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1.
A new spectrophotometric method for microgram amounts of scandium with indoferron is described. The molar absorptivity is 960 l.mole−1.mm−1 at 600 nm. Uranium and the rare earths do not interfere, if present in amounts less than 50 μg. Scandium in silicate rocks can be determined by the procedure after separation of the scandium by a three-stage ion-exchange Chromatographic technique. The acid dissociation constants of indoferron and conditional formation constants of the 1:2 complex have been determined spectrophotometrically. 相似文献
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Chiral resolution of native DL-tartaric acid was achieved by ion-pair capillary electrophoresis (CE) using an aqueous-ethanol background electrolyte with (1R,2R)-(-)-1,2-diaminocyclohexane (R-DACH) as a chiral counterion. Factors affecting chiral resolution and migration time of tartaric acid were studied. By increasing the viscosity of the background electrolyte and the ion-pair formation, using organic solvents with a lower relative dielectric constant, resulted in a longer migration time. The optimum conditions for both high resolution and short migration time of tartaric acid were found to be a mixture of 65% v/v ethanol and 35% v/v aqueous solution containing 30 mM R-DACH and 75 mM phosphoric acid (pH 5.1) with an applied voltage of -30 kV at 25 degrees C, using direct detection at 200 nm. By using this system, the resolution (Rs) of racemic tartaric acid was approximately 1. The electrophoretic patterns of tartaric and malic acids suggest that two carboxyl groups and two hydroxyl groups of tartaric acid are associated with the enantioseparation of tartaric acid by the proposed CE method. 相似文献
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Dr. Takeshi Matsumoto Risa Yamamoto Dr. Masanori Wakizaka Dr. Akinobu Nakada Prof. Dr. Ho-Chol Chang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(43):9609-9619
The global demand for energy and the concerns over climate issues renders the development of alternative renewable energy sources such as hydrogen (H2) important. A high-spin (hs) FeII complex with o-phenylenediamine (opda) ligands, [FeII(opda)3]2+ (hs- [6R] 2+), was reported showing photochemical H2 evolution. In addition, a low-spin (ls) [FeII(bqdi)3]2+ (bqdi: o-benzoquinodiimine) (ls- [0R] 2+) formation by O2 oxidation of hs- [6R] 2+, accompanied by ligand-based six-proton and six-electron transfer, revealed the potential of the complex with redox-active ligands as a novel multiple-proton and -electron storage material, albeit that the mechanism has not yet been understood. This paper reports that the oxidized ls- [0R] [PF6]2 can be reduced by hydrazine giving ls-[FeII(opda)(bqdi)2][PF6]2 (ls- [2R] [PF6]2) and ls-[FeII(opda)2(bqdi)][PF6]2 (ls- [4R] [PF6]2) with localized ligand-based proton-coupled mixed-valence (LPMV) states. The first isolation and characterization of the key intermediates with LPMV states offer unprecedented molecular insights into the design of photoresponsive molecule-based hydrogen-storage materials. 相似文献
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Tatsuro Ouchi Shinji Kitazaki Akinobu Kobayashi Minoru Imoto 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):1045-1059
The radical polymerization of methyl methacrylate (MMA) was carried out with the system of imidazole (Im), copper(n) chloride, and water at 85°C. The effects of the amount of each component on the conversion of MMA were investigated. The polymerization proceeded through a radical mechanism. The overall activation energy was estimated to be 28.7 kJ/mole. The conversion of MMA showed a maximum at pH 8-9 of the aqueous solution. The formation of a complex of CuCl2 with Im, water, and MMA was confirmed by electronic spectra. An initiation mechanism was proposed. 相似文献
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Two new friedelane-type triterpenes, salasones D and E, a new norfriedelane-type triterpene, salaquinone B, and a new polyacylated eudesmane-type sesquiterpene, salasol B, were isolated from the stems of Salacia chinensis LINN. (S. prinoides DC., Hippocrateaceae) collected in Thailand. Their stereostructures were elucidated on the basis of chemical and physicochemical evidence. Some norfriedelane-type triterpene, lignan, and catechin constituents were found to show radical scavenging activity. 相似文献
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Tetrabenzoperipentacene: Stable Five‐Electron Donating Ability and a Discrete Triple‐Layered β‐Graphite Form in the Solid State 下载免费PDF全文
Akinobu Matsumoto Dr. Mitsuharu Suzuki Dr. Daiki Kuzuhara Dr. Hironobu Hayashi Prof. Dr. Naoki Aratani Prof. Dr. Hiroko Yamada 《Angewandte Chemie (International ed. in English)》2015,54(28):8175-8178
An oxidative ring‐closure reaction of a tetranaphthylpyrene derivative led to the synthesis of a 56 all‐carbon conjugated tetrabenzoperipentacene. In the single‐crystal X‐ray structure, three molecules make a triple‐layered cluster by π‐stacking, wherein each layer rotates by 120°, and is thus considered a petit β‐graphite. As for the optical properties, the Stokes shift is extremely small (10 cm?1), thus indicating its remarkably rigid framework. The tetrabenzoperipentacene exhibits reversible five‐electron oxidation waves in cyclic voltammetry, and is regarded as a counterpart to the fullerene C60 in terms of stable multicharge‐storage nanocarbon materials. 相似文献
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