检索结果-南通市图书馆

A Real-time Data Model Based on Temporal Data

在线全文

学校读者我要写书评

暂无评论

Journal of China University of Mining and Technology 2006年第3期16卷 312-316页

作者： ZHANG xiao-fang liu yun-sheng College of Computer Science and Technology Huazhong University of Science and Technology Wuhan Hubei 430074 China

Real-time database systems contain not only transaction timing constraints, but also data timing constraints. This paper discusses the temporal characteristics of data in real-time databases and offers a definition of absolute and relative temporal consistency. In real-time database systems, it is often the case that the policies of transaction schedules only consider the deadline of real-time transactions, making it insufficient to ensure temporal correctness of transactions. A policy is given by considering both the deadlines of transactions and the “data deadline” to schedule real-time transactions. A real-time relational data model and a real-time relational algebra based on the characteristics of temporal data are also proposed. In this model, the temporal data has not only corresponding values, but also validity intervals corresponding to the data values. At the same time, this model is able to keep historical data values. When validity interval of a relation is [NOW, NOW], real-time relational algebra will transform to traditional relational algebra.

关键词： real-time database temporal data real-time data model

An Improved Car-Following Model for Multiphase Vehicular Traffic Flow and Numerical Tests

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2006年第2X期46卷 367-373页

作者： LI Zhi-Peng GONG xiao-Bo liu yun-Cai Institute of Image Processing and Pattern Recognition Shanghai Jiaotong University Shanghai 200240 China

This paper attempts to introduce an improved difference model that modifies a car-following model, which takes the next-nearest-neighbor interaction into account. The hnprovement of this model over the previous one lies in that it performs more realistically in the dynamical motion for small delay time. The traffic behavior of the improved model is investigated with analytic and numerical methods with the finding that the new consideration could further stabilize traffic flow. And some simulation tests verify that the proposed model can demonstrate some complex physical features observed recently in real traffic such as the existence of three phases： free flow, coexisting flow, and jam flow; spontaneous formation of density waves; sudden flow drop in flow-density plane; traffic hysteresis in transition between the free and the coexisting flow. Furthermore, th.e improved model also predicts that the stable state to relative density in the coexisting flow is insusceptible to noise.

关键词： car-following models density waves traffic flow

Self-assembly of Hollow PNIPAM Microgels to Form Discontinuously Hollow Fibers

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2014年第11期32卷 1544-1549页

作者： xiao-yun liu Jian-mao Yang 查刘生 Zi-jun Jiang Research Center for Analysis and Measurement Donghua University State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Donghua University

A new kind of hollow hydrogel microfiber with discontinuous hollow structure was prepared by an ice-segregation-induced self-assembly process. Monodisperse thermo-responsive hollow poly（N-isopropylacrylamide）（PNIPAM） microgels were first synthesized by seed precipitation polymerization using colloidal Si O2 nanoparticles as seeds, followed by removing the silica cores of the formed Si O2/PNIPAM core/shell composite microgels with hydrofluoric acid. Then, the discontinuously hollow hydrogel microfibers were produced by unidirectional freezing of 1 wt% hollow PNIPAM microgel aqueous dispersion in liquid nitrogen bath, followed by freeze-drying to remove the formed ice crystals. Many orderly arrayed dents were observed on the surfaces of the hydrogel microfibers by field-emission scanning electron microscopy, indicating that they are constructed by closely packed monodisperse hollow PNIPAM microgels. The effect of freezing method and the hollow microgel concentration in the aqueous dispersion on the morphological structure of the hollow hydrogel microfibers was investigated.

关键词： Discontinuously hollow microfiber Ice-segregation-induced self-assembly Thermo-responsiveness N-isopropylacrylamide Microgel.

