全文获取类型
收费全文 | 315篇 |
免费 | 5篇 |
专业分类
化学 | 238篇 |
晶体学 | 22篇 |
力学 | 2篇 |
数学 | 3篇 |
物理学 | 55篇 |
出版年
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 13篇 |
2018年 | 11篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 3篇 |
2014年 | 11篇 |
2013年 | 16篇 |
2012年 | 17篇 |
2011年 | 24篇 |
2010年 | 11篇 |
2009年 | 11篇 |
2008年 | 10篇 |
2007年 | 10篇 |
2006年 | 15篇 |
2005年 | 14篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 11篇 |
2000年 | 4篇 |
1999年 | 14篇 |
1998年 | 6篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有320条查询结果,搜索用时 312 毫秒
311.
V. E. Baulin L. Kh. Minacheva I. S. Ivanova E. N. Pyatova V. S. Sergienko A. V. Churakov O. V. Kovalenko A. Yu. Tsivadze 《Russian Journal of Inorganic Chemistry》2011,56(8):1232-1242
The ion-selective properties of 1,8-bis[2-(dihydroxyphosphinyl)phenoxy]-3,6-dioxaoctane (H4L3) have been studied and its potentiometric selectivity coefficients have been determined. New complexes [Cu(H4L3)(H2O)3][(H2L3)(H2O)] (I) and Zn(H4L3)(H2L3) · 3H2O, and Cu(H2L3) · 2(H2O) have been synthesized and characterized. The crystal and molecular structure of I has been determined by X-ray crystallography and vibrational spectroscopy. The crystals are monoclinic, a = 10.279(5) Å, b = 26.532(13) Å, c = 8.399(4) Å, β = 99.270(8)°, V = 2260.8(7) Å3, Z = 2, space group Cm, R = 0.0347 for 4325 reflections with I > 2σ(I). Ionic compound I is composed of the [Cu(H4L3)(H2O)3]2+ complex cations and [(H2L3)(H2O)]2? anions. In the cation, the Cu2+ cation located in the m plane is bound to a tetragonal pyramidal (TP) array. The equatorial plane of the TP is formed by two phosphoryl oxygen atoms of the podand (Cu(1)-O, 1.921(2) Å) and two O atoms of two water molecules (av. Cu(1)-O, 1.981(3) Å). The third water molecule is at the axial vertex of the TP at a considerably larger distance (Cu(1)-O, 2.139(3) Å). The anion is of the host-guest type. The host is the deprotonated podand (H2L3)2?, and the guest is the water molecule. The latter is bound to the terminal hydroxyl groups of two phosphoryl groups of the podand by two acceptor hydrogen bonds and to two central ether oxygen atoms of the (H2L3)2? anion by one donor bifurcated hydrogen bond. The cations and anions in the structure are linked by hydrogen bonds to form chains parallel to the c axis. 相似文献
312.
K. K. Palkina A. N. Kochetov A. V. Churakov V. S. Sergienko 《Russian Journal of Inorganic Chemistry》2011,56(8):1258-1263
The sodium complex with 2-(diphenylacetyl)indandione-1,3 (HL) have been synthesized and studied by X-ray diffraction analysis. Crystals of [Na4(H2O)4L4] (I) precipitated from aqueous acetone are monoclinic, Z = 2, space group P21/c, a = 12.171(1) Å, b = 10.527(1) Å, c = 29.777(2) Å, β = 97.455(1)°. The structure of compound I is based on a centrosymmetric tetranuclear [Na4O12] cage. Two central Na(2) atoms are coordinated to four O atoms of two L ligands. The central and peripheral atom polyhedrons [Na(2)O6] and [Na(1)O5] are joined by a common edge formed by two O atoms of two L ligands. Tetranuclear moieties are joined into the framework by hydrogen bonds, numerous C-H-π contacts, and π-π stacking-contacts between the conjugated and aromatic ligand systems of neighboring tetramers. 相似文献
313.
I. I. Seifullina L. Kh. Minacheva E. A. Chebanenko E. E. Martsinko V. S. Sergienko A. V. Churakov 《Russian Journal of Inorganic Chemistry》2011,56(12):1886-1893
Bis(citrato)hydroxogermanic(IV) acid was obtained for the first time in the complex [H5O2][Ge(H2Cit)(H2.5Cit)(OH)]2 · 2CH3COOH · 2H2O (H4Cit is citric acid). The complex was characterized by chemical analysis, X-ray powder diffraction, TGA, and IR spectroscopy.
