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A lanthanum(III) complex of catechin has been synthesized and characterized by elemental analysis, molar conductance, UV-Vis spectra, infrared spectra, thermal analysis, and 1H NMR. The complex behaves as a nonelectrolyte in methanol solvent. The spectral and thermal properties of the complex are examined. A thermogravimetric (TGA) study showed the hydrated nature of the complex. 1H NMR spectra of the lanthanum and the catechin (CT) ligands measured in CD3OD-d4 also show metal ligand coordination. The lanthanum–catechin complex shows bright luminescence in methanol solution. The interaction of the complex with calf thymus DNA has been investigated by absorption and emission spectroscopic measurements. Experimental spectral results suggest CT–DNA binding with catechin complex via an intercalative mode. 相似文献
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Martin Hölzl Alexander Jarosik Karl Grubmayr 《Monatshefte für Chemie / Chemical Monthly》2005,136(5):747-754
Summary. Two different types of conformational changes of the biliverdin chromophore were accomplished by the concept of reducing sterical hindrance. On one hand, model compounds unsubstituted at position 7 and/or 13 adopt the semi-extended geometry with anti-conformation of the dipyrrinone moiety. On the other hand, stretching of the chromophore with anti-conformation of the dipyrrin substructure was achieved with a model compound unsubstituted at position 12. Both kinds of anti-conformations have been proved by 2D NMR and UV-Vis spectroscopy.Current address: Voestalpine Stahl GmbH, Voest-Alpine-Straße 1, A-4020 Linz, Austria 相似文献
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以共轭聚合物MEH—PPV和DD—PPV为研究对象,利用UV—Vis吸收光谱和荧光光谱,研究了它们在不同溶剂中及固体膜状态下的发光性质,探索了聚合物的微观结构与其发光性能之间的关系。结果表明。由于聚合物在固体膜状态下较溶液状态有紧密的排列,因此其UV—Vis吸收光谱和荧光光谱与溶液相比发生了较大的红移;相同主链的聚合物,侧链取代基的电负性减弱,可使UV—Vis吸收光谱和荧光光谱发生蓝移;在混合溶剂中,由于每种溶剂对聚合物的溶解能力不同,而使两种构象共存于溶液中,因此在不同配比的混合溶剂中,聚合物的吸收光谱发生相应的变化。 相似文献
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This research studied optical and structural properties of SrO-Nb2O5-P2O5 glasses containing 0 ~ 25 mol% Nb2O5 and 35 ~ 60 mol% SrO using spectra of UV-Vis, FTIR and XPS. Our aim was to work new moldable glasses which are colorless with high refractive index and transmittance, and their correlation with glass structure. Nb2O5 plays the role as an intermediate of glass formation, and transforms the role to network-former or glass-modifier depending on composition. Refractive index increases monotonically with Nb2O5 content at the expense of transmittance, and specific coloring which occurs in ternary compositions with the ratio P2O5/SrO > 1. This effect arises from much increased [Nb3+ and Nb4+] fraction, as quantitatively deconvoluted in Nb3d XPS spectra, in the ligand [NbO6]octahedral which is supported by FTIR and O1s XPS spectra. As the ratio P2O5/SrO ≤ 1, Nb2O5 is more of a network former and [NbO6]octahedral structure turns into [NbO4]tetrahedron with partial Nb-O…(Sr) bonding turns into (Nb-O-Nb)tetrahedron, coloring disappears. 相似文献
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A systematically varied series of tetrahedral iridium clusters have been studied using a TDDFT method focusing on their electronic and nonlinear optical properties. The clusters W2Ir2(CO)10(η5-C5H4Me)2 (1), WIr3(μ-dppe)(CO)9(η5-C5H4Me (2), W2Ir2(μ-L)(CO)8(η5-C5H4Me)2(L = dppe 3, dppf 4), Ir4(μ-L)(CO)10(L = dppm 5, dppe 6, Ph2P(CH2)3PPh2 7, Ph2P(CH2)4PPh2 8, (Ph2P)2CHMe 9), Ir4(CO)10(phen)(phen = 1,10-phenanthroline) (10) exhibit the first static hyperpolarizabilities of medium magnitude (β tot ~ 10 × 10?30esu). The origination of β is discussed in terms of the electronic structure calculation and the expanded orbital decomposition scheme. The result suggests the origination of β for all the clusters are mainly d–d electron transitions intra metal skeleton, and d–π* electron transitions from metals to carbonyls. For cluster 5, which contains the ferrocenyl group, the main origination of β involves charge transfer from d orbitals of ferrocene to d orbirals of Ir and W. 相似文献
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ABSTRACT Revealing molecular alterations induced on kiwifruit under UV-Vis irradiation requires a discussion of biochemical-cell infrared (IR) fingerprint (900 cm?1–1800 cm?1) bands characteristic of nucleic acids. FTIR-ATR spectroscopy and statistics and nondestructive methods for screening exposure effects induced by irradiation were used. There the irradiation influence on the main molecular bonds (i.e., ν(C-C), νs(PO2?) and νas(PO2?)) can be observed. Regression methods were used for statistical investigations. Two categories of variables were used: the absorbance measured at fixed wavenumber variables and the exposure dose. The bivariate correlations, partial correlations, and polynomial regression methods from SPSS were used for statistical investigations. The obtained results show that FTIR-ATR, in correlation with statistics techniques, might be useful to assess immediate radiation and oxidative-induced damage to nucleic acids. In this case IR spectroscopy can be used successfully to study conformational changes during DNA reversible denaturation especially on the sugar-phosphate vibrations domain. 相似文献