全文获取类型
收费全文 | 3352篇 |
免费 | 21篇 |
国内免费 | 3篇 |
专业分类
化学 | 1301篇 |
晶体学 | 49篇 |
力学 | 99篇 |
数学 | 334篇 |
物理学 | 1593篇 |
出版年
2022年 | 32篇 |
2021年 | 71篇 |
2020年 | 69篇 |
2019年 | 69篇 |
2018年 | 113篇 |
2017年 | 91篇 |
2016年 | 121篇 |
2015年 | 50篇 |
2014年 | 86篇 |
2013年 | 150篇 |
2012年 | 116篇 |
2011年 | 121篇 |
2010年 | 134篇 |
2009年 | 105篇 |
2008年 | 152篇 |
2007年 | 154篇 |
2006年 | 125篇 |
2005年 | 127篇 |
2004年 | 101篇 |
2003年 | 102篇 |
2002年 | 84篇 |
2001年 | 96篇 |
2000年 | 76篇 |
1999年 | 45篇 |
1998年 | 39篇 |
1997年 | 46篇 |
1996年 | 41篇 |
1994年 | 25篇 |
1993年 | 38篇 |
1992年 | 37篇 |
1991年 | 42篇 |
1990年 | 35篇 |
1989年 | 37篇 |
1988年 | 32篇 |
1987年 | 28篇 |
1985年 | 32篇 |
1984年 | 31篇 |
1983年 | 27篇 |
1982年 | 26篇 |
1981年 | 28篇 |
1979年 | 34篇 |
1978年 | 33篇 |
1977年 | 43篇 |
1976年 | 34篇 |
1975年 | 28篇 |
1974年 | 29篇 |
1973年 | 34篇 |
1972年 | 29篇 |
1971年 | 28篇 |
1970年 | 22篇 |
排序方式: 共有3376条查询结果,搜索用时 656 毫秒
51.
Smirnov Yu. N. Komarov B. A. Kushch P. P. Ponomareva T. I. Lantsov V. M. 《Russian Journal of Applied Chemistry》2002,75(2):265-275
To control the structural contributions of the polycondensation and polymerization curing of epoxy resins, the curing kinetics of the composites diepoxide-tertiary amine and diepoxide-(primary + tertiary) amines is studied by the isothermal calorimetry. 相似文献
52.
J. C. Lpez V. A. L. Rivera Yu. F. Smirnov A. Frank 《International journal of quantum chemistry》2002,88(2):280-295
The calculation of Franck–Condon factors between different 1‐D Morse potential eigenstates using a formula derived from the Wigner function is discussed. Our numerical calculations using a simple program written in Mathematica are compared with other calculations. We show that our results have a similar accuracy as those calculations performed with more sophisticated methods. We discuss the extension of our method to include non‐Condon effects in the calculation. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem 88: 280–295, 2002 相似文献
53.
Smirnov A. V. Ilyushin M. A. Tselinskii I. V. 《Russian Journal of Applied Chemistry》2004,77(5):794-796
Physicochemical and explosive properties of Co(III) pentammine complexes containing in the inner coordination sphere monodentate polynitrogen heterocyclic ligands, 1-methyl-5-aminotetrazole and 1,5-diaminotetrazole, were studied, and it was shown that these compounds can be used in priming charges. 相似文献
54.
55.
56.
Smirnov O. Yu. Churakov A. M. Tyurin A. Yu. Strelenko Yu. A. Ioffe S. L. Tartakovsky V. A. 《Russian Chemical Bulletin》2002,51(10):1849-1856
Nucleophilic substitution in nitro- and bromobenzo-1,2,3,4-tetrazine 1,3-dioxides (BTDOs) was studied. In most cases, the bromo and nitro groups are replaced by methylamino, dimethylamino, azido, and methoxy groups without opening of the tetrazine ring. It was illustrated with the reactions of dibromo-BTDOs with sodium methoxide that the reactivity of positions 5 to 8 in their benzene ring as regards nucleophilic substitution changes in the following order: 6 > 8 > 7 > 5. The structures of the BTDOs obtained were confirmed by 1H, 13C, and 14N NMR data. 相似文献
57.
IR spectroscopy was used to study the structure and composition of Eu(III) and Sr(II) complexes formed by cation-exchange extraction of these metals from their aqueous nitrate solutions with dichlorethane solutions of mixtures of chlorinated cobalt(III) dicarbollide (CCD) as a superacid with diphenyldiphosphine dioxides containing a methyl (Me-DPDO), ethyl (Et-DPDO), or polyoxyethylene bridge between two phosphorus atoms of phosphine oxide groups. At molar ratios DPDO/CCD ≤ 1, [Eu(H2O)nL4]3+ complexes are formed in organic phases, whereas with an excess of DPDO relative to CCD, Eu(NO3)L 4 2+ complexes are formed, where L = Me-or Et-DPDO. Polyoxyethylenediphosphine dioxide forms anhydrous complexes of composition Eu:L = 1:1 and 1:2 with Eu(III) and outer-spheric complexes of composition Sr:L = 1:1 and 1:2 with Sr(II), where the organic ligand molecules envelop the hydrated Sr(H2O) n 2+ cation. The peculiarities of extraction of the complexes are explained based on data about their composition and structure. 相似文献
58.
L. D. Smirnov L. G. Stolyarova L. V. Shirokova V. P. Lezina 《Russian Chemical Bulletin》1977,26(2):408-410
Conclusions The aminomethylation, azo-coupling, and nitration of 3-hydroxyisonicotinic acid and its ester are directed to the 2 position, whereas their iodination proceeds with the formation of the 2-iodo and 2,6-diiodo derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 452–454, February, 1977. 相似文献
59.
Smirnov B. L. Tubolkin A. E. Britov V. P. Nikolaev O. O. Bogdanov V. V. 《Russian Journal of Applied Chemistry》2004,77(3):493-496
The applicability of the previously developed principles of activating mixing to modification of rubbers in solutions was tested, and a process was developed for mechanochemical modification of cis-1,4-polyisoprene in rotary pulsation apparatus. 相似文献
60.
A. P. Kilimov M. A. Svechnikova V. I. Shevchenko V. V. Smirnov F. V. Kvasnyuk-Mudryi S. B. Zotov 《Chemistry of Heterocyclic Compounds》1967,3(2):467-471
Data for the characteristic bands of cyclic ethers are reviewed. The infrared spectra of a number of 2-mono- and 2, 5-di-substituted
derivatives of tetrahydrofuran are investigated. Absorption bands at about 900 cm−1 are related to pulsation vibrations, and those at about 1200 cm−1 to antisymmetric skeletal vibrations, of the tetrahydrofuran ring. It is shown that to confirm the presence of a tetrahydrofuran
ring in a molecule, it is necessary to take into account not only the band of valence antisymmetric vibrations of the group
C-O-C (ν
C-O-C
as
1075 cm−1), but also bands due to ring pulsation vibrations (ring symmetric valence vibrations ν
sk
s
∼ 900 cm1). 相似文献