期刊文献+
共找到2,527篇文章
< 1 2 127 >
每页显示 20 50 100
家庭教养方式与流动儿童ODD行为表现的关系
1
作者 刘振敏 《中华家教》 2024年第2期85-94,共10页
本文采用问卷法对北京市218名有对立违抗障碍(ODD)行为表现的流动儿童进行调查,测查其家庭教养方式和ODD行为表现的关系。结果显示:(1)ODD行为表现在教养方式上差异显著;(2)ODD行为表现在回应性和要求性上差异显著;(3)回应性、要求性和... 本文采用问卷法对北京市218名有对立违抗障碍(ODD)行为表现的流动儿童进行调查,测查其家庭教养方式和ODD行为表现的关系。结果显示:(1)ODD行为表现在教养方式上差异显著;(2)ODD行为表现在回应性和要求性上差异显著;(3)回应性、要求性和ODD行为表现具有显著相关。研究结果表明,父母采用积极有效的家庭教养方式,重视对儿童的积极情感回应,采用正向而恰当的规则教导,掌握正确的奖惩措施,保持良好的亲子沟通,对促进流动儿童心理健康发展具有指导意义。 展开更多
关键词 家庭教养方式 对立违抗障碍 回应性 要求性
下载PDF
Advantage of log odds of positive lymph nodes in prognostic evaluation of patients with early-onset colon cancer 被引量:1
2
作者 Heng-Bo Xia Chen Chen +2 位作者 Zhi-Xing Jia Liang Li A-Man Xu 《World Journal of Gastrointestinal Surgery》 SCIE 2023年第11期2430-2444,共15页
BACKGROUND Colon cancer(CC)is one of the most common cancers of the digestive tract,the third most common cancer worldwide,and the second most common cause of cancer-related deaths.Previous studies have demonstrated a... BACKGROUND Colon cancer(CC)is one of the most common cancers of the digestive tract,the third most common cancer worldwide,and the second most common cause of cancer-related deaths.Previous studies have demonstrated a higher risk of lymph node metastasis(LNM)in young patients with CC.It might be reasonable to treat patients with early-onset locally advanced CC with extended lymph node dissection.However,few studies have focused on early-onset CC(ECC)patients with LNM.At present,the methods of predicting and evaluating the prognosis of ECC patients with LNM are controversial.From the data of patients with CC obtained from the Surveillance,Epidemiology,and End Results(SEER)database,data of young patients with ECC(≤50 years old)was screened.Patients with unknown data were excluded from the study,while the remaining patients were included.The patients were randomly divided into a training group(train)and a testing group(test)in the ratio of 7:3,while building the model.The model was constructed by the training group and verified by the testing group.Using multiple Cox regression models to compare the prediction efficiency of LNM indicators,nomograms were built based on the best model selected for overall survival(OS)and cause-specific survival(CSS).In the two groups,the performance of the nomogram was evaluated by constructing a calibration plot,time-dependent area under the curve(AUC),and decision curve analysis.Finally,the patients were grouped based on the risk score predicted by the prognosis model,and the survival curve was constructed after comparing the survival status of the high and low-risk groups.RESULTS Records of 26922 ECC patients were screened from the SEER database.N classification,positive lymph nodes(PLN),lymph node ratio(LNR)and log odds of PLN(LODDS)were considered to be independent predictors of OS and