期刊文献+
共找到219篇文章
< 1 2 11 >
每页显示 20 50 100
Impact of web-based positive psychological intervention on emotions,psychological capital,and quality of life in gastric cancer patients on chemotherapy
1
作者 Yu-Yu Xin Dan Zhao 《World Journal of Clinical Cases》 SCIE 2024年第26期5877-5884,共8页
BACKGROUND Gastric cancer is a malignant digestive tract tumor that originates from the epithelium of the gastric mucosa and occurs in the gastric antrum,particularly in the lower curvature of the stomach.AIM To evalu... BACKGROUND Gastric cancer is a malignant digestive tract tumor that originates from the epithelium of the gastric mucosa and occurs in the gastric antrum,particularly in the lower curvature of the stomach.AIM To evaluate the impact of a positive web-based psychological intervention on emotions,psychological capital,and quality of survival in gastric cancer patients on chemotherapy.METHODS From January 2020 to October 2023,121 cases of gastric cancer patients on chemotherapy admitted to our hospital were collected and divided into a control group(n=60)and an observation group(n=61)according to the admission order.They were given either conventional nursing care alone and conventional nursing care combined with web-based positive psychological interventions,respectively.The two groups were compared in terms of negative emotions,psychological capital,degree of cancer-caused fatigue,and quality of survival.RESULTS After intervention,the number of patients in the observation group who had negative feelings toward chemotherapy treatment was significantly lower than that of the control group(P<0.05);the Positive Psychological Capital Questionnaire score was considerably higher than that of the control group(P<0.05);the degree of cancer-caused fatigue was significantly lower than that of the control group(P<0.05);and the Quality of Life Scale for Cancer Patients(QLQ-30)score was significantly higher than that of the control group(P<0.05).CONCLUSION Implementing a web-based positive psychological intervention for gastric cancer chemotherapy patients can effectively improve negative emotions,enhance psychological capital,and improve the quality of survival. 展开更多
关键词 Internet positive psychology Gastric cancer chemotherapy negative emotions Psychological capital Quality of survival
下载PDF
Simulation research on surface growth process of positive and negative frequency detuning chromium atom lithographic gratings
2
作者 尹志珺 唐朝辉 +9 位作者 谭文 肖光旭 姚玉林 薛栋柏 顾振杰 雷李华 顿雄 邓晓 程鑫彬 李同保 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第10期367-376,共10页
Chromium atom photolithography gratings are a promising technology for the development of nanoscale length standard substances due to their high accuracy,uniformity,and consistency.However,the inherent difference betw... Chromium atom photolithography gratings are a promising technology for the development of nanoscale length standard substances due to their high accuracy,uniformity,and consistency.However,the inherent difference between the interaction of positive and negative frequency detuning standing wave field and the atoms can cause a difference in the adjacent peak-to-valley heights of the grating in positive and negative frequency detuning chromium atom lithography,which greatly reduces its accuracy.In this study,we performed a controlled variable growth simulation using the semi-classical theoretical model and Monte Carlo method with trajectory tracking and ballistic deposition methods to investigate the influence of key experimental parameters on the surface growth process of positive and negative frequency detuning atomic lithography gratings.We established a theoretical model based on simulation results and summarized empirical equations to guide the selection of experimental parameters.Our simulations achieved uniform positive and negative frequency detuning atomic lithography gratings with a period of 1/4 of the wavelength corresponding to the atomic transition frequency,and adjacent peak-to-valley heights differing by no more than 2 nm,providing an important theoretical reference for the controllable fabrication of these gratings. 展开更多
关键词 self-traceable grating atom lithography positive and negative frequency detuning surface growth
下载PDF
Backward Support Computation Method for Positive and Negative Frequent Itemset Mining
3
作者 Mrinmoy Biswas Akash Indrani Mandal Md. Selim Al Mamun 《Journal of Data Analysis and Information Processing》 2023年第1期37-48,共12页
