全文获取类型
收费全文 | 510篇 |
免费 | 20篇 |
专业分类
化学 | 363篇 |
晶体学 | 2篇 |
力学 | 16篇 |
数学 | 36篇 |
物理学 | 113篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 20篇 |
2021年 | 11篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 21篇 |
2017年 | 12篇 |
2016年 | 22篇 |
2015年 | 13篇 |
2014年 | 16篇 |
2013年 | 29篇 |
2012年 | 32篇 |
2011年 | 42篇 |
2010年 | 23篇 |
2009年 | 16篇 |
2008年 | 32篇 |
2007年 | 25篇 |
2006年 | 20篇 |
2005年 | 25篇 |
2004年 | 17篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 12篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
排序方式: 共有530条查询结果,搜索用时 9 毫秒
71.
Kailey A. Wyman Adel S. Girgis Pragnakiran S. Surapaneni Jade M. Moore Noura M. Abo Shama Sara H. Mahmoud Ahmed Mostafa Reham F. Barghash Zou Juan Radha D. Dobaria Ahmad J. Almalki Tarek S. Ibrahim Siva S. Panda 《Molecules (Basel, Switzerland)》2022,27(18)
We synthesized a set of small molecules using a molecular hybridization approach with good yields. The antiviral properties of the synthesized conjugates against the SAR-CoV-2 virus were investigated and their cytotoxicity was also determined. Among all the synthesized conjugates, compound 9f showed potential against SARS-CoV-2 and low cytotoxicity. The conjugates’ selectivity indexes (SIs) were determined to correlate the antiviral properties and cytotoxicity. The observed biological data were further validated using computational studies. 相似文献
72.
The interplay between superconductivity (SC) and antiferromagnetism (AFM) is studied in strongly correlated systems of high
T
c
Cuprate superconductors. It is assumed that superconductivity arises due to BCS pairing mechanism in presence of AFM in Cu lattices of Cu-O planes. The total Hamiltonian of the system is mean field one
and has been solved exactly by writing the equations of motion for the single particle Green’s functions. Equations for the
appropriate single particle co-relation functions are derived and the order parameters corresponding to SC and AFM are determined.
It is assumed that the Fermi energy ∈
F
= 0 and the renormalized localized f energy level coincide with the Fermi level. All the quantities in the final equation for h and Δ are made dimensionless by dividing by 2t, where t is the hopping integral. The temperature dependent values of staggered magnetic field (h) and SC gap (Δ) were determined by solving self-consistent equations for h and Δ. The quasiparticle energy bands are function of AFM gap (h), SC gap (Δ) and hybridization (V). Then the dispersion of quasi-particles are studied at different temperatures by considering temperature dependent values
of h and Δ and varying other different model parameters.
相似文献
73.
The kinetics of electron transfer from hexacyanoferrate(II) to tris(dimethylglyoximato)-nickelate(IV), Ni(dmg)32?, to produce Fe(CN)63? and Ni(dmgH)2, follows a pseudo-first-order disappearance in the Ni(IV). The pseudo-first-order rate constants kobs are linearly dependent on [Fe(CN)64?]0 in a fiftyfold range of 2 × 10?4?1 × 10?2M, and the average values of kobs/[Fe(CN)64?]0 range from 194M?1·s?1 at pH = 5.20 to 0.2M?1·s?1 at pH = 9.07 in aqueous medium at 35°C and μ = 0.57M. Results are interpreted in terms of a probable mechanism involving rate-determining outer sphere one-electron transfer steps from the reductant and one-protonated reductant species to the unprotonated and one-protonated Ni(IV) species present in solution. The more electrophilic one-protonated reductant species apparently reacts several orders of magnitude faster than the unprotonated one. 相似文献
74.
75.
This paper investigates the problem of free convection flow of a second order liquid in the boundary layer from a semi-infinite vertical plate in which the mean surface temperature varies as a function of the distance from the leading edge of the plate. Study of the oscillatory flow is restricted to small amplitudesε only. Several graphs have been drawn and tables have been presented to depict the effect of elasticity of the liquid and Prandtl number on the velocity and temperature distributions and Nusselt number. 相似文献
76.
