期刊文献+
共找到4,449篇文章
< 1 2 223 >
每页显示 20 50 100
The “Dead Universe” Theory: Natural Separation of Galaxies Driven by the Remnants of a Supermassive Dead Universe
1
作者 Joel Almeida 《Natural Science》 2024年第6期65-101,共37页
This article explores the dead universe theory as a novel interpretation for the origin and evolution of the universe, suggesting that our cosmos may have originated from the remnants of a preceding universe. This per... This article explores the dead universe theory as a novel interpretation for the origin and evolution of the universe, suggesting that our cosmos may have originated from the remnants of a preceding universe. This perspective challenges the conventional Big Bang theory, particularly concerning dark matter, the expansion of the universe, and the interpretation of phenomena such as gravitational waves. 展开更多
关键词 Dead Universe theory Heat Death of the Universe Big Bang theory Universe’s Ultimate Fate Universe Expansion Big Freeze Universe Cosmological Models End of Universe Theories natural Galaxy Drift Future of the Universe Universe Cooling Down Cosmology and Entropy
下载PDF
Fundamental Issues Towards Unified Design Theory of Recycled and Natural Aggregate Concrete Components 被引量:1
2
作者 Jianzhuang Xiao Kaijian Zhang +2 位作者 Tao Ding Qingtian Zhang Xuwen Xiao 《Engineering》 SCIE EI CAS CSCD 2023年第10期188-197,共10页
In the past 20 years,recycled aggregate concrete(RAC),as a type of low-carbon concrete,has become a worldwide focus of research.However,the design methodology for RAC structural components remains a challenge.Conseque... In the past 20 years,recycled aggregate concrete(RAC),as a type of low-carbon concrete,has become a worldwide focus of research.However,the design methodology for RAC structural components remains a challenge.Consequently,demands for a unified design of natural aggregate concrete(NAC)and RAC components have been presented.Accordingly,this study analyses the necessity of a unified design theory and provides an in-depth demonstration of the strength determination,compressive constitutive relationship,and design method of concrete components.The coefficient of variation of RAC strength is found to be generally higher than that of NAC strength.The compressive and tensile strengths of RAC can be defined and determined using the same method as that used for NAC.The uniaxial compressive constitutive relationship between NAC and RAC has a unified mathematical expression.However,the elastic modulus of RAC decreases,and its brittleness exhibits an increasing trend compared with that of NAC.Finally,to unify the design formulae of RAC and NAC components for bearing capacity,modification factors for RAC components are proposed considering safety and reliability.Additionally,the feasibility of the proposed unified time-dependent design theory is demonstrated in terms of conceptual design and structural measures considering the effects of strength degradation and reinforcement corrosion.It is believed that this study enriches and develops the basic theory of concrete structures. 展开更多
关键词 Recycled aggregate concrete(RAC) natural aggregate concrete(NAC) Strength determination Constitutive relation Reliability Unified design theory
下载PDF
On the Natures of English Passive Construction Based on Theta Theory
3
作者 王丽 《海外英语》 2016年第22期186-187,共2页
The study of English passive construction has always been one of the hot topics in the literature of Generative Grammar. Although many attempts have been made, the study of this structure is still not systematic enoug... The study of English passive construction has always been one of the hot topics in the literature of Generative Grammar. Although many attempts have been made, the study of this structure is still not systematic enough especially in terms of its essential natures. The present study is designed to give a full explanation of natures of English passive construction from the perspective of theta theory, which can provide English learners with a deeper understanding of passive structure. 展开更多
关键词 passive structure theta theory natures
下载PDF
A symmetric substructuring method for analyzing the natural frequencies of conical origami structures
4
作者 Chenhao Lu Yao Chen +2 位作者 Weiying Fan Jian Feng Pooya Sareh 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2024年第3期203-210,共8页
