全文获取类型
收费全文 | 1082篇 |
免费 | 23篇 |
国内免费 | 4篇 |
专业分类
化学 | 584篇 |
晶体学 | 9篇 |
力学 | 59篇 |
数学 | 63篇 |
物理学 | 394篇 |
出版年
2022年 | 14篇 |
2021年 | 14篇 |
2020年 | 26篇 |
2019年 | 14篇 |
2018年 | 22篇 |
2017年 | 27篇 |
2016年 | 30篇 |
2015年 | 18篇 |
2014年 | 21篇 |
2013年 | 81篇 |
2012年 | 45篇 |
2011年 | 57篇 |
2010年 | 36篇 |
2009年 | 39篇 |
2008年 | 53篇 |
2007年 | 47篇 |
2006年 | 59篇 |
2005年 | 41篇 |
2004年 | 43篇 |
2003年 | 27篇 |
2002年 | 35篇 |
2001年 | 14篇 |
2000年 | 23篇 |
1999年 | 10篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 15篇 |
1993年 | 15篇 |
1992年 | 9篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 18篇 |
1983年 | 8篇 |
1982年 | 16篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1978年 | 14篇 |
1977年 | 12篇 |
1976年 | 14篇 |
1973年 | 16篇 |
1972年 | 4篇 |
1956年 | 7篇 |
排序方式: 共有1109条查询结果,搜索用时 761 毫秒
991.
K. N. Shukla A. Brusly Solomon B. C. Pillai B. Jacob Ruba Singh S. Saravana Kumar 《Heat and Mass Transfer》2012,48(11):1913-1920
Nanofluids are employed as the working medium for a conventional cylindrical heat pipe. A cylindrical copper heat pipe of 19.5?mm outer diameter and 400?mm length was fabricated and tested with two different working fluids. The working fluids used in this study are DI-water and Nano-particles suspension (mixture of copper nano particle and DI-water). The overall heat transfer coefficient of the heat pipe was calculated based on the lumped thermal resistance network and compared with the heat transfer coefficient of base fluid filled heat pipe. There is a quantitative improvement in the heat transfer coefficient using nano-particles suspension as the working medium. A heat transfer correlation was also developed based on multiple regression least square method and the results were compared with that obtained by the experiment. 相似文献
992.
Sandeep Abotula Addis Kidane Vijaya B. Chalivendra Arun Shukla 《International Journal of Solids and Structures》2012,49(13):1637-1655
Mixed-mode dynamic crack growth along an arbitrarily smoothly varying path in functionally graded materials (FGMs) under thermo-mechanical loading is studied. The property gradation in FGMs is considered by varying shear-modulus, mass density, thermal conductivity and coefficient of thermal expansion exponentially along the gradation direction. Asymptotic analysis in conjunction with displacement potentials is used to develop the stress fields around propagating cracks in FGMs. Asymptotic temperature fields are developed first for the exponential variation of thermal conductivity and later these temperature fields are used to derive thermo-mechanical stress fields for a curving crack in FGMs. Using these thermo-mechanical stress fields, various components of the stresses are developed and the effect of curvature parameters, temperature and gradation on these stresses are discussed. Finally, using the minimum strain energy density criterion, the effect of curvature parameters, crack-tip speeds, non-homogeneity values and temperature gradients on crack growth directions are determined and discussed. 相似文献
993.
It is shown that the force associated with the normal component of the space charge electric field at the plasma surface, arising from the charge separation, can accelerate a charged dust particle that is sitting in the scrape-off layer (SOL) close to the chamber walls in tokamaks. The acceleration of dust particle is found to be proportional to the strength of the space charge electric field and inversely proportional to the square root of the dust mass density. 相似文献
994.
Ticoş CM Wang Z Wurden GA Kline JL Montgomery DS Dorf LA Shukla PK 《Physical review letters》2008,100(15):155002
Simultaneous acceleration of hundreds of dust particles to hypervelocities by collimated plasma flows ejected from a coaxial gun is demonstrated. Graphite and diamond grains with radii between 5 and 30 microm, and flying at speeds up to 3.7 km/s, have been recorded with a high-speed camera. The observations agree well with a model for plasma-drag acceleration of microparticles much larger than the plasma screening length. 相似文献
995.
