期刊文献+
共找到44,075篇文章
< 1 2 250 >
每页显示 20 50 100
Problematic Internet use in drug addicts under treatment in public rehab centers 预览
1
作者 Stefano Baroni Donatella Marazziti +2 位作者 Federico Mucci Elisa Diadema Liliana Dell’Osso 《世界精神病学杂志》 2019年第3期55-64,共10页
BACKGROUND Problematic Internet use(PIU)or Internet addiction has been recognized to be a behavioral addiction characterized by excessive or poorly controlled preoccupations,urges,or behaviors regarding computer use a... BACKGROUND Problematic Internet use(PIU)or Internet addiction has been recognized to be a behavioral addiction characterized by excessive or poorly controlled preoccupations,urges,or behaviors regarding computer use and Internet access that leads to impairment or distress resembling substance abuse.AIM To investigate the prevalence and characteristics of Internet use and abuse in a group of drug addicts from Southern Italy,by means of a specific questionnaire[“Questionario sull’Utilizzo delle Nuove Tecnologie”(QUNT)].METHODS All subjects(183)were heavy smokers,almost 50%of them used heroin and/or opioid compounds,30%alcohol,10%cannabis,8%cocaine,and 5%were polydrug users.Almost 10%of the individuals were also suffering from gambling disorder.RESULTS The time spent online was more than 4 hours a day in the total sample,with a slight prevalence in male subjects.Cocaine and cannabis users spent more than 6 hours online,significantly more than opioid and alcohol abusers.Distribution of the QUNT factors was not different in both sexes.Cocaine users showed higher scores at the“loss of control”,“pornography addiction”,and“addiction to social networks”factors,for the stimulant effect of this substance.Moreover,15 out of the total 17 cocaine users were pathological gamblers.Positive and statistically significant relationships were observed between some QUNT factors and body mass index.CONCLUSION These findings indicate that PIU is less severe in subjects taking sedative substances,such as heroin/opioids and alcohol,than in subjects taking stimulants.Alternatively,it may be used as a“stimulant”trigger in cocaine and cannabis users.Flattening effect of abuse drugs was noted on possible sex-related differences in QUNT items.We observed a sort of“protective”effect of a love relationship and/or living together with a partner,as those engaged subjects showed lower scores on different items than single subjects or those living alone.The relationship between time spent online(and related sedentary lifest 展开更多
关键词 INTERNET PROBLEMATIC INTERNET use BEHAVIORAL addictions Drug ABUSE Rehab CENTERS
在线阅读 免费下载
Language Training Centers: Factors Related to Their Success 预览
2
作者 翁金 菲利普 《海外英语》 2019年第5期235-237,共3页
A survey of language training centers (LTCs) in Dalian, China was conducted, to ascertain the strengths and weaknesses, or the differentiating factors, of such centers. The survey was undertaken to understand the curr... A survey of language training centers (LTCs) in Dalian, China was conducted, to ascertain the strengths and weaknesses, or the differentiating factors, of such centers. The survey was undertaken to understand the current landscape of after-school institutes in the region, particularly those that offer training in English as a second/foreign language. The information uncovered by the research is considered beneficial not only to entrepreneurs who may wish to be involved in this industry, but also to college English majors who may wish to teach at an LTC. 展开更多
关键词 LANGUAGE training CENTERS qualitative research DIFFERENTIATING FACTORS
在线阅读 免费下载
An Approach to Improve Quality of Life and Sustainability in the Centers of Old Cities 预览
3
作者 Tarek Abou Ouf Abeer Makram 《土木工程与建筑:英文版》 2019年第7期461-468,共8页
The centers of old cities have a special design with a unique urban fabric to record cultural messages with their current citizens or their visitors from the different regions of the city or from outside. It creates s... The centers of old cities have a special design with a unique urban fabric to record cultural messages with their current citizens or their visitors from the different regions of the city or from outside. It creates spaces that strongly promote social and cultural behavior. Meanwhile, life developments and the stunning technological acceleration along with high population densities have led to many problems for the old cities and their centers, which were not prepared to address these problems. Most of these problems