Complex I was studied by X-ray crystallography. The crystals are triclinic; a = 10.0651(4) ?, b = 10.1918(4) ?, c = 10.5838(4) ?, α = 85.0110(10)°, β = 85.2170(10)°, γ = 86.7670(10)°, V = 1076.50(7) ?3, Z = 1, space group P[`1]P\bar 1, R1 = 0.0353 for 5709 reflections with I > 2σ(I). Complex I is composed of centrosymmetric dimeric complex anions [Ge2(H2Cit)2(H2.5Cit)2(OH)2]−, dioxonium cations [H5O2]+, and acetic acid and water molecules of crystallization. The coordination polyhedron of the Ge atom is a trigonal bipyramid.
Its equatorial plane comprises two O atoms of the deprotonated alcohol groups of two ligands H2Cit (A) and H2.5Cit (B) and the O atom of the terminal OH group (Ge-O, 1.7585–1.7754 ?; OeqGe(1)Oeq, 116.26°–127.64°). The axial positions are occupied by the carboxy O atom of the deprotonated carboxylate group of the α
branch of ligand A (α-Ge-O(C)(carb), 1.8882(12) ?)) and the carbonyl O atom of the hemiprotonated acetate α branch of ligand
B (α-Ge-O(C) 1.9615(12) ?, O(1)Ge(1)O(8) 170.47(5)°). In structure I, the complex dianion, the cation, and acetic acid and water molecules are united through hydrogen bonds into a three-dimensional
framework. 相似文献
314.
A. V. Belushkin A. A. Bogdzel V. V. Zhuravlev Ts. Ts. Panteleev Li Yong Jai A. N. Chernikov A. V. Churakov V. N. Shvetsov 《Technical Physics》2008,53(1):117-121
Development of new high-flux-intensity neutron sources and the need to equip them with efficient spectrometers raises the problem of designing special-purpose direct-beam monitors-detectors. These detectors feature an extremely low efficiency and a very low attenuation of the incident neutron beam. In this work, a two-coordinate position-sensitive monitor-detector is described that was developed for real-time recording of the profile of neutron beams generated by both steady and pulsed neutron sources. The basic parameters of this device are the following: a coordinate resolution of 4 × 4 mm2, a sensitive area of 100 × 100 mm2, and a recording efficiency of 10?6?10?2. Use of nitrogen as a converter makes it possible to achieve a record low efficiency and still maintain other parameters at a desired level. The device can be combined not only with high-flux-intensity neutron sources already in use worldwide but also with next-generation sources being developed in the United States (SNS) and Japan (JPARC). 相似文献
315.
M.?V.?AvdeevEmail author R.?A.?Eremin V.?I.?Bodnarchuk I.?V.?Gapon V.?I.?Petrenko R.?V.?Erhan A.?V.?Churakov D.?P.?Kozlenko 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2018,12(4):638-644
The possible concepts whereby a time-of-flight small-angle diffractometer optimized for a neutron moderator operating in the cold (at 30 K) and thermal (at 300 K) modes can be implemented at the IBR-2 reactor are studied on the basis of numerical calculations. Under cold conditions, the peak of the neutronbeam energy spectrum is shifted toward low energies (long wavelengths). This extends the sensitivity range of the instrument with respect to the sizes of the objects under study (1–100 nm and higher). A classical scheme enabling the separation of thermal/cold neutrons (E ~10–3–10–2 eV) from the background (formed mainly by fast neutrons), which is based on bent neutron-optical devices, is discussed. Due to restrictions imposed by the geometry of the beamline within which the instrument is planned to be located, a configuration with a short multichannel mirror device for beam bending (beam bender) is preferable. Simulation and optimization of the proposed small-angle instrument is carried out taking into account the real beamline geometry and the available space in the experimental reactor hall. A comparison of the setup has been made with the facility based on the curved neutron guide and the facility with direct view of the moderator. 相似文献
316.
