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Chetan Tambe John Kaufmann Daniel Graiver Ramani Narayan 《Journal of polymer science. Part A, Polymer chemistry》2016,54(19):3086-3093
Reactive blends prepared from methoxysilane terminated silicone polymers and silylated soybean oil are described and characterized. Although simple mixing of soy and silicones results in gross phase separation, homogeneous polymeric products are obtained by introducing reactive sites. These products can be used as protective coatings, additives to adhesives and new sealants. Exposure of the mixtures to moisture leads to hydrolysis of the methoxysilanes and subsequent condensation of the resulting silanols that yields stable siloxane linkages between the two immiscible phases. FTIR, TGA, and swell‐gel analyses indicate effective formation of these siloxane crosslinks. Reactive blends containing less than 20% silylated oil appeared completely transparent but increasing the soy content decreased the optical transparency. SEM micrographs reveal the silicone polymer as the continuous phase with individual spherical silylated soy oil particles distributed in it. The properties of these reactive blends vary from high elongation elastomers to high modulus resins depending on the composition. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3086–3093 相似文献
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A quantitative LC–MS/MS method was developed for the determination of 13 commonly used aminoglycoside antibiotics in meat (pork muscle, fish, and veal livers and kidneys). The proposed method is sufficiently sensitive and highly selective. Unlike other previously reported methods, it uses a simple clean-up procedure based on a strong cation-exchange solid-phase cartridge that permits high sample extract loading volumes. A unique elution regime based on a volatile buffer at intermediately high pH value in combination with an organic solvent provides quantitative elution of the various aminoglycosides. This methodology ensured that neither a breakthrough of weakly retained aminoglycosides (e.g. spectinomycin) nor the incomplete elution of strongly retained analytes (e.g. neo- and gentamycin) is observed. The single-step clean-up is fast and produces clean extracts that minimize matrix-related signal suppression in the electrospray interface. 相似文献
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The determination of acceptable mass error tolerances for high‐resolution mass spectrometry based signals has been evaluated in a comprehensive way. This was achieved by using a technical approach which is based on the post‐column infusion of an analyte containing solution. This well‐known experimental setup was not used to spot signal suppression regions of a particular analyte, but to spot regions of the chromatogram where a systematic mass drift of the analyte ion can be observed (isobaric interference plot). Not the changing signal intensity but the stability of the measured analyte mass was observed. A wide range of different analytes in combinations with potentially interfering matrices has been evaluated. Furthermore, different mass resolving power settings were evaluated. Isobaric interferences between matrix compounds and analytes were common at mass resolving powers <50 000 full width at half maximum. The proposed post‐column infusion technique is a useful tool for the determination of the assay and matrix‐specific mass error tolerances. It aims to ensure the highest possible selectivity, at the same time preventing the encounter of detrimental mass error related peak deformations as well as false negative findings. Unlike conventional matrix spiking approaches, isobaric interference plots provide information of potential interferences across the whole chromatographic time range. This becomes relevant when there is a relative retention time shift between the analyte and potential interfering matrix compounds. Furthermore, the described setup can be used to study how the mass accuracy of any mass spectrometer is affected by a widely varying total ion current. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Lyubov I. Kazakova Lyudmila I. Shabarchina Salzitsa Anastasova Anton M. Pavlov Pankaj Vadgama Andre G. Skirtach Gleb B. Sukhorukov 《Analytical and bioanalytical chemistry》2013,405(5):1559-1568
The concept of enzyme-assisted substrate sensing based on use of fluorescent markers to detect the products of enzymatic reaction has been investigated by fabrication of micron-scale polyelectrolyte capsules containing enzymes and dyes in one entity. Microcapsules approximately 5 μm in size entrap glucose oxidase or lactate oxidase, with peroxidase, together with the corresponding markers Tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) dichloride (Ru(dpp)) complex and dihydrorhodamine 123 (DHR123), which are sensitive to oxygen and hydrogen peroxide, respectively. These capsules are produced by co-precipitation of calcium carbonate particles with the enzyme followed by layer-by-layer assembly of polyelectrolytes over the surface of the particles and incorporation of the dye in the capsule interior or in the multilayer shell. After dissolution of the calcium carbonate the enzymes and dyes remain in the multilayer capsules. In this study we produced enzyme-containing microcapsules sensitive to glucose and lactate. Calibration curves based on fluorescence intensity of Ru(dpp) and DHR123 were linearly dependent on substrate concentration, enabling reliable sensing in the millimolar range. The main advantages of using these capsules with optical recording is the possibility of building single capsule-based sensors. The response from individual capsules was observed by confocal microscopy as increasing fluorescence intensity of the capsule on addition of lactate at millimolar concentrations. Because internalization of the micron-sized multi-component capsules was feasible, they could be further optimized for in-situ intracellular sensing and metabolite monitoring on the basis of fluorescence reporting. 相似文献
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The Friedel–Crafts alkylation of furans by the Michael acceptor, β-nitrostyrene, is greatly accelerated by the use of the Lewis acid catalyst and solvent, 5 M lithium perchlorate in diethyl ether (LDPE). 相似文献
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