全文获取类型
收费全文 | 278篇 |
免费 | 6篇 |
专业分类
化学 | 278篇 |
晶体学 | 1篇 |
物理学 | 5篇 |
出版年
2022年 | 2篇 |
2018年 | 4篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2013年 | 5篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 12篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 14篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 10篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1973年 | 4篇 |
1972年 | 11篇 |
1971年 | 7篇 |
1970年 | 6篇 |
1969年 | 6篇 |
1967年 | 2篇 |
1966年 | 9篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1963年 | 5篇 |
1960年 | 1篇 |
排序方式: 共有284条查询结果,搜索用时 0 毫秒
141.
N. G. Akhmedov E. A. Katsman S. G. Malyugina V. I. Mstislavsky Yu. F. Oprunenko V. A. Roznyatovsky Yu. A. Ustynyuk A. S. Batsanov N. A. Ustynyuk 《Russian Chemical Bulletin》1997,46(10):1769-1786
The reaction of phenalene with Cr(CO)3Py3/BF3·OEt2 afforded a mixture of two isomeric complexes, tricarbonyl(6a,7-9,9a,9b-·6-phenalene)chromium (1) and tricarbonyl(3a,6a,9b,4-6-·6-phenalene)chromium (2). Deprotonation of the mixture of compounds1 and2 followed by treatment with MeI, BunI, or D2O gave complexesexo-1-R-1 (3–5: R=Me (3), Bun (4), or D (5)). The molecular geometry of complex3 was established by X-ray structural analysis. Heating of complex5 in toluene or C6F6 at 90–110 °C resulted in redistribution of deuterium among positionsexo-1,endo-1, and 3 in the resulting complexes of types1 and2
via sigmatropic shifts of the H
exo
and H
endo
atoms in the nonaromatic ring as well asvia inter-ring migrations of the tricarbonylchromium group. In the case of3, the methyl label is distributed among positionsexo-1 and3 to form isomeric complexes with similar structures (exo-1-Me-2 (6), 3-Me-2 (7), and 3-Me-1 (8), respectively)via processes analogous to those observed in the case of isomerization of compound5 (except for migration of the H
exo
atom). The mechanisms of these rearrangements are discussed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1863–1880, October, 1997. 相似文献
142.
Yu. K. Grishin I. P. Gloriozov S. M. Gerdov V. A. Roznyatovsky L. L. Frolova A. V. Kuchin Yu. A. Ustynyuk 《Russian Chemical Bulletin》2008,57(8):1689-1696
The selectivity of deuterium distribution between the nonequivalent positions in 3-carene (1), 4-α-acetyl-2-carene (2), and 4-(1-hydroxyethyl)-2-carene (3) has been measured by 2H-{1H} NMR spectroscopy at the natural abundance of deuterium. These “H/D-isotope portraits” were shown to be typical of terpenes
and terpenoids produced in plants via the biosynthetic DXP pathway. The mechanism of acylation of 1 was studied by the density functional theory method (PBE functional, TZ2p basis set). The six-membered ring in compound 1 is planar. However, the endo attack of electrophiles on this ring is more favorable both kinetically and thermodynamically. It was shown both experimentally
and theoretically that the elimination of a hydrogen atom in the second reaction step proceeds stereoselectively at the C(2)
atom from the anti position with respect to the three-membered ring and occurs with pronounced nucleophilic assistance from the carbonyl group.
For Part 2, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1657–1664, August, 2008. 相似文献
143.