Cellulose Nanocrystals-mediated Phase Morphology of PLLA/TPU Blends for 3D Printing

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2022年第3期40卷 299-309,I0008页

作者： xiao Wu yun-xiao liu Hai-Peng Wu Hao Wu Hai-Jun Wang Yong-Xin Duan Jian-Ming Zhang Key Laboratory of Rubber-Plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-plasticsQingdao University of Science&TechnologyQingdao 266042China Shaanxi University of Science and Technology Xi’an 710021China

Incorporation of nanoparticles into polymer blend to obtain finely dispersed morphology has been considered as an effective strategy to prepare nanocomposites. Owing to the renewable and degradable characters, cellulose nanocrystals(CNCs) have been proposed to tailor the phase morphology of poly(L-lactic acid)(PLLA) blend for producing high-performance fused deposition modeling(FDM) consumables. However,the main challenge associated with the ternary systems is the dispersion of the highly hydrophilic CNCs in non-polar PLLA blend by industrial melt blending without involving solution. Herein, with poly(vinyl acetate)(PVAc) modified CNCs powder(a mixture of PVAc grafted from CNCs and PVAc homopolymer latex), the selective dispersion of CNCs in PLLA has been achieved by simple melt processing of PLLA/TPU(polyether polyurethane)/CNCs blend. This results in the ultra-fine TPU droplets at nanoscale in PLLA and improves the melt processibility of composites in FDM due to the decreased viscosity ratio of the dispersed/matrix and the enhanced melt elasticity of PLLA. Combined with the intensive shear and continuous stretch effect during FDM, aligned TPU nanofibers(TNFs) were in situ formed along the elongational flow direction during deposition, which in turn contributed to the improvement of PLLA/TPU/CNCs with 5 wt% filler loading in tensile ductility by 418%, inter-layer adhesion strength and notched impact toughness by 261% and 210%, respectively, as well as achieved good dimensional accuracy and very fine surface quality.

关键词： Poly(L-lactic acid)blend Cellulose nanocrystals Phase morphology tailoring 3D printing Rheo-viscoelastic properties

Coexistence of cervical extramedullary plasmacytoma and squamous cell carcinoma:A case report

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2021年第24期9卷 7110-7116页

作者： Qing-yun Zhang Ting-Chao Li Jiang Lin Lian-Li He xiao-yun liu Department of Gynecology and Obstetrics The First People’s Hospital of Zunyi and Third Affiliated Hospital of Zunyi Medical UniversityZunyi 563000Guizhou ProvinceChina Pathology Department The First People’s Hospital of Zunyi and Third Affiliated Hospital of Zunyi Medical UniversityZunyi 563000Guizhou ProvinceChina Imaging Department The First People’s Hospital of Zunyi and Third Affiliated Hospital of Zunyi Medical UniversityZunyi 563000Guizhou ProvinceChina

BACKGROUND Extramedullary plasmacytoma(EMP),a variant form of myeloma,is a rare solid plasma cell tumor that originates from the bone marrow hematopoietic tissue and accounts for about 3%of all plasma cell *** can affect various tissues and organs,about 90%of which is found in the head and ***,EMP in the reproductive organs is rare,and is difficult to be distinguished from other primary or metastatic genital tumors according to clinical symptoms and imaging *** SUMMARY Herein,we report a case with coexistence of EMP and squamous cell carcinoma in the *** first histopathological report of neoplasms on the surface of the cervix and vagina showed an *** ultrasound and pelvic enhanced magnetic resonance imaging(MRI)indicated that there was a tumor in the ***,another cervical biopsy and pathological examination were performed,which indicated EMP combined with squamous cell ***,the patient underwent extensive total hysterectomy(type C1)+systemic lymph node dissection and received 25 external pelvic irradiations with a dose of 50 Gy following *** 2-year follow-up,no recurrence was *** In conclusion,EMP involving the reproductive system is relatively *** this case,MRI,B-ultrasound,and cervical canal scraping were used to further determine the diagnosis of EMP combined with squamous cell *** patient had improved prognosis after appropriate treatments.

