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排序方式: 共有105条查询结果,搜索用时 15 毫秒
41.
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
42.
The relative kinetics method was used to study the cotelomerization of ethylene and propylene by methyl chloroacetate. The rate constant for the addition of the electrophilic CCl2CO2CH3
radical to ethylene is less than the rate constant for the addition of this radical to propylene by a factor of 2.3. This discrepancy reflects the difference in the polar properties of the monomers.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2366–2368, October, 1989. 相似文献
43.
44.
I. A. Ikonnikov T. V. Voskoboinikov A. Yu. Loginov 《Reaction Kinetics and Catalysis Letters》1996,57(1):93-97
XPS spectra in the Ols range of binding energy demonstrate a steady decline of concentration of surface carbonate groups as Mn loading in Mn/Y2O3 oxide catalysts increases from 0 to 50 at.%. 相似文献
45.
Belokon Yu. N. Maleev V. I. Petrosyan A. A. Savel"eva T. F. Ikonnikov N. S. Peregudov A. S. Khrustalev V. N. Saghiyan A. S. 《Russian Chemical Bulletin》2002,51(8):1593-1599
The synthesis of new chiral auxiliaries (S)-N-(2-benzoylphenyl)-1-(3,4-dichlorobenzyl)-pyrrolidine-2-carboxamide (1a), (S)-N-(2-benzoylphenyl)-1-(pentafluorobenzyl)pyrrolidine-2-carboxamide (1b), and (S)-N-(2-benzoylphenyl)-1-(4-isopropoxytetrafluorobenzyl)pyrrolidine-2-carboxamide (1c) and their application in the asymmetric synthesis of amino acids using NiII complexes of their Schiff"s bases with alanine and glycine are described. Compound 1a is particularly appropriate for highly stereoselective synthesis of -methyl--amino acids with high enatiomeric purity (ee >95%). 相似文献
46.
Belokon" Yu. N. Maleev V. I. Savel"eva T. F. Ikonnikov N. S. 《Russian Chemical Bulletin》2001,50(6):1037-1040
Both enantiomers of -methylserine were synthesized with the use of NiII complexes based on the chiral recyclable reagent (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide. Intermediate diastereomeric complexes were separated by crystallization of their O-acetyl derivatives. 相似文献
47.
Yu. N. Belokon' K. A. Kochetkov T. D. Churkina A. A. Chesnokov V. V. Smirnov N. S. Ikonnikov S. A. Orlova 《Russian Chemical Bulletin》1998,47(1):74-81
Some chiral sodium alkoxides can be used as catalysts in the asymmetric Michael reaction as exemplified by the 1,4-addition of an achiral NiII complex of the Schiff base derived from glycine andN-(2-pyridylcarbonyl)-o-aminobenzophenone (1) to methyl methacrylate (2) or methyl acrylate (14). The products of the reaction of1 with2,viz., the corresponding diastereomeric complexes of 4-methylglutamic acid, are formed in dissimilar amounts (de 26–85%); theee value for the major diastereomer (2S,4R)-3a is 28%. After recrystallization, the enantiomeric purity of complex3a increases toee>85%. Acidcatalyzed hydrolysis of the enantiomerically enriched complex3a affords (2S,4R)-4-methylglutamic acid (ee>85%). The complex of glutamic acid15 resulting from the reaction of1 with14 is formed with anee of 45%. After recrystallization, the enantiomeric purities of complex15 and glutamic acid increase toee>90%. 相似文献
48.
Belokon YN Gutnov AV Moskalenko MA Yashkina LV Lesovoy DE Ikonnikov NS Larichev VS North M 《Chemical communications (Cambridge, England)》2002,(3):244-245
A (salen)titanium catalyst has been found to induce the asymmetric addition of potassium cyanide and acetic anhydride to aldehydes, giving enantiomerically enriched cyanohydrin esters with up to 92% enantiomeric excess using just 1 mol% of the catalyst. This is the first report of the asymmetric synthesis of cyanohydrin derivatives using a cyanide source which is non-volatile and inexpensive. 相似文献
49.
Alexey N. Bilyachenko Mikhail M. Levitsky Alexey I. Yalymov Alexander A. Korlyukov Viktor N. Khrustalev Anna V. Vologzhanina Lidia S. Shul'pina Nikolay S. Ikonnikov Alexander E. Trigub Pavel V. Dorovatovskii Xavier Bantreil Frdric Lamaty Jrme Long Joulia Larionova Igor E. Golub Elena S. Shubina Georgiy B. Shul'pin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(49):15586-15589
A series of four unprecedented heterometallic metallagermsesquioxanes were synthesized. Their cage‐like architectures have a unique type of molecular topology consisting of the hexairon oxo {Fe6O19} core surrounded in a triangular manner by three cyclic germoxanolates [PhGe(O)O]5. This structural organization induces antiferromagnetic interactions between the FeIII ions through the oxygen atoms. Evaluated for this first time in catalysis, these compounds showed a high catalytic activity in the oxidation of alkanes and the oxidative formation of benzamides from alcohols. 相似文献
50.