Association rules mining is a major data mining field that leads to discovery of associations and correlations among items in today’s big data environment. The conventional association rule mining focuses mainly on p... Association rules mining is a major data mining field that leads to discovery of associations and correlations among items in today’s big data environment. The conventional association rule mining focuses mainly on positive itemsets generated from frequently occurring itemsets (PFIS). However, there has been a significant study focused on infrequent itemsets with utilization of negative association rules to mine interesting frequent itemsets (NFIS) from transactions. In this work, we propose an efficient backward calculating negative frequent itemset algorithm namely EBC-NFIS for computing backward supports that can extract both positive and negative frequent itemsets synchronously from dataset. EBC-NFIS algorithm is based on popular e-NFIS algorithm that computes supports of negative itemsets from the supports of positive itemsets. The proposed algorithm makes use of previously computed supports from memory to minimize the computation time. In addition, association rules, i.e. positive and negative association rules (PNARs) are generated from discovered frequent itemsets using EBC-NFIS algorithm. The efficiency of the proposed algorithm is verified by several experiments and comparing results with e-NFIS algorithm. The experimental results confirm that the proposed algorithm successfully discovers NFIS and PNARs and runs significantly faster than conventional e-NFIS algorithm. 展开更多
关键词 Data Mining positive Frequent Itemset negative Frequent Itemset Association Rule Backward Support
下载PDF
Effects of positive thinking intervention on negative emotions and quality of life in stroke patients:a scoping review
4
作者 Xin Fan Mei Wang Xiang-Shu Cui 《Nursing Communications》 2023年第9期1-6,共6页
Objective:To analyze domestic and international studies on the effects of positive thought intervention therapy on negative emotions and the quality of life of stroke patients to provide a reference for future related... Objective:To analyze domestic and international studies on the effects of positive thought intervention therapy on negative emotions and the quality of life of stroke patients to provide a reference for future related studies.Methods:Using the scoping review method as a guide,computer searches of PubMed,Web of Science,Embase,Cochrane Library,China National Knowledge Infrastructure,Wanfang Database,China Vipers Full Text Database and China Biomedical Literature Database were conducted to collect relevant studies on the application of positive thinking interventions in stroke patients from the establishment to January 2023,and the literature was screened according to the inclusion and exclusion criteria,and the data were extracted and analyzed by two investigators independently.Results:The search yielded 964 publications,and a total of 19 were included.The time of publication,study site,study population,study design,study length,and type of results of the included studies was summarized and analyzed.Conclusions:Positive thinking-based interventions have shown significant changes in negative emotions such as anxiety and depression in stroke patients and can reduce somatic pain,enhance their social integration,and improve their quality of life.However,interventions in the areas of self-compassion,artificial intelligence and the adoption of tailoring need to be further explored. 展开更多
关键词 positive thinking intervention STROKE negative emotions quality of life scoping revie
下载PDF
Analysis of Positive and Negative Influence of Constructing Xianyang Lake
5
作者 王德耀 《Journal of Landscape Research》 2009年第9期25-30,共6页
Xianyang Lake is the abbreviation of Weihe River(Xianyang Urban Area Section) Comprehensive Treatment Project,which is to build a partition wall in the middle of the 500 wide Weihe River Valley,then a 270 m wide water... Xianyang Lake is the abbreviation of Weihe River(Xianyang Urban Area Section) Comprehensive Treatment Project,which is to build a partition wall in the middle of the 500 wide Weihe River Valley,then a 270 m wide water storage channel on the north side and a 230 m wide muddy water floodway channel on the south side will be formed.Two rubber dams are constructed in the water storage channels to form a 'Xianyang Lake' with an area of 1.24×106 m2,meanwhile,along both sides of Weihe River in this section,slope protection and flood prevention as well as a series of greening and cultural landscape projects are to be constructed.This project,with flood prevention as the core,aims to improve the living environment and protect ecological environment,and realize the comprehensive treatment of river way flood-proofing,desilting,sewage purification,greening and beautification.The construction of Xianyang Lake greatly improves the image of Xianyang City and generates considerable economic,social and ecological benefits,however,it also has negative effects,such as insufficient lake water supply,original ecology being intervened by human activities,aggravating local fiscal burden,and potential threats to the flood-proofing in the lower reaches of Weihe River.The author puts forwards that 'creating a lake by damming the river' in the process of urbanization and solving the conflicts between sectional interests and integrated interests should follow natural laws and go along the track of sustainable development,which is also the orientation of future work,and the concrete reform scheme is to be further studied. 展开更多