CSS.In addition,independent risk factors for OS included gender,race,marital status,primary site,histology,grade,T,and M classification,while the independent prognostic factors for CSS included race,marital status,primary site,grade,T,and M classification.The prediction model including LODDS is composed of minimal Akaike information criterion,maximal concordance indexes,and AUCs.Factors including gender,race,marital status,primary site,histology,grade,T,M classification,and LODDS were integrated into the OS nomogram,while race,marital status,primary site,grade,T,M classification,and LODDS were included into the CSS nomogram.The nomogram representing both cohorts had been successfully verified in terms of prediction accuracy and clinical practicability.CONCLUSION LODDS is superior to N-stage,PLN,and LNR of ECC.The nomogram containing LODDS might be helpful in tumor evaluation and clinical decision-making,since it provides an appropriate prediction of ECC. 展开更多
关键词 Early-onset colon cancer Log odds of positive lymph nodes Lymph node metastasis NOMOGRAM Prognosis Surveillance Epidemiology and End Results
下载PDF
Products of Odd Numbers or Prime Number Can Generate the Three Members’ Families of Fermat Last Theorem and the Theorem Is Valid for Summation of Squares of More Than Two Natural Numbers
3
作者 Susmita Pramanik Deepak Kumar Das Panchanan Pramanik 《Advances in Pure Mathematics》 2023年第10期635-641,共7页
Fermat’s last theorem, had the statement that there are no natural numbers A, B, and C such that A<sup>n</sup> + B<sup>n</sup> = C<sup>n</sup>, in which n is a natural number great... Fermat’s last theorem, had the statement that there are no natural numbers A, B, and C such that A<sup>n</sup> + B<sup>n</sup> = C<sup>n</sup>, in which n is a natural number greater than 2. We have shown that any product of two odd numbers can generate Fermat or Pythagoras triple (A, B, C) following n = 2 and also it is applicable A<sup>2</sup> + B<sup>2</sup> + C<sup>2</sup> + D<sup>2</sup> + so on =A<sub>n</sub><sup>2 </sup>where all are natural numbers. 展开更多
关键词 Fermat Last Theorem Generation of Fermat’s Numbers Extension of Fermat’s Expression Fermat’s Expression from Products of odd Numbers
下载PDF
Revolutionizing Treatment:AI-Driven Noninvasive Approaches for ODD and ADHD
4
作者 Shiva Dalili Bahman Zohuri 《Management Studies》 2023年第4期215-220,共6页
Oppositional Defiant Disorder(ODD)and Attention Deficit/Hyperactivity Disorder(ADHD)are mental health conditions that have traditionally been managed through behavioral therapies and medication.However,the integration... Oppositional Defiant Disorder(ODD)and Attention Deficit/Hyperactivity Disorder(ADHD)are mental health conditions that have traditionally been managed through behavioral therapies and medication.However,the integration of Artificial