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排序方式: 共有100条查询结果,搜索用时 15 毫秒
41.
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Jody L Tanabe Martina Vermathen Robert Miller Deborah Gelinas Michael W Weiner William D Rooney 《Magnetic resonance imaging》1998,16(10):1163-1169
The objective of this study was to test the hypothesis that magnetization transfer ratios (MTR) are decreased in the corticospinal tract of patients with amyotrophic lateral sclerosis (ALS); to determine if T2 is increased in corticospinal tract or reduced in motor cortex in ALS; to determine if corticospinal tract MTR correlates with a clinical measure of motor neuron function in ALS. Ten ALS patients and 17 age-matched controls were studied. Double spin echo MRI and 3D gradient echo MRI with and without off-resonance saturation were acquired on each subject. 3D data sets were coregistered and resliced to match the spin echo data set. MTR was calculated for corticospinal and non-corticospinal tract white matter. T2 was calculated for corticospinal and non-corticospinal tract white matter, motor cortex and non-motor cortex. MTR was reduced by 2.6% (p < .02) in corticospinal, but not in non-corticospinal, tract white matter in ALS. There was no difference in T2 in any brain region. The correlation between a clinical measure of motor neuron function and corticospinal tract MTR was statistically significant. These findings are consistent with the known pathology in ALS and suggest that MTR is more sensitive than T2 for detecting involvement of the corticospinal tract. Quantitative MTR of the corticospinal tract may be a useful, objective marker of upper motor neuron pathology in ALS. 相似文献
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Eva Eichler C. Stanley Rooney Haydn W. R. Williams 《Journal of heterocyclic chemistry》1983,20(2):419-421
The preparations of some 4-pyridylimidazo[2,1-b]thiazole and -imidazo[5,1-b]thiazole derivatives are described. In some of the cyclizations to form the imidazothiazole ring systems, trifluoroacetic anhydride, the dehydration reagent employed, participated in the reaction leading to products bearing a trifluoromethyl or trifluoroacetyl substituent. 相似文献
45.
J. M. Rooney D. R. Squire V. T. Stannett 《Journal of polymer science. Part A, Polymer chemistry》1976,14(8):1877-1887
The sequential carbenium ion block copolymerization of ethyl vinyl ether (EVE) and isobutyl vinyl ether (IBVE) with N-vinylcarbazole (NVC) is described. Requisite conditions for the successful application of the sequential synthesis technique to these systems were established: (1) the use of stable carbocation initiator salts (e.g., Ph3CSbCl6) which lead to essentially terminationless polymerizations; (2) low solvent-to-monomer ratios in order to suppress any possible chain transfer to methylene dichloride molecules; (3) high ratios of initiator to monomer which create a pseudo-“living” system. The block products (PEVE-b-PNVC and PIBVE-b-PNVC) were isolated by precipitation and extraction. The intrinsic viscosities of these products displayed minima at 30°C. 相似文献
46.
Eva Eichler Clarence Stanley Rooney Haydn Windsor Richard Williams 《Journal of heterocyclic chemistry》1976,13(1):43-44
Ethyl 2-amino-4,6-di(trifluoromethyl)nicotinate was prepared and its use as an intermediate in the synthesis of two 3-pyridyl-5,7-di(trifluoromethyr)-1,8-naphthyridin-2(1H)ones is presented. A dimer of 2-amino-4,6-di(trifluoromethyl)nieotinaldehyde is described. 相似文献
47.
Rochford J Botchway S McGarvey JJ Rooney AD Pryce MT 《The journal of physical chemistry. A》2008,112(46):11611-11618
The influence of the thiophene ring on the ground and excited state properties of the porphyrin ring is investigated, when substituted at the meso-position. A series of mono-, di-, tri-, and tetra- meso-thien-2-yl porphyrins are studied and discussed with respect to the reference compounds zinc(II)-5,10,15,20-tetra(thien-2'-yl)porphyrin ( 1a) and zinc(II)-5,10,15,20-tetraphenylporphyrin (ZnTPP). The extended conjugated system zinc(II)-5-(5'-(5'-ethynyl-2'-thiophenecarboxaldehyde)thien-2'-yl)-10,15,20-triphenylporphyrin ( 4d) is also studied and shows enhanced charge transfer character due to the presence of the terminal aldehyde accepting group. A detailed analysis of ground and excited state UV-vis absorption, steady-state and time-resolved fluorescence, laser flash photolysis, and electrochemical data all point toward substantial electronic communication between the central Zn(II) porphyrin ring and the meso-thien-2-yl substituents, which is evident from excited state charge transfer character. 相似文献
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The interactions between diquat (DQ) and p-sulfonatocalix[4]arene (C4S) were studied in an aqueous solution as a function of the ionic strength. Evidence for the formation of a complex between DQ and C4S was obtained using fluorescence measurements, while the stoichiometry of the complex was confirmed as 1:1 for DQ/C4S using UV–vis spectroscopy. The ionic strength had no influence on the stoichiometry of the complex, but exerted a significant influence on the complexation constant, Kc, decreasing with an increase in the ionic strength. The thermodynamic complexation constant, Kc′, was computed as 5.25±1.11×107 using the extended Debye–Hückel law. The rate constants for the heterogeneous electron transfer for the reduction of DQ at an electrode surface were evaluated as 0.150±0.010 cm s?1 in the absence of C4S and 0.065±0.010 cm s?1 when C4S was added to the solution in a 1:1 ratio. 相似文献