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61.
The synthesis of enantiopure unsymmetrical N-heterocyclic based zwitterions incorporating imidazolinium and alkylsulfonate or sulfamate groups is described. The desired compounds were prepared in good yields from 1,3-propanesultone or cyclic sulfamidates and imidazolines. The imidazolinium based zwitterions proved to be versatile chiral solvating agents for Mosher’s acid, alcohols, cyanohydrins, amino alcohols, nitro alcohols, thiols, and carboxylic acids with very high shifts in the 1H and 19F NMR. 相似文献
62.
Complexes of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and U(IV)O2 with (Z)-2-oxo-2-(2-(2-oxoindolin-3-ylidene)hydrazinyl)-N-phenylacetamide (H2OI) are reported and have been characterized by various spectroscopic techniques like (IR, UV–Vis, ESR 1H and 13C NMR) as well as magnetic and thermal (TG and DTA) measurements. It is found that the ligand behaves as a neutral tridentate, neutral tetradentate, monoanionic tridentate, monoanionic tridentate and dianionic tridentate. An octahedral geometry for all complexes except [Cu2(H2OI)(OAc)4](H2O)2 and [Cu(HOI)Cl](H2O)2 which have a square planar geometry. Furthermore, kinetic parameters were determined for each thermal degradation stage of some studied complexes using Coats–Redfern and Horowitz–Metzger methods. The bond lengths, bond angles, HOMO, LUMO and dipole moments have been calculated to confirm the geometry of the ligand and the investigated complexes. 相似文献
63.
Ata Allah Taleizadeh David W. Pentico Mirbahador Aryanezhad Seyed Mohammad Ghoreyshi 《European Journal of Operational Research》2012
A constant unit purchase cost is one of the main assumptions in the classic economic order quantity model. In practice, suppliers sometimes offer special sale prices to stimulate sales or decrease inventories of certain items. In this paper we develop an EOQ model with a special sale price and partial backordering. We prove the convexity of the cost-reduction function if a special order is placed at the special sale price. A solution method is proposed and numerical examples are presented. 相似文献
64.
Medhat A. Rakha 《Journal of Mathematical Analysis and Applications》2004,294(1):181-195
In previous paper [Ann. Comb. 4 (2000) 347-373], we established and proved two new q-beta integrals and two multivariate basic hypergeometric series associated with the root system of Am. In this paper we give a detailed proof of the multivariate basic hypergeometric series obtained in [Ann. Comb. 4 (2000) 347-373]. 相似文献
65.
Various flow phenomena of black particles (b-particles) and grey particles (g-particles) produced in magnesium-emulsion (Mg-Em) collisions at 4.5 A GeV /c are reported. These flows are directed and elliptic transverse flows (v1 and v2) related by the azimuthal angle (φ), directed and elliptic reaction plane flows (vR1 and vR2) related by the projected angle (ψ) on the reaction plane, and directed and elliptic polar direction flows (vP1 and vP2) related by the polar angle (θ). We extract absolute flows as the direct experimental values minus the isotropic theoretical values. The dependence of the various flows on the target particle multiplicity and on the angles (θ,φ,ψ) is investigated. Our results show that the dependence of b-particle flows on the target size is obvious and for heavy targets the dependence on target particle multiplicity is slight. Compared with b-particles, g-particles have a slight dependence on the target size and target particle multiplicity. 相似文献
66.
Heshmat Allah Samimi Fariba Mohammadian-Sabet Hedayat Haddadi 《Molecular physics》2013,111(12):1442-1450
The mutual influence between anion–π and chalcogen bond interactions is studied by ab initio calculations at the MP2/6-311++G** level of theory. These effects are analysed in detail in terms of the structural, energetic, charge-transfer and electron density properties of the complexes. Interesting cooperativity effects are found when anion–π and chalcogen-bonding interactions coexist in the same complex. The effect of anion–π on the properties of chalcogen bonding is larger than that of chalcogen bonding on the properties of anion–π. The cooperative mechanism is analysed in terms of the electrostatic potentials, orbital interaction and electron density analysis. 相似文献
67.
A constant unit purchase cost is one of the main assumptions in the classic Economic Order Quantity model. In practice, suppliers sometimes face a known price increase. In this paper, we develop EOQ models with a known price increase and partial backordering under two different assumptions about when the increase will occur. We prove the concavity of the extra profit functions for both scenarios if a special order is placed just before the price increases. A solution method is proposed and numerical examples are presented. 相似文献
68.
In this research, the magnetic and optical properties of SrFe2O4 ceramic were studied. The calculations were performed by Full Potential Linearized Augmented Plane Wave method in Density Functional Theory framework with generalized gradient (GGA), GGA+U and modified Becke–Johnson approximations for the exchange and correlation functionals. The results show that SrFe2O4 is a ferrimagnetic ceramics with six different spin configurations. The Hubbard parameter was calculated (Ueff=4.5 eV) by an ab initio method. The optical properties such as dielectric function, refraction index, electron energy-loss function, reflectivity, absorption coefficient and optical conductivity were investigated at zero up to 20 GPa pressure in x, y and z directions. The pressure coefficients of optical band, static dielectric constant, plasmon peak, static refraction index and the maximum of absorption were determined. Moreover, the pressure dependence of the static dielectric constant, plasmon peak, static refraction index, the maximum of absorption and the optical gap were investigated. 相似文献
69.
Journal of Experimental and Theoretical Physics - In this paper, we study cylindrically symmetric perfect fluid distribution in the presence of cosmological constant satisfying two cases of... 相似文献
70.
Bushra Nisar Syeda Laila Rubab Abdul Rauf Raza Sobia Tariq Ayesha Sultan Muhammad Nawaz Tahir 《Molecular diversity》2018,22(3):709-722
Novel and highly sensitive indole-based imines have been synthesized. Their synthesis has been compared employing a variety of protocols. Ultimately, a convenient, economical and high yielding set of conditions employing green chemistry have been designed for their synthesis. 相似文献