Intelligence(AI)has brought about a revolutionary shift in treatment approaches.This article explores the role of AI-driven noninvasive treatments for ODD and ADHD.AI offers personalized treatment plans,predictive analytics,virtual therapeutic platforms,and continuous monitoring,enhancing the effectiveness and accessibility of interventions.Ethical considerations and the need for a balanced approach are discussed.As technology evolves,collaborative efforts between mental health professionals and technologists will shape the future of mental health care for individuals with ODD and ADHD. 展开更多
关键词 odd ADHD Artificial Intelligence noninvasive treatment personalized treatment predictive analytics virtual therapeutic platforms continuous monitoring mental health care technology ethical considerations Artificial Intelligence Systems
下载PDF
父母心理控制与ODD症状儿童抑郁、攻击行为的关系 被引量:13
5
作者 蔺秀云 李龙凤 +3 位作者 黎燕斌 王中会 陈琦 方晓义 《心理发展与教育》 CSSCI 北大核心 2014年第6期635-645,共11页
以北京市、山东省和云南省14所小学中的340名有对立违抗障碍(Oppositional Defiant Disorder,ODD)症状的儿童及其158名班主任为被试,收集了儿童自己填写的父母心理控制、自尊、抑郁量表,班主任评估的儿童攻击行为量表,用以考察父亲与母... 以北京市、山东省和云南省14所小学中的340名有对立违抗障碍(Oppositional Defiant Disorder,ODD)症状的儿童及其158名班主任为被试,收集了儿童自己填写的父母心理控制、自尊、抑郁量表,班主任评估的儿童攻击行为量表,用以考察父亲与母亲心理控制对ODD症状儿童抑郁、攻击行为的不同影响,以及自尊在其中的中介作用和儿童性别的调节作用。结果发现:(1)与有ODD症状的女孩相比,具有ODD症状的男孩人数更多,抑郁、攻击行为问题更为严重,自尊也更差;(2)父亲对男孩的心理控制显著多于女孩,而母亲对男孩、女孩的心理控制没有显著差异;(3)父亲和母亲心理控制与ODD症状儿童的抑郁、攻击行为都呈显著正相关且父亲心理控制能显著预测儿童的抑郁和攻击行为,而母亲心理控制能显著的预测攻击行为;(4)自尊在父亲心理控制与ODD症状儿童的抑郁、母亲心理控制与儿童的攻击行为之间均起部分中介作用,在父亲心理控制与儿童的攻击行为、母亲心理控制与儿童的抑郁之间均起完全中介作用。 展开更多
关键词 odd症状儿童 父母心理控制 自尊 抑郁 攻击行为
下载PDF
Kumaraswamy-Odd Rayleigh-G Family of Distributions with Applications
6
作者 Jamilu Yunusa Falgore Sani Ibrahim Doguwa 《Open Journal of Statistics》 2020年第4期719-734,共16页
We propose a new generator of continuous distributions with at least four positive parameters called the Kumaraswamy-Odd Rayleigh-G family. Some special cases were presented. The plots of the Kumaraswamy Odd Rayleigh ... We propose a new generator of continuous distributions with at least four positive parameters called the Kumaraswamy-Odd Rayleigh-G family. Some special cases were presented. The plots of the Kumaraswamy Odd Rayleigh Log-Logistic (</span><i><span style="font-family:Verdana;">KORLL</span></i><span style="font-family:Verdana;">) distribution indicate that the distribution can take many shapes depending on the parameter values. The negative skewness and kurtosis indicates that the distribution has li</span><span style="font-family:Verdana;">ghter tails than the normal distribution. The Monte Carlo simulation results indicate that the estimated biases decrease when the sample size increases. Furthermore, </span></span><span style="font-family:Verdana;">the root mean squared error estimates decay</span><span style="font-family:""><span style="font-family:Verdana;"> towards