全文获取类型
收费全文 | 14667篇 |
免费 | 1420篇 |
国内免费 | 1440篇 |
专业分类
化学 | 3550篇 |
晶体学 | 226篇 |
力学 | 1909篇 |
综合类 | 238篇 |
数学 | 9056篇 |
物理学 | 2548篇 |
出版年
2024年 | 34篇 |
2023年 | 145篇 |
2022年 | 169篇 |
2021年 | 243篇 |
2020年 | 367篇 |
2019年 | 333篇 |
2018年 | 315篇 |
2017年 | 383篇 |
2016年 | 415篇 |
2015年 | 312篇 |
2014年 | 601篇 |
2013年 | 1030篇 |
2012年 | 747篇 |
2011年 | 879篇 |
2010年 | 857篇 |
2009年 | 928篇 |
2008年 | 1002篇 |
2007年 | 1070篇 |
2006年 | 884篇 |
2005年 | 822篇 |
2004年 | 738篇 |
2003年 | 775篇 |
2002年 | 642篇 |
2001年 | 507篇 |
2000年 | 473篇 |
1999年 | 421篇 |
1998年 | 378篇 |
1997年 | 311篇 |
1996年 | 263篇 |
1995年 | 235篇 |
1994年 | 196篇 |
1993年 | 137篇 |
1992年 | 133篇 |
1991年 | 107篇 |
1990年 | 91篇 |
1989年 | 67篇 |
1988年 | 67篇 |
1987年 | 52篇 |
1986年 | 57篇 |
1985年 | 59篇 |
1984年 | 47篇 |
1983年 | 24篇 |
1982年 | 55篇 |
1981年 | 42篇 |
1980年 | 29篇 |
1979年 | 23篇 |
1978年 | 15篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1972年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
一类二阶奇异微分方程正解的存在唯一性 总被引:2,自引:1,他引:1
利用上下解方法,不动点理论研究奇异微分方程u" f(t,u)=0,t∈(0,1)在边界条件au(0)-βu'(0)=0,γu(1) δu'(1)=0下C[0,1]正解和C1[0,1]正解的存在性与唯一性.其中非线性项f(t,u)关于u是减的,仅满足较弱的要求. 相似文献
992.
In this note we provide a characterization of a subclass of bargaining problems for which the Nash solution has the property
of disagreement point monotonicity. While the original d-monotonicity axiom and its stronger notion, strong d-monotonicity, were introduced and discussed by Thomson (J Econ Theory, 42: 50–58, 1987), this paper introduces local strong
d-monotonicity and derives a necessary and sufficient condition for the Nash solution to be locally strongly d-monotonic. This characterization is given by using the sensitivity matrix of the Nash bargaining solution w.r.t. the disagreement
point d. Moverover, we present a sufficient condition for the Nash solution to be strong d-monotonic. 相似文献
993.
Zhenhai Liu Stanisaw Migrski Anna Ochal 《Journal of Mathematical Analysis and Applications》2008,340(2):1347-1361
In this paper we consider a mathematical model describing static elastic contact problems with the Hooke constitutive law and subdifferential boundary conditions. We treat boundary hemivariational inequalities which are weak formulations of contact problems. We establish existence and uniqueness of solutions to hemivariational inequalities. Using the notion of H-convergence of elasticity tensors we investigate the limit behavior of the sequence of solutions to hemivariational inequalities. 相似文献
994.
O. Quadrat 《Colloid and polymer science》1986,264(5):399-402
An investigation of the degradation of poly(methyl methacrylate) in the case of negative thixotropy of its solutions in tricresyl phosphate showed that the number of polymer bonds broken by flow as expressed through the decrease of molecular weight in the course of the effect is determined by shear energy imposed on the system, irrespective of the velocity gradient and temperature used. 相似文献
995.
An analytical solution for the model of drug distribution and absorption in small intestine 总被引:2,自引:0,他引:2
Xu Mingyu 《Acta Mechanica Sinica》1990,6(4):316-323
According to the physiological and anatomical characteristics of small intestine, neglecting the effect of its motility on
the distribution and absorption of drug and nutrient, Y. Miyamoto et al.[1] proposed a model of two-dimensional laminar flow in a circular porous tube with permeable wall and calculated the concentration
profile of drug by numerical analysis. In this paper, we give a steady state analytical solution of the above model including
deactivation term. The obtained results are in agreement with the results of their numerical analysis. Moreover the analytical
solution presented in this paper reveals the relation among the physiological parameters of the model and describes the basic
absorption rule of drug and nutrient through the intestinal wall and hence provides a theoretical basis for determining the
permeability and reflection coefficient through in situ experiments.
The project supported by NSF of Shandong Province 相似文献
996.
In this paper, we give a new method to solve the quantum colored Yang-Baxter matrix equation (QCYBE), and a class of solutions to the QCYBE is given. 相似文献
997.
We study the variational inequality associated with a bounded-velocity control problem when discretionary stopping is allowed.
We establish the existence of a strong solution by using the viscosity solution techniques. The optimal policy is shown to
exist from the optimality conditions in the variational inequality. 相似文献
998.
Abstract. We formulate a robust optimal stopping-time problem for a state-space system and give the connection between various notions
of lower value function for the associated games (and storage function for the associated dissipative system) with solutions
of the appropriate variational inequality (VI) (the analogue of the Hamilton—Jacobi—Bellman—Isaacs equation for this setting).
We show that the stopping-time rule can be obtained by solving the VI in the viscosity sense and a positive definite supersolution
of the VI can be used for stability analysis. 相似文献
999.
不需加人工变量的两阶段法 总被引:1,自引:0,他引:1
A method is provided to achieve an initial basic feasible solution of a linear programming in this paper. This method dose not need introducing any artificial variable, but needs only solving an auxiliary linear programming. Compared with the traditional two-phase method, it has advantages of saving the memories and reducing the computational efforts. 相似文献
1000.
Sufficient conditions on the existence of mild solutions for the following semilinear nonlocal evolution inclusion with upper semicontinuous nonlinearity: u′(t)∈A(t)u(t)+F(t,u(t)), 0<t?d, u(0)=g(u), are given when g is completely continuous and Lipschitz continuous in general Banach spaces, respectively. An example concerning the partial differential equation is also presented. 相似文献