Conical origami structures are characterized by their substantial out-of-plane stiffness and energy-absorptioncapacity.Previous investigations have commonly focused on the static characteristics of these lightweight s... Conical origami structures are characterized by their substantial out-of-plane stiffness and energy-absorptioncapacity.Previous investigations have commonly focused on the static characteristics of these lightweight struc-tures.However,the efficient analysis of the natural vibrations of these structures is pivotal for designing conicalorigami structures with programmable stiffness and mass.In this paper,we propose a novel method to analyzethe natural vibrations of such structures by combining a symmetric substructuring method(SSM)and a gener-alized eigenvalue analysis.SSM exploits the inherent symmetry of the structure to decompose it into a finiteset of repetitive substructures.In doing so,we reduce the dimensions of matrices and improve computationalefficiency by adopting the stiffness and mass matrices of the substructures in the generalized eigenvalue analysis.Finite element simulations of pin-jointed models are used to validate the computational results of the proposedapproach.Moreover,the parametric analysis of the structures demonstrates the influences of the number of seg-ments along the circumference and the radius of the cone on the structural mass and natural frequencies of thestructures.Furthermore,we present a comparison between six-fold and four-fold conical origami structures anddiscuss the influence of various geometric parameters on their natural frequencies.This study provides a strategyfor efficiently analyzing the natural vibration of symmetric origami structures and has the potential to contributeto the efficient design and customization of origami metastructures with programmable stiffness. 展开更多
关键词 natural structural vibration Origami design Group theory Symmetric substructuring method(SSM) Generalized eigenvalue analysis
下载PDF
A graph theory model using human nature structure
5
作者 Liu Jia Hu Haimiao +2 位作者 Duan Miyi Li Wenfa Yuan Jiazheng 《High Technology Letters》 EI CAS 2017年第4期350-359,共10页
A graph theory model of the human nature structure( GMH) for machine vision and image/graphics processing is described in this paper. Independent from the motion and deformation of contours,the human nature structure(... A graph theory model of the human nature structure( GMH) for machine vision and image/graphics processing is described in this paper. Independent from the motion and deformation of contours,the human nature structure( HNS) embodies the most basic movement characteristics of the body. The human body can be divided into basic units like head,torso,and limbs. Using these basic units,a graph theory model for the HNS can be constructed. GMH provides a basic model for human posture processing,and the outline in the perspective projection plane is the body contour of an image. In addition,the GMH can be applied to articulated motion and deformable objects,e. g.,in the design and analysis of body posture,by modifying mapping parameters of the GMH. 展开更多
关键词 articulated motion and deformable objects(AMDO) human nature structure(HNS) graph theory machine vision image/graphics processing
下载PDF
Density functional theory study on natural hydrophobicity of sulfide surfaces 被引量:5
6
作者 赵翠华 陈建华 +1 位作者 吴伯增 龙贤灏 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第2期491-498,共8页
Adsorption of water on sulfide surfaces and natural floatability of sulfide minerals were studied using density functional theory (DFT) method. All computational models were built in a vacuum environment to eliminat... Adsorption of water on sulfide surfaces and natural floatability of sulfide minerals were studied using density functional theory (DFT) method. All computational models were built in a vacuum environment to eliminate the effects of oxygen and other factors. H2O molecule prefers to stay with pyrite and sphalerite surfaces rather than water, whereas for galena, chalcocite, stibnite, and molybdenite, H2O molecule prefers to stay with water rather than the mineral surfaces. On the other hand, pyrite surface favors N2 more than water, while sphalerite surface cannot adsorb N2. These results show that galena, stibnite, chalcocite, and molybdenite are hydrophobic, while sphalerite is hydrophilic. Although pyrite has certain hydrophilicity, it tends to be aerophilic because the reaction of pyrite with H2O is weaker than pyrite with N2. Thus, pyrite, galena, chalcocite, stibnite and molybdenite all have natural floatability. 展开更多
关键词 sulfide minerals water adsorption natural floatability density functional theory
下载PDF
亚当·斯密的自然观——对《道德情操论》中nature的解读 被引量:7
7
作者 吴红列 《浙江大学学报(人文社会科学版)》 CSSCI 北大核心 2011年第5期18-26,共9页
