期刊文献+
共找到2,136篇文章
< 1 2 107 >
每页显示 20 50 100
Memory effect in time fractional Schrödinger equation
1
作者 祖传金 余向阳 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期216-221,共6页
A significant obstacle impeding the advancement of the time fractional Schrodinger equation lies in the challenge of determining its precise mathematical formulation.In order to address this,we undertake an exploratio... A significant obstacle impeding the advancement of the time fractional Schrodinger equation lies in the challenge of determining its precise mathematical formulation.In order to address this,we undertake an exploration of the time fractional Schrodinger equation within the context of a non-Markovian environment.By leveraging a two-level atom as an illustrative case,we find that the choice to raise i to the order of the time derivative is inappropriate.In contrast to the conventional approach used to depict the dynamic evolution of quantum states in a non-Markovian environment,the time fractional Schrodinger equation,when devoid of fractional-order operations on the imaginary unit i,emerges as a more intuitively comprehensible framework in physics and offers greater simplicity in computational aspects.Meanwhile,we also prove that it is meaningless to study the memory of time fractional Schrodinger equation with time derivative 1<α≤2.It should be noted that we have not yet constructed an open system that can be fully described by the time fractional Schrodinger equation.This will be the focus of future research.Our study might provide a new perspective on the role of time fractional Schrodinger equation. 展开更多
关键词 time fractional Schrodinger equation memory effect non-Markovian environment
下载PDF
Long-term effectiveness,outcomes and complications of bariatric surgery 被引量:1
2
作者 Milena Gulinac Dimitrina Georgieva Miteva +11 位作者 Monika Peshevska-Sekulovska Ivan P Novakov Svetozar Antovic Milena Peruhova Violeta Snegarova Plamena Kabakchieva Yavor Assyov Georgi Vasilev Metodija Sekulovski Snezhina Lazova Latchezar Tomov Tsvetelina Velikova 《World Journal of Clinical Cases》 SCIE 2023年第19期4504-4512,共9页
Dietary imbalance and overeating can lead to an increasingly widespread disease-obesity.Aesthetic considerations aside,obesity is defined as an excess of adipose tissue that can lead to serious health problems and can... Dietary imbalance and overeating can lead to an increasingly widespread disease-obesity.Aesthetic considerations aside,obesity is defined as an excess of adipose tissue that can lead to serious health problems and can predispose to a number of pathological changes and clinical diseases,including diabetes;hypertension;atherosclerosis;coronary artery disease and stroke;obstructive sleep apnea;depression;weight-related arthropathies and endometrial and breast cancer.A body weight 20%above ideal for age,gender and height is a severe health risk.Bariatric surgery is a set of surgical methods to treat morbid obesity when other treatments such as diet,increased physical activity,behavioral changes and drugs have failed.The two most common procedures currently used are sleeve gastrectomy and gastric bypass.This procedure has gained popularity recently and is generally considered safe and effective.Although current data show that perioperative mortality is low and better control of comorbidities and short-term complications is achieved,more randomized trials are needed to evaluate the long-term outcomes of bariatric procedures.This review aims to synthesize and summarize the growing evidence on the long-term effectiveness,outcomes and complications of bariatric surgery. 展开更多
关键词 Bariatric surgery long-term outcomes OBESITY Roux-en-Y gastric bypass sleeve gastrectomy effectIVENESS SAFETY Quality of life
下载PDF
Effects of GBE50 on hippocampal CA1 synaptic plasticity,learning and memory in an experimental rat model of aging 被引量:9
3
作者 Lili Wu Xianwen Dong Gaiying He Zhixiong Zhang Ying Xu Xingyu Wang Yun Li 《Neural Regeneration Research》 SCIE CAS CSCD 2011年第12期892-897,共6页
