全文获取类型
收费全文 | 805篇 |
免费 | 28篇 |
国内免费 | 6篇 |
专业分类
化学 | 601篇 |
晶体学 | 9篇 |
力学 | 11篇 |
数学 | 90篇 |
物理学 | 128篇 |
出版年
2024年 | 7篇 |
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 14篇 |
2020年 | 18篇 |
2019年 | 28篇 |
2018年 | 28篇 |
2017年 | 33篇 |
2016年 | 53篇 |
2015年 | 28篇 |
2014年 | 39篇 |
2013年 | 48篇 |
2012年 | 67篇 |
2011年 | 45篇 |
2010年 | 45篇 |
2009年 | 35篇 |
2008年 | 60篇 |
2007年 | 58篇 |
2006年 | 45篇 |
2005年 | 25篇 |
2004年 | 27篇 |
2003年 | 19篇 |
2002年 | 15篇 |
2001年 | 12篇 |
2000年 | 16篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有839条查询结果,搜索用时 62 毫秒
11.
G. V. Pankina P. A. Chernavskii A. Yu. Khodakov G.-S. Girardon V. V. Lunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(5):732-737
The promotion of Co/SiO2 catalysts with noble metals such as Ru and Re substantially decreased the mean size of Co particles and increased the fraction of superparamagnetic particles. The Langevin function was used to approximate the magnetic field dependence of magnetization. This allowed the size of Co nanoparticles to be estimated. A decrease in the temperature of the reduction of Co/SiO2 in the presence of Ru and Re decreased the probability of the encapsulation of Co particles in carrier pores. 相似文献
12.
V. I. Kelarev G. A. Shvekhgeimer A. F. Lunin 《Chemistry of Heterocyclic Compounds》1984,20(9):1043-1048
On the heterocyclization of 1-(indol-3-ylcarbonyl)thiosemicarbazides, depending on the conditions of performing the reaction, either 1,2,4-triazoline-3-thiones, 2-amino-1,3,4-thiadiazoles, or 2-amino-1,3,4-oxadiazoles containing an indolyl residue in position 5 are obtained. 1,2,4-Triazoline-3-thiones and 2-amino-1,3, 4-thiadazoles have also been synthesized by the reaction of the hydrochloride of ethyl indol-3-carboximidate with thiosemicarbazides.For communication 35, see [1].Translated from Khimiya Geterotsilicheskikh Soedinenii, No. 9, pp. 1271–1276, September, 1984. 相似文献
13.
New organohalogermanes RGe(OCH2CH2NMe2)2X (R = Ph, X = I (5); R = Me, X = Cl (6) or I (7)) with an intramolecular N→Ge coordination bond were synthesized. According
to the 1H and 13C NMR spectroscopic data, iodides 5 and 7 exist in solution as ionic compounds with the pentacoordinated germanium atom. In
solution of compound 4 (R = Ph, X = Cl), there is an equilibrium between the ionic and covalent forms. The equilibrium shifts
toward the ionic form with increasing solvent polarity or temperature. In solution, chloride 6 is a covalent compound. The
structures and relative stabilities of different isomers of compounds 4–7 were studied by quantum chemical calculations at
the density functional level of theory.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 892–900, May, 2007. 相似文献
14.
Natalya F. Salivon Yaroslav E. Filinchuk Volodymyr V. Olijnyk 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(2):m57-m58
The title complex, [CuCl(C4H8OS)]n, contains infinite spiral (CuS)n chains linked by bridging Cl atoms into layers. The Cl atoms do not form polymeric fragments with CuI, but combine into isolated centrosymmetric Cu2Cl2 units. The compound is non‐isomorphous with the Br‐containing analogue, which contains Cu8S8 rings linked by Br atoms into chains. The O atom of the 1,4‐oxathiane molecule does not realize its coordination abilities in the known copper(I)–halide complexes, while in copper(II)–halide complexes, oxathiane is coordinated via the S and O atoms. This falls into a pattern of the preferred interactions, viz. weak acid (CuI atom) with weak base (S atom) and harder acid (CuII atom) with harder base (O atom). 相似文献
15.
A. A. Isaeva A. I. Baranov Th. Doert M. Ruck V. A. Kulbachinskii R. A. Lunin B. A. Popovkin 《Russian Chemical Bulletin》2007,56(9):1694-1700
New metal-rich mixed nickel-silicon and nickel-germanium chalcogenides, Ni5.68SiSe2, Ni5.46GeSe2, and Ni5.42GeTe2, were synthesized by high-temperature ceramic techniques. The X-ray diffraction study of single crystals grown from a molten
flux revealed that the compounds are isostructural and crystallize in the tetragonal system (space group I4/mmm, Z = 2). These compounds are the first members of the family of M7−δEX2-type (M = Ni or Pd; E = Sn or Sb; X is chalcogen) intergrowth structures containing “light” p elements E. Resistivity measurements on pressed textured pellets showed that both selenides are anisotropic metallic conductors
in the directions parallel and perpendicular to the heterometallic bond systems. The geometric criteria of stability of the
intergrowth structure type under consideration are discussed.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1632–1638, September, 2007. 相似文献
16.
Victor N. Khrustalev Mikhail Yu. Antipin Irina V. Borisova Valery V. Lunin Ghassoub Rima 《Journal of organometallic chemistry》2004,689(2):478-483
The reaction of equimolar quantities of LiOCH2CH2NMe2 and E14(OCH2CH2NMe2)2 (E14=Ge, Sn) in ether yielded new ate complexes [LiE14(OCH2CH2NMe2)3]2 (E14=Ge (1), Sn (2)) with bidentate ligands. The compounds 1 and 2 are white crystalline substances which are highly soluble in THF and pyridine and very sensitive to the traces of oxygen and moisture. The structures of these compounds are studied by X-ray diffraction analysis. The ate complexes 1 and 2 are powerful nucleophiles and may be employed as ligands (neutral) in the coordination chemistry of the transition metals. The electronegative O-substituents at the divalent E14 atoms render them less oxidizable than alkyl- or aryl-substituted derivatives, and the bidentate ligands, owing to intramolecular donor-acceptor interactions, make them more thermodynamically stable compared to monodentate ligands. 相似文献
17.
P. S. Timashev N. N. Vorobieva N. V. Minaev Yu. A. Piskun I. V. Vasilenko S. G. Lakeev S. V. Kostyuk V. V. Lunin V. N. Bagratashvili 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(8):1195-1200
A series of lactide and ε-caprolactone copolymers containing 4–24 mol % of ε-caprolactone with 20- to 30-kDa molecular weights are synthesized. Based on them, porous materials are produced by foaming in supercritical carbon dioxide. The pore size was shown to decrease with increasing ε-caprolactone content in copolymer, while the porosity of the entire sample was not altered. The resulting pore size also decreases if 7 wt % polyethylene glycol is added to the initial monomer mixture. The Young’s modulus of the porous samples decreases with increasing ε-caprolactone content and when polyethylene glycol is added. 相似文献
18.
Volodymyr O. Knizhnikov Zoia V. Voitenko Vladimir B. Golovko Marian V. Gorichko 《Tetrahedron: Asymmetry》2012,23(14):1080-1083
A novel regio- and diastereospecific ring cleavage of bornane-2,3-dione (camphor quinone) under Bucherer-Bergs reaction conditions has been investigated. The simplicity of this transformation provides a novel and straightforward synthetic pathway to enantiopure derivatives of cyclopentane carboxylic acid as well as functionalized hydantoins in just two steps, starting from inexpensive and easily available camphor. 相似文献
19.
20.