particles. HM-PIB with a molecular weight (MW) close to 1 × 10^6 g/mol was produced successfully with the described method.

关键词： Cationic polymerization High molecular weight polyisobutylene Micelle

Analysis and research on Maximum Power Point Tracking of Photovoltaic Array with Fuzzy Logic Control and Three-point weight Comparison Method

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2010年第8期53卷 2183-2189页

作者： LIN Kuang-Jang LIN Chii-Ruey Department of Energy and Refrigerating Air-Conditioning Engineering NTUTTaipeiChina Department of Mechanical Engineering NTUTTaipeiChina

The Photovoltaic Array has a best optimal operating point where the array operating can obtain the maximum ***, the optimal operating point can be compromised by the strength of solar radiation,angle,and by the change of environment and *** to the constant changes in these conditions,it has become very difficult to locate the optimal operating point by following a mathematical ***,this study will focus mostly on the application of Fuzzy Logic Control theory and Three-point weight Comparison Method in effort to locate the optimal operating point of solar panel and achieve maximum efficiency in power generation. The Three-point weight Comparison Method is the comparison between the characteristic curves of the voltage of photovoltaic array and output power;it is a rather simple way to track the maximum *** Fuzzy Logic Control,on the other hand,can be used to solve problems that cannot be effectively dealt with by calculation rules,such as concepts,contemplation, deductive reasoning,and ***,this paper uses these two kinds of methods to make simulation successively. The simulation results show that,the Three-point Comparison Method is more effective under the environment with more frequent change of solar radiation;however,the Fuzzy Logic Control has better tacking efficiency under the environment with violent change of solar radiation.

关键词： Photovoltaic Array Maximum Power Point Tracking(MPPT) Fuzzy Logic Control Three-point weight Comparison Method