have caused much visual deterioration and economic recession for the centers of old cities, which raise the importance of finding alternative and flexible solutions to prevent damage in urban performance, environmental pollution and lack of requirements that affect the quality of life. The paper aims to present a vision that opens up prospects for subsequent research contributions that may contribute to improving the quality of life, inspired by sustainability and humanization features. The research relies on an inductive analysis method to develop a framework that contributes to the restoration of the old centers for their role, their aesthetic value and their functional importance, while facilitating movement and supporting their valuable architectural features. 展开更多
关键词 The CENTERS of OLD CITIES social behavior quality of life HUMANIZATION SUSTAINABILITY AESTHETIC value
在线阅读 下载PDF
Magnetic field analysis in a diamond anvil cell for Meissner effect measurement by using the diamond NV~- center
4
作者 赵琳 岳冬辉 +3 位作者 刘才龙 王敏 韩永昊 高春晓 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第3期149-152,共4页
Diamond negatively charged nitrogen-vacancy(NV-) centers provide an opportunity for the measurement of the Meissner effect on extremely small samples in a diamond anvil cell(DAC) due to their high sensitivity in detec... Diamond negatively charged nitrogen-vacancy(NV-) centers provide an opportunity for the measurement of the Meissner effect on extremely small samples in a diamond anvil cell(DAC) due to their high sensitivity in detecting the tiny change of magnetic field. We report on the variation of magnetic field distribution in a DAC as a sample transforms from normal to superconducting state by using finite element analysis. The results show that the magnetic flux density has the largest change on the sidewall of the sample, where NV-centers can detect the strongest signal variation of the magnetic field. In addition, we study the effect of magnetic coil placement on the magnetic field variation. It is found that the optimal position for the coil to generate the greatest change in magnetic field strength is at the place as close to the sample as possible. 展开更多
关键词 negatively CHARGED nitrogen-vacancy(NV-) CENTERS DIAMOND ANVIL cell SUPERCONDUCTIVITY magnetic field detection
Quinine-derived thiourea promoted enantioselective Michael addition reactions of 3-substituted phthalides to maleimides
5
作者 Jie Wang Xin Li Jin-Pei Cheng 《中国科学:化学英文版》 SCIE EI CAS CSCD 2019年第5期649-652,共4页
A highly diastereoselective and enantioselective Michael addition/desymmetrization reaction of maleimides with prochiral 3-substituted phthalides catalyzed by quinine-derived bifunctional thiourea was realized. A broa... A highly diastereoselective and enantioselective Michael addition/desymmetrization reaction of maleimides with prochiral 3-substituted phthalides catalyzed by quinine-derived bifunctional thiourea was realized. A broad range of the 3,3′-disubstituted phthalides bearing vicinal quaternary-tertiary stereogenic centers were synthesized in moderate to good yields(up to 96%) with high diastereoselectivities(up to >19:1 dr) and enantioselectivities(up to 96:4 er). 展开更多
关键词 michael addition 3 3′-disubstituted PHTHALIDES VICINAL quaternary-tertiary stereogenic centers
Kinetics of the thermal disappearance of radicals formed during the radiolysis of L-α-anhydrous asparagine 预览
6
作者 Ana Neacsu Daniela Gheorghe 《化学报告(英文)》 2019年第1期13-21,共9页
An EPR study of paramagnetic centers formed by irradiation of polycrystalline L-α-anhydrous asparagine (L-Asn) was performed. The EPR spectra of gamma irradiated samples at room temperature, shown the presence of thr... An EPR study of paramagnetic centers formed by irradiation of polycrystalline L-α-anhydrous asparagine (L-Asn) was performed. The EPR spectra of gamma irradiated samples at room temperature, shown the presence of three types of paramagnetic centers. A possible mechanisms of formation for the three radical species is suggested, based also on literature data. The kinetics of the disappearance of radicals during thermal annealing indicated a complex mechanism. 展开更多
关键词 L-α-anhydrous ASPARAGINE ionizing radiation paramagnetic centers THERMAL DISAPPEARANCE UNPAIRED electron
在线阅读 免费下载
Clinical characteristics and management of patients with fat embolism syndrome in level I Apex Trauma Centre
7
作者 Richa Aggarwal Arnab Banerjee +2 位作者 Kapil dev Soni Atin Kumar Anjan Trikha 《中华创伤杂志:英文版》 CAS CSCD 2019年第3期172-176,共5页