自然是18世纪苏格兰启蒙运动关注的一个重要主题,也是亚当.斯密道德哲学的一个基本命题。当时强大的自然法传统对斯密产生了重要影响,体现在斯密的重要著作《道德情操论》中。此书对nature一词的不同区分和多重思考,反映出斯密试图建立... 自然是18世纪苏格兰启蒙运动关注的一个重要主题,也是亚当.斯密道德哲学的一个基本命题。当时强大的自然法传统对斯密产生了重要影响,体现在斯密的重要著作《道德情操论》中。此书对nature一词的不同区分和多重思考,反映出斯密试图建立所有国家法律一般准则的自然法理学的努力,以及他不同于同时代其他哲学家的较为独特的自然观。这对于我们更好地理解斯密的道德哲学具有重要的意义。 展开更多
关键词 亚当·斯密 《道德情操论》 自然 自然法
下载PDF
The Thought of the Oneness Between Man and Nature in Walden
8
作者 田烨 《科技信息》 2010年第1期162-163,共2页
From the view of the ecological theory, this paper tries to analyze that Thoreau uses Chinese traditional philosophical thought--- the oneness of man and nature to deal with the relationship of human beings and the na... From the view of the ecological theory, this paper tries to analyze that Thoreau uses Chinese traditional philosophical thought--- the oneness of man and nature to deal with the relationship of human beings and the nature in Walden. 展开更多
关键词 沃尔登 中国 传统哲学 发展现状
下载PDF
THEORY AND PRACTICE FOR COMPILING THE ATLAS OF NATURAL DISASTERS IN CHINA 被引量:1
9
作者 Wang Jingai(Department of Resources and Environmental Sciences, Bejing Normal University, Beijing 100875 People’s Republic of China) 《Journal of Geographical Sciences》 SCIE CSCD 1994年第Z2期103-111,共9页
This article inquires into theoretical and practical problems on compilation of an atlas of regional natural disasters. (1) The basic theory of compiling an atlas of regional disasters has been founded on the combinat... This article inquires into theoretical and practical problems on compilation of an atlas of regional natural disasters. (1) The basic theory of compiling an atlas of regional disasters has been founded on the combination of the sciences of disasters, cartography and regional geogrphy. The content structure of a regional disaster atlas should be composed of at least the following five parts:hazard-formative environments and hazard-affected bodies,hazards, disaster effects, monitoring and warning system for natural disasters, and countermeasures for natural disaster reduction. (2) Contents of cartographic design of a regional disaster atlas should be composed of at least the following five parts: base map system, cartographic representation, Symbol System, color system, map edition and map layout system. (3) Based on theory and cartographic design of compiling an atlas of regional disaster, the Atlas of Natural Disater in China, which reveals objectively the temporal and spaial pattern of regional natural disasters of China,has been compiled and published. 展开更多
关键词 atlas compilation natural disaster theory PRACTICE
下载PDF
The Practical Significance of Marx's Theory of Natural Force Resources 被引量:1
10
作者 Jiefang ZHU 《Asian Agricultural Research》 2020年第3期64-67,74,共5页
Marx's theory of natural force resources is an indispensable part of Marx's economic theory.Natural force resources,as a kind of natural elements that do not cost a penny,are added to the production process fr... Marx's theory of natural force resources is an indispensable part of Marx's economic theory.Natural force resources,as a kind of natural elements that do not cost a penny,are added to the production process free of charge,and play a special role in the production process.Grasping and understanding the scientific connotation of Marx's theory of natural force resources is of great theoretical value and practical significance for promoting the harmonious unity of man and nature and adhering to the strategy of sustainable economic development. 展开更多
关键词 Marx theory of naturAL FORCE RESOURCE Practical SIGNIFICANCE
下载PDF
Analysis of Marx's Theory of Natural Forces 被引量:1
11
作者 Jiefang ZHU 《Meteorological and Environmental Research》 CAS 2022年第4期37-39,共3页
Marx’s theory of natural forces is an indispensable part of Marx’s economic theory.As a natural element that does not need to spend a penny,natural forces are added to the production process free of charge,and play ... Marx’s theory of natural forces is an indispensable part of Marx’s economic theory.As a natural element that does not need to spend a penny,natural forces are added to the production process free of charge,and play a special restrictive role in the production process.Mastering and applying the scientific connotation of Marx’s theory has very important theoretical value and practical significance for adhering to the sustainable development of nature,economy and society. 展开更多
关键词 Marx theory of natural forces Sustainable development
下载PDF
“Extreme utilization”development theory of unconventional natural gas 被引量:1
12
作者 MA Xinhua 《Petroleum Exploration and Development》 CSCD 2021年第2期381-394,共14页
