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排序方式: 共有88条查询结果,搜索用时 15 毫秒
31.
A. I. Kazakov I. L. Dalinger I. N. Zyuzin D. B. Lempert N. A. Plishkin A. B. Sheremetev 《Russian Chemical Bulletin》2016,65(12):2783-2788
The standard enthalpies of combustion and formation for isomeric polynitropyrazoles, viz., 3,4- and 3,5-dinitro-1-trinitromethyl-1Н-pyrazoles, were measured by combustion calorimetry in an oxygen atmosphere. The enthalpies of formation for the 3,4-dinitro isomer by 19.7 kJ mol–1 exceeds the corresponding parameter for the 3,5-isomer. 相似文献
32.
In this paper, electrical and structural properties of mono-, di-, tri- and tetrachlorothiophenes and their radical cations
have been studied using the density functional theory and B3LYP method with 6-311++G** basis set. The effects of the number
and position of the substituent of chlorine atoms on the properties of the thiophene ring for all chlorothiophenes and their
radical cations have been studied. Vibrational frequencies, nuclear chemical shielding constants, spin-density distribution,
size and direction of dipole moment vector, ionization potential, electric polarizabilities and NICS values of these compounds
have been calculated as well. The analysis of these data showed that double bonds in 3-chlorothiophene are more delocalized
and it is the best possible candidate monomer among all chlorothiophenes for the synthesis of corresponding conducting polymers
with modified characteristics. 相似文献
33.
I. L. Dalinger I. A. Vatsadze T. K. Shkineva G. P. Popova S. A. Shevelev 《Russian Chemical Bulletin》2012,61(2):464-466
1-Methoxymethyl-3,4,5-trinitropyrazole, synthesized from 3,4,5-trinitropyrazole by the action of methoxymethyl chloride, was involved into the nucleophilic substitution reaction with N-nucleophiles (aliphatic amines, hydrazine derivatives). The reaction was effected regioselectively with substitution of the nitro group at position 5 in good yields. The thus obtained 5-R-substituted compounds under acid hydrolysis conditions give N-unsubstituted 5-R-3,4-dinitropyrazoles. 相似文献
34.
I. A. Vatsadze I. L. Dalinger T. K. Shkineva G. P. Popova S. A. Shevelev 《Russian Chemical Bulletin》2012,61(2):469-471
3,5-Dinitro-4-(phenylsulfonyl)pyrazole (5) obtained by oxidation of 3,5-dinitro-4-(phenylthio)pyrazole with 30% H2O2 in AcOH was involved into nucleophilic substitution reaction with thiophenol, which proceeded with substitution of the phenylsulfonyl group at position 4. N-Methyl-3,5-dinitro-4-(phenylsulfonyl)pyrazole obtained by methylation of 5 with dimethyl sulfate was involved into nucleophilic substitution reaction with thiophenol, p-bromophenol, and morpholine with the regioselective substitution of the nitro group at position 5 to form 5-R-3-nitro-4-(phenylsulfonyl)pyrazoles. 相似文献
35.
Liquid-phase synthesis of combinatorial libraries based on 7-trifluoromethyl-substituted pyrazolo[1,5-a]pyrimidine scaffold 总被引:1,自引:0,他引:1
Dalinger IL Vatsadse IA Shevelev SA Ivachtchenko AV 《Journal of combinatorial chemistry》2005,7(2):236-245
The parallel solution-phase synthesis of more than 2200 7-trifluoromethyl-substituted pyrazolo[1,5-a]pyrimidine and 4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidine carboxamides on a 50-100-mg scale has been accomplished. Key reactions include assembly of the pyrazolo[1,5-a]pyrimidine ring by condensation of 5-aminopyrazole derivatives with the corresponding trifluoromethyl-beta-diketones. The libraries from libraries were then obtained in good yields and purities using solution-phase acylation and reduction methodologies. Simple manual techniques for parallel reactions using special CombiSyn synthesizers were coupled with easy purification procedures (crystallization from the reaction mixtures) to give high-purity final products. The scope and limitations of the developed approach are discussed. 相似文献
36.
