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71.
Svetlana A. Popova Evgenia V. Pavlova Oksana G. Shevchenko Irina Yu. Chukicheva Aleksandr V. Kutchin 《Molecules (Basel, Switzerland)》2021,26(12)
The pyrazoline ring is defined as a “privileged structure” in medicinal chemistry. A variety of pharmacological properties of pyrazolines is associated with the nature and position of various substituents, which is especially evident in diarylpyrazolines. Compounds with a chalcone fragment show a wide range of biological properties as well as high reactivity which is primarily due to the presence of an α, β-unsaturated carbonyl system. At the same time, bicyclic monoterpenoids deserve special attention as a source of a key structural block or as one of the pharmacophore components of biologically active molecules. A series of new diarylpyrazoline derivatives based on isobornylchalcones with different substitutes (MeO, Hal, NO2, N(Me)2) was synthesized. Antioxidant properties of the obtained compounds were comparatively evaluated using in vitro model Fe2+/ascorbate-initiated lipid peroxidation in the substrate containing brain lipids of laboratory mice. It was demonstrated that the combination of the electron-donating group in the para-position of ring B and OH-group in the ring A in the structure of chalcone fragment provides significant antioxidant activity of synthesized diarylpyrazoline derivatives. 相似文献
72.
Cervenakova L Brown P Soukharev S Yakovleva O Diringer H Saenko EL Drohan WN 《Electrophoresis》2003,24(5):853-859
The emergence of a new environmentally caused variant of Creutzfeldt-Jakob disease (vCJD), the result of food-born infection by the causative agent of bovine spongiform encephalopathy (BSE), has stimulated research on a practical diagnostic screening test. The immunocompetitive capillary electrophoresis (ICCE) assay has been reported to detect disease-specific, proteinase-resistant prion protein (PrPres) in the blood of scrapie-infected sheep. We have applied this method to blood from CJD-infected chimpanzees and humans. The threshold of detection achieved with our ICCE was 0.6 nM of synthetic peptide corresponding to the prion protein (PrP) C-terminus, and 2 nM of recombinant human PrP at the optimized conditions. However, the test was unable to distinguish between extracts of leucocytes from healthy and CJD-infected chimpanzees, and from healthy human donors and patients affected with various forms of CJD. Thus, the ICCE assay as presently performed is not suitable for use as a screening test in human transmissible spongiform encephalopathies (TSEs). 相似文献
73.
Coppens P Gerlits O Vorontsov II Kovalevsky AY Chen YS Graber T Gembicky M Novozhilova IV 《Chemical communications (Cambridge, England)》2004,(19):2144-2145
A very large Rh-Rh contraction of approximately 0.85 A occurs on excitation of the [Rh(2)(1,8-diisocyano-p-menthane)(4)](2+) ion to its triplet state. 相似文献
74.
We employed four newly developed density functional theory (DFT) methods for the calculation of five pi hydrogen bonding systems, namely, H2O-C6H6, NH3-C6H6, HCl-C6H6, H2O-indole, and H2O-methylindole. We report new coupled cluster calculations for HCl-C6H6 that support the experimental results of Gotch and Zwier. Using the best available theoretical and experimental results for all five systems, our calculations show that the recently proposed MPW1B95, MPWB1K, PW6B95, and PWB6K methods give accurate energetic and geometrical predictions for pi hydrogen bonding interactions, for which B3LYP fails and PW91 is less accurate. We recommend the most recent DFT method, PWB6K, for investigating larger pi hydrogen bonded systems, such as those that occur in molecular recognition, protein folding, and crystal packing. 相似文献
75.
Eugene S. Kryachko Oksana Tishchenko Minh Tho Nguyen 《International journal of quantum chemistry》2002,89(4):329-340
We treat the present work as an attempt to elucidate the mechanism of the oxidation reaction of the Cu atom by nitrous oxide based on our recent work (Kryachko, E. S.; Vinckier, C.; Nguyen, M. T. J Chem Phys 2001, 114, 7911) on the electron attachment to this molecule. We suggest that the title reaction in its Arrhenius regime occurs via the nonadiabatic electron transfer from Cu to the oxygen atom at the crossing of the potential energy surfaces Cu(4s 2S1/2) + N2O(X 1Σ+) and Cu+ + N2O?, where the latter is linked to the complex N2O? originated from the higher‐energy T‐shape N2O molecule and discovered in the aforementioned work. The calculations performed in the present work using a variety of quantum chemical methods support the proposed model. We also show the existence of other reaction pathways of the title reaction that, we believe, contribute to its non‐Arrhenius behavior observed experimentally at T > 1190 K. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 相似文献
76.