关键词： Extramedullary plasmacytoma Cervical squamous cell carcinoma Magnetic resonance imaging Vaginal ultrasound Pathology Case report

Endogenous hydrogen sulfide and ERK1/2-STAT3 signaling pathway may participate in the association between homocysteine and hypertension

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 Geriatric Cardiology 2019年第11期16卷 822-834页

作者： Lin SHI xiao-yun liu Zhi-Gang HUANG Zhi-Yi MA Yang XI Lu-Yan WANG Ning-Ling SUN Hypertension Research Laboratory Department of CardiologyPeking University People’s HospitalBeijingChina Emergency Department Peking University Shenzhen HospitalShenzhenChina

Background Homocysteine(Hcy)is a risk factor for hypertension,although the mechanisms are poorly *** We first explored the relationship between Hcy levels and blood pressure(BP)by analyzing the clinical data of primary hypertensive patients admitted to our ***,we explored a rat model to study the effect of Hcy on blood pressure and the role of *** hyperhomocysteinemia(HHcy)rat model was induced to explore the effect of Hcy on blood pressure and the possible *** carried out tissue histology,extraction and examination of RNA and ***,we conducted cell experiments to determine a likely mechanism through renin-angiotensin-aldosterone system(RAAS)and extracellular signal-regulated kinase 1/2(ERK1/2)signaling *** In primary hypertensive inpatients with HHcy,blood pressure was significantly higher as compared with inpatient counterparts lacking *** the rat model,blood pressure of the Wistar rats was significantly increased with increases in serum Hcy levels and decreased after folate *** converting enzyme 1(ACE1)expression in the Wistar Hcy group was enhanced comparing to controls,but was decreased in the Wistar folate *** II receptor type 1(AGTR1)levels in the kidney tissue increased in the Wistar folate *** serum H2S and kidney cystathionineγ-lyase decreased with elevated levels of serum *** vitro,increased concentrations and treatment times for Hcy were associated with increased expression of collagen type 1 and *** dose and time dependent response was also observed for p-STAT3 and p-ERK1/2 *** Endogenous H2S might mediate the process of altered blood pressure in response to changes in serum Hcy levels,in a process that is partly dependent on activated RAAS and ERK1/2-STAT3 signaling pathway.

关键词： Angiotensin converting enzyme 1 Blood pressure ERK1/2-STAT3 signaling pathway Homocysteine Hydrogen sulfide

Protective effects of pinacidil hyperpolarizing cardioplegia on myocardial ischemia reperfusion injury by mitochondrial KATP channels

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2011年第24期124卷 4205-4210页

作者： YU Tian FU xiao-yun liu Xing-kui YU Zhi-hao Department of Anesthesiology Zunyi Medical College ZunyiGuizhou 563003 China

Background Many studies have indicated that hyperpolarizing cardioplegia is responsible for myocardial preservation and researchers have suggested that the adenosine triphosphate-sensitive potassium channels （KATe） were the end effectors of cardio-protection. But whether mitochondrial KATe plays an important role in hyperpolarizing cardioplegia is not apparent. The present study investigated the effect of hyperpolarizing cardioplegia containing pinacidil （a nonselective KATe opener） on ischemia/repeffusion injury in rat hearts, especially the role of mitochondrial KATe in pinacidil hyperpolarizing cardioplegia. Methods Sprague-Dawley rat hearts were Langendorff-perfused for 20 minutes with Krebs-Henseleit buffer at 37℃ before equilibration. Cardiac arrest was then induced in different treatments： there was no arrest and ischemia in the normal group, the control group were arrested by clamping the aorta, depolarizing caidioplegia （St. Thomas solution containing 16 mmol/L KCI） and hyperpolarizing cardioplegia groups used St. Thomas solution containing 0.05 mmol/L pinacidil and 5 mmol/L KCI to induce cardiac arrest in group hyperkalemic and group pinacidil, in group hyperkalemic ＋ 5-hydroxydecanote （5HD） and Pinacidil ＋ 5HD, 5HD （0.1 retool/L） was added to the above two solutions to block mitochondria KATe channels. Global ischemia was then administrated for 40 minutes at 37℃, followed by 30 minutes of reperfusion. At the end of equilibration and reperfusion, hemodynamics, ultrastructure, and mitochondrial function were measured. Results In the control group, ischemia/reperfusion decreased the left ventricular developed pressure, heart rate, coronary flow, mitochondrial membrane potential, impaired mitochondrial respiratory function, increased reactive oxygen species and left ventricular end diastolic pressure. Damage to myocardial ultrastructure was also evident. Both depolarized arrest and especially hyperpolarized cardioplegia significantly reduced these lesions