zero as the sample size increases. This part shows the consistency of the maximum likelihood estimators. From the considered analytical measures, the new </span><i><span style="font-family:Verdana;">KORLL</span></i><span style="font-family:Verdana;"> provides </span></span><span style="font-family:Verdana;">the best fit to the analysed five real data sets indicating that this new model outclasses its competitors. 展开更多
关键词 odd Rayleigh-G Family Kumuraswamy odd Rayleigh-G Family Kumuraswamy odd Rayleigh-Loglogistic Distribution Monte Carlo Simulation SKEWNESS
下载PDF
基于Odds-Matrix算法的中长期电量组合预测方法及其应用 被引量:5
7
作者 欧阳森 冯天瑞 +1 位作者 李翔 王克英 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2014年第8期39-44,共6页
中长期电量的组合预测存在权重选择困难,适应性、抗干扰性较差的问题.文中结合目前广泛应用的组合预测技术,设计了以Odds-Matrix算法为核心的Odds-Matrix组合预测方法.该组合预测方法利用Odds-Matrix算法对单一预测模型的有效性进行定... 中长期电量的组合预测存在权重选择困难,适应性、抗干扰性较差的问题.文中结合目前广泛应用的组合预测技术,设计了以Odds-Matrix算法为核心的Odds-Matrix组合预测方法.该组合预测方法利用Odds-Matrix算法对单一预测模型的有效性进行定量分析,用权重概率分布函数来描述各个方法的优劣,然后根据权重进行单一预测模型的筛选和组合.利用实际数据对所设计的Odds-Matrix组合预测方法进行测试,结果表明,文中预测方法的精确度较其他常用组合预测法较高,说明该方法具有较强的适应性与抗干扰性. 展开更多
关键词 电量预测 odds-Matrix算法 组合预测 模型筛选
下载PDF
odds ratio在医学动物实验中的应用
8
作者 迟琼 邹泽红 +1 位作者 傅意玲 陶爱林 《中国药理学通报》 CAS CSCD 北大核心 2010年第3期408-410,共3页
目的分析odds ratio在医学动物实验中的应用现状。方法以医学动物实验中常用动物模型及优势比或odds ra-tio为检索式进行搜索,分别对比分析中外数据库中7种动物模型实验中应用odds ratio的状况。同时,给出范例,说明OR值的计算方法及不... 目的分析odds ratio在医学动物实验中的应用现状。方法以医学动物实验中常用动物模型及优势比或odds ra-tio为检索式进行搜索,分别对比分析中外数据库中7种动物模型实验中应用odds ratio的状况。同时,给出范例,说明OR值的计算方法及不同结果的实际意义。结果动物模型实验中使用OR值作为统计指标的寥寥无几。结论OR值的重要性在国内没有得到足够的关注。 展开更多
关键词 数据库 动物模型 优势比 odds RATIO 关联强度 检索式
下载PDF
On the Problem of All Equal Positive Odd Number Solutions of the Dissemination of the Ends' Guess 被引量:1
9
作者 刘元宗 《Chinese Quarterly Journal of Mathematics》 CSCD 2000年第2期108-109,共2页
The thesis is concerned with the problem of the dissemination of the Ends’ guess and offers the formula of all equal positive odd number solutions.
关键词 Ends’ guess DISSEMINATION all equal positive odd number solutions
下载PDF
Oddi括约肌收缩运动与十二指肠MMC相关性的实验研究 被引量:1
10
作者 王洪江 《中国应用生理学杂志》 CAS CSCD 北大核心 2004年第4期357-358,379,共3页
目的确定Oddi括约肌收缩运动与十二指肠移行性运动综合波(migratingmotorcomplex,MMC)的相互关系,提高对胆道机能失调性疾病的诊断或药物对Oddi括约肌影响的评价。方法四只杂种成犬行十二指肠Thomas造瘘,微量灌流法连续测定十二指肠和O... 目的确定Oddi括约肌收缩运动与十二指肠移行性运动综合波(migratingmotorcomplex,MMC)的相互关系,提高对胆道机能失调性疾病的诊断或药物对Oddi括约肌影响的评价。方法四只杂种成犬行十二指肠Thomas造瘘,微量灌流法连续测定十二指肠和Oddi括约肌收缩运动。结果Oddi括约肌伴随十二指肠MMC呈周期性收缩运动,平均基础压、振幅和收缩频率在十二指肠MMC的1期,不受十二指肠收缩的影响,相对稳定。与2期或3期相比,差异显著(P〈0.01)。结论阐述Oddi括约肌收缩功能或研究药物对Oddi括约肌的作用时,应注意十二指肠对Oddi括约肌的影响。 展开更多
关键词 oddI括约肌 十二指肠 移行性运动综合波
下载PDF
基于指数分布的比例odds模型次序统计量的随机性质
11
作者 张艺馨 王丙参 《德州学院学报》 2017年第4期7-9,21,共4页
给出几种常见序关系的定义,在比例odds模型的框架下,当分布函数替换为指数分布时,对其次序统计量作了随机比较.
关键词 随机序 比例odds模型 次序统计量
下载PDF
基于比例odds模型最小次序统计量的随机比较
12
作者 张艺馨 《天水师范学院学报》 2016年第2期16-18,共3页
在比例odds模型的框架下,对它的最小次序统计量作了随机比较,包括似然比序,失效率序和随机序.
