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61.
The Padmakar–Ivan (PI) index of a graph G is defined as PI , where for edge e=(u,v) are the number of edges of G lying closer to u than v, and is the number of edges of G lying closer to v than u and summation goes over all edges of G. The PI index is a Wiener–Szeged-like topological index developed very recently. In this paper, we describe a method of computing
PI index of benzenoid hydrocarbons (H) using orthogonal cuts. The method requires the finding of number of edges in the orthogonal
cuts in a benzenoid system (H) and the edge number of H – a task significantly simpler than the calculation of PI index directly
from its definition.
On the eve of 70th anniversary of both Prof. Padmakar V. Khadikar and his wife Mrs. Kusum Khadikar. 相似文献
62.
63.
Rashmi C. Kulkarni S. Samundeeswari Farzanabi Shaikh Nirmala S. Naik Jyoti M. Madar Lokesh A. Shastri Vinay A. Sunagar 《Journal of fluorescence》2017,27(5):1613-1619
A variety of new coumarin derivatives containing C-4 bridged 2,6-dicyanoanilines (4a-4d) were synthesized via multicomponent one pot approach. These novel sensors were characterized by spectral analysis and a series of pH sensing fluorescence studies were performed, the results indicating that the sensors are highly selective and more effective at various pH. The fluorescence colour changes at different pH could be directly detected by naked eyes. 相似文献
64.
Anirban Ghosh Jyoti Ranjan Sahu S. Venkataprasad Bhat C.N.R. Rao 《Solid State Sciences》2009,11(9):1639-1642
Magnetic and dielectric measurements confirm the multiferroic nature of LuMnO3. Raman spectra of LuMnO3 have been recorded in the 77–800 K range covering both the antiferromagnetic transition at 90 K and the ferroelectric–paraelectric transition at 750 K. The changes in the phonon modes frequencies and band-widths indicate the presence of phonon–spin coupling in the antiferromagnetically ordered phase. The ferroelectric–paraelectric transition is accompanied by the broadening and disappearance of many of the phonon modes. Some of the phonon modes also show anomalies at the ferroelectric transition. 相似文献
65.
Recently measured inelastic X-ray spectra (IXS) of detailed coherent dynamical structure factor S(κ, ω) and hence the equilibrium collective dynamics, of the lightest liquid alkali metal, lithium at 475 K, have been successfully explained using the modified microscopic theory of the collective dynamics of a simple liquid, in a huge wave-vector, κ, range: 1.4 nm?1 ≤ κ ≤ 110.0 nm?1, ?κ is the linear momentum transfer. The role of single particle motion in the collective dynamics of the liquid changes from diffusive for smaller values of wave-vector, κ < 21 nm?1 to that of a free particle for higher κ-values, 21 nm?1 ≤ κ ≤ 110 nm?1. The quantum correction due to detailed balance condition in S(κ, ω) for liquid Li, whose dynamics, unlike that of quantum liquid 4He, is essentially classical, yields results in better agreement with the corresponding experimental S(κ, ω) and the quantum correction becomes significant for higher values of κ and ω. The wave-vector dependent variation of longitudinal viscosity, ηl, is in good agreement with the corresponding results obtained from memory function approach. The wave-vector dependent variation of single characteristic relaxation time lies in between the variation of two relaxation times of memory function approach. 相似文献
66.
Newton MA Dent AJ Diaz-Moreno S Fiddy SG Jyoti B Evans J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(7):1975-1985
Spatially and temporally resolved energy-dispersive EXAFS (EDE) has been utilised in situ to study supported Rh nanoparticles during CO oxidation by O2 under plug-flow conditions. Three distinct phases of Rh supported upon Al2O3 were identified by using EDE at the Rh K-edge during CO oxidation. Their presence and interconversion are related to the efficiency of the catalysts in oxidising CO to CO2. A metallic phase is only found at higher temperatures (>450 K) and CO fractions (CO/O2 > 1); an oxidic phase resembling Rh2O3 dominates the active catalyst under oxygen-rich conditions. Below about 573 K, and in CO-rich environments, high proportions of isolated Rh(I)(CO)2 species are found to co-exist with metallic Rh nanoparticles. Alongside these discrete situations a large proportion of the active phase space comprises small Rh cores surrounded by layers of active oxide. Confinement of Rh to nanoscale domains induces structural lability that influences catalytic behaviour. For CO oxidation over Rh/Al2O3 there are two redox phase equilibria alongside the chemistry of CO and O adsorbed upon extended Rh surfaces. 相似文献
67.