Marek Pietraszkiewicz Andrzej Kłonkowski Krzysztof Staniszewski Jerzy Karpiuk Sławomir Bianketti Oksana Pietraszkiewicz 《Journal of inclusion phenomena and macrocyclic chemistry》2004,48(1-2):61-67
Helical molecular assemblies of bile acids and their derivatives were systematically investigated. These molecules have a common asymmetric structure with three different directions, and form characteristic inclusion crystals with the following hierarchical structure. First, such molecules arrange along their helical axes to yield the helical tapes with a definite direction. Second, the helical tapes are combined in a parallel fashion by using their side-chains through hydrogen bonds to produce chiral sheets. Third, the sheets stack together through van der Waals forces in a parallel or antiparallel fashion. Fourth, there exist chiral spaces for including guests among their sheets. Such hierarchical structure enables us to explain a role of the side-chains with different hydrogen bonding groups and length. 相似文献
77.
Vitaliy Smokal Oksana Kharchenko Yuriy Karabets Andrii Kysil Oksana Krupka 《Molecular Crystals and Liquid Crystals》2018,672(1):11-17
ABSTRACTIn this work we report preliminary results obtained for methacrylic polymers incorporating aurone side-group as photochemical active molecule. The aurone polymers were obtained by a three-step synthetic approach: (2Z)-6-hydroxy-2-(4-R-benzyliden)-1-benzofuran-3(2H)-ones were synthesized by using condensation reation of 6-hydroxybenzofuran-3-one with benzaldehydes; then methacrylate monomers were synthesized by reaction the alcohols with methacryloyl chloride; and the polymers were synthesized by free radical polymerization. Polymers were characterized by 1HNMR spectroscopy and DSC techniques. Their physicochemical properties are determined by absorption, fluorescence excitation and emission spectroscopies. 相似文献
78.
Natalija van Well Sitaram Ramakrishnan Ketty Beauvois Navid Qureshi Eric Ressouche Markos Skoulatos Robert Georgii Oksana Zaharko Sander van Smaalen 《Annalen der Physik》2020,532(7):2000147
The triangular antiferromagnetic Cs2CuCl4-xBrx mixed system is studied by neutron single-crystal diffraction in magnetic field. It shows a rich magnetic phase diagram consisting of four regimes depending on the Br concentration and is characterized by different exchange coupling mechanisms. For the investigated compositions from regime I (0 < x ≤ 1.5), a critical magnetic field Bc is found for a Br concentration x = 0.8 at Bc = 8.10(1) T and for x = 1.1 at Bc = 7.73(1) T and from regime IV (3.2 < x < 4) for x = 3.3 at Bc = 0.99(3) T. For magnetic fields larger than the respective Bc, magnetic superlattice reflections of these compounds are not found. The incommensurate magnetic wave vector q = (0, 0.470, 0) appears below the ordering temperature TN = 0.51(1) K for Cs2CuCl3.2Br0.8, and q = (0, 0.418, 0) below TN = 1.00(6) K for Cs2CuCl0.3Br3.7. Neutron diffraction experiments at around 60 mK for x = 3.7 in a magnetic field show the critical magnetic field at Bc = 7.94(16) T and the formation of the second magnetic phase at around 8.5 T depending on the temperature. Inelastic neutron scattering experiments for the compound from regime III (2 < x ≤ 3.2) with x = 2.2 show dynamical correlations at a temperature around 50 mK giving evidence for a spin liquid phase. 相似文献
79.
A new modification of the the Lie‐algebraic scheme for solving partial differential equations with initial and boundary conditions based on constructing quasirepresentations of the Heisenberg‐Weyl algebra operators involving boundary conditions is proposed. Approximation errors for the modified scheme are evaluated. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
80.
Volodymyr Pavlyuk Pavlo Solokha Oksana Zelinska Valerie Paul‐Boncour Anna Nowik‐Zajc 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(7):i50-i52
Icosacerium nonadecamagnesium henoctacontazinc, Ce20Mg19Zn81, synthesized by fritting of the pure elements with subsequent arc melting, crystallizes with an unusually large cubic unit cell [space group F3m, a = 21.1979 (8) Å] and represents a new structure type among the technologically important family of ternary rare earth–transition metal–magnesium intermetallics. The majority of atoms (two Ce and five Zn) display .3m site symmetry, two Ce and one Mg atom occupy three 2.mm positions, one Mg and one Zn have 3m site symmetry, one Mg and three Zn atoms sit in ..m positions, and one Zn atom is in a general position. The Ce20Mg19Zn81 structure can be described using the geometric concept of nested polyhedral units, by which it consists of four different polyhedral units, viz.A (Zn+Zn4+Zn4+Zn12+Ce6), B (Mg+Zn12+Ce4+Zn24+Ce4), C (Zn4+Zn12+Mg6) and D (Zn4+Zn4+Mg12+Ce6), with the outer construction unit being an octahedron or tetrahedron. All interatomic distances in the structure indicate metallic‐type bonding. 相似文献