We present a simple analytical nonlinear theory for quantum diodes in a dense Fermi magnetoplasma. By using the steady-state quantum hydrodynamical equations for a dense Fermi magnetoplasma, we derive coupled nonlinear Schr?dinger and Poisson equations. The latter are numerically solved to show the effects of the quantum statistical pressure, the quantum tunneling (or the quantum diffraction), and the external magnetic field strength on the potential and electron density profiles in a quantum diode at nanometer scales. It is found that the quantum statistical pressure introduces a lower bound on the steady electron flow in the quantum diode, while the quantum diffraction effect allows the electron tunneling at low flow speeds. The magnetic field acts as a barrier, and larger potentials are needed to drive currents through the quantum diode. 相似文献
996.
The experimental efforts towards understanding the fracture behavior of continuously graded Functionally Graded Materials
(FGMs) using full-field optical methods are reviewed. Both quasi-static and dynamic fracture investigations involving mode-I
and -II conditions are presented. FGM configurations with crack planes perpendicular to, parallel to, and inclined to the
direction of compositional gradation are discussed. Different strategies adopted by various investigators to develop polymer-based
FGM systems for experimental mechanics studies are also described in this overview. Major theoretical developments that have
predated and paralleled the experimental studies have been presented as well. Finally, the paper notes a few potential new
directions where further contributions are possible. 相似文献
997.
Hexagonal (space group P63cm) form of YInO3 has been investigated under high pressure using synchrotron-based angle-dispersive X-ray diffraction and Raman scattering methods. Our experimental investigations suggest that it undergoes the phase transition to a new phase in the pressure range 12–15?GPa, while the ambient hexagonal phase is found to coexist with the new phase up to 29?GPa. DFT based calculations within the LDA approach on the hexagonal phase of YInO3 showed that the unit cell volume matches well with the experimentally obtained volume at ambient pressure. As the pressure increases, theoretically obtained values of unit cell volume of the hexagonal phase were found to be significantly lower than that of experimentally obtained values. This discrepancy has been corrected using LDA?+?UIn(4d) (Hubbard interaction parameter between Indium 4d electrons) method. We have proposed the high pressure phase of YInO3 to be orthorhombic with space group Pnma. 相似文献
998.
Singh Mayur Pratap Arora Kanwer Singh Shajan Nikhil Pandu Sangeetha Ranga Shome Mahadev Kumar Rajneesh Shukla Dinesh 《Journal of Thermal Analysis and Calorimetry》2019,137(4):1155-1167
Journal of Thermal Analysis and Calorimetry - Continuous cooling transformation diagrams were obtained for a simulated coarse-grain heat-affected zone of API X-80 and X-65 steels using Gleeble-3800... 相似文献
999.
Burns CA Giura P Said A Shukla A Vankó G Tuel-Benckendorf M Isaacs ED Platzman PM 《Physical review letters》2002,89(23):236404
Inelastic x-ray scattering was used to measure the plasmon as a function of electron density in liquid lithium ammonia as well as the low temperature solid phase. As the electronic density is lowered, electronic correlation effects cause the random-phase approximation (RPA) to break down, requiring more advanced theoretical treatments. The deviation from RPA becomes greatest at the lowest electronic densities. We also see evidence for decreased electronic screening as shown by an increase in the strength of the pseudopotential at lower concentrations. Plasmon behavior in the solid is similar to that of the heavier alkali metals, but surprisingly different than in the liquid. 相似文献
1000.
P.K. Shukla R. Fedele M. Onorato N.L. Tsintsadze 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):613-618
The nonlinear coupling between light beams and non-resonant ion density perturbations in a plasma is considered, taking into
account the relativistic particle mass increase and the light beam ponderomotive force. A pair of equations comprising a nonlinear
Schr?dinger equation for light beams and a driven (by the light beam pressure) ion-acoustic wave response is derived. It is
shown that the stationary solutions of our nonlinear equations can be represented in the form of a bright and dark/gray soliton
for the one-dimensional problem. We also present numerical results which exhibit that our bright soliton solutions are stable
exclusively for the values of the parameters compatible with our theory.
Received 24 July 2002 Published online 31 October 2002
RID="a"
ID="a"Permanent address: Dipartimento di Scienze Fisiche, Universitá Federico II and INFN, Complesso Universitario di M.S. Angelo, Via Cintia, 80126
Napoli, Italy e-mail: renato.fedele@na.infn.it
RID="b"
ID="b"Permanent address: Dipartimento di Fisica Generale, Universitá di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
RID="c"
ID="c"Permanent address: Institute of Physics, Georgian Academy of Sciences, Tbilisi 380077, Georgia 相似文献