A. E. Frumkin A. M. Churakov Yu. A. Strelenko V. A. Tartakovsky 《Russian Chemical Bulletin》1999,48(11):2103-2107
Oxidation of one of the amino groups of 2-bromo-4,6-dichloro-1,3-phenylenediamine to the nitroso group followed by its conversion
into thetert-butyl-NNO-azoxy group afforded a derivative ofm-(tert-butyl-NNO-azoxy)aniline,viz., 2-bromo-3-(tert-butyl-NNO-azoxyl)-4,6-dichloroaniline. Analogously, the second amino group was converted into thetert-butyl-NNO-azoxy group to form a derivative of 1,3-bis(tert-butyl-NNO-azoxy)benzene,viz., 3-bromo-2,4-bis(tert-butyl-NNO-azoxyl)-1,5-dichlorobenzene The reaction of the latter with ammonia yielded 2-amino- and 2,4-diamino-substituted 1,3-bis-(tert-butyl-NNO-azoxyl)benzenes.
For Part 1, see Ref. 1.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2126–2130, November, 1999. 相似文献
317.
K. I. Rezchikova A. M. Churakov V. A. Shlyapochnikov V. A. Tartakovsky 《Russian Chemical Bulletin》1999,48(5):870-872
Calculations of hypothetical molecules of octaazanaphthalene and itsN-oxides were performed by the MNDO method with full geometry optimization. Probable decomposition reactions of these compounds
were considered. Compounds with more pronounced alternation of charges on adjacent atoms were shown to be more thermodynamically
favorable and thermally stable.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 879–881, May, 1999. 相似文献
318.
Galina S. Zaitseva Sergei S. Karlov Gleb V. Pen'kovoy Andrei V. Churakov Judith A. K. Howard Bettina A. Siggelkow Evgueni V. Avtomonov Jrg Lorberth 《无机化学与普通化学杂志》1999,625(4):655-660
The title compounds, viz. C13H8(R)Ge · (OCHMeCH2)3N ( 1 : R = H, 2 : R = Me3Si; 3 : R = Me3Ge) were prepared as mixtures of diastereomers by the reaction of N(CH2CHMeOSnAlk3)3 ( 7 : Alk = Et; 8 : Alk = Bu) with C13H8(R)GeBr3 ( 4 : R = H, 5 : R = Me3Si; 6 : R = Me3Ge), respectively. The synthesis of C13H8(Me3Sn)Ge · (OCHMeCH2)3N ( 13 ) by the reaction of germatrane ( 1 ) with Me3SnNMe2 is reported. Identity and structures were established by elemental analyses, 1H and 13C NMR spectroscopy and mass spectrometry. The crystal structure of 1 was determined by X‐ray diffraction methods. 相似文献
319.
320.
Badma N. Mankaev Valeriia A. Serova Dr. Mikhail A. Syroeshkin Anna Ya. Akyeva Dr. Alexey V. Sobolev Dr. Andrei V. Churakov Dr. Elmira Kh. Lermontova Dr. Mikhail E. Minyaev Dr. Yury F. Oprunenko Dr. Maxim V. Zabalov Kirill V. Zaitsev Dr. Galina S. Zaitseva Prof. Dr. Sergey S. Karlov 《欧洲无机化学杂志》2023,26(11):e202200690
A series of novel tetrylenes based on three 2,6-bis(2-hydroxyphenyl)pyridines 4 a – 4 c have been obtained by the reaction of Lappert's tetrylenes E[N(SiMe3)2]2 (E=Ge, Sn) with corresponding tridentate pyridine-linked phenol-based ligands. It was found that the structure of the ligand and the size of the atom of the group 14 element drastically affect the structure of the reaction product. Ligand 4 c with a bulky tert-butyl group leads to monomeric tetrylenes, while ligands with less bulky groups lead to bis-ligand derivatives of M(IV) (M=Ge, Sn) and a coordination polymer. Also, derivatives of germanium (IV) and tin (IV) were obtained by the metathesis reaction of MCl4 (M=Ge, Sn) with lithium phenoxides. The compositions and structures of the novel compounds were established by elemental analysis and 1H, 13C, 119Sn ( 5 – 7 ), 1H DOSY ( 6 ) NMR spectroscopy, in the solid state by X-ray diffraction analysis (germylene 10 , stannylene 6 , Ge4+ compound 8 , Sn4+ compound 7 ) and 119Sn Mössbauer spectrum of tin complex 6 . All the synthesized tetrylenes are monomeric. Tetrylenes 6 and 10 were characterized by cyclic voltammetry. A study of the redox behavior of 6 , 10 by cyclic voltammetry on a glassy carbon working electrode in acetonitrile solution of 0.1 M Bu4NPF6 as a supporting electrolyte showed that these compounds can be both oxidized and reduced electrochemically in the accessible potential range. 相似文献