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51.
Shishkina SV Shishkin OV Desenko SM Leszczynski J 《The journal of physical chemistry. A》2008,112(30):7080-7089
The equilibrium geometry, ring-inversion pathway barriers for analogues of cyclohexene with an exocyclic double bond have been studied using the MP2/6-311 G(d,p) level of theory. The equilibrium conformation of the ring depends on conjugation between the endocyclic and exocyclic double bonds. Interactions between conjugated double bonds include the pi-pi conjugation and interactions between the lone pair of the heteroatom of the exocyclic double bond and the sigma-antibonding orbital of the endocyclic single bond. In the case of the tetrahydrocycles with double bonds separated by a methylene group the balance between the pi --> sigma* hyperconjugation interactions between the exocyclic double bond and the neighboring methylene group and the n --> sigma* interaction between the lone pair of the heteroatom and the sigma-antibonding orbitals of the C(sp(2))-C(sp(3)) bond determine the geometrical parameters of the ring. The character of the potential-energy surface around the saddle point depends on the position of the exocyclic double bond and the orientation of the hydrogen atom attached to the heteroatom of the V group of the periodic table in the tetrahydrocycles with double bonds separated by a methylene group. 相似文献
52.
Summary A new one-stage fast multicomponent synthesis of title compounds leads to products in 21–55% isolated yields under both conventional and microwave conditions. The primary amino group in the building blocks can be easily acylated by various usual electophilic agents that can be utilized in the synthesis of diverse heterocylic compounds libraries. 相似文献
53.
Sergey M. Desenko Victoria V. Lipson Oleg V. Shishkin Sergey A. Komykhov Valery D. Orlov Evgeny E. Lakin Valery P. Kuznetsov Herbert Meier 《Journal of heterocyclic chemistry》1999,36(1):205-208
The reaction of 3-amino-1,2,4-triazole ( 1 ) with substituted methyl cinnamates 2a-h leads selectively to the formation of 7-aryl-6,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidin-5(4H)-ones 3a-h . The structure eluci dation of the products is based on ir, 1H and 13C nmr measurements and X-ray diffraction. 相似文献
54.
DC magnetization, neutron depolarization and neutron diffraction (with both polarized and unpolarized neutrons) measurements
have been reported for the Co1.1−x
Zn
x
Ge0.1Fe1.2O1 spinels with x=0.5, 0.6 and 0.7. Neutron depolarization and neutron diffraction measurements confirm the presence of a long range ferrimagnetic
ordering of the local canted spins in these ferrite samples. The observed features of low field magnetization have been explained
under the framework of thermally activated domain wall movement of ferrimagnetic arrangement of local canted spins. An important
role of magnetic anisotropy (due to the presence of Co2+ ions) in establishing the magnetic ordering and domain kinetics in these ferrites has been observed. 相似文献
55.
56.
57.
Valentin A. Chebanov Sergey M. Desenko Oleg V. Shishkin Nadezhda N. Kolos Sergey A. Komykhov Valery D. Orlov Herbert Meier 《Journal of heterocyclic chemistry》2003,40(1):25-28
The tautomerism of 1,4‐diazepines fused with pyrimidine rings was studied by means of nmr spec‐troscopy, X‐ray analysis and quantum chemical calculations. It was found that in the case of 6,8‐diphenyl‐pyrimido[4,5‐b][1,4]diazepin‐4‐ols (7a ‐ e) the enamine form is more stable than the diimine form. This result is rationalized with the electron‐withdrawing effect of the 4‐hydroxypyrimidine ring and with the formation of intermolecular hydrogen bonds. In contrast to 7a ‐ e , the 6,8‐diaryl‐2,3,4,7‐tetrahydro‐1,3‐dimethyl‐1H‐pyrimido[4,5‐b][1,4]diazepine‐2,4‐diones (9a, c, f) exist in the diimine form. 相似文献
58.
S. M. Desenko V. D. Orlov O. V. Shishkin K. É. Barykin S. V. Lindeman Yu. T. Struchkov 《Chemistry of Heterocyclic Compounds》1993,29(10):1163-1168
The reaction of 3-amino-1,2,4-triazole with -dimethylaminopropiophenones or unsaturated ketones gives 5,7-disubstituted 4,7(6,7)-dihydro-1,2,4-triazolo[1,5-a]pyrimidines. An increase in the bulk of the substituent at C(7) in the bicyclic system leads to relative stabilization of the enamine tautomer of these compounds. An x-ray diffraction structural analysis of 7-tert-butyl-5-(4-methoxyphenyl)-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine showed that the introduction of a tert-butyl group into the dihydropyrimidine ring leads to significant loss of planarity of this system.For Communication 4, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1357–1363, October, 1993. 相似文献
59.
A. I. Zbruyev F. G. Yaremenko V. A. Chebanov S. M. Desenko O. V. Shishkin E. V. Lukinova I. V. Knyazeva 《Russian Chemical Bulletin》2006,55(2):362-368
New derivatives of photochromic 2-aryl-1-(4-nitrophenyl)-1,1a-dihydroazireno[1,2-a]quinoxalines were synthesized by condensation of 4-methyl-and 4,5-dimethyl-1,2-phenylenediamine with 1,3-diaryl-2,3-dibromopropan-1-ones.
The reactions of 4-methyl-1,2-phenylenediamine produce mixtures of regioisomers. The chemical properties of the reaction products
were studied. The structure of one of the latter was established by X-ray diffraction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 350–356, February, 2006. 相似文献
60.
V. D. Orlov S. M. Desenko K. A. Potekhin Yu. T. Struchkov 《Chemistry of Heterocyclic Compounds》1988,24(2):192-196
Dihydro-1,2,4-triazolo[1,5-a]pyrimidine derivatives were obtained by condensation of 3-amino-1,2,4-triazole with 1,3-diaryl-1-propen-3-ones. The structure of 5-phenyl-7-(4-methylphenyl)-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine was established by x-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 229–233, February, 1988. 相似文献