全文获取类型
收费全文 | 54590篇 |
免费 | 4982篇 |
国内免费 | 3484篇 |
专业分类
化学 | 35602篇 |
晶体学 | 547篇 |
力学 | 3241篇 |
综合类 | 191篇 |
数学 | 7267篇 |
物理学 | 16208篇 |
出版年
2023年 | 659篇 |
2022年 | 1315篇 |
2021年 | 1462篇 |
2020年 | 1572篇 |
2019年 | 1581篇 |
2018年 | 1451篇 |
2017年 | 1321篇 |
2016年 | 2129篇 |
2015年 | 1812篇 |
2014年 | 2227篇 |
2013年 | 3044篇 |
2012年 | 3813篇 |
2011年 | 3910篇 |
2010年 | 2814篇 |
2009年 | 2630篇 |
2008年 | 2930篇 |
2007年 | 2796篇 |
2006年 | 2454篇 |
2005年 | 2077篇 |
2004年 | 1700篇 |
2003年 | 1372篇 |
2002年 | 1344篇 |
2001年 | 1012篇 |
2000年 | 870篇 |
1999年 | 890篇 |
1998年 | 726篇 |
1997年 | 733篇 |
1996年 | 738篇 |
1995年 | 618篇 |
1994年 | 536篇 |
1993年 | 511篇 |
1992年 | 510篇 |
1991年 | 472篇 |
1990年 | 467篇 |
1989年 | 424篇 |
1988年 | 321篇 |
1987年 | 367篇 |
1986年 | 330篇 |
1985年 | 381篇 |
1984年 | 350篇 |
1979年 | 320篇 |
1978年 | 343篇 |
1977年 | 328篇 |
1976年 | 417篇 |
1975年 | 376篇 |
1974年 | 397篇 |
1973年 | 402篇 |
1972年 | 374篇 |
1971年 | 332篇 |
1970年 | 321篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
L-fuzzyRingandL-fuzzyModuleL-fuzzyRingandL-fuzzyModule¥SunRongguangJiangBaoqing(HumanUniversity,Kaifeng,475001)RenXuejun(Minq... 相似文献
182.
183.
A review of the advance in the theory of wavelet analysis in recent years is given. 相似文献
184.
P. A. Bokhan T. Ya. Dubnishcheva D. E. Zakrevskii Yu. V. Nastaushev 《Journal of Russian Laser Research》1995,16(2):164-171
A gas-discharge gold-vapor laser on self-terminating transitions with operating wavelength λ=312.2 nm has been used to develop a highly efficient system for image transfer. An optical scheme and all its parameters have been chosen optimal for image quality. It has been found both theoretically and experimentally that the best results on micron-structure image transfer are obtained with 2–5-times image reduction. Various types of masks have been used. A 1-µm structure has been resolved due to the choice of optimal exposure time of 10 ms under a period of pulse repetition (0.6 – 0.8) ms; in this case, the minimal fringe dimension was ≈2 µm with an image dimension of 2 mm for a laser tube 1.8 cm in diameter. 相似文献
185.
V. P. Germogenov O. M. Ivleva Ya. I. Otman L. E. Épiktetova 《Russian Physics Journal》1988,31(1):73-77
Studies have been carried out on the perfection of then-AlxGa1–xSb1–yAsy (0.12x0.26) layer grown on GaSb substrates under different conditions of lattice matching. During the relaxation of the mechanical stresses at first a system of tilt dislocations with a density of up to 5 · 105 cm–2 is formed while in thick layers (h 20 m) a network of misfit dislocations parallel to the heteroboundary is formed. The time required to dissolve a weighed amount of GaAs in the melt is shown to be of major importance for obtaining layers of a solid solution that are isoperiodic with the substrate. The entry of arsenic only in the initial portion of the epitaxial layer can reduce the dislocation density in the layer without decreasing the measured value of Aa. Dissolution of a weighed amount of GaAs in a Ga + Sb melt for two hours at T=730–750°C is sufficient to obtain layers of AlxGa1–xSb1–yAsy solid solution that are isoperiodic with the substrate.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 84–89, January, 1988.In conclusion, we thank L. V. Druzhinina for useful discussions as well as Z. V. Korotchenko, L. S. Khludkova, and F. S. Kim for assistance in the performance of the experiments. 相似文献
186.
Gal'tsov et al. [Vestn. Mosk. Gos. Univ., Fiz., Astron.,14, No. 5, 614 (1973)] studied the radiation spectrum of N equally spaced charges moving along a circle. In particular, it was shown that as N the intensity of the radiation from the system of charges vanishes. The present study will consider the radiation spectrum of N charges moving along an arbitrary closed curve, randomly distributed in the vicinity of equally spaced points. The coherency factor will be found for the assumption that: a) the distributions of individual charges are not intercorrelated; b) the charge distribution is such that in the vicinity of a given point only one charge is found. It will be shown that as N the radiation intensity tends to a finite limit.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 8–11, March, 1988. 相似文献
187.
B. Ya. Levin 《Journal of Mathematical Sciences》1990,52(5):3351-3364
We make use here of the definitions and theorems from our paper: Majorants in classes of subharmonic functions, from the previous issue of this journal. 相似文献
188.
The Radiative Transfer Equation is the nonlinear transport equation
相似文献
189.
Yu. M. Berezanskii B. Ya. Levin V. A. Marchenko Yu. A. Mitropol''skii I. V. Ostrovskii 《Functional Analysis and Its Applications》1990,24(2):85-85
ObituaryMark Grigor'evich Krein 相似文献190.
We investigate representations of classical noncompact Lie groups induced by representations of the maximal parabolic subgroup. Formulas are obtained for 5O0(2p, 2q)/U(p, q) and U(2p, 2q) Sp(p, q).Translated from Ukrainskii Mathematicheskii Zhurnal, Vol. 42, No. 1, pp. 128–131, January, 1990. 相似文献
|