全文获取类型
收费全文 | 145篇 |
免费 | 0篇 |
国内免费 | 11篇 |
专业分类
化学 | 19篇 |
力学 | 6篇 |
数学 | 31篇 |
物理学 | 100篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2018年 | 2篇 |
2017年 | 7篇 |
2016年 | 22篇 |
2015年 | 3篇 |
2014年 | 33篇 |
2013年 | 28篇 |
2012年 | 22篇 |
2011年 | 11篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2004年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1967年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有156条查询结果,搜索用时 15 毫秒
81.
PRAMOD KUMAR YADAWA 《Pramana》2011,76(4):613-619
The ultrasonic properties of the hexagonal closed packed structured Ni3Mo, Ni3Nb and Ni3Ta compounds were studied at room temperature for their characterization. For the investigations of ultrasonic properties,
the second-order elastic constants using Lennard–Jones potential were computed. The velocities V
1 and V
2 have minima and maxima respectively at 45° with the unique axis of the crystal, while V
3 increases with respect to angle with the unique axis of the crystal. The inconsistent behaviour of angle-dependent velocities
is associated with the action of second-order elastic constants. Debye average sound velocities of these compounds increase
with the angle and has maximum at 55° with the unique axis at room temperature. Hence, when a sound wave travels at 55° with
the unique axis of these materials, the average sound velocity is found to be maximum. The results achieved are discussed
and compared with the available experimental and theoretical results. 相似文献
82.
We present the results of elliptic flow for the collision of nearly symmetric nuclei (10Ne20+ 13Al27_{10}{\rm Ne}^{20}+\,_{13}{\rm Al}^{27}, 18Ar40+ 21Sc45_{18}{\rm Ar}^{40}+\,_{21}{\rm Sc}^{45}, 30Zn64+ 28Ni58_{30}{\rm Zn}^{64}+\,_{28}{\rm Ni}^{58}, 36Kr86+ 41Nb93_{36}{\rm Kr}^{86}+\,_{41}{\rm Nb}^{93}) using the quantum molecular dynamics (QMD) model. General features of elliptic flow are investigated with the help of theoretical
simulations. The simulations are performed at beam energies between 45 and 105 MeV /nucleon. A significant change can be seen
from in-plane to out-of-plane elliptic flow of different fragments with incident energy. A comparison with experimental data
is also made. Further, we show that elliptic flow for different fragments follows power-law dependence as given by the function
C(Atot)tC{(A_{\rm tot})^\tau}. 相似文献
83.
Bianchi type-V string cosmological models in general relativity are investigated. To get the exact solution of Einstein’s
field equations, we have taken some scale transformations used by Camci et al [Astrophys. Space Sci.
275, 391 (2001)]. It is shown that Einstein’s field equations are solvable for any arbitrary cosmic scale function. Solutions
for particular forms of cosmic scale functions are also obtained. Some physical and geometrical aspects of the models are
discussed. 相似文献
84.
A recommended isotropic dipole oscillator strength distribution (DOSD) has been constructed for the silicon tetrafluoride (SiF4) molecule through the use of quantum mechanical constraint techniques and experimental dipole oscillator strength data. The constraints are furnished by experimental molar refractivity data and the Thomas-Reiche-Kuhn sum rule. The DOSD is used to evaluate a variety of isotropic dipole oscillator strength sums, logarithmic dipole oscillator strength sums and mean excitation energies for the molecule. A pseudo-DOSD for SiF4 is also presented which is used to obtain reliable results for the isotropic dipole-dipole dispersion energy coefficients C6, for the interaction of SiF4 with itself and with 43 other species and the triple-dipole dispersion energy coefficient C9 for (SiF4)3. 相似文献
85.
In this paper, we discuss a one parameter family of complex Born–Infeld solitons arising from a one parameter family of minimal surfaces. The process enables us to generate a new solution of the B–I equation from a given complex solution of a special type (which are abundant). We illustrate this with many examples. We find that the action or the energy of this family of solitons remains invariant in this family and find that the well-known Lorentz symmetry of the B–I equations is responsible for it. 相似文献
86.
