全文获取类型
收费全文 | 211篇 |
免费 | 0篇 |
专业分类
化学 | 142篇 |
晶体学 | 2篇 |
数学 | 15篇 |
物理学 | 52篇 |
出版年
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 14篇 |
2012年 | 4篇 |
2011年 | 13篇 |
2010年 | 10篇 |
2009年 | 9篇 |
2008年 | 10篇 |
2007年 | 11篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 6篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有211条查询结果,搜索用时 0 毫秒
11.
Dr. Anton A. Anisimov Dr. Fedor V. Drozdov Yulia S. Vysochinskaya Ekaterina O. Minyaylo Prof. Alexander S. Peregudov Prof. Fedor M. Dolgushin Dr. Olga I. Shchegolikhina Prof. Aziz M. Muzafarov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11404-11407
This study presents the synthesis of organoboron derivatives of stereoregular 4-, 6-, and 12-unit phenylcyclosilsesquioxanes. All compounds obtained were isolated in good yields (70–80 %) and were fully characterized by 1H, 13C, 29Si, 11B NMR, IR spectroscopy, HRMS ESI, and elemental microanalysis. The structure of the key modifier, obtained for the first time, 4-(tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl) dimethylvinylsilane, was also confirmed by single-crystal XRD. 相似文献
12.
Furer VL Vandukova II Tatarinova EA Muzafarov AM Kovalenko VI 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(3):692-699
The FTIR spectra of G(3), G(4), and G(9) generations of polybutylcarbosilane dendrimers have been recorded and analyzed. The structural optimization and normal mode analysis were performed for G(1) generation on the basis of density functional theory (DFT). This calculation gave vibrational frequencies and infrared intensities for the t,t- and g,-g-conformers of the butyl terminal groups, attached to the same silicon atom. The g,-g-conformer is 5.83 kcal/mol less stable compared to t,t-conformer. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the studied dendrimers. The dependence of band full width at half height in the IR spectra on generation number is established. The IR spectra of carbosilane dendrimers at higher temperatures at the ambient air and isolated from atmosphere air were studied. At temperature 180 degrees C all studied carbosilane dendrimers are stable when contact with atmosphere is absent, in the air they oxidize and thus CO and SiO groups appear. 相似文献
13.
O. B. Gorbatsevich D. N. Kholodkov T. S. Kurkin Yu. N. Malakhova D. R. Strel’tsov A. I. Buzin V. V. Kazakova A. M. Muzafarov 《Russian Chemical Bulletin》2017,66(3):409-417
Methods for synthesis and optimum conditions of the formation of stable water-soluble silica nanoparticles are presented. The silica nanoparticles were synthesized by the hydrolytic polycondensation of tetraethoxysilane using two methods: under alkaline conditions (Stöber´s method) or in an acetic acid medium followed by the modification by grafting triethylene oxide moieties on the particle surface. The structure of the modified silica nanoparticles was confirmed by the data of IR and NMR spectroscopy. Polydispersity was evaluated by gel permeation chromatography and dynamic light scattering. The formation and stability of Langmuir monolayers of the silica nanoparticles modified by triethylene oxide moieties were studied. 相似文献
14.
Pavel A. Tikhonov Nataliya G. Vasilenko Marat O. Gallyamov Georgii V. Cherkaev Viktor G. Vasilev Nina V. Demchenko Mikhail I. Buzin Sergey G. Vasilev Aziz M. Muzafarov 《Molecules (Basel, Switzerland)》2021,26(11)
New multiarm stars have been synthesized based on polylithium derivatives of high-generation carbosilane dendrimers. In the synthesis of multiarm stars based on the eighth-generation dendrimer, steric hindrances were observed even during the synthesis of a polylithium initiator. Subsequently, this led to chain transfer reactions between growing arms, as well as other side effects. As a result, dense nanogel formations with a higher tendency of ordering than in classical objects of this type were isolated from the reaction mixture. The study of the rheology of multiarm stars based on sixth-generation dendrimers made it possible to determine the activation energies of viscous flow in these objects, which makes it possible to consider them as objects with a macromolecular nature and a reptation flow mechanism. 相似文献
15.
