全文获取类型
收费全文 | 680篇 |
免费 | 13篇 |
国内免费 | 2篇 |
专业分类
化学 | 435篇 |
晶体学 | 11篇 |
力学 | 13篇 |
数学 | 58篇 |
物理学 | 178篇 |
出版年
2022年 | 7篇 |
2021年 | 10篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 12篇 |
2015年 | 13篇 |
2014年 | 22篇 |
2013年 | 33篇 |
2012年 | 37篇 |
2011年 | 45篇 |
2010年 | 28篇 |
2009年 | 22篇 |
2008年 | 26篇 |
2007年 | 22篇 |
2006年 | 24篇 |
2005年 | 30篇 |
2004年 | 18篇 |
2003年 | 27篇 |
2002年 | 22篇 |
2001年 | 13篇 |
2000年 | 15篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 13篇 |
1995年 | 7篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1977年 | 15篇 |
1976年 | 6篇 |
1975年 | 8篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 8篇 |
1969年 | 4篇 |
排序方式: 共有695条查询结果,搜索用时 31 毫秒
81.
82.
S Kailas A Navin A Chatterjee P Singh A Saxena D M Nadkarni D C Biswas R K Choudhury S S Kapoor 《Pramana》1993,41(4):339-344
The measurements of fission fragment angular distributions for the system19F+232Th have been extended to the sub-barrier energies of 89.3, 91.5 and 93.6 MeV. The measured anisotropies, within errors are
nearly the same over this energy region. However, the deviation of the experimental values of anisotropies from that of standard
statistical model predictions increases as the bombarding energy is lowered. 相似文献
83.
G. K. Singh A. P. Singh V. K. Sharma A. Kapoor K. N. Tripathi 《Optics & Laser Technology》2002,34(3):219-223
A general expression for the change in extraordinary refractive index of the annealed proton exchanged LiNbO3 waveguide has been deduced. The expression deduced explains the experimental results of decrease in change of extraordinary refractive index with annealing. The effect of annealing time has also been incorporated following Cao's model (Cao, Ramaswamy, Srivastava, J. Lightwave Technol. 10 (1992) 1302–1313). The concentration profile of protons in the annealed waveguide has been deduced theoretically, which is consistent with the previous results. The spontaneous polarization has been considered as the central mechanism for change in extraordinary refractive index due to proton exchange with annealing. 相似文献
84.
M. Ghanashyam Krishna A.K. Kapoor M. Durga Prasad V. Srinivasan 《Physica E: Low-dimensional Systems and Nanostructures》2006,33(2):359-362
It is demonstrated that the chemical potential of bosons trapped in a harmonic potential shows a discontinuity as a function of the number of particles in the system. In the model used, it is shown that if the number of particles is of the order of 106 or greater, bulk-like behaviour is exhibited by the system. This translates to a ratio of V/Vc>106 for bulk behaviour, where V is the crystallite volume of the experimental sample and Vc is the volume of the unit cell. Several experimental results covering a wide range of physical phenomena that corroborate the fact that such a number-induced phase transition indeed exists are presented. 相似文献
85.
A perturbation theory of polar hard Gaussian overlap fluid mixture is discussed. Explicit analytic expressions for the second
and third varial coefficients are given. Numerical results are estimated for the thermodynamic properties of quadrupolar hard
Gaussian overlap fluid and fluid mixture. It is found that the excess free energy and internal energy depend on concentrationsc
1,c
2, molecular diameter ratioR, shape parameterK and the quadrupole momentsQ*1,Q*2. 相似文献
86.
87.
Kirti Patel Sudhir Kapoor D. P. Dave Tulsi Mukherjee 《Journal of Chemical Sciences》2005,117(1):53-60
Silver nanosized crystallites have been synthesized in aqueous and polyols viz., ethylene glycol and glycerol, using a microwave
technique. Dispersions of colloidal silver have been prepared by the reduction of silver nitrate both in the presence and
absence of stabilizer poly(vinylpyrolidone) (PVP). It was observed that PVP is capable of complexing and stabilizing Ag nanoparticles
formed through the reduction of Ag+ ions in water and ethylene glycol. In the case of ethylene glycol, it has been shown that the use of PVP leads to particles
with a high degree of stability. The colloids are stable in glycerol for months even in the absence of stabilizer. 相似文献
88.
Photophysical characteristics of capped and uncapped CdS particles have been investigated in aqueous solution. It is seen
that the fluorescence spectrum shifts towards lower energies in the presence of toluene dithiol (TDT) and dimercaptophthalic
acid (DMPA). This shift, which is due to quenching of shallow traps, is more predominant with TDT. Also, the presence of excess
Cd2+ ions at the surface of the CdS particles facilitates the binding of dithiolenes. 相似文献
89.
S. Kapoor C. Gopinathan R. M. Iyer 《Journal of Radioanalytical and Nuclear Chemistry》1988,125(1):91-96
Mixtures of methanol and isopropanol in a ratio (v/v) varying from 91 to 19 have been gamma-irradiated at 77 K and relative yields of trapped electrons have been measured. The reactivity of the trapped electrons towards acetone and uranyl nitrate has been studied at various methanol isopropanol ratios. On the basis of the results, an attempt has been made to assess the relative importance of the reaction of the electron with the solute prior to trapping with respect to the tunnelling reaction of the trapped electron with the solute. 相似文献
90.
S.C.L. Sharma G.K. Mehta R.K. Choudhury D.M. Nadkarni S.S. Kapoor 《Nuclear Physics A》1981,355(1):13-24
The emission probabilities per fission of α-particles, tritons and protons have been measured in fast neutron induced fission of 235U. The measurements were carried out at neutron energies of 120, 180, 230 and 550 keV. AΔE-E semiconductor detector telescope was used to identify different light charged particles and the fission fragments were detected with an ionization chamber. The three-parameter data corresponding to the pulse heights from the ΔE-E detectors and the ion-chamber were recorded event by event on magnetic tape and were analyzed off-line by computer. No significant variation in the most probable energy () and the standard deviation (σE) of the energy spectra of different light charged particles with incident neutron energy was observed, although was seen to have a slightly higher value beyond En = 230 keV. The yield of α-particles in fission induced by neutrons of En ~ 200 keV was found to be higher by about 20 % than that in thermal neutron induced fission. The yields of tritons and protons were found to increase significantly with neutron energy. 相似文献