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101.
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Rinaldi PL 《The Analyst》2004,129(8):687-699
This paper reviews the non-biological applications of three dimensional NMR (3D-NMR) spectroscopy methodologies for studying chemical structures in polymer science, dendrimer research, organometallic chemistry, organosilicon chemistry, and mixtures of small organic molecules. Four methodologies for solving chemical structure problems are described, where the appropriate method is determined by the presence or absence of a third X nucleus (in addition to (1)H and (13)C) with suitable NMR properties. 相似文献
104.
Piergiorgio Pecorari Marcella Rinaldi M. Paola Costi Luciano Antolini 《Journal of heterocyclic chemistry》1992,29(6):1449-1455
Derivatives of two new molecular structures, namely, 7,8-dihydro-6H,10H-[1,2,5]thiadiazolo[3′,4′:4,5]pyrimido[2,1-b][1,3]thiazin-10-one and 6,7-dihydro-9H-thiazolo[3,2-a][1,2,5]thiadiazolo[3,4-d][pyrimidin-9-one, and derivatives of N-substituted sulfamic acid, namely, (8-amino-3,4-dihydro-2H,6H-pyrimido[2,1-b][1,3]thiazin-6-on-7-yl)sulfamic acid and (7-amino-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidin-5-on-6-yl)sulfamic acid, were separated out as by-products in the reduction reaction of 8-amino-3,4-dihydro-7-nitroso-2H,6H-pyrimido[2,1- b][1,3]thiazin-6-one and 7-amino-2,3-dihydro-6-nitroso-5H-thiazolo[3,2-a]pyrimidin-5-one derivatives, respectively, with sodium hydrosulfite. A mechanism of reaction, which hypothesizes the action of sodium hydrosulfite in an asymmetic form, is proposed. The results of single-crystal X-ray investigation on 7,8-dihydro-6H,10H-[1,2,5]thiadiazolo[3′,4′:4,5]pyrimido[2,1-b][1,3]thiazin-10-one (R = 0.032 for 863 reflections) and (8-amino-3,4-dihydro-2H,6H-pyrimido[2,1-b]- [1,3]thiazin-6-on-7-yl)sulfamic acid, sodium salt (R = 0.028 for 3507 reflections) are reported. 相似文献
105.
Peter L. Rinaldi Lan Li Darlene R. Hensley Dale G. Ray H. James Harwood 《Macromolecular Symposia》1994,86(1):15-33
The utility of isotopic labeling combined with triple resonance nuclear magnetic resonance (NMR) techniques for polymer structure and reactivity investigations will be demonstrated. One dimensional (1D) and two dimensional (2D) 1H/19F/13C triple resonance NMR experiments have been used to study the structure of fluoropolymers; and 1H/2H/13C triple resonance techniques have been used to study the reactivity of poly[(styrene-alt-(methyl methacrylate)] and the structure of deuterated polybutadiene. These methods provide a unique ability to selectively detect resonances of structural features that are present in minute amounts in polymers, without interference from the much larger signals of the rest of the polymer. 相似文献
106.
Weixia Liu Dale G. Ray III Peter L. Rinaldi Toby Zens 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1999,140(2):482-486
The application of pulsed-field-gradient (PFG) techniques has been particularly important in providing the ability to detect 2D and 3D NMR cross peaks from minor structural components in synthetic organic polymers. The lack of mobility in a large percentage of polymers leads to rapid T2 relaxation which prevents the use of pulse sequences, such as the HMBC experiment, that operate based on coherence transfer via small, long-range J couplings. High-temperature NMR increases molecular motion with corresponding line narrowing (e.g., polyethylenes are typically analyzed at 120 degrees C). However, until now, the requirement for high temperature has precluded the use of PFG methods. Here we present data from a new probe which is capable of performing high-temperature PFG coherence selection experiments at temperatures typical of those used in many polymer analyses. We illustrate the performance of this probe with PFG-HMBC spectra of a copolymer from ethylene/1-hexene/1-butene at 120 degrees C. 相似文献
107.
Jens Sehested Ole John Nielsen Carlos A. Rinaldi Silvia I. Lane Juan Carlos Ferrero 《国际化学动力学杂志》1996,28(8):579-588
The reaction of CF3 with NO2 was studied at 296 ± 2K using two different absolute techniques. Absolute rate constants of (1.6 ± 0.3) × 10−11 and (2.1 −0.3+07) × 10−11 cm3 molecule−1 s−1 were derived by IR fluorescence and UV absorption spectroscopy, respectively. The reaction proceeds via two reaction channels: CF3 + NO2 → CF2O + FNO, (70 ± 12)% and CF3 + NO2 → CF3O + NO, (30 ± 12)%. An upper limit of 11% for formation of other reaction products was determined. The overall rate constant was within the uncertainty independent of total pressure between 0.4 to 760 torr. © 1996 John Wiley & Sons, Inc. 相似文献
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109.
We consider one–factorizations of complete graphs which possess an automorphism group fixing k ≥ 0 vertices and acting regularly (i.e., sharply transitively) on the others. Since the cases k = 0 and k = 1 are well known in literature, we study the case k≥ 2 in some detail. We prove that both k and the order of the group are even and the group necessarily contains k − 1 involutions. Constructions for some classes of groups are given. In particular we extend the result of [7]: let G be an abelian group of even order and with k − 1 involutions, a one–factorization of a complete graph admitting G as an automorphism group fixing k vertices and acting regularly on the others can be constructed. 相似文献
110.