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1.
S. I. Dolgaev A. A. Lyalin G. A. Shafeev Shafeev Voronov 《Applied Physics A: Materials Science & Processing》1996,63(1):75-79
The etching of polycrystalline SiC is studied with the help of radiation of a copper-vapor laser either in air or under the layer of a liquid (H2O, DMSO). The etching rate in air is as high as 0.24 m/pulse, in DMSO 0.07 gm/pulse at an energy density of 16 J/cm2. The etched surface is characterized with Scanning Electron Microscopy (SEM) and X-ray diffractometry. Etching of SiC ceramics in air revealed the partial amorphization of SiC and the formation of microcrystals of elementary Si with an average size of 300 Å. The etched surface of SiC ceramics takes on the ability to reduce Cu from a corresponding electroless plating solution. The adherence of the deposit is as high as 30 N/mm2 and is a function of the scanning velocity of the laser beam. 相似文献
2.
The possibility of direct electrosynthesis of mono- and bicyclic diaziridines is studied using, respectively, 1,2-dimethyldiaziridine and 1,5-diazobicyclo[3,1,0]hexane as an example. In either case the process is realized in a galvanostatic electrolysis in the anodic space of a diaphragm cell and proceeds through intermediate formation of alkylchloramines; other electrosynthesis conditions depend on the structure of the source aminoalkane. In the synthesis of monocyclic diaziridines, for the electrolyte, a 4 M solution of NaCl in water was used, which contained high concentrations of 0.5 and 2.0 M of, respectively, CH2O and MeNH2, and the amine excess served, in particular, for binding protons in the reaction of diaziridine synthesis. The process occurs in a homogeneous phase, and the current efficiency for 1,2-dimethyldiaziridine amounted to 40–50% in optimum conditions. In the synthesis of bicyclic diaziridines, the electrolyte was a 4 M solution of NaCl in a 20-% aqueous methanol, containing a low—0.1 M concentration of H2N(CH2)3NH2 and an equimolar quantity of CH2O, and additives of NaHCO3 were used for binding protons in the reaction of diaziridine synthesis. The process occurs in a heterophase environment because of an incomplete dissolution in the conditions of experiment of NaCl and intermediately-formed chloraminoalkane. The current efficiency for 1,5-diazobicyclo[3,1,0]hexane reached 80–85% in optimum conditions, but the loads of the source aminoalkane were 20 times lower than in the synthesis of monocyclic diaziridines. Compared are the results of a direct and an earlier-described indirect method of electrosynthesis of mono- and bicyclic diaziridines. 相似文献
3.
Quantum tunneling effects play an important role in a variety of chemical reactions considerably affecting the reaction rates via opening the classically forbidden paths and emerging as highly efficient or selective processes. However, in the case of electrochemical reactions, quantum tunneling effects are less investigated due to complicated nature of chemical interactions at the electrified interfaces. In this review, we summarize the experimental/theoretical concept of electrochemical quantum proton tunneling (EQPT), which is a key element in microscopic electrode processes. First, we review the experimental observations of EQPT, and next, we discuss possible theoretical pictures of the process. This review shows that a combination of a wide spectrum of scientific efforts is required to understand microscopic mechanism of EQPT including development of the precise electrochemistry-oriented experimental techniques and methodologies, formulation of the appropriate theoretical models for specific systems, and performance of the advanced computational simulations. 相似文献
4.
V. V. Zharov A. N. Lyalin O. V. Karban’ P. A. Perevozchikov N. N. Samartseva G. N. Konygin S. I. Leesment 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(5):804-808
The atomic force method (AFM) was used to study the processes of repair in the sclera tissue within the grafting zone of a
nanostructured biomaterial in a rabbit. The use of the nanostructured placenta has been shown to speed up the penetration
of a graft into the sclera and to induce the formation of new connective-tissue structures. Differences have been revealed
in the structure of mature and newly-formed collagen fibrils. 相似文献
5.