The content of total flavonoids in an extract of Ginkgo biloba, called GBE50, is 44% by weight. This is significantly greater than that in a standard extract of Ginkgo biloba, designated EGB761. To date, the mechanism... The content of total flavonoids in an extract of Ginkgo biloba, called GBE50, is 44% by weight. This is significantly greater than that in a standard extract of Ginkgo biloba, designated EGB761. To date, the mechanisms by which GBE50 and EGB761 function remain poorly understood. In the present study, an experimental rat model of aging was induced by intraperitoneal injection of D-galactose, followed by intragastric perfusion of GBE50 (30, 60 mg/kg), or EGB761 (60 mg/kg). The water maze scores and hippocampal CA1 synaptic plasticity were evaluated. In the place navigation test, the GBE50 group rats did better than EGB761, while similar scores were obtained in the spatial probe test, and in the platform-switched test. In addition, long-term potentiation was significantly enhanced following high-frequency stimulation in the GBE50 and EGB761 groups, compared with the model group. These results demonstrate that GBE50 and EGB761 improved the learning and memory of aging rats. In particular, GBE50 administered at the 60 mg/kg dose exhibited superior effects over EGB761 at the same 60 mg/kg dose. Furthermore, the enhancement of hippocampal synaptic plasticity may be an underlying mechanism. 展开更多
关键词 AGING GBE 50 memory impairment HIPPOCAMPUS long-term potentiation neural regeneration
下载PDF
Effects of Chronic Administration of Melatonin on Spatial Learning Ability and Long-term Potentiation in Lead-exposed and Control Rats 被引量:4
4
作者 XIU-JING CAO MING WANG +3 位作者 WEI-HENG CHEN DA-MIAO ZHU JIA-QI SHE DI-YUN RUAN 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2009年第1期70-75,共6页
Objective To explore the changes in spatial learning performance and long-term potentiation (LTP) which is recognized as a component of the cellular basis of learning and memory in normal and lead-exposed rats after... Objective To explore the changes in spatial learning performance and long-term potentiation (LTP) which is recognized as a component of the cellular basis of learning and memory in normal and lead-exposed rats after administration of melatonin (MT) for two months. Methods Experiment was performed in adult male Wistar rats (12 controls, 12 exposed to melatonin treatment, 10 exposed to lead and 10 exposed to lead and melatonin treatment). The lead-exposed rats received 0.2% lead acetate solution from their birth day while the control rats drank tap water. Melatonin (3 mg/kg) or vehicle was administered to the control and lead-exposed rats from the time of their weaning by gastric gavage each day for 60 days, depending on their groups. At the age of 81-90 days, all the animals were subjected to Morris water maze test and then used for extracellular recording of LTP in the dentate gyrus (DG) area of the hippocampus in vivo. Results Low dose of melatonin given from weaning for two months impaired LTP in the DG area of hippocampus and induced learning and memory deficit in the control rats. When melatonin was administered over a prolonged period to the lead-exposed rats, it exacerbated LTP impairment, learning and memory deficit induced by lead. Conclusion Melatonin is not suitable for normal and lead-exposed children. 展开更多
关键词 MELATONIN LEAD Learning memory long-term potentiation (LTP)
下载PDF
Kongsheng Zhenzhong pill's effect on the learning and memory ability and its neuroprotective effects in vascular dementia rats 被引量:3
5
作者 Xuming Ji Huayun Yu +4 位作者 Bin Ouyang Guowei Liu Zhichun Wu Heng Liu Fang Du 《Neural Regeneration Research》 SCIE CAS CSCD 2011年第30期2342-2346,共5页
Clinical reports have demonstrated that the Kongsheng Zhenzhong pill (KSZZP), a classical prescription deriving from Valuable Prescription for Emergencies, has good therapeutic effects on vascular dementia. However,... Clinical reports have demonstrated that the Kongsheng Zhenzhong pill (KSZZP), a classical prescription deriving from Valuable Prescription for Emergencies, has good therapeutic effects on vascular dementia. However, the mechanisms that mediate its effects remain unclear. In this study, the expression of N-methyI-D-aspartate receptor 1 mRNA, the content of nitric oxide, and the concentration of calcium in neurons was determined with in situ hybridization, spectrophotometry and flow cytometry, respectively. In addition, the expressions of N-methyI-D-aspartate receptor 1, nerve growth factor protein, and glial cell line-derived neurotrophic factor protein