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排序方式: 共有109条查询结果,搜索用时 31 毫秒
31.
S. Mahendra Kumar Parag A. Deshpande M. Krishna M. S. Krupashankara Giridhar Madras 《Plasma Chemistry and Plasma Processing》2010,30(4):461-470
Nanocrystalline TiO2 was synthesized using the microwave plasma technique and characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, laser particle size analyzer, UV–vis spectroscopy and BET surface area analyzer. The synthesized TiO2 powder crystallized in anatase phase and the crystallite sizes were in nanometers. The photocatalytic activity of the compound was determined and compared against the activity of the commercial Degussa P-25 TiO2 catalyst. The degradation rates of the dyes were found to be higher over the synthesized TiO2 as compared to that over commercial Degussa P-25 TiO2. 相似文献
32.
Three novel metal-organic frameworks (MOFs) [Co(2)(C(10)H(8)N(2))][C(12)H(8)O(COO)(2)](2), 1, [Ni(2)(C(10)H(8)N(2))(2)][C(12)H(8)O(COO)(2)](2).H(2)O, 2, and [Zn(2)(C(10)H(8)N(2))][C(12)H(8)O(COO)(2)](2), 3, with three-dimensional structures have been synthesized and characterized. The structures of the three compounds appear somewhat related, formed by the connectivity involving the metal polyhedra (Co(4)N trigonal bipyramids in 1, NiO(4)N(2) octahedra in 2, and ZnO(4) tetrahedra and ZnO(3)N(2) trigonal bipyramids in 3), 4,4'-oxybis(benzoate), and 4,4'-bipyridine. The photocatalytic studies on 1-3 indicate that they are active catalysts for the degradation of orange G, rhodamine B, Remazol Brilliant Blue R and methylene blue. The compounds have also been characterized by powder X-ray diffraction, IR, thermogravitmetric analysis, UV-vis, photoluminescence, and magnetic studies. 相似文献
33.
P. Giridhar Reddy A. Venkat Reddy A. Ratnamala S. Venkateswara Rao Sushama Kandlikar 《Reaction Kinetics and Catalysis Letters》1984,26(1-2):209-213
Kinetics of Ru(III) catalyzed oxidation of methanol, ethanol, n-propanol, n-butanol, isopropanol and iso-butanol by N-bromosuccinimide (NBS) in the presence of Hg(II) acetate have been studied in acid medium. The oxidation exhibits a fractional order in [alcohol] and first order in [NBS]. The applicability of Taft's equation was tested. The probable mechanism is discussed.
, , -, -, - () Hg(II), Ru(III), . . . .相似文献
34.
The effect of chain length on the enzymatic hydrolysis of various p-nitrophenyl esters was investigated. Specifically, the hydrolysis of various esters p-nitrophenyl butyrate (PNPB), p-nitrophenyl caprylate (PNPC), p-nitrophenyl laurate (PNPL), p-nitrophenyl myristate (PNPM) and p-nitrophenyl palmitate (PNPP) was studied in supercritical carbon dioxide (ScCO2) with lipase (Novozym 435). This indicates that the conversion of nitrophenyl esters decreases with increasing chain length.
The effect of various parameters such as amount of water added, temperature, and enzyme loading was studied. The optimum temperature
for the hydrolysis of PNPB and PNPC was 50°C but was 55°C for PNPL, PNPM, and PNPP in ScCO2. The reactions were also conducted in acetonitrile as the solvent, and it was found that the reactions reach equilibrium
much faster in ScCO2 than in acetonitrile. The kinetics of the hydrolysis reactions were modeled using a Ping Pong Bi Bi model. 相似文献
35.
Benjaram M. Reddy D. Giridhar M. Vijaya Kumar 《Research on Chemical Intermediates》2001,27(3):225-236
The vapour phase selective oxidation of 4-methylanisole to anisaldehyde was investigated over different V2O5 /MgO-Al2O3 catalysts at 673 K and normal atmospheric pressure. Among various catalysts investigated the 16 wt% V2O5 /MgO-Al2O3 catalyst provided good conversion and product selectivity. The MgO-Al2O3 mixed oxide was obtained by a co-precipitation method and V2O5 was impregnated from ammonium metavanadate. The MgO-Al2O3 support and various V2O5 /MgO-Al2O3 catalysts were characterized by means of X-ray diffraction, FT-infrared, electron spin resonance, scanning electron microscopy, ammonia and carbon dioxide chemisorption methods. The characterization results suggest that vanadia does not form layer structures on the support surface, instead interacts very strongly with the support, in particular with MgO, and forms amorphous compounds. The NH3 and CO2 uptake results provide an interesting information on the acid-base characteristics of these catalysts and correlate with their catalytic properties. 相似文献
36.
