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171.
Berestovitskaya V. M. Efremova I. E. Belyakov A. V. Tafeenko V. A. Abakumov A. M. Chernyshev V. V. 《Russian Journal of General Chemistry》2003,73(3):434-439
The structure of the first representative of the polynitrothiolene 1,1-dioxide series was studied. Complex analysis of quantum-chemical results, spectral characteristics, and powder X-ray diffraction patterns allowed this compound to be assigned the structure of 3-methyl-2,2,4-trinitro-3-thiolene 1,1-dioxide. The heteroring has an envelope conformation. The sulfur atom slightly deviates from the ring plane, the nitro group attached to the Csp
2 atom is involved in conjugation, and the nitro groups attached to the Csp
3 atom are nonequivalent and perpencular to each other. 相似文献
172.
Tishkov AA Dilman AD Faustov VI Birukov AA Lysenko KS Belyakov PA Ioffe SL Strelenko YA Antipin MY 《Journal of the American Chemical Society》2002,124(38):11358-11367
The structure and stereodynamics of N,N-bis(silyloxy)enamines (1), a new class of enamines with extraordinary reactivity, have been simulated by the DFT PBE/TZP method. The computed pattern of dynamic behavior and structural peculiarities of 1 was shown to reflect adequately the results of the studies by a series of physical methods including X-ray analysis and dynamic NMR and UV spectroscopies, which provided evidence of a rather low barrier for rotation around the C,N single bond, a negligible contribution of the n-pi-conjugation, a high barrier of inversion, and high pyramidality of the nitrogen atom. 相似文献
173.
174.
S. V. Belyakov A. F. Mishnev J. Bleidelis I. Plukse E. Gudriniece 《Journal of Structural Chemistry》1989,29(5):808-811
Riga Polytechnical Institute. Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 29, No. 5, pp. 169–172, September–October, 1988. 相似文献
175.
Belyakov AV Kieninger M Cachau RE Ventura ON Oberhammer H 《The journal of physical chemistry. A》2005,109(2):394-399
The geometric structure of 2,3,5,6-tetrafluoroanisole and the potential function for internal rotation around the C(sp2)-O bond were determined by gas electron diffraction (GED) and quantum chemical calculations. Analysis of the GED intensities with a static model resulted in near-perpendicular orientation of the O-CH3 bond relative to the benzene plane with a torsional angle around the C(sp2)-O bond of tau(C-O) = 67(15) degrees. With a dynamic model, a wide single-minimum potential for internal rotation around the C(sp2)-O bond with perpendicular orientation of the methoxy group [tau(C-O) = 90 degrees] and a barrier of 2.7 +/- 1.6 kcal/mol at planar orientation [tau(C-O) = 0 degrees] was derived. Calculated potential functions depend strongly on the computational method (HF, MP2, or B3LYP) and converge adequately only if large basis sets are used. The electronic energy curves show internal structure, with local minima appearing because of the interplay between electron delocalization, changes in the hybridization around the oxygen atom, and the attraction between the positively polarized hydrogen atoms in the methyl group and the fluorine atom at the ortho position. The internal structure of the electronic energy curves mostly disappears if zero-point energies and thermal corrections are added. The calculated free energy barrier at 298 K is 2.0 +/- 1.0 kcal/mol, in good agreement with the experimental determination. 相似文献
176.
D. Jansone S. Belyakov M. Fleisher L. Leite E. Lukevics 《Chemistry of Heterocyclic Compounds》2007,43(11):1374-1378
Single crystals of 4,6,6-trimethyl-2-oxo-5,6-dihydro-2H-pyran-3-carbonitrile and 4,6,6-trimethyl-2-oxo-1,2,5,6-tetrahydropyridine-3-carbonitrile
were prepared and submitted to X-ray diffraction analysis. Both compounds have a molecular structure belonging to the C1 symmetry group. The heterocyclic rings are in a distorted envelope conformation. The crystals belong to the monoclinic system
and each contain four molecules in the unit cell. In the crystal the pyridine derivative exists in the form of centrosymmetric
dimers stabilized by intermolecular hydrogen bonds between the oxygen atoms of the carbonyl group and the hydrogen atom at
the nitrogen atom of the ring.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1620–1624, November, 2007. 相似文献
177.
L.S. Khaikin A.V. Belyakov G.S. Koptev A.V. Golubinskii L.V. Vilkov N.V. Girbasova E.T. Bogoradovskii V.S. Zavgorodnii 《Journal of Molecular Structure》1980
The geometrical parameters of tris(trimethylstannyl)amine have been determined by gas-phase electron diffraction. The a structure has been refined using mean amplitude values calculated from the force fields of a number of tin derivatives.The experimental data are consistent with a planar bond configuration at the nitrogen in N(SnMe3)3. The final set of geometrical parameters is as follows (average bond distances, rg , in Å, angles in degrees): SnC 2.166(5), SnN 2.038(3), CH 1.117(17). NSnC 108.5(1.5), SnCH 112.1(1.6). Mean amplitude values have been varied for those distances which give considerable contributions to scattering.The results obtained fill a gap in the knowledge of structures of Group IV element μ-nitrido derivatives. They confirm the conclusion that lowering of ligand MRn electro-negativity weakens the tendency to deviation from planarity in the central fragment NM3. This tendency may be considered as a manifestation of the second-order Jahn-Teller effect. 相似文献
178.
A. V. Vasilyev S. V. Baranin P. A. Belyakov V. A. Dorokhov 《Russian Chemical Bulletin》2006,55(7):1220-1223
Reactions of alkyl 3-amino-5-aryl-2-benzoyl-2-oxopent-2-enoates with hydrazine were accompanied by debenzoylation and isomerization
to give 3-amino-5-aryl-5-oxopent-3-enohydrazides, which underwent cyclization in the presence of an excess of hydrazine into
5(3)-arylpyrazol-3(5)-ylacetohydrazides.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1175–1177, July, 2006. 相似文献
179.
K. Rubina E. Abele S. Belyakov I. Shestakova Yu. Popelis 《Russian Journal of Organic Chemistry》2006,42(5):735-738
A two-stage method was developed for the conversion of phenyl-and pyridylaldoximes and ketoximes into the corresponding O-[3-(5-tetrazolyl)propyl]oximes. The structure of the sodium salt of 2-acetylpyridine O-[3-(5-tetrazolyl)propyl]oxime was established X-ray diffraction analysis. This compound was shown to possess a high cytotoxic activity in vitro. 相似文献
180.
A. D. Dilman V. V. Gorokhov P. A. Belyakov M. I. Struchkova V. A. Tartakovsky 《Russian Chemical Bulletin》2007,56(8):1522-1525
A reaction of enamines with Me3SiCF3 and Me3SiC6F5 in the presence of carboxylic acids leading to α-CF3-and α-C6F5-substituted amines has been studied. 3-Cyanobenzoic acid was found to be the optimal promoter of these reactions.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1466–1468, August, 2007. 相似文献