全文获取类型
收费全文 | 4113篇 |
免费 | 274篇 |
国内免费 | 346篇 |
专业分类
化学 | 135篇 |
晶体学 | 2篇 |
力学 | 105篇 |
综合类 | 69篇 |
数学 | 2986篇 |
物理学 | 494篇 |
无线电 | 942篇 |
出版年
2024年 | 5篇 |
2023年 | 24篇 |
2022年 | 55篇 |
2021年 | 84篇 |
2020年 | 81篇 |
2019年 | 85篇 |
2018年 | 91篇 |
2017年 | 98篇 |
2016年 | 127篇 |
2015年 | 86篇 |
2014年 | 234篇 |
2013年 | 272篇 |
2012年 | 195篇 |
2011年 | 198篇 |
2010年 | 201篇 |
2009年 | 262篇 |
2008年 | 300篇 |
2007年 | 309篇 |
2006年 | 273篇 |
2005年 | 226篇 |
2004年 | 170篇 |
2003年 | 216篇 |
2002年 | 179篇 |
2001年 | 164篇 |
2000年 | 130篇 |
1999年 | 112篇 |
1998年 | 107篇 |
1997年 | 83篇 |
1996年 | 74篇 |
1995年 | 38篇 |
1994年 | 37篇 |
1993年 | 19篇 |
1992年 | 23篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 9篇 |
1988年 | 15篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 19篇 |
1984年 | 10篇 |
1983年 | 12篇 |
1982年 | 15篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 4篇 |
排序方式: 共有4733条查询结果,搜索用时 244 毫秒
91.
Kyle Siegrist 《Journal of Theoretical Probability》1994,7(4):725-737
Three fundamental characterizations of the standard exponential distribution on [0, ) are the remaining life, memoryless and constant failure properties. Analogs of these properties are studied for distributions on a class of semigroups in which the semigroup operation replaces addition, a compatible partial order replaces the ordinary order, and a left-invariant measure replaces Lebesgue measure. Partial characterizations of exponential distributions on such semigroups are obtained and the semigroup formulation provides new characterizations of certain aging properties studied in reliability-increasing failure rate, new better than used, and increasing failure rate average. 相似文献
92.
Masakiyo Miyazawa 《Queueing Systems》1994,15(1-4):1-58
We survey the rate conservation law, RCL for short, arising in queues and related stochastic models. RCL was recognized as one of the fundamental principles to get relationships between time and embedded averages such as the extended Little's formulaH=G, but we show that it has other applications. For example, RCL is one of the important techniques for deriving equilibrium equations for stochastic processes. It is shown that the various techniques, including Mecke's formula for a stationary random measure, can be formulated as RCL. For this purpose, we start with a new definition of the rate with respect to a random measure, and generalize RCL by using it. We further introduce the notion of quasi-expectation, which is a certain extension of the ordinary expectation, and derive RCL applicable to the sample average results. It means that the sample average formulas such asH=G can be obtained as the stationary RCL in the quasi-expectation framework. We also survey several extensions of RCL and discuss examples. Throughout the paper, we would like to emphasize how results can be easily obtained by using a simple principle, RCL. 相似文献
93.
B. Kaminski 《Proceedings of the American Mathematical Society》1996,124(5):1533-1537
It is shown that if an abelian countable group is such that is a finite group and every aperiodic positive entropy action of on a Lebesgue probability space has a countable Haar spectrum in the subspace , where denotes the Pinsker -
algebra of , then every aperiodic positive entropy action of on has the same property. A positive answer to the question of J.P. Thouvenot is obtained as a corollary.
algebra of , then every aperiodic positive entropy action of on has the same property. A positive answer to the question of J.P. Thouvenot is obtained as a corollary.
94.
Bosko Zivaljevic 《Transactions of the American Mathematical Society》1996,348(5):1921-1938
We continue the investigation of validity of Hall's theorem in the case of the Loeb space of an internal, uniformly distributed, hyperfinite measure space initiated in1992 by the author. Some new classes of graphs are introduced for which the measure theoretic version of Hall's theorem still holds.
95.
Carleson measure characterization of Bloch functions 总被引:1,自引:0,他引:1
Lou Zengjian 《数学学报(英文版)》1996,12(2):175-184
We give several equivalences of Bloch functions and little Bloch functions. Using these results we obtain the generalized Carleson measure characterization of Bloch functions and the generalized vanishing Carleson measure characterization of little Bloch functions, that is,f B if and only if |D
f(z)|
p
(1-|z|2)p-1
dm(z) is a generalized Carleson measure;f B
0 if and only if |D
f(z)|
p
(1-|z|2)p-1
dm(z) is a generalized vanishing Carleson measure, whereD
f( > 0) is the fractional derivative of analytic functionf of order, m denotes the normalised Lebesgue measure.Supported partly by the Young Teacher Natural Science Foundation of Shandong Province. 相似文献
96.
97.
El-B. Yallaoui 《Periodica Mathematica Hungarica》1991,23(2):109-120
Let X be an abstract set and L a lattice of subsets of X. To each lattice regular measure µ, we associate two induced measures
and
on suitable lattices of the Wallman space IR(L) and another measure µ on the spaceIR(L). We will investigate the reflection of smoothness properties of p onto
,
and µ; and try to set some new criterion for repleteness and measure repleteness. 相似文献
98.
The influence of CCl4 on the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), the value of the
total antioxidant status (TAS), and the concentration of malonic dialdehyde (MDA) and glutathione (GSH) was monitored in plasma
or whole blood of rabbits. The administration of CCl4 caused the increase of the SOD activity to approximately 150 % and the decrease in the activity of GPx and GR by about 50
%. These changes were accompanied with the increase in TAS value and MDA concentration and the decrease of GSH concentration.
The effect of CCl4 was suppressed by the previous 7 days lasting or simultaneous administration of vitamin E. Oxidative stress caused by CCl4 was accompanied by the development of reactive oxygen forms, especially superoxide radical anion. 相似文献
99.
100.
Starting from the axiomatic definition of finitely maxitive T-conditional possibility (where T is a continuous triangular norm), the paper aims at a comprehensive and self-contained treatment of coherence and extension of a possibilistic assessment defined on an arbitrary set of conditional events. Coherence (or consistence with a T-conditional possibility) is characterized either in terms of existence of a linearly ordered class of finitely maxitive possibility measures (T-nested class) agreeing with the assessment, or in terms of solvability of a finite sequence of nonlinear systems for every finite subfamily of conditional events. Coherence reveals to be a necessary and sufficient condition for the extendibility of an assessment to any superset of conditional events and, in the case of T equal to the minimum or a strict t-norm, the set of coherent values for the possibility of a new conditional event can be computed solving two optimization problems over a finite sequence of nonlinear systems for every finite subfamily of conditional events. 相似文献