全文获取类型
收费全文 | 202987篇 |
免费 | 1290篇 |
国内免费 | 428篇 |
专业分类
化学 | 104690篇 |
晶体学 | 3393篇 |
力学 | 10272篇 |
综合类 | 10篇 |
数学 | 21828篇 |
物理学 | 64512篇 |
出版年
2021年 | 1971篇 |
2020年 | 2011篇 |
2019年 | 2567篇 |
2018年 | 3657篇 |
2017年 | 3668篇 |
2016年 | 4808篇 |
2015年 | 2342篇 |
2014年 | 4295篇 |
2013年 | 8579篇 |
2012年 | 6832篇 |
2011年 | 8040篇 |
2010年 | 6456篇 |
2009年 | 6640篇 |
2008年 | 7631篇 |
2007年 | 7592篇 |
2006年 | 6689篇 |
2005年 | 5917篇 |
2004年 | 5636篇 |
2003年 | 5160篇 |
2002年 | 5152篇 |
2001年 | 5604篇 |
2000年 | 4137篇 |
1999年 | 3132篇 |
1998年 | 2700篇 |
1997年 | 2757篇 |
1996年 | 2540篇 |
1995年 | 2210篇 |
1994年 | 2327篇 |
1993年 | 2225篇 |
1992年 | 2522篇 |
1991年 | 2646篇 |
1990年 | 2552篇 |
1989年 | 2622篇 |
1988年 | 2531篇 |
1987年 | 2551篇 |
1986年 | 2411篇 |
1985年 | 3032篇 |
1984年 | 3102篇 |
1983年 | 2596篇 |
1982年 | 2562篇 |
1981年 | 2527篇 |
1980年 | 2335篇 |
1979年 | 2708篇 |
1978年 | 2671篇 |
1977年 | 2871篇 |
1976年 | 2872篇 |
1975年 | 2664篇 |
1974年 | 2602篇 |
1973年 | 2711篇 |
1972年 | 2085篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
N. Mandouvalos 《Transactions of the American Mathematical Society》1998,350(2):559-569
We give a simple proof of the analytic continuation of the resolvent kernel for a convex cocompact Kleinian group.
942.
943.
The kinetics of muonic atoms of hydrogen isotopes in an axially symmetric trap is studied. The problem of the determination of the initial kinetic energy distribution of µp and µd atoms from time-of-flight spectra is discussed. The effects of the scattering of muonic atoms from gas and of the stopping distribution are evaluated. When the collision length is much larger than the target radius, the moments of the kinetic energy distribution are shown to be determined by the time-of-flight spectrum in a model-independent way. 相似文献
944.
S. N. Storchak 《Theoretical and Mathematical Physics》1996,109(1):1260-1268
We obtain new formulas for the transformations of Wiener path integrals corresponding to the parabolic systems of two differential equations with time-dependent coefficients in one-dimensional space. These formulas determine the transformation of the path integrals under a rheonomous-homogeneous-pointwise transformation of integration variables and the path reparameterization transformation. These formulas allow us to obtain an integral relation between the Green's functions of related systems of differential equations. We show how to obtain the generalized Shepp formula from this relation for the path integral under consideration. We derive these new formulas using the properties of random processes under phase transitions and a random change in time.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 109, No. 1, pp. 17–27, October, 1996. 相似文献
945.
M. A. Il'in P. Yu. Karasev N. A. Denisova A. V. Rezvov S. V. Tyurina 《Russian Physics Journal》1988,31(1):19-24
On the basis of numerical calculations and experimental studies we analyze the possibilities of measuring the electrophysical parameters of indium phosphide by means of infrared reflection spectra at wavelengths ranging from 5 to 200 m. We demonstrate that contactless nondestructive measurements of the electron density in the range 1016–1020 cm–3 can be made with a relative error not exceeding 15%, and of mobility with a relative error not exceeding 25%. A nomogram method is presented for rapid conversion of data from infrared reflection spectra into the parameters being measured.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 22–27, January, 1988. 相似文献
946.
The results of a calculation of the characteristics of fluctuations in the absorption of energy of electrons and gamma rays in small sensitive volumes of a material in electronic equilibrium are presented. The calculations were performed by the method developed in [1]. The efficiency and accuracy of the method are demonstrated by comparisons with the experimental results and direct numerical simulation. The experience gained in using the method is analyzed. The main numerical result of this work is a table of coefficients enabling the calculation of the probability of the absorption of energy and the first two moments of the energy absorbed in spherical regions with radii of 1, 2, 4, and 8 m, starting only from the electronic spectrum in these regions, for water absorbers with arbitrary shape and arbitrary electronic or photonic sources with energies up to 1 MeV.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 77–82, February, 1988. 相似文献
947.
N. M. Bokalo 《Journal of Mathematical Sciences》1990,51(3):2291-2322
Questions of uniqueness and existence of solutions of the problem without initial conditions for quasilinear parabolic equations of arbitrary order with monotone spatial part, equations of nonstationary filtration type, and operator differential equations of parabolic type are studied. The cases when restrictions are and are not imposed on the behavior of solutions as t– are considered here.Translated from Trudy Seminara imeni I. G. Petrovskogo, No. 14, pp. 3–44, 1989. 相似文献
948.
Conclusion In a planar logarithmic spiral excited at its periphery there simultaneously exist surface, quasieffluent, and radiated waves; the phase velocities of surface and quasieffluent waves are identical and depend on the reduced radius k, which defines the regions of normal and anomalous dispersion; in the region kn the surface wave transforms to a radiated one by means of the quasieffluent; the directional pattern differs little from that for central excitation, with ellipticity coefficient of a spiral open at the center varying from 0.7 to 0.9 over a 1:2 frequency range; the input impedance depends weakly on the presence of reflection at the center of the spiral, is of an oscillating character, and changes more intensely than for central excitation.Khar'kov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 1, pp. 78–84, January, 1990. 相似文献
949.
H. -J. Simonis S. Kremeyer F. Hagelberg U. Reuter M. Knopp K. -H. Speidel J. Cub W. Karle P. N. Tandon J. Gerber 《Hyperfine Interactions》1990,61(1-4):1351-1354
From hyperfine interaction studles on free single electron16O(3−) ions. in a time differential mode using the recoil distance technique. It is shown that these ions are polarized when emerging
from magnetized thin layers of Fe. The observed degree of polarization
, however, is smaller than expected from transient field measurements. 相似文献
950.