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22.
23.
Chetan K. Modi Parthiv M. Trivedi Sanjeev K. Gupta Prafulla K. Jha 《Journal of inclusion phenomena and macrocyclic chemistry》2012,74(1-4):117-127
A series of zeolite-Y encapsulated hybrid catalysts, [M(STCH)·xH2O]-Y have been prepared by encapsulating Schiff base complexes [where M?=?Mn(II), Fe(II), Co(II), Ni(II); (x?=?3) and Cu(II); (x?=?1); H2STCH?=?salicylaldehyde thiophene-2-carboxylic hydrazone] in zeolite-Y matrix by flexible ligand method. These hybrid materials have been characterized by various physico-chemical techniques such as ICP-OES, elemental analyses, (FT-IR and electronic) spectral studies, BET, scanning electron micrographs, thermal analysis and X-ray powder diffraction patterns. X-ray powder diffraction analysis reveals that the structural integrity of the mother zeolite in the hybrid material remained intact upon immobilization of the complex. Density functional theory is employed to calculate the relaxed structure, bond angle, bond distance, dihedral angle, difference of highest occupied molecular orbital and lowest unoccupied molecular orbital energies gap and electronic density of states of ligand and their neat transition metal complexes. The hybrid materials are active catalysts for the hydroxylation of phenol using hydrogen peroxide (30% H2O2) as an oxidant in order to selectively synthesize catechol or hydroquinone, amongst them [Cu(STCH)·H2O]-Y shown the highest % of selectivity towards catechol (81.3%). 相似文献
24.
In the present investigation, we describe some novel calixarene based heterocyclic compounds (5a-5i) in which 1,3,4-oxadiazole and 1,3,4-thiadiazole derivatives have been coupled with 5,11,17,23-tetra-tert-butyl-25,27-bis(chlorocarbonyl-methoxy)-26,28-dihydroxy calix[4]arene. All the newly synthesized calixarene based heterocyclic compounds have been characterized by elemental analysis and various spectroscopic methods like FTIR, (1)H NMR, (13)C NMR, and FAB-MS. All the final scaffolds have been subjected to antioxidant activity, in vitro antimicrobial screening against two gram (+ve) bacteria (S. aureus, S. pyogenes), two gram (-ve) bacteria (E. coli, P. aeruginosa) and two fungal strains (C. albicans, A. clavatus) and also have been screened for their antitubercular activity against Mycobacterium tuberculosis H(37)Rv. 相似文献
25.
Ravi Vithalani Dikin S. Patel Chetan K. Modi Vaishali Sharma Prafulla K. Jha 《应用有机金属化学》2020,34(4):e5500
Graphene oxide (GO) supported transition metal complexes are apprised as sturdy and everlasting heterogeneous catalysts. GO surface was functionalized with 3-triethoxysilylpropylamine (TSPA) and this amino functionalized GO (A-f-GO) nanocomposite with vanadyl Schiff base complex (VO-f-GO) was prepared and to give credence of its potentiality, it was chosen for the selective epoxidation of styrene using environmentally benign 30% H2O2 to styrene oxide (SO). To evade the detrimental exposure of “inborn” water, a selective high boiling and potent hygroscopic solvent, ethylene glycol was chosen to make this transformation productively successful. With the assistance of theoretical studies, we have probed the effect of H2O2 on to structural properties, binding mechanism and electronic properties of the catalyst and substrate. Adsorption energy (Ead), energy band gap (Eg) and HOMO-LUMO were also calculated. Based on DFT calculations, resonance Raman and UV/Vis studies, we confirmed the formation of metal-peroxo species and propose the plausible catalytic pathway. The influence of the diverse experimental parameters, like substrate to oxidant mole ratio, catalyst concentration, type of solvents, solvent amount, time, temperature and oxidant were tested. A clear relationship was found between different reaction parameters like solvent amount, oxidant, catalyst concentration and temperature etc. and product distribution. This heterogeneous catalyst yielded styrene oxide as nearly the sole product (selectivity = 98.7%) with a conversion value of 99.2% in the oxidation of styrene with hydrogen peroxide in ethylene glycol. 相似文献
26.
The fluoroquinolone family member ciprofloxacin is well known for its drug design and coordinating ability towards metal ions. The coordination chemistry of this drug with metal ions of biological and pharmaceutical importance is of considerable interest. Novel Mn(III) mixed‐ligand complexes of ciprofloxacin with various bis‐pyrazolone‐based dinegative bidentate ligands were synthesized and characterized on the basis of their physical properties, magnetic susceptibility measurements, (FT‐IR and electronic) spectral studies. The FAB‐mass spectrum of [Mn(A9)(L)(H2O)2]·H2O [where H2A9 = 4,4′‐(p‐tolylmethylene)bis(3‐methyl‐1‐phenyl‐4,5‐dihydro‐1H‐pyrazol‐5‐ol) and HL = 1‐cyclopropyl‐6‐fluoro‐4‐oxo‐7‐(piperazin‐1‐yl)‐1,4‐dihydroquinoline‐3‐carboxylic acid] was determined. All the synthesized compounds were screened for their bioactivity. The mixed‐ligand complexes exhibited comparable activities against two Gram‐negative (Escherichia coli and Serratia marcescens) and two Gram‐positive (Staphylococcus aureus and Bacillus subtilis) microorganisms. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
27.
28.
Towards a total synthesis of the new anticancer agent mensacarcin: synthesis of the carbocyclic core
Tietze LF Stewart SG Polomska ME Modi A Zeeck A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(20):5233-5242
A synthesis of the carbocyclic core associated with the new anticancer agent mensacarcin (1) is reported. The strategy involves the synthesis of several novel highly substituted aromatic compounds, such as 12 and 23. The lithium derivative of 12 readily engages in a nucleophilic addition to benzaldehyde 4 to provide the diphenylcarbinol rac-15. The analogous benzyl ether rac-16 undergoes an intramolecular Heck reaction to provide the required tetrahydroanthracene rac-17, which can be transformed into the key tricyclic methyl ether rac-20. In a second approach, the lithium derivative of 21 is added to the hexasubstituted benzaldehyde 23 to give the diphenylcarbinol rac-35. Subsequent methylation to rac-36 followed by an intramolecular Heck reaction provides tricycle rac-37. Similarly, the oxidised compound 40 provides an electronically more suitable intramolecular Heck partner to afford compound 41. Further transformations of these substrates leads to rac-43, which incorporates the core structure of mensacarcin (1). 相似文献
29.
The synthesis of novel achiral and chiral amides incorporating 1,3,4-oxadiazole ring are reported. All the synthesized amides are characterized 1H, 13C, FTIR and elemental analysis techniques. Synthesized compounds are screened for microbial and cytotoxic activities. 相似文献
30.
K. B. Modi T. K. Pathak N. H. Vasoya V. K. Lakhani G. J. Baldha P. K. Jha 《Indian Journal of Physics》2011,85(3):411-420
The X-ray Debye temperatures, θ
M
, of spinel ferrite composition Ni0.5Zn0.5Fe2O4, mechanically milled upto 9 hrs, were determined from integrated intensities of selected Bragg reflections. The θ
M
was found to increase with milling time. The results are explained in the light of milling induced grain orientation and
surface effect. The values of θ
M
were found to be lower as compared to the Debye temperatures obtained from infrared spectral data analysis. The difference
can be explained on the basis of increase in an excess free volume in the form of vacancies and vacancy clusters associated
with grain boundaries. 相似文献