were detected with immunohistochemistry. We found that KSZZP could significantly decrease the expression of N-methyI-D-aspartate receptor 1 mRNA and protein, the content of nitric oxide, and the concentration of calcium in neurons. KSZZP also increased the expression of nerve growth factor and glial cell line-derived neurotrophic factor protein in the hippocampus CA1 region and in the cerebral cortex. Morris water maze and passive avoidance tests verified that KSZZP ameliorated the cognitive impairments of vascular dementia rats. Moreover, the KSZZP-induced improvements in the cognitive functions of vascular dementia rats were correlated with both inhibition of N-methyl-D-aspartate-induced excitable neurotoxicity and elevation of neurotrophic factor expression. 展开更多
关键词 Kongsheng Zhenzhong pill vascular dementia learning and memory ability neuroprotective effects
下载PDF
EFFECTS OF HEAT TREATMENT ON TENSILE PROPERTIES AND SHAPE MEMORY EFFECTS OF Ni-Ti-Nb ALLOY 被引量:2
6
作者 Zheng Yufeng, Cai Wei, Luo Yichun, Zhao Liancheng School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 《中国有色金属学会会刊:英文版》 CSCD 1997年第4期93-97,共5页
EFFECTSOFHEATTREATMENTONTENSILEPROPERTIESANDSHAPEMEMORYEFFECTSOFNiTiNbALLOY①ZhengYufeng,CaiWei,LuoYichun,Z... EFFECTSOFHEATTREATMENTONTENSILEPROPERTIESANDSHAPEMEMORYEFFECTSOFNiTiNbALLOY①ZhengYufeng,CaiWei,LuoYichun,ZhaoLianchengSchoo... 展开更多
关键词 Ni Ti Nb ALLOY HEAT treatment TENSILE PROPERTIES SHAPE memory effect
下载PDF
Effects of Predeformation on the Reverse Martensitic Transformation of TiNi Shape Memory Alloy 被引量:14
7
作者 Yanjun ZHENG Lishan CUI +1 位作者 Fan ZHANG Dazhi YANG 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2000年第6期611-614,共4页
DSC was used to study the effects of predeformation on the reverse martensitic transformation of near-equiatomic TiNi alloy. Both the start temperature As and the finish temperature Af of the reverse transformation in... DSC was used to study the effects of predeformation on the reverse martensitic transformation of near-equiatomic TiNi alloy. Both the start temperature As and the finish temperature Af of the reverse transformation increased with increasing degree of predeformation, but the algebraic difference between As and Af decreased with increasing predeformation until it reached a minimum value, then remained unchanged with further deformation. Transformation heat also increased with increasing predeformation until it reached a maximum value, then decreased with further predeformation. All the phenomena above were considered to be closely related with the release of elastic strain energy during predeformation. 展开更多
关键词 TINI effects of Predeformation on the Reverse Martensitic Transformation of TiNi Shape memory Alloy
下载PDF
Effects of aging on the microstructure of a Cu-Al-Ni-Mn shape memory alloy 被引量:1
8
作者 U.Sari T.Kirindi +1 位作者 F.Ozcan M.Dikici 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2011年第4期430-436,共7页
The influence of aging on the microstructure and mechanical properties of Cu-11.6wt%Al-3.9wt%Ni-2.5wt%Mn shape memory alloy(SMA) was studied by means of scanning electron microscopy(SEM),transmission electron micr... The influence of aging on the microstructure and mechanical properties of Cu-11.6wt%Al-3.9wt%Ni-2.5wt%Mn shape memory alloy(SMA) was studied by means of scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffractometer,and differential scanning calorimeter(DSC).Experimental results show that bainite,γ2,and α phase precipitates occur with the aging effect in the alloy.After aging at 300°C,the bainitic precipitates appear at the early stages of aging,while the precipitates of γ2 phase are observed for a longer aging time.When the aging temperature increases,the bainite gradually evolves into γ2 phase and equilibrium α phase(bcc) precipitates from the remaining parent phase.Thus,the bainite,γ2,and α phases appear,while the martensite phase disappears progressively in the alloy.The bainitic precipitates decrease the reverse transformation temperature while the γ2 phase precipitates increase these temperatures with a decrease of solute content in the retained parent phase.On the other hand,these precipitations cause an increasing in hardness of the alloy. 展开更多
关键词 copper alloys shape memory effect martensitic transformations AGING PRECIPITATES
下载PDF