Purpose: Fat embolism syndrome (FES) is systemic manifestation of fat emboli in the circulation seen mostly after long bone fractures. FES is considered a lethal complication of trauma. There are various case reports ... Purpose: Fat embolism syndrome (FES) is systemic manifestation of fat emboli in the circulation seen mostly after long bone fractures. FES is considered a lethal complication of trauma. There are various case reports and series describing FES. Here we describe the clinical characteristics, management in ICU and outcome of these patients in level I trauma center in a span of 6 months. Methods: In this prospective study, analysis of all the patients with FES admitted in our polytrauma intensive care unit (ICU) of level I trauma center over a period of 6 months (from August 2017 to January 2018) was done. Demographic data, clinical features, management in ICU and outcome were analyzed. Results: We admitted 10 cases of FES. The mean age of patients was 31.2 years. The mean duration from time of injury to onset of symptoms was 56 h. All patients presented with hypoxemia and petechiae but central nervous system symptoms were present in 70% of patients. The mean duration of mechanical ventilation was 11.7 days and the mean length of ICU stay was 14.7 days. There was excellent recovery among patients with no neurological deficit. Conclusion: FES is considered a lethal complication of trauma but timely management can result in favorable outcome. FES can occur even after fixation of the fracture. Hypoxia is the most common and earliest feature of FES followed by CNS manifestations. Any patient presenting with such symptoms should raise the suspicion of FES and mandate early ICU referral. 展开更多
关键词 Fat EMBOLISM TRAUMA CENTERS INTENSIVE care units Patient outcome assessment
Analysis on influencing factors of patients experience in community health centers of Shenzhen,China 预览
8
作者 CHANG Feifei CHEN Xianhui +1 位作者 HUANG Hong WANG Qiang 《中西医结合护理(中英文)》 2019年第1期224-230,共7页
Objective To investigate the patients experience in community health centers(CHCs)and explore its associated factors.Methods A cross-sectional study was conducted among 330 patients who visited CHCs in Shenzhen,China ... Objective To investigate the patients experience in community health centers(CHCs)and explore its associated factors.Methods A cross-sectional study was conducted among 330 patients who visited CHCs in Shenzhen,China from January to March 2018.Dependent variable was patient experience.Key descriptive variables were age,gender,marital status,working status groups,visits frequency for the past 6 months,whether patients had signed a family doctor,whether trusted in family doctor,whether had chronic diseases.Results Questionnaires for 300 patients were assessed.In the univariate analysis,patients experience total score was significantly associated with marital status(P<0.1),working status groups(P<0.1),frequency of visit for the past 6 months(P<0.05),whether had signed a family doctor(P<0.05),whether trusted in family doctor(P<0.05),whether had chronic diseases(P<0.05).The multivariate analysis showed that unmarried patients(P=0.011,OR=2.96,95%CI:1.24-5.43)and had signed a family doctor(P=0.023,OR=0.44,95%CI:0.22-0.85)were more likely to get a higher score.Conclusions Findings of this study showed a medium-level score of patients experience in the community.Patients had a quite good experience and more interventions should be focused upon the influence factors to improve patients experience. 展开更多
关键词 PATIENTS EXPERIENCE influencing factors COMMUNITY health CENTERS family DOCTOR chronic disease
在线阅读 下载PDF
Research Center of 3D Bioprinting in Shanghai Ninth People’s Hospital 预览
9
作者 Tao Li Xiaojun Zhou +8 位作者 Changxu Deng Xiaoxiao Yang Han Yang Zhenjiang Ma Lan Cao Zezheng Yang Lei Qiang Jinwu Wang Kerong Dai 《生物设计与制造(英文)》 CSCD 2019年第3期213-220,共8页
