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41.
Carbonylation of olefins, alcohols and halides using homogeneous as well as heterogeneous catalysts has been discussed. Highlights
of contributions on the activity, selectivity and stability of catalysts for carbonylation reactions are discussed. Kinetics
and mechanism including characterization of the intermediate catalytic species has also been reviewed. The performance of
anchored Pd complexes on mesoporous supports (MCM-41 and MCM-48), water soluble Pd complexes and supported Pd catalysts in
carbonylation of aryl alcohols and olefins has been discussed in the context of catalyst-product separation. Some aspects
of kinetic modelling and reaction engineering of these multiphase catalytic reactions have also been reviewed. 相似文献
42.
The kinetics of base hydrolysis of (αβS) (salicylato) (tetraethylenepentamine) cobalt(III) have been investigated in aquo-organic solvent media at 15.0 < t, °C < 40.0, and I = 0.10 mol dm (ClO4?) using propane-2-ol (?70% v/v), t-butanol (?60% v/v), acetone (?70% v/v), acetonitrile (?50% v/v), and ethylene glycol (?70% v/v) as cosolvents. Both the spontaneous and base-catalyzed hydrolysis of the phenoxide species [(tetren)CoO2CC6H4O]+ were appreciably accelerated by the cosolvents PriOH, ButOH, Me2CO, and MeCN. On the contrary the base hydroylsis (k2) was retarded while spontaneous aquation (k1) was accelerated to a small extent with increased EG content. Variation of log k1 and log k (k = k2 at I = 0) with mole fraction (X0.S) or reciprocal of the relative permitivity (Ds?1) of the media were nonlinear. The transfer free energy of the transition state relative to that of the initial state of the substrate for transfer of species from water to mixed solvents also varied nonlinearly with X0.S, or Ds?1 indicating solvent specificity. The activation parameters, ΔH≠ and ΔS≠ varied nonlinearly with solvent composition exhibiting extrema. The preferential solvation and solvent structural effects mediated the kinetics and energetics of the reaction. © 1995 John Wiley & Sons, Inc. 相似文献
43.
Kaul Neeraj Agrawal Himani Paradkar Anant Raghunath Mahadik Kakasaheb Ramoo 《平面色谱法杂志一现代薄层色谱法》2004,17(4):264-274
JPC – Journal of Planar Chromatography – Modern TLC - A sensitive, selective, precise, and stability-indicating high-performance thin-layer chromatographic method has been established... 相似文献
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Madhukar N.?JachakEmail author Chanda D.?Tantak Raghunath B.?Toche Naresh S.?Badgujar 《Monatshefte für Chemie / Chemical Monthly》2004,135(12):1529-1538
Summary. A series of ureidopropenenitriles were synthesised by Knoevenagel condensation of ArCOCH2CN and HC(OEt)3 in presence of ureas in a one pot reaction. These ureidopropenenitriles were cyclised to 4-aryl-5-cyano-3-substituted pyrimidines (in acid) or to 4-amino-5-benzoylpyrimidines (in base) in 60–70% yields. The amine pyrimidine derivatives were further converted to substituted uracils by hydrolysis with isopentyl nitrite in DMF. Alkylation of uracils furnished 1,3-dimethyluracil derivatives with DMS in alkali. All new compounds were characterised by spectral and analytical methods. 相似文献
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We report the formation of a double-gyroid network morphology in normal-tapered poly(isoprene-b-isoprene/styrene-b-styrene) [P(I-IS-S)] and inverse-tapered poly(isoprene-b- styrene/isoprene-b-styrene) [P(I-SI-S)] diblock copolymers. Our tapered diblock copolymers with overall poly(styrene) volume fractions of 0.65 (normal-tapered) and 0.67 (inverse-tapered), and tapered regions comprising 30 volume percent of the total polymer, were shown to self-assemble into the double-gyroid network morphology through a combination of small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The block copolymers were synthesized by anionic polymerization, where the tapered region between the pure poly(isoprene) and poly(styrene) blocks was generated using a semi-batch feed with programmed syringe pumps. The overall composition of these tapered copolymers lies within the expected network-forming region for conventional poly(isoprene-b-styrene) [P(I-S)] diblock copolymers. Dynamic mechanical analysis (DMA) clearly demonstrated that the order-disorder transition temperatures (T(ODT)'s) of the network-forming tapered block copolymers were depressed when compared to the T(ODT) of their non-tapered counterpart, with the P(I-SI-S) showing the greater drop in T(ODT). These results indicate that it is possible to manipulate the copolymer composition profile between blocks in a diblock copolymer, allowing significant control over the T(ODT), while maintaining the ability to form complex network structures. 相似文献
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