A. A. Zaitsev I. L. Dalinger A. M. Starosotnikov V. V. Kachala Yu. A. Strelenko T. K. Shkineva S. A. Shevelev 《Russian Journal of Organic Chemistry》2005,41(10):1507-1515
A preparative procedure for the synthesis of 1,4-dimethyl-3,5-dinitropyrazole by nitration of 1,4-dimethylpyrazole was developed. The reaction of 1,4-dimethyl-3,5-dinitropyrazole with dimethoxymethyl- (dimethyl)amine (N,N-dimethylformamide dimethyl acetal) gave (E)-N,N-dimethyl-2-(1-methyl-3,5-dinitropyrazol- 4-yl)ethenylamine. Acid hydrolysis of the latter afforded (1-methyl-3,5-dinitropyrazol-4-yl)acetaldehyde, and the reaction with sodium nitrite in hydrochloric acid led to formation of 2-hydroxymino-2-(1-methyl- 3,5-dinitropyrazol-4-yl)acetaldehyde. The corresponding O-methyloxime and phenylhydrazone reacted with K2CO3 to give 6-methyl-4-nitropyrazolo[4,3-d]isoxazole-3-carbaldehyde O-methyloxime and 1-methyl-3-nitro-4-(2-phenyl-2H-1,2,3-triazol-4-yl)pyrazol-5-ol, respectively. Treatment of (1-methyl-3,5-dinitropyrazol-4-yl)-acetaldehyde with benzenediazonium chloride gave (1-methyl-3,5-dinitropyrazol-4-yl)acetaldehyde phenylhydrazone which underwent intramolecular cyclization with replacement of the 5-nitro group by the action of K2CO3 in acetonitrile; in the reaction with K2CO3 in ethanol, the 5-nitro group was replaced by ethoxy. 相似文献
37.
B. I. Ugrak V. M. Vinogradov I. L. Dalinger S. A. Shevelev 《Russian Chemical Bulletin》1995,44(11):2087-2092
The structures of substitutedN-aminonitropyrazoles and 1- and 2-amino-4-nitro-1,2,3-triazoles as well as the site of protonation of 1-aminopyrazole were determined based on the1H,13C, and15N (14N) NMR spectra. The13C NMR spectra were recorded under conditions of13C-{1H,14N} triple resonance. Effects of substituents in the pyrazole ring on the13C and14N chemical shifts were studied. The13C,1H and15N,1H spin-spin coupling constants, obtained using techniques of [1H]13C and [1H]15N polarization transfer (SPT, INEPT), were measured, fully assigned, and discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2181–2186, November, 1995.For Part 8, see Ref. 1. 相似文献
38.
Yonglin Xu Ted Belytschko Dept. of Civil Engineering Northwestern University Evanston IL U. S. A 《Acta Mechanica Solida Sinica》1996,9(2):104-123
The Self-Similar Crack Expansion (SSCE) method is proposed to evaluate stress intensi-ty factors at crack tips, whereby stress intensity factors of a crack can be determined by the crackopening displacement over the crack, not just by the local displacement around the crack tip. The crackexpansion rate is estimated by taking advantage of the crack self-similarity. Therefore, the accuracy ofthe calculation is improved. The singular integrals on crack tip elements are also analyzed and are pre-cisely evaluated in terms of a special integral analysis. Combination of these two techniques greatly in-creases the accuracy in estimating the stress distribution around the crack tip. A variety of two-dimen-sional cracks, such as subsurface cracks, edge cracks, and their interactions are calculated in terms ofthe self-similar expansion rate. Solutions are satisfied with errors less than 0.5% as compared with theanalytical solutions. Based on the calculations of the crack interactions, a theory for crack interactionsis proposed such that for a group of aligned cracks the summation of the square of SIFs at the right tipsof cracks is always equal to that at the left tips of cracks. This theory was proved by the mehtod ofSelf-Similar Crack Expansion in this paper. 相似文献
39.
Prof. Igor L. Dalinger Dr. Aleksandr V. Kormanov Dr. Kyrill Yu. Suponitsky Dr. Nikita V. Muravyev Prof. Aleksei B. Sheremetev 《化学:亚洲杂志》2018,13(9):1165-1172
High‐nitrogen‐content compounds have attracted great scientific interest and technological importance because of their unique energy content, and they find diverse applications in many fields of science and technology. Understanding of structure–property relationship trends and how to modify them is of paramount importance for their further improvement. Herein, the installation of oxygen‐rich modules, C(NO2)3, C(NO2)2F, or C(NO2)2NF2, into an endothermic framework, that is, the combination of a nitropyrazole unit and tetrazole ring, is used as a way to design novel energetic compounds. Density, oxygen balance, and enthalpy of formation are enhanced by the presence of these oxygen‐containing units. The structures of all compounds were confirmed by XRD. For crystal packing analysis, it is proposed to use new criterion, ΔOED, that can serve as a measure of the tightness of molecular packing upon crystal formation. Overall, the materials show promising detonation and propulsion parameters. 相似文献
40.
Shakhnes A. Kh. Dalinger I. L. Shashkov A. S. Chernoburova E. I. Shchetinina M. A. Zavarzin I. V. 《Russian Chemical Bulletin》2018,67(10):1920-1926
Russian Chemical Bulletin - Chemoselective methods for O- and N-nitration of steroids fused to the pyrazole ring were developed. The nitrating agents were acetyl, propionyl, and trifluoroacetyl... 相似文献