全文获取类型
收费全文 | 306篇 |
免费 | 2篇 |
专业分类
化学 | 144篇 |
晶体学 | 1篇 |
力学 | 3篇 |
数学 | 53篇 |
物理学 | 107篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 16篇 |
2012年 | 13篇 |
2011年 | 13篇 |
2010年 | 16篇 |
2009年 | 7篇 |
2008年 | 27篇 |
2007年 | 14篇 |
2006年 | 20篇 |
2005年 | 13篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1955年 | 3篇 |
1954年 | 3篇 |
1944年 | 4篇 |
1942年 | 3篇 |
1940年 | 1篇 |
1935年 | 2篇 |
1903年 | 1篇 |
排序方式: 共有308条查询结果,搜索用时 484 毫秒
21.
22.
23.
We have considered a model of two component mixture i.e., mixture of Chaplygin gas and barotropic fluid with tachyonic field.
In the case, when they have no interaction then both of them retain their own properties. Let us consider an energy flow between
barotropic and tachyonic fluids. In both the cases we find the exact solutions for the tachyonic field and the tachyonic potential
and show that the tachyonic potential follows the asymptotic behavior. We have considered an interaction between these two
fluids by introducing a coupling term. Finally, we have considered a model of three component mixture i.e., mixture of tachyonic
field, Chaplygin gas and barotropic fluid with or without interaction. The coupling functions decays with time indicating
a strong energy flow at the initial period and weak stable interaction at later stage. To keep the observational support of
recent acceleration we have considered two particular forms (i) Logamediate Scenario and (ii) Intermediate Scenario, of evolution
of the Universe. We have examined the natures of the recent developed statefinder parameters and slow-roll parameters in both
scenarios with and without interactions in whole evolution of the universe. 相似文献
24.
Shalini Bagchi Kasturi Roychowdhury A.P. Mishra A. Roy Chowdhury 《Communications in Nonlinear Science & Numerical Simulation》2010,15(2):275-280
Excitation of nonlinear waves in a quantum dusty plasma with various effects is analyzed when the geometry is cylindrical.This introduces the effect of finite boundary conditions on the solitary waves so generated. it is observed that the nonlinear equation deduced is cylindrical KP–Burger type leading to the generation of Shock Wave. Different situations which arises in various parameter regions are considered separately and the form of the nonlinear excitations are obtained explicitly. 相似文献
25.
The paper shows how various interior point methods for linear programming may all be derived from logarithmic barrier methods. These methods include primal and dual projective methods, affine methods, and methods based on the method of centers. In particular, the paper demonstrates that Karmarkar's algorithm is equivalent to a classical logarithmic barrier method applied to a problem in standard form.Invited paper presented at the Workshop on Supercomputers in Optimization, Minneapolis, Minn., May 1988.The work of this author was supported by the Air Force Office of Scientific Research, Air Force Systems Command, USA, under Grants AFOSR-87-0215 and AFOSR-85-0271. The US Government is authorized to reproduce and distribute reprints for Governmental purposes not withstanding any copyright notation thereon. 相似文献
26.
Sunanda Banerjee 《Pramana》2000,55(1-2):85-100
Several studies have been made to the hadronic final states in e
+
e
− collisions at LEP. Studies of the annihilation process at LEP2 have given rise to results on jet rate, event shape, heavy
flavour production, inclusive momentum spectra, Bose-Einstein correlation and colour reconnection effects. Event shape studies
have given rise to accurate determination of the strong coupling constant α
s using O (α
s
2
) with resummed leading and next-to-leading log calculation and also with power law corrections. Studies of 2-photon processes
have yielded results on γγ cross-section, heavy flavour production, photon structure function and γ*γ* scattering. 相似文献
27.
Biman Bagchi 《Journal of Chemical Sciences》1997,109(6):379-388
Non-exponential electron transfer kinetics in complex systems are often analyzed in terms of a quenched, static disorder model.
In this work we present an alternative analysis in terms of a simple dynamic disorder model where the solvent is characterized
by highly non-exponential dynamics. We consider both low and high barrier reactions. For the former, the main result is a
simple analytical expression for the survival probability of the reactant. In this case, electron transfer, in the long time,
is controlled by the solvent polarization relaxation—in agreement with the analyses of Rips and Jortner and of Nadler and
Marcus. The short time dynamics is also non-exponential, but for different reasons. The high barrier reactions, on the other
hand, show an interesting dynamic dependence on the electronic coupling element,V
el. 相似文献
28.
A simple method for preparing redispersible nanofibers from sugar beet residue and their use as a well-dispersed reinforcement for a polyvinyl alcohol (PVA) matrix is reported. It is known that the redispersion of dried cellulose nanofibers is difficult because of the formation of strong hydrogen bonds between the nanofibers. The results show that the properties of the initial sugar beet nanofiber suspension can be recovered without the use of chemical modification or additives with higher pectin and hemicellulose content. Undried and redispersed nanofibers with and without pectin were used as nanocomposite reinforcement with PVA. The redispersed nanofibers were as good reinforcements as the undried nanofibers. The tensile strength and elastic modulus of the nanocomposites with the redispersed sugar beet nanofibers were as good as those of the nanocomposites with undried nanofibers. Interestingly, the nanofiber dispersion in the PVA matrix was better when sugar beet nanofibers containing pectin and hemicellulose were used as reinforcements. 相似文献
29.
Keshab Chandra Bagchi 《Applied Scientific Research》1966,16(1):131-140
Summary The flow of a Reiner-Rivlin fluid between two coaxial porous circular cylinders has been studied. The inner cylinder performs a steady oscillation while the outer one is fixed.The exact solution of this problem has been obtained and approximate solutions for the two extreme cases, very small and very high frequencies, have been derived. 相似文献
30.
A palladium catalyzed domino intermolecular Suzuki followed by intramolecular Heck coupling is described. This strategy afforded a novel and convenient synthesis of various 9-fluorenylidene derivatives in one-pot under relatively mild reaction condition. 相似文献