全文获取类型
收费全文 | 254059篇 |
免费 | 3857篇 |
国内免费 | 1567篇 |
专业分类
化学 | 138265篇 |
晶体学 | 3799篇 |
力学 | 10365篇 |
综合类 | 53篇 |
数学 | 28502篇 |
物理学 | 78499篇 |
出版年
2021年 | 1833篇 |
2020年 | 2065篇 |
2019年 | 2360篇 |
2018年 | 2718篇 |
2017年 | 2660篇 |
2016年 | 4214篇 |
2015年 | 2995篇 |
2014年 | 4359篇 |
2013年 | 11844篇 |
2012年 | 8922篇 |
2011年 | 10969篇 |
2010年 | 7195篇 |
2009年 | 7113篇 |
2008年 | 9702篇 |
2007年 | 9802篇 |
2006年 | 8962篇 |
2005年 | 8336篇 |
2004年 | 7472篇 |
2003年 | 6615篇 |
2002年 | 6500篇 |
2001年 | 7502篇 |
2000年 | 5609篇 |
1999年 | 4406篇 |
1998年 | 3700篇 |
1997年 | 3701篇 |
1996年 | 3449篇 |
1995年 | 3252篇 |
1994年 | 3093篇 |
1993年 | 3114篇 |
1992年 | 3400篇 |
1991年 | 3419篇 |
1990年 | 3240篇 |
1989年 | 3175篇 |
1988年 | 3244篇 |
1987年 | 3084篇 |
1986年 | 2990篇 |
1985年 | 4070篇 |
1984年 | 4201篇 |
1983年 | 3461篇 |
1982年 | 3791篇 |
1981年 | 3680篇 |
1980年 | 3556篇 |
1979年 | 3578篇 |
1978年 | 3807篇 |
1977年 | 3639篇 |
1976年 | 3842篇 |
1975年 | 3416篇 |
1974年 | 3555篇 |
1973年 | 3852篇 |
1972年 | 2340篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
953.
I. A. Begishev R. A. Ganeev V. V. Gorbushin A. A. Gulamov Sh. R. Kamalov T. Usmanov 《Journal of Applied Spectroscopy》1989,51(5):1218-1221
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 51, No. 5, pp. 867–870, November, 1989. 相似文献
954.
955.
R. Möller und H. Viefhaus 《Fresenius' Journal of Analytical Chemistry》1987,329(2-3):331
956.
957.
Andreas Rößler 《BIT Numerical Mathematics》2007,47(3):657-680
The weak approximation of the solution of a system of Stratonovich stochastic differential equations with a m–dimensional Wiener process is studied. Therefore, a new class of stochastic Runge–Kutta methods is introduced. As the main
novelty, the number of stages does not depend on the dimension m of the driving Wiener process which reduces the computational effort significantly. The colored rooted tree analysis due
to the author is applied to determine order conditions for the new stochastic Runge–Kutta methods assuring convergence with
order two in the weak sense. Further, some coefficients for second order stochastic Runge–Kutta schemes are calculated explicitly.
AMS subject classification (2000) 65C30, 65L06, 60H35, 60H10 相似文献
958.
In this research, we investigate stopping rules for software testing and propose two stopping rules from the aspect of software reliability testing based on the impartial reliability model. The impartial reliability difference (IRD-MP) rule considers the difference between the impartial transition-probability reliabilities estimated for both software developer and consumers at their predetermined prior information levels. The empirical–impartial reliability difference (EIRD-MP) rule suggests stopping a software test when the computed empirical transition reliability is tending to its estimated impartial transition reliability. To insure the high-standard requirement for safety-critical software, both rules take the maximum probability (MP) of untested paths into account. 相似文献
959.
We report the coexistence of γ(γ′) and θ alumina grown on the CoAl(1 0 0) surface. Both phases were observed after annealing of alumina at 1150 K by means of scanning tunnelling microscopy (STM). The crystal structures of γ(γ′) and θ alumina were indexed based on low energy electron diffraction (LEED) and STM experimental data. 相似文献
960.
Ts. A. Gavasheli D. M. Daraseliya D. L. Dzhaparidze R. I. Mirianashvili O. V. Romelashvili T. I. Sanadze 《Physics of the Solid State》2006,48(1):58-62
An empirical relationship describing the radial dependence of the nondipole part of the anisotropic constant for the ligand
hyperfine interaction in alkaline-earth fluorides is proposed. This relationship is used for calculating the distances between
the magnetic ion and the fluorine ions involved in its nearest environment. The results of the calculations are in good agreement
with the values obtained by other methods for both cubic and tetragonal fluorine centers in these crystals. The distances
from the magnetic ion to different groups of nonequivalent fluorine ions of the nearest environment in Yb3+ trigonal centers of SrF2 and BaF2 are determined. It is found that the Yb3+ ion is slightly displaced along the trigonal axis away from the compensating fluorine ion. 相似文献