In the process of unconventional natural gas development practice,the"extreme utilization"concept that focuses on"continuously breaking through the limit of development technology"is gradually form... In the process of unconventional natural gas development practice,the"extreme utilization"concept that focuses on"continuously breaking through the limit of development technology"is gradually formed,and supports the scale benefit exploration of unconventional gas in China.On this basis,the development theory of"extreme utilization"is proposed,its theoretical connotation together with development technologies of unconventional natural gas are clarified.The theoretical connotation is that,aiming at"extreme gas reservoirs","extreme techniques"are utilized to build subsurface connected bodies,expand the discharge area,and enlarge the production range,to obtain the maximum single-well production,extreme recovery,and eventually achieve the"extreme effect"of production.The series of development technologies include micro/nano-scale reservoir evaluation,"sweet spot"prediction,unconventional percolation theory and production capacity evaluation,optimization of grid well pattern,optimal-fast drilling and volume fracturing,and working regulation optimization and"integrated"organizing system.The"extreme utilization"development theory has been successfully applied in the development of unconventional gas reservoirs such as Sulige tight gas,South Sichuan shale gas,and Qinshui coalbed methane.Such practices demonstrate that,the"extreme utilization"development theory has effectively promoted the development of unconventional gas industry in China,and can provide theoretical guidance for effective development of other potential unconventional and difficult-to-recovery resources. 展开更多
关键词 unconventional natural gas extreme gas reservoir extreme development theory of extreme utilization subsurface connected body production capacity evaluation grid well pattern drainage and extraction optimization
下载PDF
BASIC EQUATIONS, THEORY AND PRINCIPLE OF COMPUTATIONAL STOCK MARKET (Ⅲ)—BASIC THEORIES
13
作者 云天铨 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2000年第8期861-868,共8页
By basic equations, two basic theories are presented: 1.Theory of stock's value v *(t)=v *(0) exp (ar * 2t); 2. Theory of conservation of stock's energy. Let stock's energy be defined as a q... By basic equations, two basic theories are presented: 1.Theory of stock's value v *(t)=v *(0) exp (ar * 2t); 2. Theory of conservation of stock's energy. Let stock's energy be defined as a quadratic function of stock's price v and its derivative , =Av 2+ Bv+C 2+Dv, under the constraint of basic equation, the problem was reduced to a problem of constrained optimization along optimal path. Using Lagrange multiplier and Euler equation of variation method, it can be proved that keeps conservation for any v,. The application of these equations and theories on judgement and analysis of tendency of stock market are given, and the judgement is checked to be correct by the recorded tendency of Shenzhen and Shanghai stock markets. 展开更多
关键词 political economics theory of value of goods variational method Euler equation conservation law
下载PDF
Preliminary Explanation on "Natural Activation Theory" Based on "Fenlong"
14
作者 Benhui Wei 《Agricultural Biotechnology》 CAS 2019年第3期112-115,共4页
Based on action mechanism of "Fenlong technology" with the maximum activation potential of global natural resources,"natural resources activation theory"("activation theory") is proposed ... Based on action mechanism of "Fenlong technology" with the maximum activation potential of global natural resources,"natural resources activation theory"("activation theory") is proposed firstly.Its connotation contains two parts.One is directly activating some natural resources in land,such as unutilized plough bottom of existing cultivated land and soil resources below it,saline-alkali land,degraded grassland,ecological reconstruction of desertification land,inter-row of fruit trees,lawn of sponge city,etc.The other is indirectly activating some natural resources in ground space,such as natural precipitation,solar energy,oxygen,terrestrial eco-environment,soil resources,river waters and even climate change factors.It could release and generate huge physical endogenous force and cyclic force,and increase food source and available water resources,which is favorable for human survival,nature's own ecological balance,harmonious coexistence and balance between man and nature,without harming nature itself.Moreover,its supporting theoretical system is explained from five aspects.It is pointed that the "activation theory" is deep derivation of "Fenlong technology" and "Fenlong science".By sufficiently playing the potential of natural resources,it could reach human-dominated comprehensive balance and coordinated development of air,sunshine,water,soil,nutrient,microorganism,plant,livestock and poultry,marine organism in the nature.The "activation theory" is concrete embodiment of respecting,changing and using the nature,and new channel of realizing sublimation of "life community of human and nature" and benefiting mankind. 展开更多