关键词 随机序 反失效率序 似然比序 比例odds模型
下载PDF
果蝇odd蛋白的原核表达及多克隆抗体的制备研究 被引量:1
13
作者 张义 叶湘漓 +8 位作者 鲁建鑫 彭佩莹 赵阳 江志钢 李发祥 王跃群 袁婺洲 吴秀山 邓云 《激光生物学报》 CAS CSCD 2011年第6期778-781,共4页
odd是一个新发现的心脏特异表达基因。为了进一步研究odd在心脏发育中的功能,根据已报道的odd基因序列,以果蝇cDNA文库为模板进行PCR扩增,将所得的odd部分编码区序列连接到pET-28a载体上构建原核表达载体;重组子经酶切测序鉴定后,转化... odd是一个新发现的心脏特异表达基因。为了进一步研究odd在心脏发育中的功能,根据已报道的odd基因序列,以果蝇cDNA文库为模板进行PCR扩增,将所得的odd部分编码区序列连接到pET-28a载体上构建原核表达载体;重组子经酶切测序鉴定后,转化到大肠杆菌BL21菌株,IPTG诱导融合蛋白表达,Ni-IDA凝胶柱亲和纯化,纯化后的His-odd融合蛋白免疫新西兰大白兔以制备多克隆抗体,Western Blot检测抗体活性。结果表明,获得了odd原核表达重组融合蛋白以及高效价的、特异性兔抗Odd多克隆抗体,为后续的odd功能研究奠定了基础。 展开更多
关键词 odd 融合蛋白 原核表达 多克隆抗体
下载PDF
急性胰腺炎时Oddi括约肌的生长抑素的表达及其作用 被引量:4
14
作者 徐赫一 高丽娟 陈平 《内蒙古医科大学学报》 2014年第6期487-490,496,共5页
目的:探讨急性胰腺炎时Oddi括约肌(SO)生长抑素(SST)的表达及其作用。方法::采用逆行胰胆管牛磺胆酸钠注射造成豚鼠急性胰腺炎动物模型,随机分为正常对照组、急性胰腺炎模型组和生长抑素预防性治疗组。观察三组胰腺组织及SO组织病理学... 目的:探讨急性胰腺炎时Oddi括约肌(SO)生长抑素(SST)的表达及其作用。方法::采用逆行胰胆管牛磺胆酸钠注射造成豚鼠急性胰腺炎动物模型,随机分为正常对照组、急性胰腺炎模型组和生长抑素预防性治疗组。观察三组胰腺组织及SO组织病理学改变和外周血淀粉酶及脂肪酶水平;免疫组化检测三组SO内SST的表达情况。结果:急性胰腺炎豚鼠均见整个胰腺肿大,质软,部分肿大胰腺散在有黄白色脂肪坏死灶。镜下见广泛细胞变性,间质水肿,炎性细胞浸润。部分伴广泛腺泡细胞及胰岛细胞坏死,腺体内片状间质出血斑;生长抑素预防性治疗的急性胰腺炎豚鼠胰腺病理组织学较AP时组织水肿减轻,细胞变性和坏死明显减少,评分明显低于急性胰腺炎组,P<0.05。急性胰腺炎时SO内SST的表达减少。结论:急性胰腺炎的发生静脉给予SST,维持了豚鼠急性胰腺炎后循环中的SST水平,SO内SST神经分泌明显减少,显著防止了胰腺炎症病变。 展开更多
关键词 odd括约肌 急性胰腺炎 生长抑素
下载PDF
Filtration Structure of Finite-Dimensional Special Odd Hamiltonian Superalgebras in Prime Characteristic 被引量:5
15
作者 何英华 刘文德 李彬 《Journal of Beijing Institute of Technology》 EI CAS 2009年第4期488-491,共4页
The filtration structure of finite-dimensional special odd Hamilton superalgebras over a field of prime characteristic was studied. By determining ad-nilpotent dements in the even part, the natural filtration of speci... The filtration structure of finite-dimensional special odd Hamilton superalgebras over a field of prime characteristic was studied. By determining ad-nilpotent dements in the even part, the natural filtration of special odd Hamiltonian superalgebras is proved to be invariant. Using this result, the special odd Hamilton superalgebras is classified. Finally, the automorphism group of the restricted special odd Hamilton superalgebras is determined. 展开更多
关键词 finite-dimensional special odd Hamilton superalgebras ad-nilpotent elements FILTRATION
下载PDF
Optimum design of equivalent accelerated life testing plans based on proportional hazards-proportional odds model 被引量:3
16
作者 Tingting Huang Tongmin Jiang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2011年第5期871-878,共8页
The optimum design of equivalent accelerated life testing plan based on proportional hazards-proportional odds model using D-optimality is presented. The defined equivalent test plan is the test plan that has the same... The optimum design of equivalent accelerated life testing plan based on proportional hazards-proportional odds model using D-optimality is presented. The defined equivalent test plan is the test plan that has the same value of the determinant of Fisher information matrix. The equivalent test plan of step stress accelerated life testing (SSALT) to a baseline optimum constant stress accelerated life testing (CSALT) plan is obtained by adjusting the censoring time of SSALT and solving the optimization problem for each case to achieve the same value of the determinant of Fisher information matrix as in the baseline optimum CSALT plan. Numer- ical examples are given finally which demonstrate the equivalent SSALT plan to the baseline optimum CSALT plan reduces almost half of the test time while achieving approximately the same estimation errors of model parameters. 展开更多
