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排序方式: 共有103条查询结果,搜索用时 31 毫秒
31.
Yu. N. Belokon V. A. Larionov A. F. Mkrtchyan V. N. Khrustalev A. Nijland A. S. Saghyan I. A. Godovikov A. S. Peregudov K. K. Babievsky N. S. Ikonnikov V. I. Maleev 《Russian Chemical Bulletin》2012,61(12):2252-2260
Schiff bases derived from (1R,2R)-1,2-diaminocyclohexane and 1 eq. of salycylic (or substituted salycylic) aldehyde form stereochemically inert positively charged chiral octahedral Co iii complexes of Δ-configuration with the stereoselectivity approaching 100%. To evaluate the calatylic activity and stereoinduction of the resulting complexes with various counteranions in the outer sphere, a model reaction of trimethylsilyl cyanide addition to benzaldehyde was used. O-trimethylsilylmandelonitrile formed in the process had an enantiomeric purity up to 27%. Complexes with F? counterion showed high catalytic activity. 相似文献
32.
V. K. Ikonnikov T. V. Dobrodskaya N. D. Romaschenkova S. A. Sirotin S. A. Dobrusina N. I. Podgornaya 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(8):1196-1206
A method for nonaqueous neutralization of various brands of paper with alcohol solutions of magnesium methoxide and methoxycarbonate
is investigated. The minimum level of alkali reserve (100–150 mg-eq/kg) required for a prolonged preservation of the properties
of paper is determined. A method for paper treatment with a neutralizing solution containing Freon, alcohol, and a neutralizing
agent and saturated with subcritical carbon dioxide is proposed and experimentally tested. It is shown that, under certain
conditions, supersaturation with carbon dioxide leads to the recrystallization of neutralizing agent and its deposition in
the pores of paper in the form highly dispersed particles. The method makes it possible to adjust the alkali reserve (AR)
level by varying the concentration of neutralizing agent and the degree of saturation of the solution with CO2. The possibility of using supercritical CO2 as a solvent and transport medium for neutralizing agent (magnesium methoxycarbonate) to treat paper-based printings is examined.
The optimal regimes of dissolution of neutralizing agent in supercritical CO2 and of paper treatment were selected, and the working parameters in the reactor and the ratio between the components at which
the required level of the AR in paper is achieved are determined. The proposed methods for large-batch neutralization of the
acidity of paper provide the minimum required AR level capable of ensuring the preservation of paper for a long period (up
to 100 years) under conditions of natural aging with minimum amounts of expensive organic solvents, which indicates a high
competitiveness of the proposed technologies of large-batch treatment of printed materials. 相似文献
33.
V. K. Ikonnikov P. A. Egoyants S. A. Sirotin Truong Tat Hieu 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(8):1265-1271
The extraction of biologically active substances by carbon dioxide from various plant raw materials (amaranth seeds, Sophora japonica flower buds, Stephania rotunda stems, and Stevia rebaudiana leaves) was studied at sub- and supercritical parameters. A laboratory unit for the extraction of plant raw materials by
liquefied gases and supercritical fluids at 5–35 MPa pressures and 285–350 K temperatures was developed. The maximum yield
of the extracted substances from plants specified was obtained at temperature and pressure exceeding the critical parameters
of CO2 (320–330 K, 28–30 MPa). 相似文献
34.
Illariia A. Razumkova Yuriy G. Denisenko Andrey N. Boyko Denis A. Ikonnikov Aleksandr S. Aleksandrovsky Nikita O. Azarapin Oleg V. Andreev 《无机化学与普通化学杂志》2019,645(24):1393-1401
Rare earth fluorides are mainly obtained from aqueous solutions of oxygen‐containing precursors. Probably, this method is simple and efficient, however, oxygen may partially be retained in the fluoride structure. We offer an alternative method: obtaining fluorides and solid solutions based on them from an oxygen‐free precursor. As starting materials, we choose sulfides of rare‐earth elements and solid solutions based on them. The fluorination is carried out by exposure to hydrofluoric acid of various concentrations. The transmission electron microscopy images revealed the different morphologies of the products, which depend on the concentration of the fluorinating component (HF) and the host element. The solid solution particle size varied from 30–35 nm in the case of GdF3:Yb3+, Tm3+ (4 % HF) to larger structures with dimensions exceeding 200 nm, such as that for LaF3:Yb3+, Ho3+ (40 % HF). The thermal characteristics, such as the temperatures of the transitions and melting and enthalpies, were determined for the solid solutions and simple fluorides. Applicability of the materials obtained as biological luminescent markers was tested on the example of upconversion luminescence, and good upconversion properties were detected. 相似文献
35.
36.
Bovkun L. S. Ikonnikov A. V. Krishtopenko S. S. Aleshkin V. Ya. Zholudev M. S. Ruffenach S. Consejo C. Teppe F. Dvoretskii S. A. Mikhailov N. N. Potemski M. Orlita M. Gavrilenko V. I. 《JETP Letters》2020,112(8):508-512
JETP Letters - Magneto-absorption in HgTe/CdHgTe quantum wells with an inverted band structure in magnetic fields up to 30 T has been studied. It has been shown that the positions of... 相似文献
37.
