全文获取类型
收费全文 | 14708篇 |
免费 | 1467篇 |
国内免费 | 1448篇 |
专业分类
化学 | 1849篇 |
晶体学 | 26篇 |
力学 | 844篇 |
综合类 | 238篇 |
数学 | 11743篇 |
物理学 | 2923篇 |
出版年
2024年 | 47篇 |
2023年 | 182篇 |
2022年 | 217篇 |
2021年 | 275篇 |
2020年 | 327篇 |
2019年 | 376篇 |
2018年 | 387篇 |
2017年 | 450篇 |
2016年 | 510篇 |
2015年 | 358篇 |
2014年 | 639篇 |
2013年 | 1130篇 |
2012年 | 675篇 |
2011年 | 723篇 |
2010年 | 690篇 |
2009年 | 852篇 |
2008年 | 918篇 |
2007年 | 987篇 |
2006年 | 887篇 |
2005年 | 836篇 |
2004年 | 700篇 |
2003年 | 624篇 |
2002年 | 644篇 |
2001年 | 554篇 |
2000年 | 511篇 |
1999年 | 518篇 |
1998年 | 411篇 |
1997年 | 376篇 |
1996年 | 301篇 |
1995年 | 214篇 |
1994年 | 178篇 |
1993年 | 136篇 |
1992年 | 128篇 |
1991年 | 107篇 |
1990年 | 80篇 |
1989年 | 63篇 |
1988年 | 59篇 |
1987年 | 55篇 |
1986年 | 52篇 |
1985年 | 77篇 |
1984年 | 71篇 |
1983年 | 27篇 |
1982年 | 54篇 |
1981年 | 30篇 |
1980年 | 42篇 |
1979年 | 37篇 |
1978年 | 26篇 |
1977年 | 24篇 |
1976年 | 17篇 |
1974年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The generalized Morrey spaces are introduced under the hypothesis that Rn is endowed with the general parabolic metric , and the boundedness properties are established in generalized Morrey spaces for a class of singular integral operators, which include Calderon-Zygmund singular integrals and their commutators with BMO. 相似文献
92.
A generalized linear differential equation in a Banach space is studied. The construction of a phase space and solutions with the help of the spectral theory of linear operators, ergodic theorems, and degenerate semigroups of linear operators is carried out. 相似文献
93.
Antonio Jimé nez-Melado Claudio H. Morales 《Proceedings of the American Mathematical Society》2006,134(2):501-507
We show a fixed point theorem for condensing mappings under a new condition of the Leray-Schauder type. We call it the Interior Condition. We also discuss examples that demonstrate the independence of these two conditions.
94.
对线性模型参数,讨论了Bayes估计的Pitman最优性,将已有结果进行了改进,去掉了附加条件,证明了在Pitman准则下,Bayes估计一致优于最小二乘估计(LSE),在此基础上,提出了一种基于先验信息的方差分量估计,通过和基于LSE的方差分量估计作比较,证明了新估计是无偏估计且有更小的均方误差.最后,证明了在Pitman准则下生长曲线模型参数的Bayes估计优于最佳线性无偏估计. 相似文献
95.
??We study the linear quadratic optimal stochastic control problem which is jointly driven by Brownian motion and L\'{e}vy processes. We prove that the new affine stochastic differential adjoint equation exists an inverse process by applying the profound section theorem. Applying for the Bellman's principle of quasilinearization and a monotone iterative convergence method, we prove the existence and uniqueness of the solution of the backward Riccati differential equation. Finally, we prove that the optimal feedback control exists, and the value function is composed of the initial value of the solution of the related backward Riccati differential equation and the related adjoint equation. 相似文献
96.
Jeannette Van Iseghem 《Numerical Algorithms》2002,29(1-3):267-279
A method for solving a linear system is defined. It is a Lanczos-type method, but it uses formal vector orthogonality instead of scalar orthogonality. Moreover, the dimension of vector orthogonality may vary which gives a large freedom in leading the algorithm, and controlling the numerical problems. The ideas of truncated and restarted methods are revisited. The obtained residuals are exactly orthogonal to a space of increasing dimension. Some experiments are done, the problem of finding automaticaly good directions of projection remains partly open. 相似文献
97.
L. Jackowska-Strumillo J. Sokolowski A. Żochowski A. Henrot 《Computational Optimization and Applications》2002,23(2):231-255
The new method is proposed for the numerical solution of a class of shape inverse problems. The size and the location of a small opening in the domain of integration of an elliptic equation is identified on the basis of an observation. The observation includes the finite number of shape functionals. The approximation of the shape functionals by using the so-called topological derivatives is used to perform the learning process of an artificial neural network. The results of computations for 2D examples show, that the method allows to determine an approximation of the global solution to the inverse problem, sufficiently closed to the exact solution. The proposed method can be extended to the problems with an opening of general shape and to the identification problems of small inclusions. However, the mathematical theory of the proposed approach still requires futher research. In particular, the proof of global convergence of the method is an open problem. 相似文献
98.
The aim of this article is to derive stable generalized sampling in a shift-invariant space by using some special dual frames in L2(0,1). These sampling formulas involve samples of filtered versions of the functions in the shift-invariant space. The involved samples are expressed as the frame coefficients of an appropriate function in L2(0,1) with respect to some particular frame in L2(0,1). Since any shift-invariant space with stable generator is the image of L2(0,1) by means of a bounded invertible operator, our generalized sampling is derived from some dual frame expansions in L2(0,1). 相似文献
99.
100.
通过分析双层线性规划可行域的结构特征和全局最优解在约束域的极点上达到这一特性,对单纯形方法中进基变量的选取法则进行适当修改后,给出了一个求解双层线性规划局部最优解方法,然后引进上层目标函数对应的一种割平面约束来修正当前局部最优解,直到求得双层线性规划的全局最优解.提出的算法具有全局收敛性,并通过算例说明了算法的求解过程. 相似文献