全文获取类型
收费全文 | 443篇 |
免费 | 31篇 |
国内免费 | 3篇 |
专业分类
化学 | 117篇 |
力学 | 138篇 |
数学 | 126篇 |
物理学 | 96篇 |
出版年
2024年 | 2篇 |
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 17篇 |
2020年 | 19篇 |
2019年 | 21篇 |
2018年 | 37篇 |
2017年 | 22篇 |
2016年 | 29篇 |
2015年 | 13篇 |
2014年 | 17篇 |
2013年 | 17篇 |
2012年 | 33篇 |
2011年 | 57篇 |
2010年 | 35篇 |
2009年 | 35篇 |
2008年 | 41篇 |
2007年 | 16篇 |
2006年 | 6篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有477条查询结果,搜索用时 46 毫秒
1.
Khan M. Ijaz Qayyum Sumaira Waqas M. Hayat T. Alsaedi A. 《Journal of Thermal Analysis and Calorimetry》2020,139(2):1291-1299
Journal of Thermal Analysis and Calorimetry - Here, MHD stagnation point flow of non-Newtonian fluid over a stretchable surface is considered. Process of modeling is characterized for basic... 相似文献
2.
Baoquan Zhou Daqing Jiang Bingtao Han Tasawar Hayat 《Mathematical Methods in the Applied Sciences》2022,45(1):423-455
Considering the effect of stochasticity including white noise and colored noise, this paper aims to study a hybrid stochastic cholera epidemic model with waning vaccine-induced immunity and nonlinear telegraph perturbations. First, we derive a critical value related to the basic reproduction number of the deterministic model. The key aim of this paper is to generalize the θ-stochastic criterion method proposed by the recent work (Han et al. in Chaos Solit Fract 140:110238, 2020) to eliminate nonlinear telegraph perturbations. Next, via constructing several θ-stochastic Lyapunov functions and using the generalized method, we further prove that the stochastic model have a unique ergodic stationary distribution under . Results show that the prevention and control of cholera epidemic depend on low transmission rate and small telegraph perturbations. Finally, the corresponding numerical simulations are performed to illustrate our analytical results and a practical application on the Somalia cholera outbreak is shown at the end of this paper. 相似文献
3.
Xiangxue Wang Shujun Yu Zhongshan Chen Wencheng Song Yuantao Chen Tasawar Hayat Ahmed Alsaedi Wei Guo Jun Hu Xiangke Wang 《中国科学:化学(英文版)》2017,60(1):107-114
To contribute to the understanding of Eu(III) interaction preperties on hydrous alumina particles in the absence and presence of fulvic acid (FA), the complexation properties of Eu(III) with hydrous alumina, FA and FA-alumina hybrids are studied by batch and time-resolved laser fluorescence spectroscopy (TRLFS) techniques. The continuous increase in the fluorescence lifetime of Eu-alumina and Eu-FA with increasing pH indicates that the complexation is accompanied by decreasing number of hydration water in the first coordination sphere of Eu(III). Eu(III) is adsorbed onto alumina particles as outer-sphere surface complexes of ≡(Al?O)?Eu· (OH)· 7H2O and ≡(Al?O)?Eu· 6H2O at low pH values, and as inner-sphere surface complexes as ≡(Al?O)2?Eu+· 4H2O at high pH. In FA solution, Eu(III) forms complexes with FA as (COO)2Eu+(H2O) x and the hydration water number in the first coordination sphere decreases with pH increasing. The formation of ≡COO?Eu?(O?Al≡)· 4H2O is observed on FA-alumina hybrids, suggesting the formation of strong inner-sphere surface complexes in the presence of FA. The surface complexes are also characterized by their emission spectra [the ratio of emission intensities of 5 D 0→7 F 1 (λ=594 nm) and 5 D 0→7 F 2 (λ=619 nm) transitions] and their fluorescence lifetime. The findings is important to understand the contribution of FA in the complexation properties of Eu(III) on FA-alumina hybrids that the clarification of the environmental behavior of humic substances is necessary to understand fully the behavior of Eu(III), or its analogue trivalent lanthanide and actinide ions in natural environment. 相似文献
4.
