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101.
A group of novel 2-aryl imidazole derivatives were synthesized and characterized by NMR spectra, X-ray, mass and CHN analysis.
An excited state intramolecular proton transfer (ESIPT) process in hydroxy imidazoles (dmip and dmtip) have been studied using
emission spectroscopy and it was detected that the two distinct ground state rotamers of I and II are responsible for the
normal and the tautomer emission respectively. In hydrocarbon solvent, the tautomer emission predominates over the normal
emission for both dmip and dmtip. This reveal that rotamer II is responsible for the tautomer emission and it is stabler than
rotamer I which causes the normal emission. In alcoholic solvent like ethanol, a dramatic enhancement of normal emission is
observed which was due to increased solvation, the more polar rotamer I become stabler than rotamer II. In dioxane—water mixtures
it is observed that the addition of water inhibits the ESIPT process due to the formation of the intermolecular hydrogen bonding
involving water. DFT calculations on energy, dipole moment, charge distribution of the rotamers in the ground and excited
states of the imidazole derivatives were performed and discussed. PES calculation indicates that the energy barrier for the
interconversion of two rotamers is too high in the excited state than the ground state. 相似文献
102.
Patil NR Melavanki RM Kapatkar SB Ayachit NH Saravanan J 《Journal of fluorescence》2011,21(3):1213-1222
The absorption and fluorescence spectra of three Carboxamides namely (E)-2-(4-Chlorobenzylideneamino)-N-(2-chlorophenyl)-4,
5, 6, 7-tetrahydrobenzo[b]thiophene-3-carboxamide (C1), (E)-N-(3-Chlorophenyl)-2-(3, 4-dimethoxybenzylideneamino)-4, 5, 6, 7-tetrahydrobenzo[b]thiophene-3-carboxamide (C2) and (E)-N-(3-Chlorophenyl)-2-(3, 4, 5-trimethoxybenzylideneamino)-4, 5, 6, 7-tetrahydrobenzo[b]thiophene-3-carboxamide (C3) have been recorded at room temperature in solvents of different polarities using dielectric constant (ε) and refractive
index (n). Experimental ground (μg) and excited (μe) state dipole moments are estimated by means of solvatochromic shift method and also the excited dipole moments are estimated
in combination with ground state dipole moments. It was estimated that dipole moments of the excited state were higher than
those of the ground state of all three molecules. Further, the changes in dipole moment (Dm \Delta \mu ) were calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter
(ETN E_T^N ) and the values are compared. 相似文献
103.
Saravanan Vinnarasi Rajamani Akilan Subramaniam Vijayakumar Ramasamy Shankar 《Structural chemistry》2020,31(1):465-484
Structural Chemistry - The present study is focused to cast light on the structural, electronic and energetic properties of isolated (G4)2 and (X4)2 DNA quadruplexes with transition metal cations... 相似文献
104.
Jielin Zhang Eleonora Grandi Haigen Fu Thangavelu Saravanan Laura Bothof Pieter G. Tepper Andy‐Mark W. H. Thunnissen Gerrit J. Poelarends 《Angewandte Chemie (International ed. in English)》2020,59(1):429-435
Aspartic acid derivatives with branched N‐alkyl or N‐arylalkyl substituents are valuable precursors to artificial dipeptide sweeteners such as neotame and advantame. The development of a biocatalyst to synthesize these compounds in a single asymmetric step is an as yet unmet challenge. Reported here is an enantioselective biocatalytic synthesis of various difficult N‐substituted aspartic acids, including N‐(3,3‐dimethylbutyl)‐l ‐aspartic acid and N‐[3‐(3‐hydroxy‐4‐methoxyphenyl)propyl]‐l ‐aspartic acid, precursors to neotame and advantame, respectively, using an engineered variant of ethylenediamine‐N,N′‐disuccinic acid (EDDS) lyase from Chelativorans sp. BNC1. This engineered C–N lyase (mutant D290M/Y320M) displayed a remarkable 1140‐fold increase in activity for the selective hydroamination of fumarate compared to that of the wild‐type enzyme. These results present new opportunities to develop practical multienzymatic processes for the more sustainable and step‐economic synthesis of an important class of food additives. 相似文献
105.
Dr. Saravanan Gowrisankar Dr. Jayasree Seayad 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):12754-12758
A novel copper‐catalyzed C?H arylation of heteroarenes with anilines by an in situ diazonium reaction is established by using silver nitrite (AgONO) as an unconventional nitrosating reagent under acid‐free conditions. It provides a complementary approach for the C?H arylation of electron‐rich heteroarenes with aromatic amines affording a variety of heterobiaryls in moderate to good yields. 相似文献
106.
