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81.
Olefins are converted into allylic acetates by treatment in acetic acid with a catalytic amount of palladium bis(trifluoroacetate) and one equivalent of benzoquinone as oxidant. The reaction is selective for oxidation of a terminal methyl group of geranylacetone. 相似文献
82.
The Stoichiometry of thermal decomposition was studied for the following compounds: Ni(NCS)2(2-Mepy)2 (I), (Me=methyl, py=pyridine), Ni(NCS)2(2-Etpy)2 (II) (Et=ethyl), Ni(NCS)2(2-Clpy)2 (III), Ni(NCS)2(2-Brpy)2 (IV), Ni(NCS)2(2-NH2py)2 (V), Ni((NCS)2(2-NH2py)2·3/4 (C2H5)2O (VI). The release of volatile ligands 2-Rpy is a one-step process for complexes I, II, III and IV, while for V and VI it is a two-step process, Ni(NCS)2(2-NH2py)1 (VII) being formed as an intermediate complex. It was found that complexes I and II are square-planar; the others exhibited pseudo-octahedral geometry. The differences in stereochemistry of the above complexes are explained by the different electronic properties of 2-Rpy. 相似文献
83.
The optical properties of reaction systems composed from a pseudoisocyanine (PIC) solution and dispersed layered silicates were studied using visible spectroscopy. Two series of reduced-charge montmorillonites were used as the silicate materials. Each series consisted of eight samples with different layer charges, which were prepared from one parent material. Observed trends were verified with another series of dioctahedral and trioctahedral smectites of different layer charges, structure, and origin. The layer charge density of the silicates significantly affected the aggregation of PIC cations. In addition to the formation of J-aggregates, dye spectral bleaching was also observed. Silicates with very low charge densities induced neither significant aggregation nor spectral bleaching of the dye. The highest levels of PIC J-aggregate formation were found in dispersions of the layered silicates with a medium surface charge. However, reversible spectral bleaching was also observed in some cases. PIC dye cations probably change their conformations during the adsorption process, due to the tension resulting from the large size of the cations and the relatively high charge density at the silicate surface. The bleached dye recovers, at least partially, with the rearrangement and redistribution of the dye cations over the time. In contrast, the presence of silicates with very high charge densities (synthetic taeniolite and fluorohectorite) led to the very fast and irreversible decomposition of the PIC. Perhaps, the tension in adsorbed dye cations, induced by the high charge density at the silicate surface, resulted in significant destabilization and a decomposition reaction of the chromophore. 相似文献
84.
Bernard R Cornu D Baldeck PL Cáslavský J Létoffé JM Scharff JP Miele P 《Dalton transactions (Cambridge, England : 2003)》2005,(18):3065-3071
Non-centrosymmetric pi-conjugated systems incorporating closo-dodecaborate clusters, [NC-C6H4-C(H=N(H)-B12H11]-(2), [NC-C6H4-C(H)=C(H)-C(6)H(4)-C(H)=N(H)-B12H11]-(3), and [NC-C6H4-C(H)=C(H)-C6H4-C(H)=C(H)-C6H4-C(H)=N(H)-B12H11]-(4) have been synthesized by reaction of the monoamino derivative of B12, [B12H11NH3]-(1), with various arylaldehydes, R-C6H4-CHO. These Schiff base-like compounds were fully characterized by multinuclear NMR spectroscopy and mass spectrometry. In order to evaluate these boron rich pi-systems as potential materials for two-photon absorption (TPA) processes, UV linear absorption curves were recorded for 3 and 4, and comparatively studied with those of the boron-free pi-systems NC-C6H4-C(H)=N-CH3(5) and NC-C6H4-C(H)=C(H)-C6H4-C(H)=N-CH3(6). The donor effect of the boron cluster was evidenced by a shift to the lower energy of the absorption band in the spectra of systems incorporating B12. The two photon absorption (TPA) spectrum of compound , obtained by the up-conversion method, shows a resonance at 720 nm with a cross-section sigma(TPA) of 35 x 10(-50) cm(4) s photon(-1) molecule(-1). This value suggests the potential of B12 clusters to be used as new donor groups for the synthesis of non-linear materials. 相似文献
85.
Ladislav Halás Andrej Oriňák Abubaker Sharif Monika Ádámová Juraj Ladomerský 《Central European Journal of Chemistry》2005,3(3):570-582
Acrylate monomers methylmethacrylate (MMA) and cyclohexylmethacrylate (CHMA) bioaccumulation has been determined in aquatic
organism, algae (Chlorella kessleri). Algae were collected in amount of 0.4 mg and directly injected to the pyrolytical cell. In algae bodies accumulated monomers
were analysed by pyrolysis gas chromatography (Py-GC) and pyrolysis gas chromatography coupled with mass spectrometry (Py-GC/MS).
