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1.
The effect of the incorporation of small amounts (1–5 wt%) of semiconducting BaBiO3 and metallic Ba0.6K0.4BiO3 additives on the rechargeability of electrolytic manganese dioxide (EMD) cathodes in alkaline cells in the one-electron regime has been investigated. Both the BaBiO3 and Ba0.6K0.4BiO3 additives lead to better cyclability compared to the previously known binary oxide additive Bi2O3. X-ray diffraction patterns recorded before and after 30 cycles as well as cyclic voltammograms recorded after first and 30 cycles reveal that the better cyclability in the presence of BaBiO3 and Ba0.6K0.4BiO3 additives is due to the suppression of the formation of unwanted, electrochemically inactive birnessite and hausmannite phases and a shifting of the second-electron capacity of Mn to higher potentials.  相似文献   
2.
A linear free energy relationship was found betweenv max, the energy of the absorption maximum of chloride, bromide, or iodide ion in various solvents, and the solvatochromic parameter which is a measure of the hydrogen bond donor ability of the solvent. The relationships are: for chloride,v max=6.99+50.16 kK; for bromide,v max=5.52+45.20 kK; for iodide,v max=5.02+40.33 kK. The correlation ofv max for iodide ion with gave a larger correlation coefficient and smaller standard deviation than a correlation with the E T (30) parameter of Dimroth. From the values ofv max for iodide ion and the solvated electron in liquid ammonia at 25°C, these correlations indicate a preliminary value of 0.00 for the parameter of liquid ammonia. This had not been reported before and is lower than expected from a general knowledge of the physical and chemical properties of liquid ammonia but is consistent with a more detailed consideration and recent gas phase measurements of hydrogen bond donor strength.  相似文献   
3.
The chemical stability of the layered Li1−xCoO2 and Li1−xNi0.85CoO.15O2 cathodes is compared by monitoring the oxygen content with lithium content (1−x) in chemically delithiated samples. The Li1−xCoO2 system tends to lose oxygen from the lattice at deep lithium extraction while the Li1−xNi0.85Co0.15O2 system does not lose oxygen at least for (1−x)>0.3. This difference seems to result in a lower reversible (practical) capacity (140 mA h/g) for LiCoO2 compared to that for LiNi0.85Co0.15O2 (180 Ma h/g). The loss of significant amount of oxygen leads to a sliding of oxide layers and the formation of a major P3 and a minor O1 phase for the end member CoO2−δ with δ=0.33. In contrast, Ni0.85Co0.15O2−δ with a small amount of δ=0.1 maintains the initial O3 layer structure.  相似文献   
4.
Biomaterials in total joint replacement   总被引:9,自引:0,他引:9  
The current state of materials systems used in total hip replacement is presented in this paper. An overview of the various material systems used in total hip replacement reported in literature is presented in this paper. Metals, polymers, ceramics and composites are used in the design of the different components of hip replacement implants. The merits and demerits of these material systems are evaluated in the context of mechanical properties most suitable for total joint replacement such as a hip implant. Current research on advanced polymeric nanocomposites and biomimetic composites as novel materials systems for bone replacement is also discussed. This paper examines the current research in the materials science and the critical issues and challenges in these materials systems that require further research before application in biomedical industry.  相似文献   
5.
The catalytic activity of carbon supported Pd-Co-Mo for the oxygen reduction reaction (ORR) in a single cell proton exchange membrane fuel cell (PEMFC) has been investigated at 60 degrees C and compared with data from commercial Pt catalyst and our previously reported Pd-Co-Au and Pd-Ti catalysts. The Pd-Co-Mo catalyst with a Pd:Co:Mo atomic ratio of 70:20:10 exhibits slightly higher catalytic activity like the Pd-Co-Au catalyst than the commercial Pt catalyst, but with excellent chemical stability unlike the Pd-Co-Au catalyst. The Pd-Co-Mo catalyst also exhibits better tolerance to methanol poisoning than Pt. Investigation of the catalytic activity of the Pd-Co-Mo system with varying composition and heat treatment temperature reveals that a Pd:Co:Mo atomic ratio of 70:20:10 with a heat treatment temperature of 500 degrees C exhibits the highest catalytic activity. Although the degree of alloying increases with increasing temperature from 500 to 900 degrees C as indicated by the X-ray diffraction data, the catalytic activity decreases due to an increase in particle size and a decrease in surface area.  相似文献   
6.
A novel one-pot synthesis of four new classes of amidothiophosphoric esters and trisamidothiophosphoric esters is developed. (1-Alkyl-2-pyrimidinylidenamido)bis(diethylamido)thiophosphates, (1-alkyl-2-pyrimidinylidenamido)bis (O-2/4-methylphenyl)thiophosphates, (3-alkyl-2-thiazolinylidenamido)bis (diethylamido)thiophosphate and (3-alkyl-2-thiazolinylidenamido)bis(O-2/4-methylphenyl)thiophosphates are obtained from the nucleophilic substitution and oxidation of N-alkyl-2-cycloiminylidenaminodichlorophosphines generated in situ from the reaction of the corresponding N-alkyl-2-aminocycloiminium halide with phosphorus trichloride and triethylamine. The synthesized thiophosphoric esters have been investigated for fungicidal properties.  相似文献   
7.
Abstract

A series of biologically active organophosphorus compounds have been synthesized by the reactions of O,O-diethylchlorophosphate with Schiff bases derived from 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-oxadiazole and salicylaldehyde/2-hydroxyacetophenone. The compounds have been characterized on the basis of analyses and spectral (IR, 1H, 13C NMR) data. Fungicidal activities of these derivatives against Colletotrichum falcatum, Fusarium oxysporum, and Curvularia pallescence have been evaluated. All compounds showed moderate to significant antifungal activity.  相似文献   
8.
The cathodic reactions in Li–S batteries can be divided into two steps. Firstly, elemental sulfur is transformed into long‐chain polysulfides (S8?Li2S4), which are highly soluble in the electrolyte. Next, long‐chain polysulfides undergo nucleation reaction and convert into solid‐state Li2S2 and Li2S (Li2S4?Li2S) by slow processes. As a result, the second‐step of the electrochemical reaction hinders the high‐rate application of Li–S batteries. In this report, the kinetics of the sulfur/long‐chain‐polysulfide redox couple (theoretical capacity=419 mA h g?1) are experimentally demonstrated to be very fast in the Li–S system. A Li–S cell with a blended carbon interlayer retains excellent cycle stability and possesses a high percentage of active material utilization over 250 cycles at high C rates. The meso‐/micropores in the interlayer are responsible for accommodating the shuttling polysulfides and offering sufficient electrolyte accessibility. Therefore, utilizing the sulfur/long‐chain polysulfide redox couple with an efficient interlayer configuration in Li–S batteries may be a promising choice for high‐power applications.  相似文献   
9.
rac-BINAP-PdCl2 catalytic system catalyzed Heck reaction of 3-formylquinolin-2-yl chlorides with methyl acrylate in DMA is described to the synthesis of methyl 3-(3-formyl-quinolin-2-yl)-acrylates, in good to excellent yields. The reaction could be also extended with other activated alkenes to afford Heck products. Fused-benzene ring in heterocyclic and carbocyclic moieties was found to enhance the yields.  相似文献   
10.
Russian Journal of Organic Chemistry - A series of 2-amino-4-aryl-5-oxochromeno[4,3-b]pyridine-3-carbonitriles have been synthesized with good yields (85–90%) by reacting...  相似文献   
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