Development and investigation of the flexible hydrogen sensor based on ZnO-decorated Sb2O3 nanobelts
Natarajan Pradeep Gopal Tamil Selvi Uma Venkatraman Quyet Van Le Soon Kwan Jeong Saravanan Pandiaraj Abdullah Alodhayb Muthumareeswaran Muthuramamoorthy Andrews Nirmala Grace 《Materials Today Chemistry》2021
Hydrogen is regarded as the next-gen fuel for vehicles to avoid the emission of toxic gases, which needs a continuous monitoring of the concentration level. In the design of the H2 sensor, especially of flexible type, a sensing layer will be blended, which affects the sensing performance of the device. Based on this concern, the present investigation is carried out to understand the effect of the bending angle toward the sensing performance of bare and ZnO (n-type)-decorated Sb2O3 (p-type) nanobelt–based sensors for hydrogen gas. The sensing element was prepared by the thermal chemical vapor deposition followed by the drop-casting method. Furthermore, the role of the zinc precursor (molar concentration—1 M–3 M) on the preparation of ZnO-decorated Sb2O3 nanobelts was studied. Various techniques were used to confirm the formation of ZnO-decorated nanobelts such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), and Fourier transform infrared spectroscopy (FTIR). From these analyses, 1 M concentration of the zinc precursor shows uniform distribution of nanoparticles over the surface of Sb2O3 nanobelts. However, agglomeration was observed when the concentration of the zinc precursor increases from 1 M to 3 M. Later, the prepared nanobelts were deposited on the OverHead Projector (OHP) sheet by the doctor blade method for sensing hydrogen gas at 100 °C at a concentration of 1000–3000 ppm. In addition to it, the effect of the substrate bending angle (0°, 45°, 60°, and 90°) was analyzed at a fixed concentration of H2 gas (1000 ppm). From this study, it is clear that the highest sensing response was achieved for 1 M decorated nanobelts compared with bare as well as other concentrations because of uniform distribution of nanoparticles on the surface of nanobelts. Moreover, the prepared sample demonstrates better sensing performance with the bending of substrates, which suggests that the prepared sensor could be used for flexible electronic devices. The prepared nanobelts show a good H2 gas–sensing response even with bending of the substrates. The work suggests that the prepared sensor is applicable for flexible electronic devices. 相似文献
107.
Balasubramanian KP Karvembu R Prabhakaran R Chinnusamy V Natarajan K 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(1):50-54
Complexes of the type [Ru(CO)(EPh(3))(B)(L)] (E = P or As; B = PPh(3), AsPh(3), py or pip; L=dianion of the Schiff bases derived from thiosemicarbazone with acetoacetanilide, acetoacet-o-toluidide and o-chloro acetoacetanilide) have been synthesized from the reactions of equimolar amounts of [RuHCl(CO)(EPh(3))(2)(B)] and Schiff bases in benzene. The new complexes have been characterized by analytical and spectral (IR, electronic, NMR) data. The arrangement of PPh(3) groups around ruthenium metal was determined from (31)P NMR spectra. An octahedral structure has been assigned for all the new complexes. All the complexes exhibited catalytic activity for the oxidation of benzyl alcohol and cyclohexanol in presence of N-methylmorpholine-N-oxide as co-oxidant. The complexes also exhibited antibacterial activity against E. coli, Aeromonas hydrophilla and Salmonella typhi. The activity was compared with standard streptomycin. 相似文献
108.
Pascual Winter MF Rozas G Fainstein A Jusserand B Perrin B Huynh A Vaccaro PO Saravanan S 《Physical review letters》2007,98(26):265501
Femtosecond pump-probe experiments on a Ga0.85In0.15As nanocavity enclosed by two Ga(0.85)In(0.15)As/AlAs phonon Bragg mirrors reveal selective generation of terahertz confined acoustic modes and regular folded phonons. Selective generation of the confined modes alone is achievable for laser excitation at certain energies below the mirror absorption edges, corresponding to electronic transitions within the cavity layer only. Calculations based on the photoelastic effect explain the experimental results. Decay times of cavity and regular modes evidence longer decay times and anharmonic effects for the cavity mode. 相似文献
109.
G. Sai Saravanan K. Mahadeva Bhat H. P. Vyas K. Muraleedharan A. P. Pathak 《辐射效应与固体损伤》2013,168(9):737-748
The active layers of Metal Semiconductor Field Effect Transistors (MESFETs) are obtained by Si29+ ion implantation in GaAs. Implantation was done at 35 keV with a higher dose near the wafer surface for facilitating easier formation of ohmic contacts, and at 180 keV with a lower dose for obtaining the device channel. Post-implantation annealing was carried out in a rapid thermal processor for activating the implants. Very high activation levels of about 60% for the n+ GaAs layer, and 85% for the n-GaAs channel layer were achieved by annealing at 955 °C for 25 s. Activation was characterized using C–V profiling, secondary ion mass spectrometry and by electrical device data of fabricated MESFETs. We attempt an experimental correlation between the ohmic contact resistance (R c) and activation of both the n+ and the channel layer. It was found that very high and simultaneous activation of the n+ and channel layers results in very low contact resistances. The conduction of source-drain current into the channel is easily facilitated due to reduction in the resistance of the transition region at the interface of n+-contact and n-channel layers. 相似文献
110.