关键词 equivalent test plan proportional hazards-proportional odds (PH-PO) model D-OPTIMALITY constant stress step stress accelerated life testing (ALT).
下载PDF
OSCILLATION FOR FORCED ODD ORDER NEUTRAL DIFFERENTIAL EQUATIONS 被引量:2
17
作者 Tao Youshan Gao GuozhuDept.ofAppl.Math.,DongHuaUniv.,Shanghai200051 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2001年第2期133-140,共8页
In this paper, the forced odd order neutral differential equations of the form are considered d n d t n[x(t)-R(t)x(t-τ)]+P(t)x(t-σ)=f(t),t≥t 0.A sufficient condition for the oscillation of all solutions is... In this paper, the forced odd order neutral differential equations of the form are considered d n d t n[x(t)-R(t)x(t-τ)]+P(t)x(t-σ)=f(t),t≥t 0.A sufficient condition for the oscillation of all solutions is obtained. 展开更多
关键词 OSCILLATION neutral equation forcing term odd order.
下载PDF
Development and validation of prognostic nomogram based on log odds of positive lymph nodes for patients with gastric signet ring cell carcinoma 被引量:2
18
作者 Zijie Xu Jing Jing Guiliang Ma 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 2020年第6期778-793,共16页
Objective: Our aims were to establish novel nomogram models, which directly targeted patients with signet ring cell carcinoma(SRC), for individualized prediction of overall survival(OS) rate and cancer-specific surviv... Objective: Our aims were to establish novel nomogram models, which directly targeted patients with signet ring cell carcinoma(SRC), for individualized prediction of overall survival(OS) rate and cancer-specific survival(CSS).Methods: We selected 1,365 SRC patients diagnosed from 2010 to 2015 from Surveillance, Epidemiology and End Results(SEER) database, and then randomly partitioned them into a training cohort and a validation cohort.Independent predicted indicators, which were identified by using univariate testing and multivariate analyses, were used to construct our prognostic nomogram models. Three methods, Harrell concordance index(C-index), receiver operating characteristics(ROC) curve and calibration curve, were used to assess the ability of discrimination and predictive accuracy. Integrated discrimination improvement(IDI), net reclassification improvement(NRI) and decision curve analysis(DCA) were used to assess clinical utility of our nomogram models.Results: Six independent predicted indicators, age, race, log odds of positive lymph nodes(LODDS), T stage, M stage and tumor size, were associated with OS rate. Nevertheless, only five independent predicted indicators were associated with CSS except race. The developed nomograms based on those independent predicted factors showed reliable discrimination. C-index of our nomogram for OS and CSS was 0.760 and 0.763, which were higher than American Joint Committee on Cancer(AJCC) 8 th edition tumor-node-metastasis(TNM) staging system(0.734 and 0.741, respectively). C-index of validation cohort for OS was 0.757 and for CSS was 0.773. The calibration curves also performed good consistency. IDI, NRI and DCA showed the nomograms for both OS and CSS had a comparable clinical utility than the TNM staging system.Conclusions: The novel nomogram models based on LODDS provided satisfying predictive ability of SRC both in OS and CSS than AJCC 8 th edition TNM staging system alone. 展开更多
关键词 Log odds of positive lymph nodes NOMOGRAMS PROGNOSIS signet ring cell
下载PDF
Wigner functions and tomograms of the photon-depleted even and odd coherent states 被引量:1
19
作者 王继锁 孟祥国 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第4期1254-1262,共9页