Umpolung of Methylenephosphonium Ions in Their Manganese Half‐Sandwich Complexes and Application to the Synthesis of Chiral Phosphorus‐Containing Ligand Scaffolds 下载免费PDF全文
Dr. Dmitry A. Valyaev Dr. Oleg A. Filippov Dr. Noël Lugan Dr. Guy Lavigne Prof. Dr. Nikolai A. Ustynyuk 《Angewandte Chemie (International ed. in English)》2015,54(21):6315-6319
Half‐sandwich manganese methylenephosphonium complexes [Cp(CO)2Mn(η2‐R2P?C(H)Ph)]BF4 were obtained in high yield through a straightforward reaction sequence involving a classical Fischer‐type manganese complex and a secondary phosphine as key starting materials. The addition of various nucleophiles (Nu) to these species took place regioselectively at the double‐bonded carbon center of the coordinated methylenephosphonium ligand R2P+?C(H)Ph to produce the corresponding chiral phosphine complexes [Cp(CO)2Mn(κ1‐R2P? C(H)(Ph)Nu)], from which the phosphines were ultimately recovered as free entities upon simple irradiation with visible light. The synthetic potential of this umpolung approach is illustrated herein by the preparation of novel chiral pincer‐type phosphine–NHC–phosphine ligand architectures. 相似文献
144.
Kolesnikov GV German KE Kirakosyan G Tananaev IG Ustynyuk YA Khrustalev VN Katayev EA 《Organic & biomolecular chemistry》2011,9(21):7358-7364
The design and synthesis of a neutral macrocyclic host that is capable of perrhenate and pertechnetate recognition is described. The anion affinities and underlying coordination modes were estimated by several experimental and theoretical methods including a new technique--reverse (99)Tc NMR titration. 相似文献
145.
It is shown that the Widom method of evaluating the chemical potential of a fluid [6] which has been exploited recently to obtain liquid entropies and vapour pressures by computer simulation [5] can be used very simply and economically to predict the liquid-vapour coexistence line and the vapour pressure given the form of the potential. The method is illustrated explicitly for liquid chlorine and liquid bromine. It is quite general, is simpler to use than might have been anticipated and provides a powerful test of an assumed form of intermolecular potential. 相似文献
146.
L. Yu. Ustynyuk E. A. Fushman S. S. Lalayan 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(8):1342-1349
Density functional theory was used to study gas-phase reactions between the Cp2*ZrMe+ cations, where Cp* = C5H5 (1), Me5Cp = C5Me5 (2), and Flu = C13H9 (3), and the ethylene molecule, Cp2*ZrMe+ + C2H4 → Cp2*ZrPr+ → Cp2*ZrAllyl+ + H2. The reactivity of the Cp2*ZrMe+ cations with respect to the ethylene molecule decreased in the series 1 > 3 ≈ 2. Substitution in the Cp ring decreased the reactivity of the Cp2*ZrMe+ cations toward ethylene, in agreement with the experimental data on the comparative reactivities of complexes 1 and 3. The two main energy barriers along the reaction path (the formation of the C-C bond leading to the primary product Cp2*ZrPr+ and hydride shift leading to the secondary product Cp2*Zr(H2)Allyl+) vary in opposite directions in the series of the compounds studied. For Flu (3), these barriers are close to each other, and for the other compounds, the formation of the C-C bond requires the overcoming
of a higher energy barrier. A comparison of the results obtained with the data on the activity of zirconocene catalysts in
real catalytic systems for the polymerization of ethylene led us to conclude that the properties of the catalytic center changed
drastically in the passage from the model reaction in the gas phase to real catalytic systems. 相似文献
147.
148.
N.A. Ustynyuk V.N. Vinogradova V.N. Korneva D.N. Kravtsov V.G. Andrianov Yu.T. Struchkov 《Journal of organometallic chemistry》1984,277(2):285-296
Thermolysis of C5H5(CO)3MoCCC6H5 (I) in octane at 110–115°C results in the formation of [(η-C5H5)(CO)2Mo]2(μ-1,2-η-C6H5CCCCC6H5) (II). The structure of II was determined by X-ray analysis. The reaction scheme is discussed. 相似文献
149.
150.
Conclusion In the reaction of cis--nitrostilbene with cis-dipyridinetungsten tetracarbonyl, the nitrostilbene is converted to the trans form, while the tungsten complex is not changed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1388–1390, June, 1982. 相似文献