Shujun Yu Xiangxue Wang Shitong Yang Guodong Sheng Ahmed Alsaedi Tasawar Hayat Xiangke Wang 《中国科学:化学(英文版)》2017,60(2):170-187
The X-ray absorption fine structure (XAFS) technology has exhibited a very unique application in the study of sorption mechanism, chemical species and microstructures of radionuclides at the natural solid-water interfaces. In this review, the interaction mechanism of radionuclides with clay minerals and nanomaterials under different environmental conditions are summarized from the XAFS spectroscopy analysis. The coordination number and the bond distances of radionuclides, the oxidation-reduction reactions, the influence of humic substances and microorganisms on the species and structures of radionuclides at molecule level are reviewed and compared. This review is helpful to understand the interactions of radionuclides with oxides, natural clay minerals and nanomaterials, which is also crucial to evaluate the physicochemical behaviors of radionuclides in the natural environment. 相似文献
5.
The flow of a second-grade fluid past a porous plate subject to either suction or blowing at the plate has been studied. A
modified model of second-grade fluid that has shear-dependent viscosity and can predict the normal stress difference is used.
The differential equations governing the flow are solved using homotopy analysis method (HAM). Expressions for the velocity
have been constructed and discussed with the help of graphs. Analysis of the obtained results showed that the flow is appreciably
influenced by the material and normal stress coefficient. Several results of interest are deduced as the particular cases
of the presented analysis. 相似文献
6.
This study investigates the rotating magnetohydrodynamic (MHD) flow of a third-grade fluid in a porous space. Modified Darcy's
law has been utilized for the flow modeling. The Hall effects are taken into consideration. The basic equations governing
the flow are reduced to a highly nonlinear ordinary differential equation. This equation has been solved analytically by employing
the homotopy analysis method (HAM). The effects of the various interesting parameters on the velocity distribution have been
discussed. 相似文献
7.
On Solutions of Some Non-Linear Differential Equations Arising in Newtonian and Non-Newtonian Fluids
Mohyuddin M. R. Hayat T. Mahomed F. M. Asghar S. Siddiqui A. M. 《Nonlinear dynamics》2004,35(3):229-248
Some steady as well as unsteady solutions of the equations of motion for an incompressible Newtonian and non-Newtonian (second-grade)
fluids are obtained by applying different methods including the Lie symmetry group method. The flows considered are axially
symmetric with the swirling motion, and the governing equations for second-grade fluid flow have been modeled. Expressions
for streamlines, velocity and vorticity components are constructed explicitly in each case. Exact analytical solutions in
second-grade fluid are obtained and compared with the corresponding viscous solutions. 相似文献
8.
Exact analytical solutions for a class of unsteady unidirectional flows of an incompressible second-order fluid are constructed. The flows are generated impulsively from rest by motion of a plate or two plates or by sudden application of a pressure gradient. Expressions for velocity, flux and skin friction are obtained for both large and small times. It is found that large and small times solutions are dependent on the coefficient of viscoelasticity. The solutions corresponding to Newtonian fluids can be easily obtained from those for fluids of second order by letting the viscoelastic parameter to be zero. 相似文献
9.
In this article, analysis is presented to study the effect of Hall current on the rotating flow of a non-Newtonian fluid in
a porous medium taking into consideration the modified Darcy's law. The Oldroyd-B fluid model is used to characterize the
non-Newtonian fluid behavior. The governing equations for unsteady rotating flow have been modeled in a porous medium. The
analysis includes the flows induced by general periodic oscillations and elliptic harmonic oscillations of a plate. The effect
of the various emerging parameters is discussed on the velocity distribution. The analytical results are confirmed mathematically
by giving comparison with previous studies in the literature. It is observed that the velocity distribution increases with
an increase of Hall parameter. The behavior of permeability is similar to that of the Hall parameter. 相似文献
10.
This article reports the magnetohydrodynamic (MHD) three-dimensional flow of viscoelastic fluid over a stretching surface with heat transfer. Mathematical analysis is formulated using convective boundary conditions. Computations of dimensionless velocity and temperature fields are presented. The tabulated values show excellent agreement between present and previous limiting analysis. Graphical results show the impact of embedded parameters entering into the problem. 相似文献