全文获取类型
收费全文 | 5614篇 |
免费 | 307篇 |
国内免费 | 393篇 |
专业分类
化学 | 1969篇 |
晶体学 | 8篇 |
力学 | 232篇 |
综合类 | 13篇 |
数学 | 3135篇 |
物理学 | 957篇 |
出版年
2024年 | 2篇 |
2023年 | 61篇 |
2022年 | 101篇 |
2021年 | 107篇 |
2020年 | 110篇 |
2019年 | 136篇 |
2018年 | 109篇 |
2017年 | 111篇 |
2016年 | 143篇 |
2015年 | 146篇 |
2014年 | 219篇 |
2013年 | 462篇 |
2012年 | 301篇 |
2011年 | 321篇 |
2010年 | 305篇 |
2009年 | 402篇 |
2008年 | 438篇 |
2007年 | 413篇 |
2006年 | 280篇 |
2005年 | 235篇 |
2004年 | 222篇 |
2003年 | 180篇 |
2002年 | 148篇 |
2001年 | 108篇 |
2000年 | 97篇 |
1999年 | 83篇 |
1998年 | 104篇 |
1997年 | 92篇 |
1996年 | 116篇 |
1995年 | 83篇 |
1994年 | 98篇 |
1993年 | 80篇 |
1992年 | 66篇 |
1991年 | 39篇 |
1990年 | 39篇 |
1989年 | 33篇 |
1988年 | 28篇 |
1987年 | 25篇 |
1986年 | 31篇 |
1985年 | 41篇 |
1984年 | 33篇 |
1983年 | 12篇 |
1982年 | 41篇 |
1981年 | 19篇 |
1980年 | 22篇 |
1979年 | 26篇 |
1978年 | 17篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1973年 | 2篇 |
排序方式: 共有6314条查询结果,搜索用时 15 毫秒
11.
SUN Qiyu 《数学年刊B辑(英文版)》2003,24(3):367-386
In this paper, the author at first develops a method to study convergence of the cascade algorithm in a Banach space without stable assumption on the initial (see Theorem 2.1), and then applies the previous result on the convergence to characterizing compactly supported refinable distributions in fractional Sobolev spaces and Holder continuous spaces (see Theorems 3.1, 3.3, and 3.4). Finally the author applies the above characterization to choosing appropriate initial to guarantee the convergence of the cascade algorithm (see Theorem 4.2). 相似文献
12.
An Application of Branch and Cut to Open Pit Mine Scheduling 总被引:5,自引:0,他引:5
The economic viability of the modern day mine is highly dependent upon careful planning and management. Declining trends in average ore grades, increasing mining costs and environmental considerations will ensure that this situation will remain in the foreseeable future. The operation and management of a large open pit mine having a life of several years is an enormous and complex task. Though a number of optimization techniques have been successfully applied to resolve some important problems, the problem of determining an optimal production schedule over the life of the deposit is still very much unresolved. In this paper we will critically examine the techniques that are being used in the mining industry for production scheduling indicating their limitations. In addition, we present a mixed integer linear programming model for the scheduling problems along with a Branch and Cut solution strategy. Computational results for practical sized problems are discussed. 相似文献
13.
The natural modes of a discrete linear system are orthogonal with respect to the mass and stiffness matrices in a generalized sense. However, these modes are usually not orthogonal to each other in the ordinary sense. The purpose of this paper is to document a number of conditions under which the modes are also orthogonal in an ordinary fashion. 相似文献
14.
The crystallization of poly(ethylene terephthalate) under uniaxial tensile strain at different extension rates was investigated with optical polarimetry in a temperature range between the glass-transition temperature and the quiescent crystallization temperature. The evolution of the optical properties of the polymer, including the turbidity, birefringence, and dichroism, were monitored simultaneously with the mechanical parameters. To complete the semicrystalline microstructure characterization of the polymer under strain, an online wide-angle X-ray diffraction (WAXD) technique was used in separate experiments, which were performed under the same thermomechanical conditions. For real-time measurements, a high-energy synchrotron radiation source was used. The optical properties provided information about both the crystalline and amorphous phases, whereas the WAXD patterns essentially gave information about the crystalline phase. The two experimental techniques were then used in a complementary way to characterize the semicrystalline microstructure. Significant deviations from the stress-optical rule were found. This was attributed to both transient effects and the appearance of crystallites, which consisted of highly oriented molecular segments that could contribute to the optical anisotropy but not necessarily to the stress. The behavior of the optical dichroism was found to be qualitatively different from that of the birefringence. The latter monotonically increased with the strain, whereas the former first increased with the strain, passed through a maximum, and then decreased to a steady-state value. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1915–1927, 2004 相似文献
15.
16.
A server needs to compute a broadcast schedule for n pages whose request times are known in advance. Outputting a page satisfies all outstanding requests for the page. The goal is to minimize the average waiting time of a client. In this paper, we show the equivalence of two apparently different relaxations that have been considered for this problem. 相似文献
17.
Robust linear optimization under general norms 总被引:1,自引:0,他引:1
We explicitly characterize the robust counterpart of a linear programming problem with uncertainty set described by an arbitrary norm. Our approach encompasses several approaches from the literature and provides guarantees for constraint violation under probabilistic models that allow arbitrary dependencies in the distribution of the uncertain coefficients. 相似文献
18.
The projective method for solving linear matrix inequalities 总被引:2,自引:0,他引:2
Numerous problems in control and systems theory can be formulated in terms of linear matrix inequalities (LMI). Since solving
an LMI amounts to a convex optimization problem, such formulations are known to be numerically tractable. However, the interest
in LMI-based design techniques has really surged with the introduction of efficient interior-point methods for solving LMIs
with a polynomial-time complexity. This paper describes one particular method called the Projective Method. Simple geometrical
arguments are used to clarify the strategy and convergence mechanism of the Projective algorithm. A complexity analysis is
provided, and applications to two generic LMI problems (feasibility and linear objective minimization) are discussed. 相似文献
19.
Lai Chunhui 《东北数学》1997,(1)
SomePropertiesofQuasi┐keep┐rangeOperatorsandTheirApplicationsLaiChunhui(赖春晖)(DepartmentofMathematics,ZhangzhouTeachersColege,... 相似文献
20.
In [5] Phillips proved that one can obtain the additive group of any nonstandard model *? of the ring ? of integers by using a linear mod 1 function h : F ?, where F is the α-dimensional vector space over ? when α is the cardinality of *?. In this connection it arises the question whether there are linear mod 1 functions which are neither addition nor quasi-linear. We prove that this is the case. 相似文献