关键词 Xianyang LAKE Weihe RIVER positive and negative INFLUENCE
下载PDF
Positive and negative terrains on northern Shaanxi Loess Plateau 被引量:35
6
作者 ZHOU Yi TANG Guo'an +3 位作者 YANG Xin XIAO Chenchao ZHANG Yuan LUO Mingliang 《Journal of Geographical Sciences》 SCIE CSCD 2010年第1期64-76,共13页
The Loess positive and negative terrains (P-N terrains), which are widely distributed on the Loess Plateau, are discussed for the first time by introducing its characteristic, demarcation as well as extraction metho... The Loess positive and negative terrains (P-N terrains), which are widely distributed on the Loess Plateau, are discussed for the first time by introducing its characteristic, demarcation as well as extraction method from high-resolution Digital Elevation Models. Using 5 m-resolution DEMs as original test data, P-N terrains of 48 geomorphological units in different parts of Shaanxi Loess Plateau are extracted accurately. Then six indicators for depicting the geomorphologic landscape and spatial configuration characteristic of P-N terrains are proposed. The spatial distribution rules of these indicators and the relationship between the P-N terrains and Loess relief are discussed for further understanding of Loess landforms. Finally, with the integration of P-N terrains and traditional terrain indices, a series of un-supervised classification methods are applied to make a proper landform classification in northern Shaanxi. Results show that P-N terrains are an effect clue to reveal energy and substance distribution rules on the Loess Plateau. A continuous change of P-N terrains from south to north in Shaanxi Loess Plateau shows an obvious spatial difference of Loess land-forms and the positive terrain area only accounted for 60.5% in this region. The P-N terrains participant landform classification method increases validity of the result, especially in the Loess tableland, Loess tableland-ridge and the Loess low-hill area. This research is significant on the study of Loess landforms with the Digital Terrains Analysis methods. 展开更多
关键词 Loess Plateau positive and negative terrains DEM shoulder-lines spatial differentiation
下载PDF
Quantifying spatial scale of positive and negative terrains pattern at watershed-scale:Case in soil and water conservation region on Loess Plateau 被引量:7
7
作者 YANG Feng ZHOU Yi 《Journal of Mountain Science》 SCIE CSCD 2017年第8期1642-1654,共13页
The positive and negative terrains(P-N terrains) widely distributed across China's Loess Plateau constitute the dual structure characteristic of loess landforms. Analysis of loess P-N terrains at the watershed sca... The positive and negative terrains(P-N terrains) widely distributed across China's Loess Plateau constitute the dual structure characteristic of loess landforms. Analysis of loess P-N terrains at the watershed scale can serve to elucidate the structural characteristics and spatial patterns of P-N terrains, which benefits a better understanding of watershed evolution and suitable scales for loess landform research. The Two-Term Local Quadrat Variance Analysis(TTLQV) is calculated as the average of the square of the difference between the block totals of all possible adjacent pairs of block size, which can be used to detect both the scale and the intensity of landscape patches(e.g., plant/animal communities and gully networks). In this study, we determined the latitudinal and longitudinal spatial scale of P-N terrain patterns within 104 uniformly distributed watersheds in our target soil and water conservation region. The results showed that TTLQV is very effective for examining the scale of P-N terrain patterns. There were apparently three types of P-N terrain pattern in latitudinal direction(i.e., Loess Tableland type, Loess Hill type, and Transitional Form between Sand and Loess type), whereas there were both lower and higher values for P-N terrain pattern scales in all loess landforms in the longitudinal direction. The P-N terrain pattern alsoclearly presented anisotropy, suggesting that gully networks in the main direction were well-developed while others were relatively undeveloped. In addition, the relationships between the first scales and controlling factors(i.e., gully density, nibble degree, watershed area, mean watershed slope, NDVI, precipitation, loess thickness, and loess landforms) revealed that the first scales are primarily controlled by watershed area and loess landforms. This may indicate that the current spatial pattern of P-N terrains is characterized by internal force. In selecting suitable study areas in China' Loess Plateau, it is crucial to understand four control variables: the spatial scale of the P-N terrain pattern, the watershed area, the main direction of the watershed, and the loess landforms. 展开更多
