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131.
The critical point (Kc) of the two-layer Ising model on the Kagome lattice has been calculated with a high precision, using the probabilistic cellular automata with the Glauber algorithm. The critical point is calculated for different values of the inter- and intra-layer couplings (K1≠K2≠K3≠Kz), where K1, K2 and K3 are the nearest-neighbor interactions within each layer in the 1, 2 and 3 directions, respectively, and Kz is the intralayer coupling. A general ansatz equation for the critical point is given as a function of the inter- and intra-layer interactions, ξ=K3/K1,σ=K2/K1 and ω=Kz/K1 for the one- and two-layer Ising models on the Kagome lattice. 相似文献
132.
Lili Zhang Mehrdad Negahban 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2012,63(6):1143-1176
We study the theory of propagation of infinitesimal thermo-mechanical waves in a special class of nonlinear viscoelastic materials under homogeneous and inhomogeneous finite static and time-varying deformations. These results are based on a thermodynamically consistent finite-deformation nonlinear viscoelastic model that reduces to a general linear viscoelastic model of integral form. On a thermo-mechanically deforming body, we impose a thermo-mechanical perturbation history and obtain the equations to solve for the perturbation parameters from the constitutive model and the balance laws. We use these equations to study the characteristics of different perturbations. We develop the special equations for both time-harmonic and time-damping plane waves for homogeneous pre-loads. 相似文献
133.
Amir A. Mehrdad Sharif Ali M. Astaraki Parviz Aberoomand Azar Saeed Abedini Khorrami Shahram Moradi 《Arabian Journal of Chemistry》2012,5(1):41-44
The effect of NaCl and Na2SO4 concentrations in aqueous phase on the phase inversion temperature (PIT) in nanoemulsions of water/Brij30/n-hexadecane system has been studied separately, and then compared. The variation of conductivity with temperature was measured by Cyber Scan PC510 conductivity meter for emulsions with 20 wt% hexadecane and 8 wt% Brij30 concentration and different concentrations of NaCl and Na2SO4 in aqueous phase. The results showed that with increasing concentrations of NaCl and Na2SO4 in aqueous phase, the PIT of nanoemulsions decreases. The effect of the elevation of concentration on the decrease of PIT was more for Na2SO4 in aqueous phase than NaCl with equal concentrations. 相似文献
134.
Mehrdad Pourayoubi Jerry P. Jasinski Samad Shoghpour Bayraq Hossein Eshghi Amanda C. Keeley Giuseppe Bruno Hadi Amiri Rudbari 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(10):o399-o404
In the phosphoric triamides N,N,N′,N′‐tetrabenzyl‐N′′‐(2‐chloro‐2,2‐difluoroacetyl)phosphoric triamide, C30H29ClF2N3O2P, (I), N,N,N′,N′‐tetrabenzyl‐N′′‐(3‐fluorobenzoyl)phosphoric triamide, C35H33FN3O2P, (II), and N,N,N′,N′‐tetrabenzyl‐N′′‐(3,5‐difluorobenzoyl)phosphoric triamide, C35H32F2N3O2P, (III), the tertiary N atoms of the dibenzylamido groups have sp2 character with minimal deviation from planarity. The sums of the three bond angles about the N atoms in (I)–(III) deviate by less than 8° from the planar value of 360°. The geometries of the tertiary N atoms in all phosphoric triamides with C(O)NHP(O)[N]2 skeletons deposited in the Cambridge Structural Database [CSD; Allen (2002). Acta Cryst. B 58 , 380–388] have been examined and the bond‐angle sums at the two tertiary N atoms (SUM1 and SUM2) and the parameter ΔSUM (= SUM1 − SUM2) considered. It was found that in compounds with a considerable ΔSUM value, the more pyramidal N atoms are usually oriented so that the corresponding lone electron pair is anti with respect to the P=O group. In (I), (II) and (III), the phosphoryl and carbonyl groups, separated by an N atom, are anti with respect to each other. In the C(O)NHP(O) fragment of (I)–(III), the P—N bond is longer and the O—P—N angle is contracted compared with the other two P—N bonds and the O—P—N angles in the molecules. These effects are also seen in analogous compounds deposited in the CSD. Compounds with [C(O)NH]P(O)[N]X (X≠ N), such as compounds with a [C(O)NH]P(O)[N][O] skeleton, have not been considered here. Also, compounds with a [C(O)NH]2P(O)[N] fragment have not been reported to date. In the crystal structures of all three title compounds, adjacent molecules are linked via pairs of P=O...H—N hydrogen bonds, forming dimers with Ci symmetry. 相似文献
135.
