全文获取类型
收费全文 | 1077篇 |
免费 | 26篇 |
国内免费 | 4篇 |
专业分类
化学 | 550篇 |
晶体学 | 26篇 |
力学 | 55篇 |
数学 | 109篇 |
物理学 | 367篇 |
出版年
2022年 | 14篇 |
2021年 | 14篇 |
2020年 | 12篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 17篇 |
2016年 | 32篇 |
2015年 | 15篇 |
2014年 | 22篇 |
2013年 | 60篇 |
2012年 | 47篇 |
2011年 | 60篇 |
2010年 | 45篇 |
2009年 | 41篇 |
2008年 | 65篇 |
2007年 | 45篇 |
2006年 | 58篇 |
2005年 | 46篇 |
2004年 | 32篇 |
2003年 | 26篇 |
2002年 | 25篇 |
2001年 | 19篇 |
2000年 | 23篇 |
1999年 | 14篇 |
1998年 | 10篇 |
1997年 | 13篇 |
1996年 | 14篇 |
1995年 | 19篇 |
1994年 | 20篇 |
1993年 | 28篇 |
1992年 | 24篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1964年 | 5篇 |
1955年 | 5篇 |
排序方式: 共有1107条查询结果,搜索用时 15 毫秒
151.
152.
The corrected cathodoluminescence (CL) emission spectrum for undeformed MgO in the wavelength range 300–650nm consists of two overlapping bands with peaks at 425 nm (2.92 eV) and 488 nm (2.54 eV). After deformation one broad band at 466 nm (2.66 eV) of much higher intensity is observed. In the near IR part of the spectrum a further broad band occurs, consisting of a number of unresolved peaks the strongest of which is at 726 nm (1.71 eV). This band is unaffected by deformation and is thought to be due to iron impurities. Panchromatic and monochromatic SEM micrographs show that the enhanced 466 nm band luminescence comes from the slipped planes of the crystal. Shape analysis of the 466 nm emission band showed that it is a Gaussian form around the intensity maximum with an exponential high energy tail. 相似文献
153.
Uma Basu Indira Addy Bidyut Kumar Datta 《International Journal of Theoretical Physics》1980,19(9):681-691
Recently Addy and Datta have obtained a linearized solution for isentropic motions of a perfect fluid by assigning Cauchy data on the hypersurfacex
4=0 and by imposing a restriction on the equation of state. In the present paper we pursue this study and discuss the problem of singularities from the standpoint of a local observer for which a singularity is defined as a state with an infinite proper rest mass density. It is shown that for a closed universe with any distribution of matter whatsoever there occurred a singularity in the past in the nonrotating parts of the universe and it must recur in the future. Furthermore, the collapse of a rotating fluid to a singularity seems inevitable when the relativistic equation of state is considered. 相似文献
154.
Sunil Datta 《Applied Scientific Research》1965,11(1):43-48
Summary This paper presents the solution to the problem of determining the flow field and the fluctuating torque necessary to sustain the motion of a torsionally oscillating plate in a viscous conducting fluid subjected to a uniform axial field under the assumptions that the amplitude of the oscillation is small and that the magnetic Prandtl number Pr
m
() is small enough to justify the neglect of induced fields. The analysis reveals that the field decreases the flow velocities, but increases the magnitude of the fluctuating torque. 相似文献
155.
156.
Subhendu K. Datta 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1961,12(6):558-563
Zusammenfassung Es werden die Transversalwellen untersucht, welche in einem viskoelastischen Halbraum unter einem plötzlich an der Grenzebene angebrachten Moment entstehen. Insbesondere werden die Verschiebungen an der Grenzfläche für kleine und grosse Distanzen vom Störungszentrum angegeben. Das Medium wird als isotroper Kelvin-Stoff angenommen. 相似文献
157.
158.
159.
Sambhu N Datta 《Pramana》1984,22(2):L125-L130
Pseudopotential is used as a formal operator to write the exact time-dependence of a pseudoexciton and hence that of an initial
excitation spatially localized in a crystal. The exponential operator where pseudopotential occurs at the argument is readily
evaluated using the property of projection operators. Migration of an initially localized excitation is of considerable experimental
importance and can be of conceptual use since it should eventually generate the characteristics of a migrating exciton. From
the formal time-dependence of a localized excitation, its spread with time can be calculated with relative ease. In a concurrent
discussion, the previous work of Merrifield (1958) on the propagation of excitation is criticized and an error is pointed
out. The spread, however, remains wavelike and is not dissipative in the absence of a collisional mechanism. 相似文献
160.
H. Naik T. Datta S. P. Dange P. K. Pujari S. Prakash M. V. Ramaniah 《Zeitschrift für Physik A Hadrons and Nuclei》1988,331(3):335-342
In the present work angular momenta of the fragments corresponding to132Im,g have been deduced from the radiochemically determined independent isomeric yield ratios and statistical model based analysis in neutron induced fission of235U,239Pu and245Cm and spontaneous fission of252Cf. These data along with similar data on134I, reported earlier from this laboratory, bring out the effects of deformed 66n and spherical 82n shells on fragment angular momentum showing also an inverse correlation of the latter with elemental yields. Quantitative estimates of fragment scission point deformation and the coefficient of change of fragment angular momentum with kinetic/excitation energy have been deduced and are seen to be in good agreement with the expected theoretical estimates. 相似文献