关键词： cardioplegic solutions heart arrest pinacidil ischemia/reperfusion injury myocardial mitochondrial ultrastructure potassium channel blockers

Molecular characterization and genetic analysis of Gnrh2 and Gthβin different ploidy level fishes

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

Progress in Natural Science:Materials International 2009年第11期19卷 1569-1579页

作者： Yu Long~1,Huan Zhong~1,Shaojun liu~*,Min Tao,Lin Chen,Jun xiao,yun liu Key Laboratory of Protein Chemistry and Developmental Biology of Education of Ministry of China,College of Life Sciences, Hunan Normal University,Changsha 410081,China Key Laboratory of Protein Chemistry and Developmental Biology of Education of Ministry of China College of Life Sciences Hunan Normal University Changsha 410081 China

The gonadotropin-releasing hormone(GnRH) and the gonadotropin hormone(GTH) play crucial roles in regulating the gonadal development of the *** this study,the Gnrh2,Fshβand LhβcDNAs were cloned and characterized in red crucian carp,triploids and tetraploids,and their phylogenetic relations were comparatively *** the Gnrh2 cDNAs in different ploidy fishes encoded proteins of 86 amino acids,which consisted of a signal peptide,a GnRH2 decapeptide and a GnRH-associated peptide (GAP) linked by a proteolytic cleavage site(Gly-Lys-Arg).The GnRH2 decapeptide and proteolytic cleavage site were absolutely consistent among the three ploidy fishes,but the differences in signal peptide and GAP between diploids and tetraploids were fewer than those between diploids and *** was presumed that the red crucian carp was the original maternal parent of tetraploids,so they had closer *** addition,the Fshβand LhβcDNAs of these three fishes encoded proteins of 130 and 140 amino acids,respectively. Compared with the molecules of other teleosts,the cysteine residues and potential glycosylation sites of Lhβin these three fishes are fully ***,most teleosts of Fshβhad 12 cysteine residues,while those of these three fishes were 13,and 12 of which might form six conserved disulfide bridges by utilizing the cleavage sites between the first and the second cysteine ***,the lack of the second glycosylation site in Fshβof these three fishes might influence the special structure and biological *** the other hand,the phylogenic tree analyses revealed that Gnrh2,Fshβand Lhβhad similar phylogeny relationships among the cyprinids, which indicated that they were conserved in molecular structure and function during the evolution.

关键词： Gnrh2 Gthβ Molecular structure Genetic analyses Triploids Tetraploids

The effectiveness of E-learning in continuing medical education for tuberculosis health workers: a quasi-experiment from China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Infectious Diseases of Poverty 2021年第3期10卷 102-102页

作者： Zi-Yue Wang Li-Jie Zhang Yu-Hong liu Wei-Xi Jiang Jing-yun Jia Sheng-Lan Tang xiao-yun liu China Centre for Health Development Studies Peking UniversityBeijing 100191China 不详

Background:Given the context of rapid technological cha nge and COIVD-19 pan demies,E-lear ning may provide a unique opportunity for addressing the challenges in traditional face-to-face continuing medical education(CME).However,the effectiveness of E-learning in CME interventions remains *** study aims to evaluate whether E-learning training program can improve TB health personnel's knowledge and behaviour in China.

关键词： Continuing medical education Training Tuberculosis E-learning Program evaluation