The center was first established in 2013 and affiliated to the Shanghai Ninth People’s Hospital,Shanghai Jiao Tong University School of Medicine.In 2015,the center was entitled as 3D Bioprinting Clinical Transformati... The center was first established in 2013 and affiliated to the Shanghai Ninth People’s Hospital,Shanghai Jiao Tong University School of Medicine.In 2015,the center was entitled as 3D Bioprinting Clinical Transformation Collaborative Innovation Center.In 2016,the center was renamed as Medical 3D Printing Innovation Research Center of Shanghai Jiao Tong University School of Medicine.Although the center was established in 2013,the clinical application of 3D printing in Shanghai Ninth People’s Hospital can be traced back to the 1990s.As early as 30 years ago,Prof.Kerong Dai had tried to rebuild patients pelvic by manually cutting the foam boards and layering them together based on the theory of 3D printing for preoperative planning model of abnormal skeleton structures and development of personalized prosthesis.That was the first application of 3D printing in the area of medicine in China.Now,The Research Center of 3D Bioprinting in Shanghai Ninth People’s Hospital comprised of subcenters including the outpatient department of 3D printing,medical 3D printing innovation research center and Shanghai key laboratory of orthopedic implant. 展开更多
关键词 PRINTING TRANSFORMATION CENTERS
在线阅读 免费下载
中国城市群片区划分与区域城市群构建对策分析 预览
10
作者 孟祥林 《中国名城》 2019年第4期4-12,共9页
城市群不能独立发展,城市群彼此间只有建立起紧密联系,才能整合为高效互动的城市体系。根据城市群的空间分布情况,我国的城市群可以区分为7个片区:"黑+吉+辽"、"京+津+冀+晋+鲁+豫"、"沪+苏+浙+闽+赣+皖"... 城市群不能独立发展,城市群彼此间只有建立起紧密联系,才能整合为高效互动的城市体系。根据城市群的空间分布情况,我国的城市群可以区分为7个片区:"黑+吉+辽"、"京+津+冀+晋+鲁+豫"、"沪+苏+浙+闽+赣+皖"、"湘+鄂"、"粤+桂"、"川+渝+滇+黔"、"陕+甘+宁"。这些片区内的核心城市间的联系程度不同,核心城市的辐射力也有较大差别,所以需要对这些片区进行详细分析,通过构建"子城市链"、"子城市团"等措施,不断完善各个片区内核心城市与腹地间的联系,在各个片区内形成"分层+分片"的发展秩序,使得核心城市与腹地间的联系更加紧密,各个片区内都逐渐形成"核心城市-子中心城市-县级中心地"的多层次的城市发展结构,推动全国城镇化水平稳步提升。 展开更多
关键词 城市群片区 片区城市群 子城市团 城市链 中心地
在线阅读 下载PDF
Practice and Challenge of International Peer Review: A Case Study of Research Evaluation of CAS Centers for Excellence
11
作者 Fang Xu Xiaoxuan Li 《数据与情报科学学报:英文版》 CSCD 2019年第3期22-34,共13页
Purpose: The main goal of this paper is to show that international peer review can work in China’s context with satisfactory outcomes. Moreover, this paper also provides a reference for the practice of science and te... Purpose: The main goal of this paper is to show that international peer review can work in China’s context with satisfactory outcomes. Moreover, this paper also provides a reference for the practice of science and technology management.Design/methodology/approach: This paper starts with a discussion of two critical questions about the significance and design of international peer review. A case study of international peer review of CAS Centers for Excellence is further analyzed. Findings: International peer review may provide a solution to address the problem of quantitative oriented research evaluation in China. The case study of research evaluation of CAS Centers for Excellence shows that it is possible and feasible to conduct an international peer review in China’s context. When applying this approach to other scenarios, there are still many issues to consider including individualized design of international peer review combined with practical demands, and further improvement of theories and methods of international peer review. Research limitation: 1) Only the case of international peer review of CAS Centers for Excellence is analyzed;2) A relatively small number of respondents were surveyed in the questionnaire. Practical implications: The work presented in this study can be used as a reference for future studies.Originality/value: Currently, there are no similarly detailed studies exploring the significance and methodology of international peer review in China. 展开更多
关键词 Chinese ACADEMY of SCIENCES CAS CENTERS for Excellence INTERNATIONAL PEER review Research evaluation
Origin of Luminescent Centers and Edge States in Low-Dimensional Lead Halide Perovskites:Controversies,Challenges and Instructive Approaches
12
作者 Jiming Bao Viktor G.Hadjiev 《纳微快报:英文版》 CAS CSCD 2019年第2期109-126,共18页
With only a few deep-level defect states having a high formation energy and dominance of shallow carrier non-trapping defects,the defect-tolerant electronic and optical properties of lead halide perovskites have made ... With only a few deep-level defect states having a high formation energy and dominance of shallow carrier non-trapping defects,the defect-tolerant electronic and optical properties of lead halide perovskites have made them appealing materials for high-efficiency,low-cost,solar cells and light-emitting devices.As such,recent observations of apparently deep-level and highly luminescent states in low-dimensional perovskites have attracted enormous attention as well as intensive debates.The observed green emission in 2D CsPb2Br5 and 0 D Cs4PbBr6 poses an enigma over whether it is originated from