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排序方式: 共有84条查询结果,搜索用时 15 毫秒
31.
Shailendra K. Saxena Rupnayan Borah Vivek Kumar Hari Mohan Rai Ravikiran Late V.G. Sathe Ashisha Kumar Pankaj R. Sagdeo Rajesh Kumar 《Journal of Raman spectroscopy : JRS》2016,47(3):283-288
A combined effect of doping (type and species) and size on Raman scattering from silicon (Si) nanowires (NWs) has been presented here to study interplay between quantum confinement and Fano effects. The SiNWs prepared from low doping Si wafers show only confinement effect, as evident from the asymmetry in the Raman line‐shape, irrespective of the doping type. On the other hand SiNWs prepared from wafer with high doping shows the presence of electron–phonon interaction in addition to the phonon confinement effect as revealed from the presence of asymmetry and antiresonence in the corresponding Raman spectra. This combined effect induces an extra asymmetry in the lower energy side of Raman peak for n‐type SiNWs whereas the asymmetry flips from lower energy side to the higher energy side of the Raman peak in p‐type SiNWs. Such an interplay can be represented by considering a general Fano‐Raman line‐shape equation to take care of the combined effect in SiNWs. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
32.
The N,N′-disubstituted urea derivatives such as amino acid hydantoins and dihydrouracil derivatives were prepared starting from natural and unnatural amino acid esters using dibutylphosphate (DBP). During the attempted synthesis of N-heterocycles with larger than six-membered rings containing the N,N′-disubstituted urea functionalities, three unexpected products namely squamolone, N-methyl pyrrolidine-2-one, and diketopiperazine were isolated. 相似文献
33.
Pramod S. Phatak Bhaurao P. Sathe Sambhaji T. Dhumal Naziya N. M. A. Rehman Prashant P. Dixit Vijay M. Khedkar Kishan P. Haval 《Journal of heterocyclic chemistry》2019,56(7):1928-1938
A series of molecules containing acetylphenoxymethyl, triazole, and N‐phenylacetamide moieties were synthesized via the click chemistry approach. All the synthesized compounds were screened for their antimicrobial activities in vitro. The synthesized compounds 8a , 8b , 8m , and 8n showed better activities. We further performed exploratory docking studies to gain some insight regarding the molecular mechanism of antibacterial action of these compounds that could guide further structure‐activity relationship (SAR) studies. We examined the interaction of the most active compound with DNA gyrase (pdb id:1KZN). Based on antimicrobial and docking studies, the compounds 8a , 8b , 8m , and 8n were identified as potential antimicrobial agents. 相似文献
34.
W Wang Z Liu L Ma C Hao S Liu VG Voinov NI Kalinovskaya 《Rapid communications in mass spectrometry : RCM》1999,13(12):1189-1196
Electrospray ionization (ESI) combined with multiple-stage tandem mass spectrometry (MS(n)) was used to directly analyze the glycolipid mixture from bacteria Bacillus pumilus without preliminary separation. Full scan ESI-MS revealed the composition of picomole quantities of glycerolglycolipid species containing C(14)-C(19) fatty acids, some of which were monounsaturated. Two main components were identified from their molecular masses and fragmentation pathways. The fragmentation pathway of the known compound compared with the investigated compound verified the proposed structure as 1(3)-acyl-2-pentadecanoyl-3(1)-O-[beta-D-glucopyranosyl-(1-->6)-O-beta-D-glucopyranosyl]-sn-glycerols. A comparison of the multiple tandem mass spectra of the different alkali-metal cation adducts indicates that the intensity of fragments and the dissociation pathways are dependent on the alkali-metal type. The basic structures of glycerolglycolipids were reflected clearly from the fragmentation patterns of the sodium cations. The intense fragments of the sugar residue from the precursor ions were obtained from the lithiated adduct ions. ESI-MS(n) spectra of [M + K](+) ions did not provide as much fragmentation as [M + Na](+) and [M + Li](+) adducts, but their spectra allow the position of glycerol acylation to be determined. On the basis of MS(2) spectra of [M + K](+) ions, it was established that all components have a C(15:0) fatty acid at the sn-2 position of the glycerol backbone and C(14)-C(19) acids at the sn-1 position of the glycerol backbone. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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38.
Vijay L. Suryavanshi Padmakar A. Sathe Vikas V. Vaidya Manisha M. Baing Ganesh R. Singh 《Chromatographia》2008,67(1-2):189-191
A simple, reproducible and efficient reverse phase high performance liquid chromatographic method has been developed for the
determination of rutin in whole plant powder of Amaranthus spinosus Linn. The analysis was done with Waters Cosmosil C18 column (150 × 4.6 mm i.d., 5 μm particle size) as stationary phase at a wavelength of 361 nm for detection and determination.
The proposed HPLC method was validated for linearity, accuracy, precision and limit of quantitation. 相似文献
39.
Evidence of the Fano resonance in a temperature dependent Raman study of CaCu3Ti4O12 and SrCu3Ti4O12
Phononic excitations have been investigated using Raman scattering studies on CaCu(3)Ti(4)O(12) and SrCu(3)Ti(4)O(12) compounds as a function of temperature down to 10 K. Evidence of the Fano resonance effect is found in the A(g)(1) mode with an asymmetric phonon line shape that occurs because of composite electron-phonon scattering due to the onset of metallic fractions in the system. The evolution of the Fano line shape with temperature affirms the existence of nanoscale phase separation and the prominence of orbitally disrupted metallic regions above 100 K. Anomalies in the evolution of the line width of the A(g)(1) Raman mode with temperature are observed around 100 K where these compounds show an orbital order/disorder transition. These anomalies manifest mutual coupling of orbital degrees of freedom to lattice degrees of freedom. 相似文献
40.
K. Ravikumar B. Sridhar D. G. Sathe A. V. Naidu K. D. Sawant 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(12):o681-o683
Donepezil, a cholinesterase inhibitor with good central nervous system penetration, has been crystallized as a tertiary amine salt with a disordered oxalate anion to give the title compound, (R,S)‐1‐benzyl‐4‐[(5,6‐dimethoxy‐1‐oxoindan‐2‐yl)methyl]piperidinium hydrogen oxalate trihydrate, C24H30NO3+·C2HO4−·3H2O. The indanone and piperidine ring planes are inclined at an angle of 33.4 (1)°. A comparison is made with the piperidinium cation bound in acetylcholinesterase in the solid state. The methylene units bridging the indanone–piperidine–benzyl groups determine the molecular shape and conformational features. The structure is stabilized mainly by O—H⋯O and N—H⋯O hydrogen bonds, with water molecules mediating interactions between oxalate anions and donepezilium cations. 相似文献