Microwave sintering effects on the microstructure and mechanical properties of Ti–51at%Ni shape memory alloys 被引量:1
9
作者 Mustafa K. Ibrahim E. Hamzah +2 位作者 Safaa N. Saud E. N. E. Abu Bakar A. Bahador 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2017年第3期280-288,共9页
Ti–51at%Ni shape memory alloys(SMAs) were successfully produced via a powder metallurgy and microwave sintering technique.The influence of sintering parameters on porosity reduction,microstructure,phase transformatio... Ti–51at%Ni shape memory alloys(SMAs) were successfully produced via a powder metallurgy and microwave sintering technique.The influence of sintering parameters on porosity reduction,microstructure,phase transformation temperatures,and mechanical properties were investigated by optical microscopy,field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),compression tests,and microhardness tests.Varying the microwave temperature and holding time was found to strongly affect the density of porosity,presence of precipitates,transformation temperatures,and mechanical properties.The lowest density and smallest pore size were observed in the Ti–51at%Ni samples sintered at 900°C for 5 min or at 900°C for 30 min.The predominant martensite phases of β2 and β19′ were observed in the microstructure of Ti–51at%Ni,and their existence varied in accordance with the sintering temperature and the holding time.In the DSC thermograms,multi-transformation peaks were observed during heating,whereas a single peak was observed during cooling;these peaks correspond to the presence of the β2,R,and β19′ phases.The maximum strength and strain among the Ti–51at%Ni SMAs were 1376 MPa and 29%,respectively,for the sample sintered at 900°C for 30 min because of this sample's minimal porosity. 展开更多
关键词 TITANIUM nickel alloys shape memory effect POWDER METALLURGY (PM) microwave HEATING SINTERING microstructure mechanical properties
下载PDF
Effects of Ta Addition on NiTi Shape Memory Alloys 被引量:3
10
作者 Jianlu MA, Jiangnan LIU+, Zhengpin WANG and Fei XUE (Dept. of Materials Science & Engineering, Xi’an Institute of Technology, Xi’an 710032, China) Kuang-Hsi WU and Zhongjie PU (Department of Mechanical Engineering, Florida International University, USA) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2000年第5期534-536,共3页
The effect of Ta addition on the martensitic transformation characteristics and the X-ray visibility on NiTi shape memory alloy have been studied in (Ni51Ti49)1-xTax system. It was found that the transformation temper... The effect of Ta addition on the martensitic transformation characteristics and the X-ray visibility on NiTi shape memory alloy have been studied in (Ni51Ti49)1-xTax system. It was found that the transformation temperatures of the Ni51Ti49 binary alloy increased drastically by an addition of 0~4 at. pet Ta, but only slightly when the concentration exceeded 4 at. pct; the addition of Ta greatly decreases the sensitivity of the martensitic transformations to the variation in the Ni-Ti ratio. The addition of Ta to the NiTi binary alloy can improve its X-ray visibility. 展开更多
关键词 NITI effects of Ta Addition on NiTi Shape memory Alloys TA
下载PDF
Effects of aging treatment on the microstructure and superelasticity of columnar-grained Cu71Al18Mn11 shape memory alloy 被引量:3
11
作者 Ji-li Liu Hai-you Huang Jian-xin Xie 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2016年第10期1157-1166,共10页
The effect of aging treatment on the superelasticity and martensitic transformation critical stress in columnar-grained Cu_(71)Al_(18)Mn_(11) shape memory alloy(SMA) at the temperature ranging from 250°C ... The effect of aging treatment on the superelasticity and martensitic transformation critical stress in columnar-grained Cu_(71)Al_(18)Mn_(11) shape memory alloy(SMA) at the temperature ranging from 250°C to 400°C was investigated. The microstructure evolution during the aging treatment was characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results show that the plate-like bainite precipitates distribute homogeneously within austenitic grains and at grain boundaries. The volume fraction of bainite increases with the increase in aging temperature and aging time, which substantially improves the martensitic transformation critical stress of the alloy, whereas the bainite only