Bikshandarkoil R. Srinivasan Sunder N. Dhuri Jyoti V. Sawant Christian N?ther Wolfgang Bensch 《Journal of Chemical Sciences》2006,118(2):211-218
The organic diammonium salt N,N′-dibenzyl-N,N,N′,N′-tetramethylethylenediammonium dibromide dihydrate, (dbtmen)Br2.2H2O (1), was prepared by the reaction of N,N,N′,N′-tetramethyl-ethylenediamine (tmen) with benzyl bromide.1 crystallizes in the triclinic space group
with the following unit cell dimensions for C20H34Br2N2O2 (M = 494.31):a = 8.6672(6) ?,b = 11.7046(8) ?,c = 11.7731(8) ?, α = 76.988(8)°, β = 88.978(8)°, γ= 76.198(8)γ,V= 1129.26(13) ?3, Z=2. Three components, namely the (dbtmen)2+ dication, two bromide anions and two crystal water molecules constitute the structural arrangement of1. H2O molecules are linked to bromide anions via O-H...Br hydrogen bonding interactions resulting in the formation of a four-membered
O2Br2 cyclic dibromide. The O2Br2 units and the dications are arranged as alternating layers extending in the crystallographicbc plane. The arrangement of anions and cations may be viewed as a typical lamellar structure. The crystal water molecules can
be removed by heating 1 at 140°C and the anhydrous dibromide thus formed can be fully rehydrated as evidenced by IR spectra
and X-ray powder patterns.
Dedicated to Prof S Chandrasekaran on the occasion of his 60th birthday 相似文献
68.
Plaban Jyoti Sarma Debojyoti Bhattacharjee Bhupesh Kumar Mishra 《Molecular physics》2017,115(8):962-970
Dual level of quantum mechanical calculations have been carried out for hydrogen abstraction from Piperazine [HN(CH2CH2)2NH] initiated by OH radical. Geometry optimisation and frequency calculations of all species involved in the titled reaction have been performed at M06-2X/6-31+G(d,p) level of theory. For the accuracy in the thermochemistry and kinetics data, single-point energy calculations have been further carried out at coupled cluster CCSD(T) method along with 6-311G(d,p) basis set. An energy profile diagram for the reaction has been plotted along with pre-reactive and post-reactive complexes at entrance and exit channels. Intrinsic reaction coordinates (IRCs) calculations have been performed for identification of real transition states that connect it via reactant to product. Our result shows that the H-atom abstraction takes place from the C–H position of Piperazine. The rate constant is calculated using canonical transition state theory (CTST) is found to be 2.86 × 10?10 cm3 molecule?1 s?1 which is in good agreement with the reported experimental rate constant (2.38 ± 0.28) × 10?10 cm3 molecule?1 s?1 at 298 K. We have also reported rate constant for the temperature range 300–500 K. Using group-balance isodesmic reaction, the standard enthalpies of formation for Piperazine and product radicals generated by hydrogen abstraction are reported. The branching ratios for both reaction channel (i.e. H-abstraction from –CH2 and –NH position of Piperazine) are found to be 93% and 7%, respectively. The calculated atmospheric life time of Piperazine is found to be 0.97 hour. 相似文献
69.
Jyoti Rani K. L. Yadav Satya Prakash 《Applied Physics A: Materials Science & Processing》2014,117(3):1131-1137
Lead-free polycrystalline ceramic 0.55Ba(Zr0.2Ti0.8)O3–0.45(Ba0.7Ca0.3)TiO3 (0.55BZT–0.45BCT) was synthesized by sol–gel method and the dielectric, impedance and optical properties of this ceramic were studied. X-ray diffraction analysis revealed the formation of pure perovskite phase with the coexistence of tetragonal and rhombohedral structures. The high value of dielectric constant (~6,985) with low dielectric loss (~0.013) was obtained at room temperature. Bulk and grain boundary resistances were measured by impedance analysis, which revealed negative temperature coefficient of resistance behaviour in this ceramic. The estimated value of optical band gap was found to be ~3.16 eV, which is related to the presence of intermediate energy levels. Two emission bands one at ~365 nm (UV region) and another at ~465 nm (blue region) were observed in photoluminescence spectrum at room temperature. 相似文献
70.
Akshita Khandelwal Danish Khan Jyoti Kuntail Indrajit Sinha 《International journal of quantum chemistry》2024,124(1):e27237
Reducing p-nitrophenol (PNP) to p-aminophenol is an industrially relevant synthesis. Nevertheless, only a few heterogeneous catalysts have been evaluated for the reduction of PNP by glycerol. Appropriate quantum computational studies can screen potential catalysts for this crucial green reaction. The present research investigates the catalytic activities of Pd@Ag and Ni@Ag core-shell nanogeometries toward PNP reduction by glycerol through density functional theory (DFT) calculations. The central atom of a geometry-optimized 13-atom Ag cluster was replaced by Pd and Ni atoms to create the core-shell morphologies. The interaction energies of PNP and glycerol with each of the (metal/bimetallic) clusters were evaluated by DFT calculations to find the best PNP and glycerol molecule orientation with the respective bimetallic cluster. Electrostatic potential surface and natural bond orbital analyses were performed to study the charge distribution and transfer between atomic orbitals. The frequencies of vibrational modes in isolated PNP/glycerol structures were compared to those when these molecules were in the presence of the different metal clusters to infer the effect of the interactions. All performed analyses indicated improved catalytic activity toward PNP reduction by glycerol upon Ni-doping of the Ag13 cluster. 相似文献