全文获取类型
收费全文 | 224篇 |
免费 | 10篇 |
专业分类
化学 | 102篇 |
晶体学 | 9篇 |
力学 | 4篇 |
综合类 | 1篇 |
数学 | 28篇 |
物理学 | 45篇 |
无线电 | 45篇 |
出版年
2023年 | 2篇 |
2022年 | 14篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 10篇 |
2007年 | 8篇 |
2006年 | 3篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1976年 | 1篇 |
排序方式: 共有234条查询结果,搜索用时 359 毫秒
121.
We focus on one critical issue in mobile ad hoc networks that is multicast routing. Advantages and limitations of existing routing protocols are illustrated. Optimal routes, stable links, power conservation, loop freedom, and reduced channel overhead are the main features to be addressed in a more efficient mechanism. In this paper, we propose a new on-demand multicast routing protocol, named Source Routing-based Multicast Protocol (SRMP). Our proposition addresses two important issues in solving routing problems: (i) path availability concept, and (ii) higher battery life paths. SRMP applies a source routing mechanism, and constructs a mesh to connect group members. It provides stable paths based on links' availability according to future prediction of links' states, and higher battery life paths. This protocol succeeded to minimize network load via designing optimal routes that guarantee reliable transmission and active adaptability. A performance comparison study with On-demand Multicast Routing Protocol (ODMRP) and Adaptive Demand-driven Multicast Routing (ADMR) protocol is undertaken. Analysis results show the strength of the SRMP nodes' selection criteria and its efficient energy consumption compared to the other two protocols. 相似文献
122.
123.
Sloshing behavior of a magnetic fluid in a cylindrical container 总被引:1,自引:0,他引:1
Sloshing of a magnetic fluid in a laterally vibrated cylindrical container subject to a non-uniform vertical magnetic field
was examined. Internal velocity profiles were measured using ultrasound Doppler velocimetry. The effect of the magnetic field
on the resonant frequency of the fluid–container system was examined and the results were compared with theoretical results.
The second and third peaks of the power spectra of velocity shifted to lower frequencies as the magnetic field was increased.
It was observed that these derived frequency peaks were connected with swirling in the cylindrical container.
Received: 9 May 2000 / Accepted: 29 May 2001 Published online: 29 November 2001 相似文献
124.
Exploring physical features of anisotropic quark stars in Brans-Dicke theory with a massive scalar field via embedding approach
下载免费PDF全文
![点击此处可从《中国物理C(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Abdelghani Errehymy G. Mustafa Youssef Khedif Mohammed Daoud 《中国物理C(英文版)》2022,46(4):045104-045104-14
The main aim of this study is to explore the existence and salient features of spherically symmetric relativistic quark stars in the background of massive Brans-Dicke gravity. The exact solutions to the modified Einstein field equations are derived for specific forms of coupling and scalar field functions using the equation of state relating to the strange quark matter that stimulates the phenomenological MIT-Bag model as a free Fermi gas of quarks. We use a well-behaved function along with the Karmarkar condition for class-one embedding as well as junction conditions to determine the unknown metric tensors. The radii of strange compact stars viz., PSR J1416-2230, PSR J1903+327, 4U 1820-30, CenX-3, and EXO1785-248, are predicted via their observed mass for different values of the massive Brans-Dicke parameters. We explore the influences of the mass of scalar field \begin{document}$m_{\phi}$\end{document} ![]()
![]()
, coupling parameter \begin{document}$\omega_{\rm BD}$\end{document} ![]()
![]()
, and bag constant \begin{document}${\cal{B}}$\end{document} ![]()
![]()
on state determinants and perform several tests on the viability and stability of the constructed stellar model. Conclusively, we find that our stellar system is physically viable and stable as it satisfies all the energy conditions and necessary stability criteria under the influence of a gravitational scalar field. 相似文献
125.
A linearized variant of relative entropy is used to quantify in a unified scheme the different kinds of correlations in a bipartite quantum system. As illustration, we consider a two-qubit state with parity and exchange symmetries for which we determine the total, classical and quantum correlations. We also give the explicit expressions of its closest product state, closest classical state and the corresponding closest product state. A closed additive relation, involving the various correlations quantified by linear relative entropy, is derived. 相似文献
126.
The lattice dynamics and the elastic properties of the ternary AlAs x Sb1?x alloy have been studied using the density-functional perturbation theory within the local density approximation and employing the virtual-crystal approximation. We study the variation of the optical phonon frequencies (ωTO and ωLO), the high-frequency (?∞) and static (?0) dielectric coefficients, the dynamic effective charge (Z*) and the elastic constants (C 11, C 12, C 44) as a function of the composition (x) and the pressure. We have also predicted the behavior of the optical and acoustical phonons with composition x at the X and L high symmetry points under pressure and determined the Grüneisen parameter. We have found that no mechanical instabilities are associated with the structural transition at high pressures for all compositions. 相似文献
127.
We investigate quantum key distribution where information is carried by a d-level optical quantum system. The sender uses the mutually unbiased bases generated from the phase states of the quantum
system. We consider the effects of several intercept and resend attacks. We derive explicitly the mutual information between
the legitimate parties as well as the mutual information between the sender and the different eavesdroppers in the communication
channel. We discuss the security of the cryptographic scheme and present some numerical analysis. 相似文献
128.
Russian Journal of Applied Chemistry - In this work, acrylamide (AAm) and crotonic acid (CA) were grafted onto carboxymethyl cellulose (CMC) by free-radical polymerization in aqueous solution at... 相似文献
129.
130.