slightly affects the superelasticity. This behavior is attributed to a coherent relationship between the bainite and the austenite, as well as to the bainite and the martensite exhibiting the same crystal structure. The variations of the martensitic transformation critical stress and the superelasticity of columnar-grained Cu_(71)Al_(18)Mn_(11) SMA with aging-temperature and aging time are described by the Austin-Rickett equation, where the activation energy of bainite precipitation is 77.2 kJ ·mol1. Finally, a columnar-grained Cu_(71)Al_(18)Mn_(11) SMA with both excellent superelasticity(5%-9%) and high martensitic transformation critical stress(443-677 MPa) is obtained through the application of the appropriate aging treatments. 展开更多
关键词 copper aluminum manganese alloys shape memory effect columnar grains aging bainite superelasticity
下载PDF
The Function of Oxytocin in Memory —A General Review of Oxytocin’s Effect on Memory
12
作者 Fan Gao 《World Journal of Neuroscience》 2023年第4期192-209,共18页
Introduction: While oxytocin (OT) is widely recognized for its pivotal role in reproductive behavior and the formation of social bonds, there remains a significant gap in our understanding of its potential influence o... Introduction: While oxytocin (OT) is widely recognized for its pivotal role in reproductive behavior and the formation of social bonds, there remains a significant gap in our understanding of its potential influence on learning and memory processes, encompassing both social and non-social aspects. Thus this paper serves as an attempt to investigate the comprehensive role of OT in Physiological, Cognitive, and Behavioral processes. Method: A comprehensive literature review was conducted to assemble evidence related to the influence of OT on learning and memory. Studies encompassing both social and non-social memory were incorporated into the analysis. Additionally, molecular mechanisms through which OT could potentially impact neuronal activity in the hippocampus and amygdala, consequently affecting learning and memory, were also investigated. Results: Our review reveals a spectrum of evidence that both supports and contradicts the theory that OT plays a significant role in social and non-social memory. While certain studies suggest a positive impact of OT on memory, others present findings that argue otherwise. However, multiple potential molecular mechanisms were discovered that may elucidate OT’s effects on learning and memory, particularly its potential to modulate neuronal activity in the hippocampus and amygdala. Conclusion: Despite the mixed evidence, OT might have a significant role in both social and non-social memory. Identified molecular mechanisms propose potential ways in which OT could influence learning and memory. The key role appears to be the modulation of neuronal activity in the hippocampus and amygdala by OT. Furthermore, it is plausible that OT’s function in memory is crucial for the social behaviors previously associated with it. Future research is necessitated to fully unravel the exact mechanisms and implications of OT’s role in learning and memory. 展开更多
关键词 OXYTOCIN Learning and memory long-term memory Short-Term memory EMOTION
下载PDF
Pruned Volterra Models with Memory Effects for Nonlinear Power Amplifiers 被引量:1
13
作者 Pengpeng Li Qingfang Zhang +2 位作者 Ping Wang Zhongshan Xie Bing Liu 《Communications and Network》 2013年第3期570-572,共3页
In this letter, a novel model is proposed for modeling the nonlinearity and memory effects of power amplifiers. The classical Volterra model is modified through a function of the sum of nonlinearity order with sum of ... In this letter, a novel model is proposed for modeling the nonlinearity and memory effects of power amplifiers. The classical Volterra model is modified through a function of the sum of nonlinearity order with sum of memory length. The parameters of this model can be extracted in digital domain since the model is analyzed based on the envelope signals. The model we proposed enables a substantial reduction in the number of coefficients involved, and with excellent accuracy. 展开更多
关键词 VOLTERRA SERIES Power AMPLIFIER (PA) BEHAVIORAL Model memory effect
下载PDF
New finite strain elastoplastic equations for accurately and explicitly simulating pseudoelastic-to-plastic transition effects of shape memory alloys 被引量:1