关键词 Fenlong technology naturAL RESOURCES ACTIVATION theory Life COMMUNITY
下载PDF
Research on Supervision of Country Public Goods Supply Based on Public Choice Theory
15
作者 MA Guojun WANG Dawei +1 位作者 MA Ping WANG Yalin 《Journal of Northeast Agricultural University(English Edition)》 CAS 2009年第4期84-86,共3页
To increase the provision of rural public goods is a major task of Chinese new rural construction, while it can not do without the necessary supervision. This paper described the relationship between public choice the... To increase the provision of rural public goods is a major task of Chinese new rural construction, while it can not do without the necessary supervision. This paper described the relationship between public choice theory and the provision of rural public goods and it was a basis for in-depth study of the government's subject behavior from the perspective of public choice, and led to the necessity of regulation of rural public goods provision in rural areas, then it presented a strengthen monitoring of the rationalization proposals. 展开更多
关键词 public choice theory provision of rural public goods SUPERVISION
下载PDF
Questions of Theory and Practice: To Synthesis, Analysis and Evaluation Natural Systems of Pacific Russia Based on Models of Landscape Geosystems
16
作者 V. T. Starozhilov 《Journal of Geoscience and Environment Protection》 2019年第1期81-92,共12页
The results of long-term author’s scientific research in the field of geological and geographical study and landscape mapping of large regional links, such as Sikhote-Alinsky, Sakhalinsky, Kamchatsky, Anadyrsky, loca... The results of long-term author’s scientific research in the field of geological and geographical study and landscape mapping of large regional links, such as Sikhote-Alinsky, Sakhalinsky, Kamchatsky, Anadyrsky, located in the Pacific landscape belt of Russia, are considered (Starozhilov, 2013). The studies were conducted at the medium scale (1:500,000) and were accompanied by landscape mapping (Starozhilov, 2016). The proposed article discusses the theory and practice of the overall results and the strategic vision of applying the landscape approach with selected examples. The wide range of possibilities of applying the landscape approach in studying the interaction of nature and society is emphasized. The importance and the indisputable need for the synthesis, analysis and assessment of natural systems based on the mapping of landscape geosystems to assess the environmental management of not only regional territories, but also of Pacific Russia as a whole are noted. 展开更多
关键词 SYNTHESIS Analysis Assessment nature LANDSCAPE Geosystems theory Practice
下载PDF
A Theory of Evolving Natural Constants Based on the Unification of General Theory of Relativity and Dirac’s Large Number Hypothesis
17
作者 PENGHuan-Wu 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第1期81-88,共8页
Talcing Dirac's large number hypothesis as true, we have shown [Commun.Theor. Phys. (Beijing, China) 42 (2004) 703] the inconsistency of applying Einstein's theory ofgeneral relativity with fixed gravitation c... Talcing Dirac's large number hypothesis as true, we have shown [Commun.Theor. Phys. (Beijing, China) 42 (2004) 703] the inconsistency of applying Einstein's theory ofgeneral relativity with fixed gravitation constant G to cosmology, and a modified theory for varyingG is found, which reduces to Einstein's theory outside the gravitating body for phenomena of shortduration in small distances, thereby agrees with all the crucial tests formerly supportingEinstein's theory. The modified theory, when applied to the usual homogeneous cosmological model,gives rise to a variable cosmological tensor term determined by the derivatives of G, in place ofthe cosmological constant term usually introduced ad hoc. Without any free parameter thetheoretical Hubble's relation obtained from the modified theory seems not in contradiction toobservations, as Dr. Wang's preliminary analysis of the recent data indicates [Commun. Theor. Phys.