关键词 positive and negative terrains TTLQV Spatial PATTERN SCALE LOESS LandFORMS LOESS Plateau
下载PDF
Oscillation in a Class of Neutral Differential Equations with Positive and Negative Coefficients
8
作者 单文锐 葛渭高 郭彦平 《Journal of Beijing Institute of Technology》 EI CAS 2002年第3期321-324,共4页
The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscilla... The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscillation of neutral differential equation with positive and negative coefficients are obtained. 展开更多
关键词 neutral differential equation OSCILLATION fixed point principle positive and negative coefficients
下载PDF
Propagation of positive, negative, and recoil leaders in upward lightning flashes 被引量:2
9
作者 XiuShu Qie ShanFeng Yuan +9 位作者 HongBo Zhang RuBin Jiang ZhiJun Wu MingYuan Liu ZhuLing Sun YunJiao Pu JinLiang Li Abhay Srivastava ZiLong Ma GaoPeng Lu 《Earth and Planetary Physics》 CSCD 2019年第2期102-110,共9页
Leader propagation is a fundamental issue in lightning physics. The propagation characteristics of positive leaders and negative leaders are summarized and compared based on data from high-speed camera and electromagn... Leader propagation is a fundamental issue in lightning physics. The propagation characteristics of positive leaders and negative leaders are summarized and compared based on data from high-speed camera and electromagnetic field in rocket-triggered lightning and tower-initiated lightning discharges; available channel base current data recorded in rocket-triggered lightning are also used. The negative leaders propagate in a stepped fashion accompanied by many branches. The stems ahead of the negative leader tip determine the manner and direction of the leader propagation, and even the branching and winding of the lightning channel. The impulsive current, electromagnetic field, and related optical images suggest that the positive leader may develop in a step-like fashion at its initial stage of triggered lightning. However, the stepping processes of the positive leader are obviously different from those of the negative leader. Tower-initiated lightning revealed that the most conspicuous characteristics of the stepwise positive leader involve the intermittent brush-like corona zone in front of the leader tip and the luminosity enhancement of the channel behind the tip. In rockettriggered lightning flashes, the charge transferred during an individual step for the negative leader was nearly an order greater than for the positive counterpart. The successive streamers ahead of the leader tip are essential for both negative and positive leader propagation, and the stems could be formed from one or more streamers in the previous negative streamer zone with the main leader channel dim. High-resolution observation of tower lightning also revealed a new type of bidirectional recoil leader, with polarity contrary to the traditional one, traversing in negative channels associated with tower-initiated and rocket-triggered lightning. 展开更多
关键词 LIGHTNING PROPAGATION negative LEADER positive LEADER RECOIL LEADER
下载PDF
GLOBAL ATTRACTIVITY OF NEUTRAL DIFFERENCE EQUATIONS WITH POSITIVE AND NEGATIVE COEFFICIENTS 被引量:2
10
作者 Li Xiaoping Jiang Jianchu Gao PingDept. of Math., Loudi Teacher’s College, Loudi 417000,China. 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2002年第3期258-266,共9页
A neutral difference equation with positive and negative coefficientsΔ(x n-c nx n-k )+p nx n-l -q nx n-r =0, n=0,1,2,...,is considered and a sufficient condition for the global attractivity of the ze... A neutral difference equation with positive and negative coefficientsΔ(x n-c nx n-k )+p nx n-l -q nx n-r =0, n=0,1,2,...,is considered and a sufficient condition for the global attractivity of the zero solution of this equation is obtained, which improves and extends the all known results in the literature. 展开更多
关键词 global attractivity neutral difference equations positive and negative coefficients.
下载PDF
EXISTENCE OF POSITIVE SOLUTIONS FOR NEUTRAL DIFFERENCE EQUATIONS WITH POSITIVE AND NEGATIVE COEFFICIENTS 被引量:1
11
作者 Luo Zhiguo Shen JianhuaDept. of Math., Hunan Normal Univ., Changsha 410081,China. 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2002年第3期251-257,共7页
In this paper the sufficient conditions for the existence of positive solutions of the neutral difference equations with positive and negative coefficients are established. The results improve some known conclusions i... In this paper the sufficient conditions for the existence of positive solutions of the neutral difference equations with positive and negative coefficients are established. The results improve some known conclusions in the literature. 展开更多
关键词 positive solutions neutral difference equations positive and negative coefficients.