Chitta R. Panda Vivekananda Chakravortty Kailash C. Dash 《Transition Metal Chemistry》1988,13(4):287-290
Summary Interaction of ZrOCl2:8H2O, [Zr4(OH)8(H2O)16]Cl8 12H2O, with the heterocyclic, aldimines (PyAlA) and heterocyclic ketimines (AcPyA) in Me2CO in the presence of HC(OEt)3 yields white amorphous compounds of the type [Zr4(OH)12(H2O)8(PyAlA)2]Cl4 and [Zr4(OH)12(H2O)10(AcPyA)]Cl4. Presumably these compounds have a tetrameric dodecahedral structure, derived from the parent. The analytical data, i.r., electrical conductance and t.g. measurements all favour the tetrameric formulation. The t.g. studies also indicate the intermediacy of complex species, which lose water and the Schiff base ligands, with increase in temperature. 相似文献
77.
Reactions of PdL2 complexes, where LH = benzoylacetone, dibenzoyl methane, or dipivaloyl methane, with pyridine and neat β-diketones (L 1H trifluoroacetylacetone, hexafluoroacetylacetone, thenoyltrifluoroacetone and pivaloyltrifluoroacetone) in toluene resulted in the formation of central carbon (C3) bonded hetero-β-diketonate complexes of the formula [Pd(L)(C3-L′)py]. These were characterized by microanalyses, IR and 1H NMR spectral data. 相似文献
78.
The kinetics of oxidation of thiosulfate to tetrathionate by trans-dihydroxotetraoxoosmate(VIII) in aqueous alkaline media have been studied. The oxidation follows a rate expression where KOs is the formation constant of trans-dihydroxotetraoxoosmate (VIII), and K2 and k3, respectively, represent the formation constants of the intermediate complex involving Os(VIII) and S2O and its decomposition constant. The KOs, K2, and k3 values have been computed to be (19.5 ± 3) dm3/mol, (6.12 ± 0.5) and (3.32 ± 0.3) × 10?1 dm3/mol s at 303 K, and I = 0.32 mol/dm3, respectively. The rate law is consistent with a mechanism envisaging the equilibrium formation of an intermediate complex involving Os(VIII) and S2O, followed by a rate-determining decomposition of the complex with concomitant electron transfer. 相似文献
79.
The oxidation of trans-stilbene, phenylacetylene, and diphenylacetylene by Tl(OAc)3 in aqueous acetic acid medium in the presence of HClO4 follows the rate law in [H+] of 0.1–1.0M, the [H+] dependence below 0.1M being marginal. The reactions are strongly dielectric dependent. The order of reactivity among the substrates is styrene > phenylacetylene and trans-stilbene > diphenylacetylene. A mechanism involving the oxythallation adduct by the Tl+(OAc)2 species has been discussed. The use of Ru(III) as a homogeneous catalyst brings a change in the kinetic orders for trans-stilbene, the rate law being The formation constants K for the Ru(III)–alkene π complex at 40, 50, and 60°C are 90.14M?1, 105.2M?1, and 127.7M?1, respectively. Interestingly the oxidation of phenylacetylene and diphenylacetylene does not undergo catalysis by Ru(III). The mechanism involving the metal–arene π complex is discussed. 相似文献
80.
S. Panda B. K. Panda 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,76(2):187-196
In the fractional dimensional space, the ground state properties
of the charged-boson fluid
are studied in a theory which goes beyond the random
phase approximation by including correlations through
a static local-field-factor. The structure factor and static
local field-factor
are obtained in
the self-consistent method.
Qualitative agreement with
the Monte Carlo results on static screening is achieved
by imposing self-consistency
on the compressibility of the fluid in addition to self-consistency
on the structure factor.
Using the structure
factors obtained in these methods, several properties
of the charged boson system such as the energy spectrum of elementary
excitations, the pair-correlation function,
the ground state energy,
the pressure,
the chemical potential and the compressibility are obtained in several
dimensions including both integer and fractional values.
Results obtained in the later method in two and three dimensional
systems are close to the Monte Carlo and hypernetted-chain methods.
The Wigner crystallisation in the lower dimensional system is found at
higher density of bosons. However, it vanishes
in any lower dimensional system whose dimension lies below 2. 相似文献