Traces of the accumulated monomers in algae body can be determined after 1-, 2-, 3-weeks of incubation. Maximum content of
MMA was determined after 3-week of experiment, contrariwise in the case of CHMA after 2-week exposition. Relationship with
pyrolysis temperature has also been studied. 相似文献
86.
J. V. Dubský 《Mikrochimica acta》1941,29(3-4):213-218
Zusammenfassung Die Farbreaktion der Ferrisalze mit der Isonitroso-thioglykolsäure wurde durch die Isolierung dreier basischer innerer Komplexsalze mit 1 bzw. 2 Mol der Säure aufgeklärt (I, II, III). Das Eisen bindet mit der Hauptvalenz das Schwefelatom, mit der Nebenvalenz den Sauerstoff der Carbonylgruppe. Erfassungsgrenze der blauen Färbung 3 Eisen bei der Grenzkonzentration 1:7333000.
(Experimentell ausgeführt vonB. Mareth.)
XVI. Mitteilung: Chem. Listy34, 307 (1940) 相似文献
Summary The colour reaction of the ferric salts with the isonitrosothioglycolic acid was enlightened by the insulation of three basic inner complex salts with 1, respectively 2 moles of the acid (I, II, III). The iron is fixed by the principal valency to the sulphur atom, by the secondary valency to the oxygen of the carbonyl group. Limit of identification of the blue colour 3 Fe; concentration limit 1:7333000.
Résumé (W) Le réaction colorée des sels ferriques avec l'acide isonitrosothioglycolique a été expliquée en isolant trois sels complexes internes basiques, avec respectivement une ou deux molécules d'acide (I. II, III). Le fer avec valence principale, se lie à l'atome de soufre, tandis qu'avec une valence secondaire, il se lie à l'oxygène du groupe carbonyle. Limite de perceptibilité: 3 de fer, avec une limite de dilution: 1:7333000.
(Experimentell ausgeführt vonB. Mareth.)
XVI. Mitteilung: Chem. Listy34, 307 (1940) 相似文献
87.
M. Šícha J. Glosík J. Pavlík Z. Němeček J. Šafránková M. Tichý 《Czechoslovak Journal of Physics》1983,33(11):1226-1229
Conclusion In the present report an attempt has been made to use the second derivative method for measurements of the electron distribution function in flowing afterglow plasma. It has been shown that using the cross-correlation technique, this method seems to be a useful tool for flowing afterglow plasma investigation. 相似文献
88.
We report synthesis of temperature- and redox-responsive multiblock copolymers by reversible addition-fragmentation chain transfer (RAFT) polymerization. Well-defined α,ω-bis(dithioester)-functionalized poly(N-isopropylacrylamide) (PNIPAM) and poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) were prepared using 1,4-bis(thiobenzoylthiomethyl)benzene and 1,4-bis(2-(thiobenzoylthio)prop-2-yl)benzene as RAFT agents, respectively. Dually responsive multiblock copolymers were synthesized in a single aminolysis/oxidation step from the α,ω-bis(dithioester)-terminated PNIPAM and PDMAEMA. The copolymers and their stimulus-responsive behavior were characterized by size exclusion chromatography, NMR, light scattering and atomic force microscopy. Due to the presence of redox-sensitive disulfide bonds between the blocks, the copolymers were readily reduced to the starting polymer blocks. The presence of temperature-responsive PNIPAM blocks provided the copolymers with the ability to assemble into core-shell nanostructures with hydrophobic PNIPAM as a core and cationic PDMAEMA as stabilizing shell when above the phase transition temperatures of PNIPAM. The temperature-induced assembly of the copolymers also showed substantial pH sensitivity. The phase transition temperature increased with decreasing pH, while molecular weight of the assemblies decreased. 相似文献
89.
A new method for the determination of nickel in the presence of cobalt, based on the masking of the cobalt with potassium cyanide and hydrogen peroxide, is proposed. The yellow, or orange-yellow, complex of cobalt(III) is formed, from which cobalt is not displaced upon the addition of silver nitrate. Tetracyanonickelate, however, reacts quantitatively with silver nitrate, and the displaced nickel can be determined directly with EDTA, using Murexide as indicator. Up to 30 mg of cobalt can be tolerated in the solution. 相似文献
90.
Vratislav Langer Dalma Gyepesov Jozef Lusto Juraj Kronek Eva Scholtzov Miroslav Ko 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(7):o416-o418
In the crystal structure of the title compound, C11H13NO2, there are strong intermolecular O—H⋯N hydrogen bonds which, together with weak intramolecular C—H⋯O hydrogen bonds, lead to the formation of infinite chains of molecules, held together by weak intermolecular C—H⋯O hydrogen bonds. A theoretical investigation of the hydrogen bonding, based on density functional theory (DFT) employing periodic boundary conditions, is in agreement with the experimental data. The cluster approach shows that the influence of the crystal field and of hydrogen‐bond formation are responsible for the deformation of the 2‐oxazoline ring, which is not planar and adopts a 4T3 (C3TC2) conformation. 相似文献