Using the coherent state representation of Wigner operator and the technique of integration within an ordered product (IWOP) of operators, this paper derives the Wigner functions for the photon-depleted even and odd... Using the coherent state representation of Wigner operator and the technique of integration within an ordered product (IWOP) of operators, this paper derives the Wigner functions for the photon-depleted even and odd coherent states (PDEOCSs). Moreover, in terms of the Wigner functions with respect to the complex parameter a the nonclassical properties of the PDEOCSs are discussed. The results show that the nonclassicality for the state |β, m〉o (or |β,m〉e) is more pronounced when m is even (or odd). According to the marginal distributions of the Wigner functions, the physical meaning of the Wigner functions is given. Further, the tomograms of the PDEOCSs are calculated with the aid of newly introduced intermediate coordinate-momentum representation in quantum optics. 展开更多
关键词 photon-depleted even and odd coherent state Wigner function intermediate coordinate-momentum representation TOMOGRAM
下载PDF
Improvement of the Lewis-Abegg-Octet Rule Using an “Even-Odd” Rule in Chemical Structural Formulas: Application to Hypo and Hyper-Valences of Stable Uncharged Gaseous Single-Bonded Molecules with Main Group Elements 被引量:11
20
作者 Geoffroy Auvert 《Open Journal of Physical Chemistry》 2014年第2期60-66,共7页
As Lewis proposed his octet rule, itself inspired by Abegg’s rule, that a molecule is stable when all its composing atoms have eight electrons in their valence shell, it perfectly applied to the vast majority of know... As Lewis proposed his octet rule, itself inspired by Abegg’s rule, that a molecule is stable when all its composing atoms have eight electrons in their valence shell, it perfectly applied to the vast majority of known stable molecules. Only a few stable molecules were known that didn’t fall under this rule, such as PCl5 and SF6, and Lewis chose to leave them aside at the time of his research. With further advances in chemistry, more exceptions to this rule of eight have been found, usually with the central atom of the structure having more or less than eight electrons in its valence shell. Theories have been developed in order to modify the octet rule to suit these molecules, defining these as hyper- or hypo-valent molecules and using other configurations for the electrons. The present paper aims to propose a representation rule for gaseous single-bonded molecules that makes it possible to reconcile both;molecules following the octet theory and those which do not. In this representation rule, each element of the molecule is subscripted with two numbers that follow a set of simple criteria. The first represents the number of valence electrons of the element;while the second is calculated by adding the first number to the number of the element’s covalent bonds within the molecule. The latter is equal to eight for organic molecules following the octet rule. Molecules being exceptions to the octet rule are now encompassed by this new even-odd rule: they have a valid chemical structural formula in which the second number is even but not always equal to eight. Both rules—octet and even-odd—are discussed and compared, using several well-known gaseous molecules having one or several single-bonded elements. A future paper will discuss the application of the even-odd rule to charged molecules. 展开更多
关键词 Octet RULE Hypervalence Hypovalence Even-odd RULE Electron-Pair SINGLE Bond MOLECULE Chemistry
下载PDF
上一页 1 2 127 下一页 到第
使用帮助 返回顶部