下载PDF
Forced Oscillation of Neutral Advanced Dynamic Equations with Positive and Negative Coeffcients on Time Scales 被引量:1
12
作者 YANG Jun WU Hui-ning 《Chinese Quarterly Journal of Mathematics》 CSCD 2011年第3期466-469,共4页
In this paper,we consider the forced neutral advanced dynamic equations with positive and negative coeffcients[x(t)-R(t)x(t+r)]+P(t)x(t+τ)△Q(t)x(t+δ)= f(t),t≥t0 on a time scale T.Several suffcient conditions are o... In this paper,we consider the forced neutral advanced dynamic equations with positive and negative coeffcients[x(t)-R(t)x(t+r)]+P(t)x(t+τ)△Q(t)x(t+δ)= f(t),t≥t0 on a time scale T.Several suffcient conditions are obtained for the oscillation of the dynamic equations.The main result is illustrated by an example. 展开更多
关键词 time scales FORCED NEUTRAL ADVANCED oscillation positive and negative coeffcients
下载PDF
Short-Term Mindfulness Intervention on Adolescents’ Negative Emotion under Global Pandemic
13
作者 Yue Yuan Aibao Zhou +3 位作者 Tinghao Tang Manying Kang Haiyan Zhao Zhi Wang 《International Journal of Mental Health Promotion》 2023年第4期563-577,共15页
Objective:In this research,we tried to explore how short-term mindfulness(STM)intervention affects adoles-cents’anxiety,depression,and negative and positive emotion during the COVID-19 pandemic.Design:10 classes were... Objective:In this research,we tried to explore how short-term mindfulness(STM)intervention affects adoles-cents’anxiety,depression,and negative and positive emotion during the COVID-19 pandemic.Design:10 classes were divided into experiment groups(5 classes;n=238)and control(5 classes;n=244)randomly.Hospital Anxi-ety and Depression Scale(HADS)and Positive and Negative Affect Schedule(PANAS)were used to measure par-ticipants’dependent variables.In the experiment group,we conducted STM practice interventions every morning in theirfirst class from March to November 2020.No interventions were conducted in the control group.Methods:Paired-sample t-tests were used to identify if a significant difference exists between every time point of the experimental and control groups.Repeated ANOVA and Growth Mixture Model(GMM)were used to analyze the tendency of positive and negative emotions,anxiety,and depression in the experimental group.Results and Conclusions:(1)With the intervention of STM,there was a significant decrease in negative emotions and an increase in positive emotions in the experimental group,whereas there were non-significant differences in the control group.(2)To explore the heterogeneity trajectories of dependent variables,we built a GMM and found there were two latent growth classes in the trajectories.(3)The results of the models showed their trajec-tories were downward,which meant that the levels of anxiety,depression,and negative emotions of participants decreased during the STM training period.Nonetheless,the score of positive affect showed upward in three loops of intervention,which indicated that the level of the participants’positive affect increased through the STM inter-vention.(4)This research indicated that STM should be given increasing consideration to enhance mental health during the worldwide outbreak of COVID-19. 展开更多
关键词 negative and positive emotional anxiety depression short-term mindfulness randomized controlled trial growth mixture model global pandemic of each of the two class groups illustrated in Fig.4B which showed obvious differences between the two class groups.