14
作者 Siyu WANG Lin ZHAN +1 位作者 Huifeng XI Heng XIAO 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2020年第10期1583-1596,共14页
A new finite strain elatoplastic J2-flow model with coupling effects of both isotropic and anisotropic hardening is proposed with the co-rotational logarithmic rate.In terms of certain single-variable shape functions ... A new finite strain elatoplastic J2-flow model with coupling effects of both isotropic and anisotropic hardening is proposed with the co-rotational logarithmic rate.In terms of certain single-variable shape functions representing uniaxial loading and unloading curves,explicit multi-axial expressions for the three hardening quantities incorporated in the new model proposed are derived in unified forms for the purpose of automatically and accurately simulating complex pseudoelastic-to-plastic transition effects of shape memory alloys(SMAs)under multiple loading-unloading cycles.Numerical examples show that with only a single parameter of direct physical meaning for each cycle,accurate and explicit simulations may be achieved for extensive data from multiple cycle tests. 展开更多
关键词 shape memory alloy(SMA) finite deformation PSEUDO-ELASTICITY plasticity cyclic loading transition effect elastoplastic equation explicit and accurate approach
下载PDF
Medium-term and Long-term Momentum and Contrarian Effects on China during 1994-2004 被引量:1
15
作者 DU Xing-qiang NIE Zhi-ping 《Journal of Modern Accounting and Auditing》 2007年第2期63-69,共7页
We examine momentum and contrarian effects in China's stock market during 1994-2004 and find that no medium momentum effects exist. Meanwhile, contrarian strategy works effectively over the horizon of 18-36 months. 1... We examine momentum and contrarian effects in China's stock market during 1994-2004 and find that no medium momentum effects exist. Meanwhile, contrarian strategy works effectively over the horizon of 18-36 months. 1-month gap for avoiding bid-ask bounce and lead-lag effect make no considerable change to our empirical results. Transaction costs seem to have no significant impact on contrarian strategies' profit. 展开更多
关键词 medium-term momentum long-term momentum contrafian effects transaction costs
下载PDF
Wavelet network based predistortion method for wideband RF power amplifiers exhibiting memory effects 被引量:1
16
作者 JIN Zhe SONG Zhi-huan HE Jia-ming 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2007年第4期625-630,共6页
RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. Nevertheless, in wideband communication systems, PA memory effects can no longer be ignored and memoryl... RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. Nevertheless, in wideband communication systems, PA memory effects can no longer be ignored and memoryless predistortion cannot linearize PAs effectively. After analyzing PA memory effects, a novel predistortion method based on wavelet networks (WNs) is proposed to linearize wideband RF power amplifiers. A complex wavelet network with tapped delay lines is applied to construct the predistorter and then a complex backpropagation algorithm is developed to train the predistorter parameters. The simulation results show that compared with the previously published feed-forward neural network predistortion method, the proposed method provides faster convergence rate and better performance in reducing out-of-band spectral regrowth. 展开更多
关键词 Power amplifiers. Predistortion. memory effects. Wavelet networks
下载PDF
Effects of ginsenoside of stem and leaf combined with choline on learning and memory ability of rat models with Alzheimer diseases 被引量:1
17
作者 Xiaomin Zhao Xianglin Xie +3 位作者 Zuoli Xia Yunsheng Gao Yuyun Zhu Hongxia Gu 《Neural Regeneration Research》 SCIE CAS CSCD 2006年第4期331-334,共4页