The absorption, luminescence, and luminescence excitation spectra of ruthenium(II) complexes cis-[Ru(bpy)2(L)Cl]+[bpy=2,2′-bipyridyl; L=NH3, pyrazine, pyridine, 4-aminopyridine, 4-picoline, isonicotinamide, 4-cyanopyridine, 4,4′-bipyridyl, or trans-1,2-bis(4-pyridyl)ethylene] in alcoholic (4: 1 EtOH-MeOH) solutions are studied. At 77 K, the quantum yields and decay times of the luminescence of the complexes are measured and the deactivation rate constants of the lowest electronically excited metal-to-ligand charge transfer state (3MLCT) are determined. The linear correlation between the energy of the lowest state 3MLCT d π(Ru)>π*(bpy) of the cis-[Ru(bpy)2(L)Cl]+ complexes and the parameter pKa of the free 4-substituted pyridines and pyrazine used as ligands is established. 相似文献
6.
7.
Ershov A. Yu. Litke S. V. Litke A. S. Mezentseva T. V. Grigor'ev Ya. M. Lyalin G. N. 《Russian Journal of General Chemistry》2001,71(9):1329-1332
Spectral-kinetic luminescence characteristics of the complexes cis-[Ru(bpy)(dppe)X2], cis- [Ru(bpy)2(PPh3)X](BF4) and cis-[Ru(bpy)2X2] [bpy = 2,2'-bipyridyl, dppe = 1,2-bis(diphenylphosphino)ethane, PPh3 is triphenylphosphine, X = NO2
- and CN-] in the ethanol-methanol 4:1 mixtures and adsorbed on the oxide SiO2 or porous polyacrylonitrile polymer surface were studied. Luminescence and luminescence exitation spectra were registered at 77 and 293 K in 230-750 nm range and the luminescence decay time was measured. Introduction of phosphine ligands to the ruthenium(II) bipyridyl complexes inner sphere leads to rise in singlet and triplet state energy at the charge transfer from Ru(II) to 2,2'-bipyridyl in the series [Ru(bpy)2X2] < Ru(bpy)2(PPh3)X](BF4) < [Ru(bpy)(dppe)X2]. The complex adsorption on SiO2 or polyacrylonitrile surface affects noticeably the luminescence spectro-kinetic characteristics. 相似文献
8.
The possibility of indirect and direct electrosyntheses of thiocarbamates is studied. The indirect synthesis is based on producing
monochloramines by the chlorination of an aqueous solution containing an amine and sodium chloride on a dimensionally stable
anode (DSA) in diaphragm electrolysis and a subsequent interaction of monochloramines with potassium xanthate. Optimum synthesis
conditions are found ensuring a current efficiency for thiocarbamates of 43-60%. These are:c
amine
= 0.17-2 M, cNaC1 = 4 M,ja = 20-30 A dm-2, electrolysis temperature 10‡C, the chloramine : potassium xanthate : amine molar ratio of 1 : 1.1 : 2, and the temperature
of the reaction between chloramine and potassium xanthate of 8‡C. The direct synthesis of thiocarbamates is realized in diaphragm
electrolysis when oxidizing an aqueous solution containing an amine, potassium xanthate, and sodium chloride on DSA. With
the electrosynthesis of ethyl ester of methylthiocarbamic acid as an example, conditions are found that allow one to obtain
a target product with a current efficiency of about 44%. However, the direct synthesis is accompanied by the destruction of
the anode material. 相似文献
9.
An indirect two-stage method for the electrosynthesis of NH2Cl was elaborated. In the first stage, NH4Cl was electrolyzed in a nondivided cell in the NaCl (aqueous solution)—CCl4 heterophase system to give NCl3 as a solution in CCl4. Under the optimum conditions, the yield of NCl3 was 80%, and the current efficiency 60%. In the second stage, the obtained solution reacted with an aqueous solution of NH3 to give an aqueous solution of NH2Cl in 50% yield (converted to NH3).
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2011–2014, October, 1998. 相似文献
10.
Boris V. Lyalin Vera L. Sigacheva Vladimir A. Kokorekin Vladimir A. Petrosyan 《Tetrahedron letters》2018,59(28):2741-2744
A nickel oxyhydroxide [NiO(OH)] anode was exploited to develop a new synthetic route for the electrocatalytic N-N homocoupling of N-alkylaminopyrazoles in an alkaline aqueous medium. The advantages of this green electrochemical methodology include low cost, atom economy and high yields. 相似文献