intrinsic point defects or simply from highly luminescent CsPbBr3 nanocrystals embedded in the otherwise transparent wide band gap semiconductors.The nature of deep-level edge emission in 2D Ruddlesden–Popper perovskites is also not well understood.In this mini review,the experimental evidences that support the opposing interpretations are analyzed,and challenges and root causes forthe controversy are discussed.Shortcomings in the current density functional theory approaches to modeling of properties and intrinsic point defects in lead halide perovskites are also noted.Selected experimental approaches are suggested to better correlate property with structure of a material and help resolve the controversies.Understanding and identification of the origin of luminescent centers will help design and engineer perovskites for wide device applications. 展开更多
关键词 LOW-DIMENSIONAL perovskites LUMINESCENT CENTERS Edge STATES Cesium LEAD halides Deep-level STATES Ruddlesden–Popper perovskites
Global Serial Promoting Events of China Tourism and Culture Week 预览
13
作者 Xie Ningxin 《中外文化交流:英文版》 2019年第6期9-12,共4页
From May 15 to June 30, 257 cultural and tourist exchange events have been held for China Tourism and Culture Week by 34 China Cultural Centers and 19 China National Tourist Offices stationed abroad, with "Beauti... From May 15 to June 30, 257 cultural and tourist exchange events have been held for China Tourism and Culture Week by 34 China Cultural Centers and 19 China National Tourist Offices stationed abroad, with "Beautiful China" as the theme. 展开更多
关键词 GLOBAL SERIAL Promoting EVENTS China Tourism and CULTURE WEEK China Cultural CENTERS
在线阅读 下载PDF
Earthquake planning and crisis management with an emphasis on the facilities, utilities, and services of the health care centers of Tiran and Karvan County, Isfahan Province, Iran: A case study
14
作者 Rouhullah Dehghani Narges Mohammadzadeh +1 位作者 Maryam Salehi Hamid Kassiri 《急性病杂志(英文版)》 2018年第3期115-121,共7页
Objective: To study earthquake planning and crisis management with an emphasis on the facilities, utilities, and services of the health care centers of Tiran and Karvan County, Isfahan Province. Methods: This is a des... Objective: To study earthquake planning and crisis management with an emphasis on the facilities, utilities, and services of the health care centers of Tiran and Karvan County, Isfahan Province. Methods: This is a descriptive-analytical survey based on the quantitative and qualitative characteristics of Tiran and Karvan County Health Care Centers(HCCs). Twenty quantitative and qualitative indicators were derived from the studied HCCs and analyzed using the strengths, weaknesses, opportunities and threats analysis technique. The top crisis management strategies were identified and a number of strategies and solutions were proposed. Results: The HCC utilities such as water, electricity, gas, and heating and cooling systems were in average condition, whereas the facilities of the majority of HCCs were in vulnerable-to-average condition. In addition, they sustained relatively high degree of instability which calls for reassessment and effective policies to minimize weaknesses and eliminate threats using strengths and opportunities. Conclusions: It is recommended that the condition of Tiran and Karvan County HCCs be enhanced by distributing new HCCs based on the population density, expanding the road network and creating vast, wide-open spaces to enable field hospital construction in times of crisis. 展开更多
关键词 CRISIS management EARTHQUAKE Strategy Health care CENTERS Iran
The mechanism of the UV band edge photorefractivity suppression in highly doped LiNbO3:Zr crystals
15
作者 辛非非 《光电子快报:英文版》 EI 2017年第6期419-422,共4页
The ultraviolet(UV) band edge photorefractivity of LiNbO_3:Zr at 325 nm has been investigated. The experimental results show that the resistance against photorefraction at 325 nm is quite obvious but not as strong as ... The ultraviolet(UV) band edge photorefractivity of LiNbO_3:Zr at 325 nm has been investigated. The experimental results show that the resistance against photorefraction at 325 nm is quite obvious but not as strong as that at 351 nm, when the doping concentration of Zr reaches 2.0 mol%. It is reported that the photorefractivity in other tetravalently doped LiNbO_3 crystals, such as LiNbO_3:Hf and Li NbO_3:Sn, is enhanced dramatically with doping concentration over threshold. Here we give an explicit explanation on such seemly conflicting behaviors of tetravalently doped LiNbO_3, which is ascribed to the combined effect of increased photoconductivity and the absorption strength of the band edge photorefractive centers. 展开更多