(Beijing, China) 42 (2004) 703]. As a complement to Commun. Theor. Phys. (Beijing, China) 42 (2004)703 we shall study in this paper the modification of electromagnetism due to Dirac's large numberhypothesis in more detail to show that the approximation of geometric optics still leads to nullgeodesies for the path of light, and that the general relation between the luminosity distance andthe proper geometric distance is still valid in our theory as in Einstein's theory, and give theequations for homogeneous cosmological model involving matter plus electromagnetic radiation.Finally we consider the impact of the modification to quantum mechanics and statistical mechanics,and arrive at a systematic theory of evolving natural constants including Planck's h as well asBoltzmann's k_B by finding out their cosmologically combined counterparts with factors ofappropriate powers of G that may remain truly constant to cosmologically long time. 展开更多
关键词 general theory of relativity natural constants dirac's large numberhypothesis
下载PDF
Problems and Countermeasures of Bike-Sharing System in China Based on the theory of Public Goods
18
作者 Danlin Ruan Liping Pan 《Journal of Finance Research》 2020年第2期87-91,共5页
Under the new normal of China’s economic development,bike-sharing,a new product of the“Internet+”era,opens the door to a novel lifestyle for the society,and is in the stage of rapid development.Nevertheless,with th... Under the new normal of China’s economic development,bike-sharing,a new product of the“Internet+”era,opens the door to a novel lifestyle for the society,and is in the stage of rapid development.Nevertheless,with the explosive growth of the number of bicycles,some new problems gradually come out,such as disorderly parking,serious damage and waste of resources,which in turn restrict its further development.Based on the theory of public goods,this article studies the quasi-public goods attributes and problems of bike-sharing,as well as provides feasible measures for its long-term development,so as to realize the co-governance and sharing among enterprises,consumers and government. 展开更多
关键词 Bike-sharing theory of public goods Quasi-public goods Private goods
下载PDF
An Analysis of Irony in A Good Man is Hard to Find From the Perspective of Speech Act Theory
19
作者 蒋天晨 《海外英语》 2014年第5X期190-191,共2页
Speech Act Theory is one of the most important theories in pragmatic field.And this theory has gradually been applied into literary criticism.Irony is not only a generally-used communicative skill,but also a hot langu... Speech Act Theory is one of the most important theories in pragmatic field.And this theory has gradually been applied into literary criticism.Irony is not only a generally-used communicative skill,but also a hot language phenomenon in literature which aroused linguists,writers and even philosophers'interest.The speech act theory and the irony have one thing in common,which is the illocutionary act they both have.Accordingly,the combination of both can enable readers have a better understanding of the literature works.Hence,this thesis reviews theoretical research to analyze the relationship between irony and Speech Act Theory;elaborates on irony in A Good Man is Hard to Find on the basis of Speech Act Theory. 展开更多
关键词 IRONY Speech ACT theory A good MAN is HARD to FIND
下载PDF
A theoretical insight about co-pyrolysis reaction of natural gas and coal
20
作者 Mingjun Pan Chengkai Jin +3 位作者 Bingying Han Runping Ye Rongbin Zhang Gang Feng 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第11期220-225,共6页
The co-pyrolysis of natural gas and coal is a promising way for the production of acetylene due to its high efficiency for energy and hydrogen utilization.This work investigated the thermodynamics for the copyrolysis ... The co-pyrolysis of natural gas and coal is a promising way for the production of acetylene due to its high efficiency for energy and hydrogen utilization.This work investigated the thermodynamics for the copyrolysis reaction of natural gas and coal using density functional theory.The favorable reaction conditions are presented in the form of phase diagrams.The calculation results show that the extra amount of methane may benefit the production of acetylene in the co-pyrolysis reaction,and the C/H ratio of 1:1,temperature around 3000 K and pressure at 0.1 MPa are most favorable.The results would provide basic data for related industrial process for the production of acetylene. 展开更多
关键词 natural gas THERMODYNAMICS Hydrocarbons CO-PYROLYSIS Gibbs free energy Density functional theory
下载PDF
上一页 1 2 223 下一页 到第
使用帮助 返回顶部