BACKGROUND: Central adrenergic nerve and 5-serotonergic nerve can influence central cholinergic nerve on learning and memory and make easy for study; however, ginsenoside of stem and leaf (GSL) can improve function... BACKGROUND: Central adrenergic nerve and 5-serotonergic nerve can influence central cholinergic nerve on learning and memory and make easy for study; however, ginsenoside of stem and leaf (GSL) can improve functions of central adrenergic nerve; moreover, 5-serotonergic nerve and the combination with choline can produce synergistic effect and enhance learning and memory ability so as to improve learning and memory disorder of patients with Alzheimer disease (AD). OBJECTIVE : To observe the effects of GSL combining with choline on learning and memory of AD model rats DESIGN : Randomized grouping design and controlled animal study SETIING : Department of Pharmacology, Taishan Medical College MATERIALS : The experiment was carried out in the Pharmacological Department of Medical College of Jilin University from October 1996 to January 1997. Forty healthy male Wistar rats of clean grade were randomly divided into 5 groups, including sham-injury group, model group, GSL group, choline group and combination group, with 8 rats in each group. Main medications: GSL with the volume more than 92.8% was provided by Department of Chemistry, Norman Bethune Medical College of Jilin University. Panaxatriol, the main component, was detected with thin layer scanning technique and regarded as the index of GSL quality [(55±1)%, CV= 2%, n = 5]. Choline was provided by the Third Shanghai Laboratory Factory. METHODS : 150 nmol quinolinic acid was used to damage bilateral Meynert basal nuclei of adult rats so as to establish AD models. Rats in GSL, choline and combination groups were intragastric administrated with 400 mg/kg GSL, 200 mg/kg choline (20 mL/kg), and both respectively last for 17 days starting from two days before operation. Rats in sham-injury group and model group were perfused with the same volume of distilled water once in each morning for the same days. (1) Passive avoidance step-down test: Five minutes later, rats jumped up safe platform when they were shocked with 36 V alternating current. If rats jumped down from the platform and the feet touched railings, the response was wrong. Numbers of wrong response were recorded within 3 minutes, and then the test was redone after 24 hours. (2) Morris water-maze spatial localization task: Swimming from jumping-off to platform directly was regarded as right response. Additionally, 4 successively right responses were regarded as the standard. Each rat was trained 10 times a day with 120 s per time for 3 successive days. The interval was 30 s. Three days later, numbers of right response were recorded. The training times were increased to 30 for unlearned rats. (3) Measurement of activity of choline acetylase in cerebral cortex: Rats were sacrificed at 17 days after operation to obtain cerebral cortex to measure activity of choline acetylase with radiochemistry technique. (4) Synergistic effect: It was expressed as Q value: Q value = factual incorporative effect/anticipant incorporative effect; Q ≥ 1 was regarded as synergistic effect. Anticipant incorporative effect = (EA+EB-EA·EB), EA and EB were single timing effect, respectively in GSL group and choline group. E(step-down test and Morris water maze test) = (x in model group - factual value in medicine groups)/x in model group; E (activity of choline acetylase) = (factual value in medicine groups -xin model group)/xin model group. MAIN OUTCOME MEASURES : (1) Passive avoidance step-down test and Morris water-maze spatial localization task in the study of learning and memory; (2) activity of choline acetylase. RESULTS : All 40 rats were involved in the final analysis. (1) Passive avoidance response: At learning phase on first day and retesting phase on the next day, numbers of wrong responses within 3 minutes were more in model group than sham operation group, and there was significant difference [(5.88±1.46), (2.25±0.87) times; (2.63±1.06), (0.50±0.53) times; P 〈 0.01]; numbers of wrong responses within 3 minutes were less in combination group than model group, and there was significant difference [learning phase: (1.12±0.83), (5.88±1.46) times; retesting phase: (0.38±0.74), (2.63±1.06)times, P 〈 0.01]; moreover, effect was stronger than that in GSL group and choline group. The Q value was 1.07 and 1.59, respectively and it showed synergistic effect. Spatial localization task: Training times were more in model group than sham operation group, and there was significant difference [(2.9±2.5), (12.6±3.5) times; P 〈 0.01]. Training times were less in combination group than model group, and there was significant difference [(11.8±2.4), (27.9±2.5) times, P 〈 