Analysis of the lifetime and culling reasons for AI boars 预览
16
作者 Damian Knecht Anna Jankowska-Maosa Kamil Duziński 《畜牧与生物技术杂志:英文版》 SCIE CAS CSCD 2017年第4期866-874,共9页
Background: The aim of the study was to analyze the lifetime and culling reasons for boars used in insemination centers (AI centers).Methods: The data collected from 355 culled boars from 1998 to 2013 included: age at... Background: The aim of the study was to analyze the lifetime and culling reasons for boars used in insemination centers (AI centers).Methods: The data collected from 355 culled boars from 1998 to 2013 included: age at start of semen collection,boar herd life, culling reason, daily gain and lean meat content, and number of ejaculates not meeting sales requirements after dilution. Culling reasons were divided into 7 groups: low semen value (LSV), low or lack of libido (LL), leg problems (LP), infectious diseases (ID), old age (OA), reduced demand for semen from the given boar (RD),and others (OT).Results: The most common culling reasons for boars were LSV (23.7%) and RD (22.5%). It was observed that the lowest daily gains were noted in boars culled due to OA. Boars culled due to OA and RD were maintained in production for the longest time (over 1000 d), for LSV and ID retention was about 700 d, and due to LL below 400d. The survival probability was over 0.9 until 1.5 yr, and just over 0.2 until 4 yr. The highest relative frequency was observed in the 36th and 42nd mo of life (over 16%). Hazard risk analysis revealed a more than 10 times higher risk of culling in the case of LL, ID or OT, in comparison to OA.Conclusions: The results can be used as a direct point of reference for the identification of emerging problems in AI boar exploitation and the development of an appropriate culling policy in AI centers. 展开更多
关键词 AI CENTERS BOARS CULLING Exploitation Management
在线阅读 下载PDF
Understanding “software-defined” from an OS perspective: technical challenges and research issues
17
作者 Hong MEI 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2017年第12期267-269,共3页
<正>What is'software-defined'?Software-defined has become one of the hottest buzzwords in the information technology(IT)community.It is used to describe a family of technologies,including software-define... <正>What is'software-defined'?Software-defined has become one of the hottest buzzwords in the information technology(IT)community.It is used to describe a family of technologies,including software-defined networking(SDN),softwaredefined storage(SDS),and software-defined data centers(SDDC).These are part of a broader trend that is referred to as software-defined everything 展开更多
关键词 软件定义 信息技术 操作系统 SDDC 数据中心 流行语 SDN SDS
Randomized control multi-center clinical study of mycophenolate mofetil and cyclophosphamide in the treatment of connective tissue disease related interstitial lung disease
18
作者 张光峰 《中国医学文摘:内科学分册(英文版)》 2016年第1期56-57,共2页
<正>Objective To investigate the efficacy and safety of mycophenolate mofetil(MMF)in the treatment of connective tissue disease-related interstitial lung disease(CTD-ILD).Methods A total of 60 patients with CTDI... <正>Objective To investigate the efficacy and safety of mycophenolate mofetil(MMF)in the treatment of connective tissue disease-related interstitial lung disease(CTD-ILD).Methods A total of 60 patients with CTDILD,confirmed by high resolution computer tomography(HRCT),were enrolled from five clinical centers from 展开更多
关键词 INTERSTITIAL CONNECTIVE CENTERS assessed enrolled INTRAVENOUS maintenance expiratory MONOXIDE completed
中心循环的有限p-群中的非交换集
19
作者 王玉雷 刘合国 《数学学报》 SCIE CSCD 北大核心 2015年第2期321-328,共8页
设G是一个群,X是G的一个子集,若对于任意x,y∈X且x≠y,都有xy≠yx,则称X是G的一个非交换集.进一步,如果对于G中的任意其他非交换子集Y,都有|X|≥|Y|,那么称X是G的一个极大非交换集.本文界定了中心循环的有限p-群中极大非交换集的势.
关键词 有限P-群 中心 非交换集
一类三次系统的细中心与局部临界周期分支 预览 被引量:1
20
作者 陈挺 黄文韬 马皖川 《中北大学学报:自然科学版》 CAS 北大核心 2014年第5期499-503,共5页
研究了一类三次实自治系统细中心与局部临界周期分支问题.利用计算机代数系统Mathematica分别计算出了该实系统所对应的伴随复系统在三个中心条件下的复周期常数,得到原点为k(k=0,1,2,3)阶细中心的充分必要条件.得到了当原点为k(k=0,... 研究了一类三次实自治系统细中心与局部临界周期分支问题.利用计算机代数系统Mathematica分别计算出了该实系统所对应的伴随复系统在三个中心条件下的复周期常数,得到原点为k(k=0,1,2,3)阶细中心的充分必要条件.得到了当原点为k(k=0,1,2,3)阶细中心时,该系统从原点能分支不多于k个局部临界周期分支.证明了该实系统恰有3个局部临界周期分支. 展开更多
关键词 中心 周期常数 细中心 临界周期分支
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