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71.
James R. Wilson Anh T. Duong Marcio Gameiro Hsun-Yi Chen Katsuyo Thornton Daniel R. Mumm Scott A. Barnett 《Electrochemistry communications》2009,11(5):1052-1056
Solid oxide fuel cells (SOFCs) are being actively developed world wide for clean and efficient electrical generation from fuels such as natural gas, hydrogen, coal, and gasoline. The cathode in state of the art SOFCs is typically a porous composite of electronically-conducting La1?xSrxMnO3 (LSM) and ionically-conducting Y2O3-stabilized ZrO2 (YSZ) that facilitates the critical oxygen reduction reaction. Here we describe the three-dimensional characterization and quantification of key structural parameters from an LSM-YSZ cathode, using imaging and volume reconstruction based on focused ion beam – scanning electron microscopy. LSM-YSZ-pore three-phase boundaries (TPBs) were identified. Approximately 1/3 of the TPBs were found to be electrochemically inactive, as they were on isolated LSM particles, yielding an active TPB density of 4.9 μm?2. Cathode electrochemical modeling, which included a measured YSZ tortuosity of 3.4, yielded an effective TPB resistance of ≈2.5 × 105 Ω cm at 800 °C. 相似文献
72.
J. F. Bergmann N. R. Pike J. B. Ficklen I. L. Newell S. Terrat Tcheng Da-Tcheng Li Houong R. Roseman und W. M. Thornton 《Fresenius' Journal of Analytical Chemistry》1936,106(7-8):290-292
Ohne Zusammenfassung 相似文献
73.
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75.
Summary A spectrophotometric study has been made on the cobalt-3-nitroso-2, 6-pyridinediol reaction. The yellow complex formed has an absorption maximum at 411 nm and a molar absorptivity of 3.4·104 l mole–1 cm–1. The system follows Beer's law.
Zusammenfassung Die Reaktion zwischen Kobalt und 3-Nitroso-2,6-Pyridindiol wurde spektrophotometrisch untersucht. Die maximale Absorption des sich bildenden gelben Komplexes liegt bei 411 nm, seine molare Extinktion beträgt 3,4·104 l Mol–1 cm–1. Die Farbreaktion entspricht dem Beerschen Gesetz.相似文献
76.
N. Thornton Lipscomb Yassin Tarshiani 《Journal of polymer science. Part A, Polymer chemistry》1988,26(2):529-540
The kinetics of the photopolymerization of styrene in bulk and in dilute systems in the presence of benzoin isobutyl ether as photoinitiator have been examined. The values of the intensity exponent, calculated at different temperatures or at different styrene concentrations, and the monomer exponent, calculated at various intensities, showed significant departure from those predicted by the ideal kinetic scheme, particularly at high intensity, at low temperature, or at low styrene concentrations. Low molecular weight polymer was the dominant product when high light intensity or low polymerization temperature was used. As the temperature was raised, however, or as the intensity was reduced, a high molecular weight polymer became progressively more important. Kinetic and molecular weight data suggest that at low temperature, high intensity, and/or at low monomer concentration, the benzoyl radical is the dominant initiating species; and the benzyl ether radical was consumed mainly in the termination step. At low intensity, high temperature and/or high monomer concentration, however, it appears that both benzoyl and benzyl ether radicals initiated polymerization. 相似文献
77.
The available data (supplemented where necessary) on the electronic, nuclear magnetic resonance and vibrational spectra of metal -ketoenolates has been analysed to assess the relative contributions of donor and acceptor metal-ligand -bonding in the first transition period metal (III) -ketoenolates. The effects of the metal ion and the ligand substituent on the -interaction in the -ketoenolate ring are discussed in terms of established theoretical concepts.
This work was supported by University of Cape Town and C.S.I.R. Research Grants. We thank the National Institute for Metallurgy for a bursary (to R.D.H.). 相似文献
Zusammenfassung Die bekannten Daten (ergÄnzt, falls notwendig) der elektronischen und kernmagnetischen Resonanz sowie der Schwingungsspektren von Metall--ketoenolaten wurden analysiert, um die relativen BeitrÄge von Donor- und Akzeptor (Metall-Ligand) -Bindung in Metall(III)ketoenoIaten der ersten übergangsperiode zu ermitteln. Die Einwirkung des Metallions und des Ligandsubstituenten auf die -Bindung im -Ketoenolatring werden diskutiert auf der Grundlage von bekannten theoretischen Prinzipien.