Lipase specificity for the hydrolysis of poly (vinyl acetate) 总被引:2,自引:0,他引:2
Sujay Chattopadhyay G. Sivalingam Giridhar Madras 《Polymer Degradation and Stability》2003,80(3):477-483
The effect of lipases on the side chain hydrolysis of poly (vinyl acetate) (PVAc) was investigated in toluene by various lipases, Hog-pancreas (HP), Candida Rugosa (CR), Lipolase-100T (LL), and Novozyme 435 (NV) at 60 °C. Gas chromatographs and GC–MS spectra showed the presence of different ester side chains. The different size side chain esters in PVAc get hydrolyzed at different specific rates by the various lipases. Longer side chains are hydrolyzed in the order HP>NV>LL>CR whereas the short chains are hydrolyzed in the reverse order. A continuous distribution kinetics model was proposed that accounts for lipase deactivation and determines the rate coefficients of hydrolysis of various chain lengths. Lipase deactivation and hydrolysis rate coefficients were determined for each case. The proposed model predicts the experimental data satisfactorily. 相似文献
37.
Margherita Brindisi Sandra Gemma Gloria Alfano Giridhar Kshirsagar Ettore Novellino Giuseppe Campiani Stefania Butini 《Tetrahedron letters》2013
We developed a novel and convenient stereoselective path for the preparation of pyrrolo-1,5-benzoxazepinones (PBOs). This innovative route envisaged the employment of (−)-menthol as convenient chiral auxiliary and a key SNAr for the stereoselective preparation of a tertiary aryl–alkyl ether. As a further advancement, we exploited this newly conceived synthetic route for the preparation of 2-substituted PBO analogues to either undergo biological evaluation themselves or give access to a variety of further functionalization options. 相似文献
38.
Balakrishna Dulla Sunder Kumar Kolli Upendar Reddy Chamakura Giridhar Singh Deora R. Ramesh Raju 《合成通讯》2014,44(10):1466-1474
A simple and inexpensive synthesis of novel 2-(3-oxo-3-arylpropyl)-2,3-dihydro-1H-inden-1-one derivatives has been achieved via Pd/C-mediated arylation followed by I2-mediated regioselective hydration of 2-(prop-2-ynyl)-2,3-dihydro-1H-inden-1-ones. A wide variety of 3-aryl substituted 2-propynyl indanone derivatives were conveniently prepared by using 10% Pd/C-PPh3-CuI as a catalyst system, some of which were used to prepare the corresponding ketones via alkyne hydration in the presence of catalytic I2. In an in vitro study a representative compound showed inhibition of PDE4B (phosphodiesterase type 4B) and binding with this protein in silico 相似文献
39.
Venkata Giridhar Poosarla T. S. Chandra 《Applied biochemistry and biotechnology》2014,173(6):1375-1390
An aerobic xylanolytic moderately halophilic and alkali-tolerant bacterium, Gracilibacillus sp. TSCPVG, produces multiple xylanases of unusual halo-acid-alkali-thermo-stable nature. The purification of a major xylanase from TSCPVG culture supernatant was achieved by hydrophobic and gel permeation chromatographic methods followed by electroelution from preparatory PAGE. The molecular mass of the purified xylanase was 42 kDa, as analyzed by SDS-PAGE, with a pI value of 6.1. It exhibited maximal activity in 3.5 % NaCl and retained over 75 % of its activity across the broad salinity range of 0–30 % NaCl, indicating a high halo-tolerance. It showed maximal activity at pH 7.5 and had retained 63 % of its activity at pH 5.0 and 73 % at pH 10.5, signifying the tolerance to broad acid to alkaline conditions. With birchwood xylan as a substrate, K m and specific activity values were 21 mg/ml and 1,667 U/mg, respectively. It is an endoxylanase that degrades xylan to xylose and xylobiose and had no activity on p-nitrophenyl-β-d-xylopyranoside, p-nitrophenyl-β-d-glucopyranoside, p-nitrophenyl acetate, carboxymethylcellulose, and filter paper. Since it showed remarkable stability over different salinities, broad pH, and temperature ranges, it is promising for application in many industries. 相似文献
40.
Electrodeposition and Magnetic Characterization of Iron and Iron–Silicon Alloys from the Ionic Liquid 1‐Butyl‐1‐methylpyrrolidinium Trifluoromethylsulfonate 下载免费PDF全文
Dr. Pulletikurthi Giridhar Dr. Bernd Weidenfeller Dr. Sherif Zein El Abedin Prof. Dr. Frank Endres 《Chemphyschem》2014,15(16):3515-3522
The electrodeposition of soft magnetic iron and iron–silicon alloys for magnetic measurements is presented. The preparation of these materials in 1‐butyl‐1‐methylpyrrolidinium trifluoromethylsulfonate, [Py1,4]TfO, at 100 °C with FeCl2 and FeCl2+SiCl4 was studied by using cyclic voltammetry. Constant‐potential electrolysis was carried out to deposit either Fe or FeSi, and deposits of approximately 10 μm thicknesses were obtained. By using scanning electron microscopy and X‐ray diffraction, the microstructure and crystallinity of the deposits were investigated. Grain sizes in the nanometer regime (50–80 nm) were found and the presence of iron–silicon alloys was verified. Frequency‐dependent magnetic polarizations, coercive forces, and power losses of some deposits were determined by using a digital hysteresis recorder. Corresponding to the small grain sizes, the coercive forces are around 950–1150 A m?1 and the power losses were at 6000 J m?3, which is much higher than in commercial Fe(3.2 wt %)Si electrical steel. Below a polarization of 1.8 T, the power losses are mainly caused by domain wall movements and, above 1.8 T, by rotation of magnetic moments as well as domain wall annihilation and recreation. 相似文献