Nikolaev I. D. Uaman Svetikova T. A. Rumyantsev V. V. Zholudev M. S. Kozlov D. V. Morozov S. V. Dvoretsky S. A. Mikhailov N. N. Gavrilenko V. I. Ikonnikov A. V. 《JETP Letters》2020,111(10):575-581
JETP Letters - Photoconductivity spectra in a HgTe/CdHgTe double quantum well with a normal band structure have been studied. Photosensitivity bands associated with the ionization of a mercury... 相似文献
38.
Iakov S. Fomenko Medhanie Afewerki Marko I. Gongola Eugene S. Vasilyev Lidia S. Shulpina Nikolay S. Ikonnikov Georgiy B. Shulpin Denis G. Samsonenko Vadim V. Yanshole Vladimir A. Nadolinny Alexander N. Lavrov Alexey V. Tkachev Artem L. Gushchin 《Molecules (Basel, Switzerland)》2022,27(13)
The reactions of CuX2 (X = Cl, Br) with dipinodiazafluorenes yielded four new complexes [CuX2L1]2 (X = Cl (1), Br (2), L1 = (1R,3R,8R,10R)-2,2,9,9-Tetramethyl-3,4,7,8,9,10-hexahydro-1H-1,3:8,10-dimethanocyclopenta [1,2-b:5,4-b’]diquinolin-12(2H)-one) and [(CuX2)2L2]n (X = Cl (3), Br (4), L2 = (1R,3R,8R,10R,1’R,3’R,8’R,10’R)-2,2,2’,2’,9,9,9’,9’-Octamethyl-1,1’,2,2’,3,3’,4,4’,7,7’,8,8’,9,9’,10,10’-hexadecahydro-1,3:1’,3’:8,10:8’,10’-tetramethano-12,12’-bi(cyclopenta [1,2-b:5,4-b’]diquinolinylidene). The complexes were characterized by IR and EPR spectroscopy, HR-ESI-MS and elemental analysis. The crystal structures of compounds 1, 2 and 4 were determined by X-ray diffraction (XRD) analysis. Complexes 1–2 have a monomeric structure, while complex 4 has a polymeric structure due to additional coordinating N,N sites in L2. All complexes contain a binuclear fragment {Cu2(μ-X)2×2} (X = Cl, Br) in their structures. Each copper atom has a distorted square-pyramidal coordination environment formed by two nitrogen atoms and three halogen atoms. The Cu-Nax distance is elongated compared to Cu-Neq. The EPR spectra of compounds 1–4 in CH3CN confirm their paramagnetic nature due to the d9 electronic configuration of the copper(II) ion. The magnetic properties of all compounds were studied by the method of static magnetic susceptibility. For complexes 1 and 2, the effective magnetic moments are µeff ≈ 1.87 and 1.83 µB (per each Cu2+ ion), respectively, in the temperature range 50–300 K, which are close to the theoretical spin value (1.73 µB). Ferromagnetic exchange interactions between Cu(II) ions inside {Cu2(μ-X)2X2} (X = Cl, Br) dimers (J/kB ≈ 25 and 31 K for 1 and 2, respectively) or between dimers (θ′ ≈ 0.30 and 0.47 K for 1 and 2, respectively) were found at low temperatures. For compounds 3 and 4, the magnetic susceptibility is well described by the Curie–Weiss law in the temperature range 1.77–300 K with µeff ≈ 1.72 and 1.70 µB for 3 and 4, respectively, and weak antiferromagnetic interactions (θ ≈ −0.4 K for 3 and −0.65 K for 4). Complexes 1–4 exhibit high catalytic activity in the oxidation of alkanes and alcohols with peroxides. The maximum yield of cyclohexane oxidation products reached 50% (complex 3). Based on the data on the study of regio- and bond-selectivity, it was concluded that hydroxyl radicals play a decisive role in the oxidation reaction. The initial products in reactions with alkanes are alkyl hydroperoxides. 相似文献
39.
40.
V. I. Dostovalova A. B. Terent'ev N. S. Ikonnikov R. Kh. Freidlina 《Magnetic resonance in chemistry : MRC》1983,21(1):11-19
Carbon-13 NMR spectra of 56 long-chain polybranched carboxylic acids their esters, including chloroand acetoxy-substituted derivatives, have been studied. An empirical linear two-parameter equation, relating carbon chemical shifts in α-branched carboxylic acids and their derivatives to the chemical shifts of the corresponding carbon atoms in analogous hydrocarbons, and to the degree of branching at the α-carbon atom, is suggested for the assignment of the signals, where δX is the shift in the acid (ester), δH the shift in its hydrocarbon counterpart and n the degree of branching. The regression coefficients, A, B and C, are given for X=COOH, COOMe and COOEt. It is shown that with polysubstituted derivatives, the equation may be applied sequentially. The secondary coefficients for the α-substituent then depend on the nature of the substituent X entering the primary equation. The equation may, if necessary, be applied in combination with the additive and structural increments of halogen atoms. 相似文献