Résumé L'examen des résultats antérieurement publiés (supplementés ou nécessaire) des spectres électroniques, résonance nucléaire magnétiques et vibrationnel nous a amenés à préciser les contributions relatifs de liaison- donneur et accepteur entre métal et ligand de la première période transitionelle métal(III) -kétoénolates. Les effects de l'ion métallique et du ligand substituent exercés sur l'interaction- dans le noyau -kétoénolate sont discutés selon les idées théoriques déjà établies.
This work was supported by University of Cape Town and C.S.I.R. Research Grants. We thank the National Institute for Metallurgy for a bursary (to R.D.H.). 相似文献
78.
The infrared spectra (500–140 cm?1) of the complexes [M(pyridine)n(NCS)2] (n = 2, M = Mn, Co, Ni, Cu, or Zn; n = 4, M = Mn, Fe, Co, or Ni) are discussed. The v/M-pyridine and v/M-NCS bands are assigned by observing the band shifts induced by isotopic labelling of the coordinated pyridine and isothiocyanate, by comparing the spectra with those of the [M(pyridine)2Cl2] complexes and from symmetry considerations based on their known structures. The two types of metal-ligand stretching bands occur within a rather narrow frequency range and there is evidence of some vibrational coupling between these two modes. Some earlier assignments of vM-pyridine bands require revision. The spectra of the yellow [Fe(py)4(NCS)2] complex and its violet oxidation product suggest that the oxidation reaction involves the transformation of trans-[Fe(py)4(NCS)2] into cis-[Fe(py)3(NCS)3] 相似文献
79.
Tommy J. Mccord David R. Smith Janet K. Swan Anna M. Goebel Donald E. Thornton Criss C. Yakshe Alvie L. Davis 《Journal of heterocyclic chemistry》1979,16(6):1249-1252
Methyl 5-chloro- and 5,7-dichloro-2,1-benzisoxazole-3-carboxylates have been synthesized by treatment of o-nitromandelic and 5-chloro-2-nitroamandelic methyl esters, respectively, with thionyl chloride under appropriate reaction conditions. The structural assignments of both heterocyclic products were based on elemental and spectral analyses, and their conversion to the corresponding 5-chloro- and 5,7-dichloro substituted 2,1-benzisoxazole-3-carboxylic acids and isatins. Methyl α-chloro-o-nitrophenylacetate and o-nitrophenylcarbomethoxymethinyl sulfite were also obtained from reactions of methyl o-nitromandelate and thionyl chloride. A possible reaction mechanism involving two consecutive nucleophilic substitutions of methyl o-nitromandelate with thionyl chloride was proposed to account for the formation of methyl 5-chloro-2,1-benzisoxazole-3-carboxylate. 相似文献
80.
The IR spectra (3500—150 cm?1) of the complexes [M(aniline)2,X2 (M = Co, Ni, Cu, Zn; X = Cl, Br), [Zn(aniline)2I2] are discussed. Assignments of the internal ligand vibrations are based on the band shifts which result from 15N-labelling of the amino group. The metal—ligand stretching frequencies, ν(M—N) and ν(M—X), are assigned on the basis of the band shifts which occur on 15N-labelling and metal ion and halogen substitution. Two bands within the range 350–450 cm?1 are assigned to ν(M—N) while the ν(M—X) bands occur within the range 170–320 cm?1. The effects of structure and coordination number on ν(M—N) and ν(M—X) are discussed. The spectra of two ethanol adducts, [M(aniline)2-(ethanol)2Cl2] (M = Co, Ni) compared with those of the unsolvated species [M(aniline)2-Cl2], exhibit a unique band near 480 cm?1 which is insensitive to 15N-labelling and is assigned to ν(M—O). 相似文献