全文获取类型
收费全文 | 418篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
化学 | 39篇 |
力学 | 21篇 |
数学 | 293篇 |
物理学 | 67篇 |
出版年
2020年 | 2篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 13篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 7篇 |
2009年 | 15篇 |
2008年 | 10篇 |
2007年 | 16篇 |
2006年 | 10篇 |
2005年 | 20篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 25篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1998年 | 13篇 |
1997年 | 16篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 12篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有420条查询结果,搜索用时 15 毫秒
11.
We establish sufficient conditions for a nonlinear system of difference equations x(t + 1) =x(t) + + P(x(t),t)+ to be reducible to the system y(t + 1) =y(t) + . Here, P(x, t) is a function 2-periodic in xi(i = 1, ...,n) and almost periodic int with a frequency basis .Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 46, No. 4, pp. 404–412, April, 1994.This work was supported by Ukrainian State Committee on Science and Technology. 相似文献
12.
A. Yu. Shaulov V. K. Skachkova O. B. Salamatina S. N. Rudnev A. N. Shchegolikhin S. M. Lomakin U. Eichhoff S. Steuernagel A. A. Samoilenko A. A. Berlin 《Polymer Science Series A》2006,48(3):228-233
The possibility of modifying boron polyoxide with an oligomeric amide upon thermal dehydration of orthoboric acid and oligomerization of caprolactam in a common melt is shown. The products obtained after thermal pretreatment of the initial blend containing 30 wt % caprolactam are investigated. It is shown that the main processes at T < 200°C are dehydration of orthoboric acid and hydrolysis of caprolactam with the formation of ε-aminocaproic acid. At temperatures of 225–260°C, the predominant process is the formation of boron polyoxide and a caprolactam-based oligomeric product. The data of 11B NMR spectroscopy show that the chemical transformations of caprolactam occur against the background of the N:B donor-acceptor interaction. The two-dimensional [11B-1H] heteronuclear correlation spectrum indicates that the systems obtained upon thermal treatment are solid solutions. 相似文献
13.
Fedorov A. N. Samoilenko D. E. Shafeeva M. V. Abzianidze V. V. Trishin Yu. G. 《Russian Journal of General Chemistry》2018,88(9):1948-1950
Russian Journal of General Chemistry - The action of sulfur diethylaminotrifluoride on 19β,28-epoxyoleanan-3-ol (allobetulin) causes dehydration of the terpenoid and isomerization of the ring... 相似文献
14.
15.
G. B. Manelis K. G. Shkadinskii N. G. Samoilenko G. V. Shkadinskaya 《Doklady Physical Chemistry》2015,465(2):291-294
A model of the process of methane delivery from seafloor deposits of solid hydrates to the surface has been developed and approved. The model considers methane delivery through a vertical pipe lowered from the sea surface to the seafloor deposit. The model allows to determine important characteristics of the flow through the pipe—the possibility of stationary self-sustained flow of the medium to the surface; the gushing character of the flow; medium velocity, pressure, and composition distribution along the pipe—and thus to optimize the process of gas production. 相似文献
16.
17.
O. I. Kudinova V. G. Krasheninnikov A. A. Samoilenko T. A. Ladygina L. A. Novokshonova E. S. Petrov L. F. Rybakova 《Kinetics and Catalysis》2013,54(5):566-571
The polymerization of 1-butene over the TiCl4/MgCl2 (TMC) catalyst with the use of substituted phosphine oxides R n P(O)(CH2OR′)3 ? n (R = alkyl, R′ = methyl or acyl, n = 0–2)—new external electron donors-has been investigated. The electron-donating (coordinating) centers in these compounds are the phosphoryl group (P=O) and the oxygen atoms of the substituents at the phosphorus atom. The dependence of the 1-butene polymerization activity of TMC on the nature of the substituents in the phosphine oxides has been studied. The microstructure, degree of crystallinity, molecular weight, and strain-strength characteristics of the synthesized polybutene-1 and the effect of hydrogen on these properties are reported. The most efficient external donor is Me2P(O)CH2OAc. 相似文献
18.
Varyukhin V. N. Moroz T. T. Shkuratov B. E. Izotov A. I. Nepochatykh Yu. I. Burkhovetskii V. V. Samoilenko Z. A. Pushenko E. I. 《Technical Physics》2020,65(6):904-908
Technical Physics - Structural data and dependences of the film resistance on magnetic field strength R(H) are presented for Co–Gd and Al–Co–Gd alloy films obtained by vacuum... 相似文献
19.
Yu. A. Gostintsev N. I. Peregudov L. V. Kustova N. G. Samoilenko B. L. Korsunskii 《Russian Journal of Physical Chemistry B, Focus on Physics》2009,3(4):606-609
A mathematical model of the ignition of unmixed of fuel and oxidizer (a finite spherical volume of fuel surrounded by an infinite
oxidizer medium) was developed. The regularities of the autoignition of this system were examined. It was demonstrated that
the temperature maximum arising at the fuel-oxidizer interface propagates with increasing amplitude and velocity toward the
center of the spherical volume and that the time it takes to attain the maximum temperature (below the autoignition threshold)
and the ignition delay time (above the threshold) depend on the parameter δ nonmonotonically, more specifically, exhibit well-pronounced
maxima 相似文献
20.
N. G. Samoilenko B. L. Korsunskii V. A. Bostandzhiyan A. V. Il’ichev L. V. Kustova 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(6):973-977
The characteristics of a thermal explosion in an ideal mixing batch reactor charged with a liquid–solid heterogeneous system are studied. The reactor initially contains both phases. The solid reagent dissolves and reacts in the liquid phase. A strong dependence of the critical value of the Semenov parameter on the dimensionless time of complete dissolution of the solid reagent is established. It is shown that, at short times of complete dissolution, the critical value of the Semenov parameter is practically independent on this time, and the thermal explosion occurs as in a homogeneous system, according to Semenov theory. The heterogeneous properties of the reaction system manifest themselves only at long times of complete dissolution. 相似文献