下载PDF
Effect of psychological nursing interventions on effectiveness and quality of life in schizophrenia patients receiving modified electroconvulsive therapy
14
作者 Jing Lu 《World Journal of Clinical Cases》 SCIE 2024年第16期2751-2757,共7页
BACKGROUND Schizophrenia is a common and severe mental disorder characterized by severe thought disturbances,hallucinations,delusions,and emotional instability.For some patients,conventional treatment methods may not ... BACKGROUND Schizophrenia is a common and severe mental disorder characterized by severe thought disturbances,hallucinations,delusions,and emotional instability.For some patients,conventional treatment methods may not effectively alleviate symptoms,necessitating the use of alternative therapeutic approaches.Modified electroconvulsive therapy(MECT)is an effective treatment modality for schizophrenia,inducing anti-depressive and antipsychotic effects through the stimulation of brain electrical activity.AIM To explore the impact of psychological nursing intervention(PNI)before and after MECT on the efficacy and quality of life of patients with schizophrenia.METHODS Eighty patients with schizophrenia who received MECT treatment from 2021 to 2023 were randomly divided into two groups:The intervention group(n=40)and the control group(n=40).The intervention group received PNI before and after MECT,while the control group received routine nursing care.The efficacy of MECT was evaluated by the Positive and Negative Syndrome Scale(PANSS)and the Clinical Global Impression Scale(CGI)before and after the treatment.The quality of life was assessed by the Short Form 36 Health Survey(SF-36)after the treatment.RESUITS The intervention group had significantly lower scores of PANSS and CGI than the control group after the treatment(P<0.05).The intervention group also had significantly higher scores of SF-36 than the control group in all domains except physical functioning(P<0.05).CONCLUSION PNI before and after MECT can improve the efficacy and quality of life of patients with schizophrenia.It is suggested that nurses should provide individualized and comprehensive psychological care for patients undergoing MECT to enhance their recovery and well-being. 展开更多
关键词 Psychological nursing interventions Modified electroconvulsive therapy SCHIZOPHRENIA EFFICACY Quality of life positive and negative syndrome scale
下载PDF
Characteristics of water volatilization and oxides generation by using positive and negative corona
15
作者 Ke CHEN Lianghao WAN +8 位作者 Bingyan CHEN Tao CHU Renyue GENG Deyu SONG Xiang HE Wei SU Cheng YIN Minglei SHAN Yongfeng JIANG 《Plasma Science and Technology》 SCIE EI CAS CSCD 2022年第4期61-70,共10页
The physical and chemical properties have significant differences for the positive and negative charged particles generated by discharge.In this work,a positive and negative corona discharge system was established,and... The physical and chemical properties have significant differences for the positive and negative charged particles generated by discharge.In this work,a positive and negative corona discharge system was established,and two discharge reactors for charged particles restraining and acting were designed by a needle electrode covered with a quartz tube and a plate electrode filled with water.The corona discharges happened within the needle-plate electrodes were excited by a positive and negative high voltage source,and the characteristics of both water volatilization and oxides generation were examined within influence of the distances of both quartz tube inside and outside.The results show that the characteristics of both the water volatilization and oxides generation can be affected by the distances of both quartz tube inside and outside.When the distances of tube inside were increased from 5.00 to 13.00 mm,the water volatilizations decreased under negative corona,and increased firstly and declined immediately under positive corona.The maximum value of the water volatilization appeared in the distances of tube inside with 6.00–8.00 mm.In addition,the concentrations of the HNO_(x) and H_(2)O_(2)in treated water decreased with increasing the distances of tube inside.Moreover,with increasing the distances of tube outside from 4.00 to 14.00 mm,the change trends of both the water volatilizations and oxides presented the same as the distances of tube inside,and the maximum value of the water volatilization and oxides appeared in the distance of tube outside with about 9.00 mm.Overall,the positive corona can generate more water volatilizations and oxides in water than negative corona,and non H_(2)O_(2)can be produced by negative corona.The results reflect the difference between positive and negative corona interaction with water,which can provide reference for plasma application. 展开更多
关键词 positive corona negative corona water volatilization oxides generation
下载PDF
Characteristic studies on positive and negative streamers of double-sided pulsed surface dielectric barrier discharge
16
作者 Yan JIANG Bangfa PENG +4 位作者 Zhengyan LIU Nan JIANG Na LU Kefeng SHANG Jie LI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2022年第4期37-52,共16页