Mehrdad Pourayoubi Marek Ne
as Monireh Negari 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(2):o51-o56
In the hydrogen‐bond patterns of phenyl bis(2‐chlorobenzylamido)phosphinate, C20H19Cl2N2O2P, (I), and N,N′‐bis(2‐chlorobenzyl)‐N′′‐(2,2,2‐trifluoroacetyl)phosphoric triamide, C16H15Cl2F3N3O2P, (II), the O atoms of the related phosphoryl groups act as double H‐atom acceptors, so that the P=O...(H—N)2 hydrogen bond in (I) and the P=O...(H—Namide)2 and C=O...H—NC(O)NHP(O) hydrogen bonds in (II) are responsible for the aggregation of the molecules in the crystal packing. The presence of a double H‐atom acceptor centre is a result of the involvement of a greater number of H‐atom donor sites with a smaller number of H‐atom acceptor sites in the hydrogen‐bonding interactions. This article also reviews structures having a P(O)NH group, with the aim of finding similar three‐centre hydrogen bonds in the packing of phosphoramidate compounds. This analysis shows that the factors affecting the preference of the above‐mentioned O atom to act as a double H‐atom acceptor are: (i) a higher number of H‐atom donor sites relative to H‐atom acceptor centres in molecules with P(=O)(NH)3, (N)P(=O)(NH)2, C(=O)NHP(=O)(NH)2 and (NH)2P(=O)OP(=O)(NH)2 groups, and (ii) the remarkable H‐atom acceptability of this atom relative to the other acceptor centre(s) in molecules containing an OP(=O)(NH)2 group, with the explanation that the N atom bound to the P atom in almost all of the structures found does not take part in hydrogen bonding as an acceptor. Moreover, the differences in the H‐atom acceptability of the phosphoryl O atom relative to the O atom of the alkoxy or phenoxy groups in amidophosphoric acid esters may be illustrated by considering the molecular packing of compounds having (O)2P(=O)(NH) and (O)P(=O)(NH)(N)groups, in which the unique N—H unit in the above‐mentioned molecules almost always selects the phosphoryl O atom as a partner in forming hydrogen‐bond interactions. The P atoms in (I) and (II) are in tetrahedral coordination environments, and the phosphoryl and carbonyl groups in (II) are anti with respect to each other (the P and C groups are separated by one N atom). In the crystal structures of (I) and (II), adjacent molecules are linked via the above‐mentioned hydrogen bonds into a linear arrangement parallel to [100] in both cases, in (I) by forming R22(8) rings and in (II) through a combination of R22(10) and R21(6) rings. 相似文献
136.
We report a type-II superlattice mid-wave infrared 320×256 imager at 81 K with the M-barrier design that achieved background limited performance (BLIP) and ~99% operability. The 280 K blackbody's photon irradiance was limited by an aperture and a band-pass filter from 3.6 μm to 3.8 μm resulting in a total flux of ~5×10(12) ph.cm(-2).s(-1). Under these low-light conditions, and consequently the use of a 13.5 ms integration time, the imager was observed to be BLIP thanks to a ~5 pA dark current from the 27 μm wide pixels. The total noise was dominated by the photon flux and read-out circuit which gave the imager a noise equivalent input of ~5×10(10) ph.cm(-2).s(-1) and temperature sensitivity of 9 mK with F/2.3 optics. Excellent imagery obtained using a 1-point correction alludes to the array's uniform responsivity. 相似文献
137.
Akbar Ghaffar Pour Rahbar 《Optics Communications》2009,282(5):798-808
Contention is a major problem for Optical Packed Switched (OPS) networks. Many studies have shown that to obtain a very small optical packet loss rate, a large number of specific contention resolution or contention avoidance hardware must be used. However, this may not be so cost-effective. Instead of using the same technique to achieve a very low packet loss rate, the idea of this paper is to use the combination of different contention avoidance and contention resolution schemes, but using a lower amount of each scheme, to reduce packet loss rate in slotted bufferless OPS networks. A number of cost-effective contention resolution and avoidance schemes are studied in order to decrease traffic loss and increase TCP throughput as a result. Designing a multi-fiber architecture that uses inexpensive shared-per-node wavelength converters and additional drop-ports can significantly reduce network-wide traffic loss. The lost traffic can also be retransmitted in the optical domain in order to have a loss-free OPS network. A cost model is also provided to obtain cost-effective combinations of fibers, wavelength converters and drop ports under a desirable TCP throughput and investment on network hardware. The effectiveness of the combined contention avoidance and resolution schemes are demonstrated under Internet traffic. 相似文献
138.
Mehrdad Lakestani Mehdi Dehghan 《Numerical Methods for Partial Differential Equations》2009,25(2):418-429
In this article a numerical technique is presented for the solution of Fokker‐Planck equation. This method uses the cubic B‐spline scaling functions. The method consists of expanding the required approximate solution as the elements of cubic B‐spline scaling function. Using the operational matrix of derivative, the problem will be reduced to a set of algebraic equations. Some numerical examples are included to demonstrate the validity and applicability of the technique. The method is easy to implement and produces very accurate results. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009 相似文献
139.
In this work the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions were measured at 283.1–313.1 K. The expansion factor of polymer chain was calculated by use of the intrinsic viscosities data. The thermodynamic parameters of polymer solution (the entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer–solvent interaction parameter and second osmotic virial coefficient) were evaluated by temperature dependence of polymer chain expansion factor. The obtained thermodynamic parameters indicate that quality of water was decreased for solutions of poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(ethylene oxide)/poly(vinyl pyrrolidone) blends by increasing temperature. Compatibility of poly(ethylene oxide)/poly(vinyl pyrrolidone) blends were explained in terms of difference between experimental and ideal intrinsic viscosity and solvent–polymer interaction parameter. The results indicate that the poly(ethylene glycol)/poly(vinyl pyrrolidone) blends were incompatible. 相似文献
140.
Izadi Mohsen Hashemi Pour S. M. R. Karimdoost Yasuri Amir Chamkha Ali J. 《Journal of Thermal Analysis and Calorimetry》2019,136(6):2461-2475
Journal of Thermal Analysis and Calorimetry - The paper presents the mixed convection heat transfer and entropy generation of a nanofluid containing carbon nanotubes, flowing in a 3D rectangular... 相似文献