全文获取类型
收费全文 | 102篇 |
免费 | 3篇 |
专业分类
化学 | 58篇 |
数学 | 27篇 |
物理学 | 20篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 7篇 |
2014年 | 6篇 |
2013年 | 14篇 |
2012年 | 8篇 |
2011年 | 4篇 |
2010年 | 7篇 |
2009年 | 3篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有105条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
Albert Bruix Yaroslava Lykhach Iva Matolínov Armin Neitzel Tom Skla Nataliya Tsud Mykhailo Vorokhta Vitalii Stetsovych Klra ev
íkov Josef Myslive
ek Roman Fiala Michal Vclav Kevin C. Prince Stphanie Bruyre Valrie Potin Francesc Illas Vladimír Matolín Jrg Libuda Konstantin M. Neyman 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(39):10693-10698
85.
Marina Shelyapina Irina Zvereva Liliya Yafarova Dmitrii Bogdanov Stanislav Sukharzhevskii Yurii Zhukov Vitalii Petranovskii 《Journal of Thermal Analysis and Calorimetry》2018,131(1):71-79
The main work of this thesis is to study and discuss flame-retardant properties of the flexible polyurethane foam (FPUF) added with borax, expanded graphite (EG), and EG/Borax as flame retardant, respectively. The thermal behavior of samples has been using thermogravimetry (TG) and differential thermogravimetry in air. The activation energies for different stages of thermal degradation are obtained following the equation of Kissinger. The flammability parameters, including limiting oxygen index, rate of heat release, total heat release, yield of CO, yield of CO2, and smoke production rate, were recorded simultaneously. The char structure was studied by SEM, and their thermal stability and evolved gaseous products were examined by TG analysis–Fourier transform infrared spectroscopy. By analyzing these data, it was concluded that most combustion parameters of FPUF were decreased by the treatment, especially for EG/Borax treatment, which indicated a synergistic effect of flame retardancy. Meanwhile, the probable flame retardation mechanism was proposed. 相似文献
86.
Bohdan A. Chalyk Vitalii V. Izhyk Kyrylo Danyleiko Bohdan Sosunovych Bohdan V. Vashchenko Oleksandr Zginnyk Violetta Olshanska Dr. Peter Teodorovic Dr. Angelina V. Biitseva Prof. Dr. Dmitriy M. Volochnyuk Prof. Dr. Oleksandr O. Grygorenko 《European journal of organic chemistry》2023,26(22):e202300282
A highly efficient multigram synthesis of spirocyclic and fused isoxazoline building blocks is described. Isoxazoline-3-carboxylates were synthesized via a regioselective 1,3-dipolar cycloaddition reaction of 2-chloro-2-(hydroxyimino)acetate and carbo- or heterocyclic alkenes bearing endo- or exocyclic C=C double bonds, resulting in fused or spirocyclic isoxazolines, respectively. The preparation of up to 300 g of these compounds was achieved in a single run. The ester group of isoxazolines was then subjected to common synthetic transformations for the synthesis of corresponding building blocks, including alcohols, chlorides, azides, amines, aldehydes, carboxylic acids, amino acids and their derivatives, difluoromethyl-substituted compounds, and bicyclic γ-lactones. Additionally, a direct cycloaddition-based approach to the synthesis of aminoalkyl- and chloromethyl-substituted isoxazolines was proposed to improve their preparation. The described isoxazoline building blocks are expected to be valuable tools for drug discovery. 相似文献
87.
Kirill P. Birin Dmitry S. Dunin Maxim V. Tolstykh Vitalii Yu. Kotov 《Mendeleev Communications》2012,22(6):320-322
The heteroselective preferential solvation of the iodides of N-heterocyclic aromatic cations in acetone–chloroalkane (chloroform and dichloromethane) binary mixtures results in not only a shift in the maxima of outer-sphere charge transfer absorption bands but also a considerable decrease in the molar extinction coefficients of ion pairs. 相似文献
88.
Ghosh D Kosenkov D Vanovschi V Williams CF Herbert JM Gordon MS Schmidt MW Slipchenko LV Krylov AI 《The journal of physical chemistry. A》2010,114(48):12739-12754
The implementation of the effective fragment potential (EFP) method within the Q-CHEM electronic structure package is presented. The EFP method is used to study noncovalent π-π and hydrogen-bonding interactions in DNA strands. Since EFP is a computationally inexpensive alternative to high-level ab initio calculations, it is possible to go beyond the dimers of nucleic acid bases and to investigate the asymptotic behavior of different components of the total interaction energy. The calculations demonstrated that the dispersion energy is a leading component in π-stacked oligomers of all sizes. Exchange-repulsion energy also plays an important role. The contribution of polarization is small in these systems, whereas the magnitude of electrostatics varies. Pairwise fragment interactions (i.e., the sum of dimer binding energies) were found to be a good approximation for the oligomer energy. 相似文献
89.
90.
Ella Kh. Kazakova Alexander V. Prosvirkin Vitalii V. Yanilkin Roland Froehlich Wolf D. Habicher 《Journal of inclusion phenomena and macrocyclic chemistry》2003,47(3-4):149-153
The synthesis of rigid tube-shape structures from resorcin[4]arene unitscombined in the ``head-to-tail'' manner is described.Tetrabromomethylenecalix-[4]resorcinarene with all OH-groups connected viamethylene bridges was used as a starting material. Reaction withp-hydroxybenzaldehyde led to the tetraaldehyde derivative and the following condensation with resorcinol resulted in formation of a third aromatic rim. An electrochemical study comparing properties of both resorcin[4]arene and itstube-shaped analogs was performed. 相似文献