0.01]; moreover, effect was stronger than that in GSL group and choline group. The Q value was 1.07 and it showed synergistic effect. (3) Activity of choline acetylase: Activity was lower in model group than sham operation group, and there was significant difference [(30.56±8.33), (61.11 ±8.33) nkat/g; P 〈 0.01]. Activity was higher in combination group than model group and there was significant difference [(50.00±8.33), (30.56±8.33) nkat/g, P 〈 0.01];moreover, effect was stronger than that in GSL group and choline group. The Q value was 1.5 and it showed synergistic effect. CONCLUSZON: GSL in combination with choline can synergically improve the disorder of learning and memory of AD model rats. Its mechanism may be involved in enhancing the function of central cholinergic system. 展开更多
关键词 stem effects of ginsenoside of stem and leaf combined with choline on learning and memory ability of rat models with Alzheimer diseases
下载PDF
Total Ionization Dose Effects on Charge Storage Capability of Al2O3/HfO2/Al2O3-Based Charge Trapping Memory Cell 被引量:1
18
作者 Yan-Nan Xu Jin-Shun Bi +5 位作者 Gao-Bo Xu Bo Li Kai Xi Ming Liu Hai-Bin Wang Li Luo 《Chinese Physics Letters》 SCIE CAS CSCD 2018年第11期86-89,共4页
Because of the discrete charge storage mechanism, charge trapping memory(CTM) technique is a good candidate for aerospace and military missions. The total ionization dose(TID) effects on CTM cells with Al2O3/HfO2/... Because of the discrete charge storage mechanism, charge trapping memory(CTM) technique is a good candidate for aerospace and military missions. The total ionization dose(TID) effects on CTM cells with Al2O3/HfO2/Al2O3(AHA) high-k gate stack structure under in-situ 10 keV x-rays are studied. The C-V characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation,thereby inducing the shift of flat band voltage(V(fb)). The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed. 展开更多
关键词 AHA Total Ionization Dose effects on Charge Storage Capability of Al2O3/HfO2/Al2O3-Based Charge Trapping memory Cell Al
下载PDF
Volterra series based predistortion for broadband RF power amplifiers with memory effects
19
作者 Jin Zhe Song Zhihuan He Jiaming 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2008年第4期666-671,共6页
RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. However, in broadband communication systems, such as WCDMA, the PA memory effects are significant, an... RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. However, in broadband communication systems, such as WCDMA, the PA memory effects are significant, and memoryless predistortion cannot linearize the PAs effectively. After analyzing the PA memory effects, a novel predistortion method based on the simplified Volterra series is proposed to linearize broadband RF PAs with memory effects. The indirect learning architecture is adopted to design the predistortion scheme and the reeursive least squares algorithm with forgetting factor is applied to identify the parameters of the predistorter. Simulation results show that the proposed predistortion method can compensate the nonlinear distortion and memory effects of broadband RF PAs effectively. 展开更多
关键词 power amplifiers PREDISTORTION memory effects Volterra series
下载PDF
Synergistic effects of total ionizing dose on single event upset sensitivity in static random access memory under proton irradiation
20
作者 肖尧 郭红霞 +7 位作者 张凤祁 赵雯 王燕萍 张科营 丁李利 范雪 罗尹虹 王园明 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第11期612-615,共4页
Synergistic effects of the total ionizing dose (TID) on the single event upset (SEU) sensitivity in static random access memories (SRAMs) were studied by using protons. The total dose was cumulated with high flu... Synergistic effects of the total ionizing dose (TID) on the single event upset (SEU) sensitivity in static random access memories (SRAMs) were studied by using protons. The total dose was cumulated with high flux protons during the TID exposure, and the SEU cross section was tested with low flux protons at several cumulated dose steps. Because of the radiation-induced off-state leakage current increase of the CMOS transistors, the noise margin became asymmetric and the memory imprint effect was observed. 展开更多
关键词 single event upset total dose static random access memory imprint effect
下载PDF
上一页 1 2 107 下一页 到第
使用帮助 返回顶部