全文获取类型
收费全文 | 8193篇 |
免费 | 556篇 |
国内免费 | 738篇 |
专业分类
化学 | 150篇 |
力学 | 349篇 |
综合类 | 113篇 |
数学 | 7645篇 |
物理学 | 878篇 |
无线电 | 352篇 |
出版年
2024年 | 16篇 |
2023年 | 98篇 |
2022年 | 109篇 |
2021年 | 109篇 |
2020年 | 185篇 |
2019年 | 198篇 |
2018年 | 174篇 |
2017年 | 221篇 |
2016年 | 208篇 |
2015年 | 189篇 |
2014年 | 379篇 |
2013年 | 632篇 |
2012年 | 310篇 |
2011年 | 431篇 |
2010年 | 393篇 |
2009年 | 486篇 |
2008年 | 581篇 |
2007年 | 589篇 |
2006年 | 505篇 |
2005年 | 499篇 |
2004年 | 369篇 |
2003年 | 387篇 |
2002年 | 306篇 |
2001年 | 275篇 |
2000年 | 243篇 |
1999年 | 242篇 |
1998年 | 224篇 |
1997年 | 213篇 |
1996年 | 143篇 |
1995年 | 92篇 |
1994年 | 80篇 |
1993年 | 63篇 |
1992年 | 60篇 |
1991年 | 61篇 |
1990年 | 32篇 |
1989年 | 32篇 |
1988年 | 33篇 |
1987年 | 19篇 |
1986年 | 26篇 |
1985年 | 44篇 |
1984年 | 32篇 |
1983年 | 20篇 |
1982年 | 25篇 |
1981年 | 31篇 |
1980年 | 20篇 |
1979年 | 26篇 |
1978年 | 24篇 |
1977年 | 17篇 |
1976年 | 16篇 |
1973年 | 6篇 |
排序方式: 共有9487条查询结果,搜索用时 11 毫秒
11.
A. Račkauskas 《Acta Appl Math》1995,38(1):109-129
Let(X
i
) be a martingale difference sequence. LetY be a standard normal random variable. We investigate the rate of uniform convergence
相似文献
12.
H. Kunita 《Journal of Theoretical Probability》1994,7(2):279-308
We discuss the Cauchy problem of a certain stochastic parabolic partial differential equation arising in the nonlinear filtering theory, where the initial data and the nonhomogeneous noise term of the equation are given by Schwartz distributions. The generalized (distributional) solution is represented by a partial (conditional) generalized expectation ofT(t)°
0,t
–1
, whereT(t) is a stochastic process with values in distributions and
s,t
is a stochastic flow generated by a certain stochastic differential equation. The representation is used for getting estimates of the solution with respect to Sobolev norms.Further, by applying the partial Malliavin calculus of Kusuoka-Stroock, we show that any generalized solution is aC
-function under a condition similar to Hörmander's hypoellipticity condition. 相似文献
13.
Frank J.S. Wang 《Stochastic Processes and their Applications》1977,5(2):173-193
Consider a population consisting of one type of individual living in a fixed region with area A. In [8], we constructed a stochastic population model in which the death rate is affected by the age of the individual and the birth rate is affected by the population density PA(t), i.e., the population size divided by the area A of the given region. In [8], we proposed a continuous deterministic model which in general is a nonlinear Volterra type integral equation and proved that under appropriate conditions the sequence PA(t) would converge to the solution P(t) of our integral equation in the sense that .In this paper, we obtain a “central limit theorem” for the random element √A(PA(t)?P(t)). We prove that under appropriate conditions √A(PA(t)?P(t)) will converge to a Gaussian process. (See Theorem 3.4 for the explicit formula of this Gaussian process.) 相似文献
14.
Hooman Moradpour Mohsen Javaherian Ebrahim Namvar Amir Hadi Ziaie 《Entropy (Basel, Switzerland)》2022,24(6)
Relying on the quantum tunnelling concept and Maxwell–Boltzmann–Gibbs statistics, Gamow shows that the star-burning process happens at temperatures comparable to a critical value, called the Gamow temperature () and less than the prediction of the classical framework. In order to highlight the role of the equipartition theorem in the Gamow argument, a thermal length scale is defined, and then the effects of non-extensivity on the Gamow temperature have been investigated by focusing on the Tsallis and Kaniadakis statistics. The results attest that while the Gamow temperature decreases in the framework of Kaniadakis statistics, it can be bigger or smaller than when Tsallis statistics are employed. 相似文献
15.
Jaime Aspas-Caceres Marc Rico-Pasto Isabel Pastor Felix Ritort 《Entropy (Basel, Switzerland)》2022,24(7)
Nonequilibrium work relations and fluctuation theorems permit us to extract equilibrium information from nonequilibrium measurements. They find application in single-molecule pulling experiments where molecular free energies can be determined from irreversible work measurements by using unidirectional (e.g., Jarzynski’s equality) and bidirectional (e.g., Crooks fluctuation theorem and Bennet’s acceptance ratio (BAR)) methods. However, irreversibility and the finite number of pulls limit their applicability: the higher the dissipation, the larger the number of pulls necessary to estimate G within a few . Here, we revisit pulling experiments on an RNA three-way junction (3WJ) that exhibits significant dissipation and work-distribution long tails upon mechanical unfolding. While bidirectional methods are more predictive, unidirectional methods are strongly biased. We also consider a cyclic protocol that combines the forward and reverse work values to increase the statistics of the measurements. For a fixed total experimental time, faster pulling rates permit us to efficiently sample rare events and reduce the bias, compensating for the increased dissipation. This analysis provides a more stringent test of the fluctuation theorem in the large irreversibility regime. 相似文献
16.
串联稳压电路主要工作在线性状态,因此调整管的功耗大。很多情况下调整管的损坏系因其功耗过大发热所致,所以计算调整管的最大功耗是选择调整管的关键,但一些教材中对调整管功耗的计算方法不够严密。本文利用最大功率传递定理,对调整管的最大功耗进行了分析计算。 相似文献
17.
18.
19.
《Expositiones Mathematicae》2022,40(2):357-394
We give an informal exposition of pushforwards and orientations in generalized cohomology theories in the language of spectra. The whole note can be seen as an attempt at convincing the reader that Todd classes in Grothendieck–Hirzebruch–Riemann–Roch type formulas are not Devil’s appearances but rather that things just go in the most natural possible way. 相似文献
20.
We revisit recent results on integrable cases for higher-dimensional generalizations of the 2D pentagram map: short-diagonal, dented, deep-dented, and corrugated versions, and define a universal class of pentagram maps, which are proved to possess projective duality. We show that in many cases the pentagram map cannot be included into integrable flows as a time-one map, and discuss how the corresponding notion of discrete integrability can be extended to include jumps between invariant tori. We also present a numerical evidence that certain generalizations of the integrable 2D pentagram map are non-integrable and present a conjecture for a necessary condition of their discrete integrability. 相似文献
|