全文获取类型
收费全文 | 1774篇 |
免费 | 192篇 |
国内免费 | 36篇 |
专业分类
化学 | 530篇 |
晶体学 | 1篇 |
力学 | 121篇 |
综合类 | 5篇 |
数学 | 638篇 |
物理学 | 707篇 |
出版年
2024年 | 6篇 |
2023年 | 23篇 |
2022年 | 54篇 |
2021年 | 70篇 |
2020年 | 61篇 |
2019年 | 50篇 |
2018年 | 44篇 |
2017年 | 57篇 |
2016年 | 71篇 |
2015年 | 52篇 |
2014年 | 112篇 |
2013年 | 105篇 |
2012年 | 115篇 |
2011年 | 117篇 |
2010年 | 94篇 |
2009年 | 94篇 |
2008年 | 106篇 |
2007年 | 88篇 |
2006年 | 91篇 |
2005年 | 111篇 |
2004年 | 81篇 |
2003年 | 70篇 |
2002年 | 67篇 |
2001年 | 47篇 |
2000年 | 51篇 |
1999年 | 31篇 |
1998年 | 27篇 |
1997年 | 22篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1981年 | 2篇 |
1978年 | 2篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有2002条查询结果,搜索用时 46 毫秒
91.
Arnold D. Seifer 《Journal of statistical physics》1969,1(4):571-584
A random configuration of objects in space, or a stochastically rough boundary, is considered to scatter an incident acoustic or electromagnetic wave having harmonic time dependencee
iwt
. In the case of a stochastic surface, Beckmann has compared the Kirchhoff solution with his approach, which employs random walk. The latter approach is used to demonstrate the Rayleigh-distributed amplitude of a field scattered by a very rough surface. This demonstration requires the conjecture that large standard deviations in the random phases of the scattered elementary waves result in an incoherent scattered field. Beckmann's conjecture has not been rigorously proven. However, in this paper, incoherence of the scattered field and broad distributions, over many cycles, in the phases of the elementary waves are both shown to be implied by a third condition, which is defined. Furthermore, the random phase of an incoherent field is shown to be statistically independent of its amplitude and uniformly distributed on a 2-rad interval. 相似文献
92.
In this paperwewill derive a generalized uncertainty principle (GUP) in a simple varying speed of light (VSL) model. First
we will show that VSL is an immediate consequence of GUP. Then, within the framework of a simple VSL model, we will show that
GUP can be expressed as a function of cosmological scale factor. This expression gives two main results: uncertainties in
position and momentum are actually cosmological models dependent and these uncertainties depend on mass and momentum of the
particle under consideration. The relationship between matter content of the Universe and the values of uncertainties in early
stages of the evolution of the Universe will be discussed in a mini-superspace approach. 相似文献
93.
This text summarises the PhD thesis that Roel Leus presented to obtain the degree of Doctor in Applied Economics at the Katholieke Universiteit Leuven, in September 2003. The promotor of the thesis was professor Willy Herroelen. The thesis is written in English and is available from the authors website. The goal of the thesis was to provide recommendations for the detailed scheduling of multi-project organisations, when a certain degree of uncertainty exists about a number of characteristics of the project. Up till now, the majority of the literature on project scheduling has consisted of deterministic models for planning a single project: both the uncertainty aspect as well as the intrinsic difficulty of coordination of a portfolio of projects have been largely ignored.Received: October 2003, MSC classification:
09B35, 90B36 相似文献
94.
Ilya?KuselmanEmail author Alexander?Weisman Wolfhard?Wegscheider 《Accreditation and quality assurance》2003,8(11):530-531
The current situation in the pharmaceutical industry is discussed, when the traceability of measurement (analytical) results to certified values of pharmacopoeial reference standards is required, without evaluating their uncertainties. It is shown that the evaluation of measurement uncertainty is necessary for understanding the level of confidence of the analytical results and their comparability, particularly during preparation and characterisation of the reference standards.Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board and the Publisher. Apart from exceptional circumstances, they are not submitted to the usual referee procedure and go essentially unaltered. 相似文献
95.
Clifford algebraic geometry corresponds to Minkowski space. Using the discrete structure of Minkowski space, we can abstract
a class n-dimensional hyperbolic Hilbert phase space. To discussing the causality of physical event in Minkowski space, we
can obtain the geometrical interpretation of uncertainty relation. 相似文献
96.
97.
98.
C. S. Unnikrishnan 《Foundations of Physics Letters》2000,13(2):197-200
An experiment proposed earlier by Karl Popper in his critique of the Copenhagen interpretation was realized recently by Kim and Shih. We show that the Copenhagen interpretation is consistent with the results, contrary to Popper's expectation. We examine the role of signal locality and momentum conservation in Popper's experiment and in the realization by Kim and Shih. 相似文献
99.
随机需求下仓库容量有限的物流库存管理问题的研究 总被引:4,自引:0,他引:4
在随机需求下,本文研究当物流企业自有仓库容量限时的物流库存管理问题,给出了使库存成本期望最小的订货量. 相似文献
100.
For many industries (e.g., apparel retailing) managing demand through price adjustments is often the only tool left to companies once the replenishment decisions are made. A significant amount of uncertainty about the magnitude and price sensitivity of demand can be resolved using the early sales information. In this study, a Bayesian model is developed to summarize sales information and pricing history in an efficient way. This model is incorporated into a periodic pricing model to optimize revenues for a given stock of items over a finite horizon. A computational study is carried out in order to find out the circumstances under which learning is most beneficial. The model is extended to allow for replenishments within the season, in order to understand global sourcing decisions made by apparel retailers. Some of the findings are empirically validated using data from U.S. apparel industry. 相似文献