R SUNDAR B K PANT HARISH KUMAR P GANESH D C NAGPURE P HAEDOO RAKESH KAUL K RANGANATHAN K S BINDRA S M OAK L M KUKREJA 《Pramana》2014,82(2):347-351
Fretting-fatigue is an important factor influencing service life of turbine blades. The present paper describes laser shock peening of potential crack nucleation site in the root region of steam turbine blade for its enhanced service life. The experimental study, performed with an in-house developed 2.5 J/7 ns Nd:YAG laser demonstrated that laser peening introduced a residual surface compressive stress of ?260 to ?390 MPa. Case depth of laser peened surface layer was found to be more than 900 μm. 相似文献
87.
A K TICKOO R KOUL R C RANNOT K K YADAV P CHANDRA V K DHAR M K KOUL M KOTHARI N K AGARWAL A GOYAL H C GOYAL S KOTWAL N KUMAR P MARANDI K VENUGOPAL K CHANCHALANI N BHATT S BHATTACHARYYA C BORWANKAR N CHOUHAN S R KAUL A K MITRA S SAHAYNATHAN M SHARMA K K SINGH C K BHAT 《Pramana》2014,82(3):585-605
The TeV atmospheric Cherenkov telescope with imaging camera (TACTIC) γ-ray telescope has been in operation at Mt. Abu, India since 2001 to study TeV γ-ray emission from celestial sources. During the last 10 years, apart from consistently detecting a steady signal from the Crab Nebula above ~1.2 TeV energy, at a sensitivity level of ~5.0 σ in ~25 h, the telescope has also detected flaring activity from Mrk 421 and Mrk 501 on several occasions. Although we used Crab Nebula data partially, in some of the reported results, primarily for testing the validity of the full data analysis chain, the main aim of this work is to study the long term performance of the TACTIC telescope by using consolidated data collected between 2003 and 2010. The total on-source data, comprising ~402 h, yields an excess of ~(3742±192) γ-ray events with a statistical significance of ~19.9 σ. The off-source data, comprising ~107 h of observation, is found to be consistent with a no-emission hypothesis, as expected. The resulting γ-ray rate for the on-source data is determined to be ~(9.31±0.48) h ?1. A power law fit (dΦ/dE=f 0 E ?Γ ) with f 0 ~ (2.66±0.29) × 10?11 cm?2 s?1 TeV?1 and Γ ~ 2.56±0.10 is found to provide reasonable fit to the inferred differential spectrum within statistical uncertainties. The spectrum matches reasonably well with that obtained by other groups. A brief summary of the improvements in the various subsystems of the telescope carried out recently, which has resulted in a substantial improvement in its detection sensitivity (viz., ~5 σ in an observation period of ~13 h as compared to ~25 h earlier) are also presented in this paper. Encouraged by the detection of strong γ-ray signals from Mrk 501 and Mrk 421 on several occasions, there is considerable scope for the TACTIC telescope to monitor similar TeV γ-ray emission activity from other active galactic nuclei on a long-term basis. 相似文献
88.
89.
NIRAJ KUMAR NALINI PAREEK UDIT NARAYAN PAL DEEPAK KUMAR VERMA JITENDRA PRAJAPATI MAHESH KUMAR BHARAT LAL MEENA RAM PRAKASH 《Pramana》2014,82(6):1075-1084
This paper presents the experimental studies on self-breakdown-based single-gap plasma cathode electron (PCE) gun (5–20 kV/50–160 A) in argon, gas atmosphere and its performance evaluation based on particle-in-cell (PIC) simulation code ‘OOPIC-Pro’. The PCE-Gun works in conducting phase (low energy, high current) of pseudospark discharge. It produces intense electron beam, which can propagate more than 200 mm in the drift space region without external magnetic field. The profile of this beam in the drift space region at different breakdown conditions (i.e., gas pressures and applied voltages) has been studied and the experimental results are compared with simulated values. It is demonstrated that ~30% beam current is lost during the propagation possibly due to space charge neutralization and collisions with neutral particles and walls. 相似文献
90.
Surface plasmons at the metal–dielectric interface have emerged as an important candidate to propagate and localize light at subwavelength scales. By tailoring the geometry and arrangement of metallic nanoarchitectures, propagating and localized surface plasmons can be obtained. In this brief perspective, we discuss: (1) how surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs) can be optically excited in metallic nanoarchitectures by employing a variety of optical microscopy methods; (2) how SPPs and LSPs in plasmonic nanowires can be utilized for subwavelength polarization optics and single-molecule surface-enhanced Raman scattering (SERS) on a photonic chip; and (3) how individual plasmonic nanowire can be optically manipulated using optical trapping methods. 相似文献