全文获取类型
收费全文 | 3773篇 |
免费 | 199篇 |
国内免费 | 177篇 |
专业分类
化学 | 480篇 |
晶体学 | 10篇 |
力学 | 68篇 |
综合类 | 42篇 |
数学 | 3040篇 |
物理学 | 509篇 |
出版年
2023年 | 18篇 |
2022年 | 45篇 |
2021年 | 84篇 |
2020年 | 85篇 |
2019年 | 82篇 |
2018年 | 90篇 |
2017年 | 91篇 |
2016年 | 114篇 |
2015年 | 82篇 |
2014年 | 148篇 |
2013年 | 406篇 |
2012年 | 154篇 |
2011年 | 157篇 |
2010年 | 142篇 |
2009年 | 212篇 |
2008年 | 209篇 |
2007年 | 256篇 |
2006年 | 171篇 |
2005年 | 155篇 |
2004年 | 120篇 |
2003年 | 136篇 |
2002年 | 139篇 |
2001年 | 126篇 |
2000年 | 99篇 |
1999年 | 109篇 |
1998年 | 79篇 |
1997年 | 80篇 |
1996年 | 62篇 |
1995年 | 65篇 |
1994年 | 64篇 |
1993年 | 32篇 |
1992年 | 32篇 |
1991年 | 37篇 |
1990年 | 20篇 |
1989年 | 25篇 |
1988年 | 23篇 |
1987年 | 19篇 |
1986年 | 16篇 |
1985年 | 35篇 |
1984年 | 18篇 |
1983年 | 18篇 |
1982年 | 17篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 20篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1973年 | 3篇 |
排序方式: 共有4149条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
In this paper we show that the Boltzmann weights of the three-dimensional Baxter-Bazhanov model give representations of the braid group if some suitable spectral limits are taken. In the trigonometric case we classify all possible spectral limits which produce braid group representations. Furthermore, we prove that for some of them we get cyclotomic invariants of links and for others we obtain tangle invariants generalizing the cyclotomic ones. 相似文献
25.
26.
OU型Markov过程的不变测度及弱对偶性 总被引:1,自引:1,他引:0
本文研究OU型Markov过程的不变测度、参考测度和弱对偶半群的存在性问题,并得出了不变测度的唯一性。 相似文献
27.
N.-K. Lee T.A. Vilgis 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(4):451-465
We study the elastic properties of single A/B random copolymer chains, with a specific sequence and use them as theoretical
model for so called HP proteins. HP proteins carry hydrophilic (P) and hydrophobic (H) monomers. We predict a rich structure
in the force-extension relations which can be attributed to the information in the sequence. The variational method is used
to probe local minima on the path of stretching and releasing for the chain molecules. At a given force, we find multiple
configurations which are separated by energy barriers. A collapsed globular configuration consists of several domains which
unravel cooperatively. Upon stretching, the unfolding path shows a stepwise pattern corresponding to the unfolding of each
domain. While releasing, several cores can be created simultaneously in the middle of the chain, resulting in a different
path of collapse. The long-range interactions and stiffness of the chain simplify the potential landscape given by the disorder
in sequence.
Received 5 March 2002 / Received in final form 16 May 2002 Published online 13 August 2002 相似文献
28.
E. Mathieu Y. Foucher P. Dellamonica J. P. Daures 《Methodology and Computing in Applied Probability》2007,9(3):389-397
In AIDS control, physicians have a growing need to use pragmatically useful and interpretable tools in their daily medical
taking care of patients. Semi-Markov process seems to be well adapted to model the evolution of HIV-1 infected patients. In
this study, we introduce and define a non homogeneous semi-Markov (NHSM) model in continuous time. Then the problem of finding
the equations that describe the biological evolution of patient is studied and the interval transition probabilities are computed.
A parametric approach is used and the maximum likelihood estimators of the process are given. A Monte Carlo algorithm is presented
for realizing non homogeneous semi-Markov trajectories. As results, interval transition probabilities are computed for distinct
times and follow-up has an impact on the evolution of patients.
相似文献
29.
We introduce the time-consistency concept that is inspired by the so-called “principle of optimality” of dynamic programming
and demonstrate – via an example – that the conditional value-at-risk (CVaR) need not be time-consistent in a multi-stage
case. Then, we give the formulation of the target-percentile risk measure which is time-consistent and hence more suitable
in the multi-stage investment context. Finally, we also generalize the value-at-risk and CVaR to multi-stage risk measures
based on the theory and structure of the target-percentile risk measure. 相似文献
30.
The Efficient Determination Criterion (EDC) generalizes the AIC and BIC criteria and provides a class of consistent estimators
for the order of a Markov chain with finite state space. In this note, we derive rates of convergence for the EDC estimates.
*Partially supported by CNPq, CAPES/PROCAD, FAPDF/PRONEX, FINATEC and FUNPE/UnB.
**Partially supported by CAPES. 相似文献