Yuriy N. Kononevich Ivan B. Meshkov Natalia V. Voronina Nikolay M. Surin Viacheslav A. Sazhnikov Andrei A. Safonov Alexander A. Bagaturyants Mikhail V. Alfimov Aziz M. Muzafarov 《Heteroatom Chemistry》2013,24(4):271-282
Alkoxysilyl derivatives of dibenzoylmethanatoboron difluoride (DBMBF2) are synthesized by the hydrosilylation reaction of the corresponding O‐allyl derivatives of DBMBF2 with triethoxysilane. The photophysical properties of the synthesized O‐allyl and alkoxysilyl derivatives are investigated. It is found that the absorption and fluorescence spectra of the DBMBF2 derivatives essentially depend on the position of the O‐allyl or O‐propyl alkoxysilyl substituent. The highest fluorescence quantum yield is obtained for the para‐position, whereas the substitution at the meta‐position gives the largest bathochromic shift in the fluorescence spectrum. Density functional theory calculations of the structures and time‐dependent density functional theory calculations of the gas‐phase excitation and emission energies of alkoxysilyl derivatives are performed at the PBE0/SVP level of theory. Some spectral features of para‐, ortho‐, and meta‐substituted derivatives can be adequately explained by the overlapping of two absorption bands. 相似文献
16.
M. V. Mironova E. A. Tatarinova I. B. Meshkov A. M. Muzafarov V. G. Kulichikhin 《Polymer Science Series A》2012,54(3):177-186
The rheological properties of MQ copolymer melts are investigated under steady-state shear flow and dynamic oscillatory shear
within a wide temperature range. The MQ copolymers are highly branched polycyclic compounds (densely crosslinked nanosized
networks) incapable of further intermolecular interactions. The samples have identical chemical compositions, but their detailed
molecular structures are different. The polymers under consideration show Newtonian behavior in a wide shear-stress range.
The values of viscosity vary considerably with the molecular structure of the copolymers. The generalized frequency dependence
of complex dynamic modulus components is constructed with the use of the temperature-frequency superposition method. In a
first approximation, the viscoelastic behavior of the materials is satisfactorily described by the Maxwell model with a single
relaxation time. In this respect, the studied materials are similar to micellar colloids. The relaxation spectra of the copolymers
distinguished by narrow distributions are calculated. 相似文献
17.
Aluminum and zinc phthalocyanines (AlPc and ZnPc, respectively) adsorbed on the surface of silica nanoparticles (60 nm in diameter) in aqueous solutions have been found to form H-aggregates, which possess characteristic absorption spectra with bands (having a maximum at 640 nm) in a shorter wavelength region with respect to the main Q-band of the monomer (having a maximum at 670 nm). For AlPc on the surface, J-aggregates of two types (long-wavelength bands with maximums at 740 and 770 nm) are also observed. Using nanosecond laser photolysis (with the excitation wavelength of 337 nm) in deoxygenated solutions of AlPc on the surface, the formation of the triplet electronically excited states of J-aggregates has been detected, which are characterized by a broad absorption spectrum in the region of 400–800 nm and a lifetime of 360 μs. No intermediate products have been detected during the photolysis of H-aggregates of ZnPc on the surface. 相似文献
18.
The enthalpies of combustion (ΔH
comb) of five primary, secondary, and tertiary alkyl(aryl)arsines in the condensed state were calculated using the equation ΔH
comb = −385.8–110.3N, where N is the number of bond-forming electrons. The dependence presented is used for the calculation of the enthalpies of combustion
of full esters and amidoesters of arsinous acid of noncyclic and cyclic structures.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1042–1043, May, 2007. 相似文献
19.
E. V. Agina N. I. Boiko R. M. Richardson B. I. Ostrovskii V. P. Shibaev E. A. Rebrov A. M. Muzafarov 《Polymer Science Series A》2007,49(4):412-424
Two series of carbosilane LC dendrimers with terminal protonated and deuterated butoxyphenylbenzoate mesogenic groups linked to carbosilane dendritic matrices of the first to fifth generations via an undecylene spacer have been synthesized. The chemical structure of new dendrimers has been studied by 1H NMR spectroscopy and gel-permeation chromatography. The dendrimers of first-fourth generations are characterized by formation of the smectic C mesophase in a wide temperature range, whereas much more complex columnar supramolecular structures are formed in dendrimers of the fifth generation. Structural studied of mesophases by X-ray diffraction and small-angle neutron scattering show that segregation takes place in mixtures of deuterated and protonated LC dendrimers; as a result, huge aggregates composed of hundreds of chemically unbound molecules develop and the sizes of these aggregates reversibly change with temperature. 相似文献
20.
The leading asymptotic term for the function that counts theeigenvalues of the Stokes operator is determined for fairlygeneral underlying bounded domains. Moreover, the remainderis estimated in terms of the fractality of the boundary of thedomain. The results obtained resemble corresponding ones forthe Dirichlet Laplacian. 1991 Mathematics Subject Classification:35P20. 相似文献