全文获取类型
收费全文 | 1525篇 |
免费 | 13篇 |
国内免费 | 18篇 |
专业分类
化学 | 616篇 |
晶体学 | 9篇 |
力学 | 41篇 |
数学 | 403篇 |
物理学 | 487篇 |
出版年
2020年 | 19篇 |
2019年 | 17篇 |
2018年 | 18篇 |
2017年 | 16篇 |
2016年 | 25篇 |
2015年 | 10篇 |
2014年 | 20篇 |
2013年 | 75篇 |
2012年 | 66篇 |
2011年 | 56篇 |
2010年 | 33篇 |
2009年 | 29篇 |
2008年 | 43篇 |
2007年 | 69篇 |
2006年 | 59篇 |
2005年 | 54篇 |
2004年 | 44篇 |
2003年 | 34篇 |
2002年 | 41篇 |
2001年 | 21篇 |
2000年 | 32篇 |
1999年 | 23篇 |
1998年 | 16篇 |
1997年 | 23篇 |
1996年 | 29篇 |
1995年 | 26篇 |
1994年 | 35篇 |
1993年 | 38篇 |
1992年 | 42篇 |
1991年 | 23篇 |
1990年 | 30篇 |
1989年 | 22篇 |
1988年 | 19篇 |
1986年 | 12篇 |
1985年 | 24篇 |
1984年 | 31篇 |
1983年 | 25篇 |
1982年 | 31篇 |
1981年 | 28篇 |
1980年 | 26篇 |
1979年 | 31篇 |
1978年 | 19篇 |
1977年 | 24篇 |
1976年 | 20篇 |
1975年 | 26篇 |
1974年 | 21篇 |
1973年 | 22篇 |
1972年 | 9篇 |
1971年 | 9篇 |
1969年 | 9篇 |
排序方式: 共有1556条查询结果,搜索用时 15 毫秒
71.
Let G be a finite group. A complete Sylow product of G is a product of Sylow subgroups of G, one for each prime divisor of |G|. We shall call G a Sylow factorizable group if it is equal to at least one of its complete Sylow products. We prove that if G is a Sylow factorizable group then the
intersection of all complete Sylow products of G is equal to the solvable radical of G. We generalize the concepts and the result to Sylow products which involve an arbitrary subset of the prime divisors of |G|.
Received: 26 January 2005 相似文献
72.
We examine the limiting average availability of a maintained system that deteriorates due to random shock process and as a response to its usage (wear out). System’s failures are not self-announcing, hence, failures must be detected via inspection. We consider randomly occurring shocks that arrive according to a Poisson process and cumulatively damage the system. Two models are considered: in Model 1 the shock and wear out processes are independent of the external environment and in Model 2, the shocks arrival rate, the shock magnitudes and the wear out rate are governed by a random environment which evolves as a Markov process. We obtain the system’s availability for both models. 相似文献
73.
We study the expected delay in cyclic polling models with general ‘branching-type’ service disciplines. For this class of
models, which contains models with exhaustive and gated service as special cases, we obtain closed-form expressions for the
expected delay under standard heavy-traffic scalings. We identify a single parameter associated with the service discipline
at each queue, which we call the ‘exhaustiveness’. We show that the scaled expected delay figures depend on the service policies
at the queues only through the exhaustiveness of each of the service disciplines. This implies that the influence of different
service disciplines, but with the same exhaustiveness, on the expected delays at the queues becomes the same when the system
reaches saturation. This observation leads to a new classification of the service disciplines. In addition, we show monotonicity
of the scaled expected delays with respect to the exhaustiveness of the service disciplines. This induces a complete ordering
in terms of efficiency of the service disciplines. The results also lead to new rules for optimization of the system performance
with respect to the service disciplines at the queues. Further, the exact asymptotic results suggest simple expected waiting-time
approximations for polling models in heavy traffic. Numerical experiments show that the accuracy of the approximations is
excellent for practical heavy-traffic scenarios.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
74.
Moshe Jarden 《Mathematische Zeitschrift》1997,224(4):555-565
75.
Amihood Amir Alberto Apostolico Moshe Lewenstein 《Journal of Algorithms in Cognition, Informatics and Logic》1997,24(2):325-339
Let a textstringTofnsymbols from some alphabet Σ and an integerm < nbe given. A patternPof lengthmover Σ is sought such thatPminimizes (alternatively, maximizes) the total number of pairwise character mismatches generated whenPis compared with allm-character substrings ofT. Two additional variants of the problem are obtained by adding the constraint thatPbe (respectively, not be) a substring ofT. Efficient sequential algorithms are proposed in this paper for the problem and its variants. 相似文献
76.
77.
Victor Oxman Moshe Stupel 《International Journal of Mathematical Education in Science & Technology》2018,49(3):442-455
A geometrical task is presented with multiple solutions using different methods, in order to show the connection between various branches of mathematics and to highlight the importance of providing the students with an extensive ‘mathematical toolbox’. Investigation of the property that appears in the task was carried out using a computerized tool. 相似文献
78.
79.
80.
Moshe Goldberg Robert Guralnick W. A. J. Luxemburg 《Linear and Multilinear Algebra》2013,61(2):209-219
In this paper we continue our study of stability properties of subnorms on subsets of finite-dimensional, power-associative algebras over the real or the complex numbers. 相似文献