The mechanisms of streamer generation and propagation in double-sided pulsed surface dielectric barrier discharge(SDBD)on both sides have been analyzed and investigated by experiment and numerical simulation.The fully... The mechanisms of streamer generation and propagation in double-sided pulsed surface dielectric barrier discharge(SDBD)on both sides have been analyzed and investigated by experiment and numerical simulation.The fully exposed asymmetric SDBD has two discharge processes located on the high voltage electrode(HVE)side and the ground electrode(GE)side.Discharge images of the HVE side and GE side are taken by a digital camera under continuous pulse and ICCD(Intensified Charge Coupled Device)is utilized to diagnose the generation and propagation of streamers in single pulse discharge.In order to understand the physical mechanisms of streamer evolution more deeply,we establish a 2D simulation model and analyze it from the aspects of electron density,ion density,reduced electric field and electron impact ionization source term.The results show that the primary and secondary discharges on the HVE side and the GE side of the double-sided SDBD are composed of positive streamer and negative streamer,respectively.On the HVE side,the accumulation of positive charges on the dielectric surface causes the direction of the electric field to reverse,which is the principal factor for the polarity reversal of the streamer.On the GE side,both the negative charges accumulated on the dielectric surface and the falling voltage are the key factors for the streamer polarity switch. 展开更多
关键词 double-sided SDBD positive streamer negative streamer nanosecond pulse
下载PDF
Two integrable generalizations of WKI and FL equations: Positive and negative flows, and conservation laws
17
作者 Xian-Guo Geng Fei-Ying Guo Yun-Yun Zhai 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第5期70-73,共4页
With the aid of Lenard recursion equations, an integrable hierarchy of nonlinear evolution equations associated with a 2 × 2 matrix spectral problem is proposed, in which the first nontrivial member in the positi... With the aid of Lenard recursion equations, an integrable hierarchy of nonlinear evolution equations associated with a 2 × 2 matrix spectral problem is proposed, in which the first nontrivial member in the positive flows can be reduced to a new generalization of the Wadati–Konno–Ichikawa(WKI) equation. Further, a new generalization of the Fokas–Lenells(FL) equation is derived from the negative flows. Resorting to these two Lax pairs and Riccati-type equations, the infinite conservation laws of these two corresponding equations are obtained. 展开更多
关键词 integrable generalizations positive flow and negative flow infinite conservation laws
下载PDF
Definition of Laplace Transforms for Distribution of the First Passage of Zero Level of the Semi-Markov Random Process with Positive Tendency and Negative Jump
18
作者 Tamilla I. Nasirova Ulviyya Y. Kerimova 《Applied Mathematics》 2011年第7期908-911,共4页
One of the important problems of stochastic process theory is to define the Laplace transforms for the distribution of semi-markov random processes. With this purpose, we will investigate the semimarkov random process... One of the important problems of stochastic process theory is to define the Laplace transforms for the distribution of semi-markov random processes. With this purpose, we will investigate the semimarkov random processes with positive tendency and negative jump in this article. The first passage of the zero level of the process will be included as a random variable. The Laplace transforms for the distribution of this random variable is defined. The parameters of the distribution will be calculated on the basis of the final results. 展开更多
关键词 Laplace Transforms Semi-Markov RandOM PROCESS RandOM Variable PROCESS with positive TENDENCY and negative JUMPS
下载PDF
Seroconverting profile for a donor presenting as hepatitis C RNA positive and antibody negative
19
《中国输血杂志》 CAS CSCD 2001年第S1期408-,共1页
关键词 RNA Seroconverting profile for a donor presenting as hepatitis C RNA positive and antibody negative
下载PDF
The Historical Evolvement of Computer-Assisted Language Teaching and Its Positive and Negative Effects
20
作者 Jie HE 《International Journal of Technology Management》 2017年第5期35-38,共4页
With the development of computer and network technologies, computer--assisted language teaching and learning have been changing from the presentation of single text materials and response model to the integration of o... With the development of computer and network technologies, computer--assisted language teaching and learning have been changing from the presentation of single text materials and response model to the integration of outside classroom education media combining text, graphics, images, sound, animation and network communication (CMC) technology. As an auxiliary tool of foreign language teaching, the computer plays its huge potential and promotes the completion of all kinds of language learning tasks. However, high cost and lack of technical support bringing the negative effects to the foreign language teaching is also cannot be ignored. Therefore, in the study of the historical evolvement of the CALL, to fully understand the positive and negative effects from the foreign language teaching will help make the positive effect of foreign language teaching maximized, and avoid misuse and abuse of the CALL. 展开更多
关键词 Computer--assisted language learning positive and negative effects MULTIMEDIA virtual world
下载PDF
上一页 1 2 11 下一页 到第
使用帮助 返回顶部