全文获取类型
收费全文 | 301篇 |
免费 | 29篇 |
国内免费 | 53篇 |
专业分类
化学 | 14篇 |
力学 | 9篇 |
综合类 | 7篇 |
数学 | 316篇 |
物理学 | 37篇 |
出版年
2024年 | 1篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 16篇 |
2019年 | 12篇 |
2018年 | 14篇 |
2017年 | 23篇 |
2016年 | 11篇 |
2015年 | 3篇 |
2014年 | 13篇 |
2013年 | 31篇 |
2012年 | 11篇 |
2011年 | 10篇 |
2010年 | 15篇 |
2009年 | 12篇 |
2008年 | 19篇 |
2007年 | 13篇 |
2006年 | 12篇 |
2005年 | 10篇 |
2004年 | 19篇 |
2003年 | 6篇 |
2002年 | 18篇 |
2001年 | 26篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 15篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有383条查询结果,搜索用时 19 毫秒
51.
A lumped parameter model of the sub-system of left ventricle, aortic valve, systemic arteries, systemic capillaries and systemic
veins was considered during systole. A model of aortic valve dynamics based solely on geometrical and kinematical consideration
is defined. The model is described by two geometrical parameters of aortic valve and a few kinematical relationships. The
proposed model mimics the incisures in the aortic flow and aortic pressure very well. We showed that the dicrotic notch could
be explained by aortic valve closing in terms of a lumped parameter model, without a need for any wave reflection theory.
According to the proposed model the effects of aortic valve dynamics on the aortic flow and pressure are mainly limited to
the valve opening and closing periods. The model offers a new paradigm for defining a more realistic left ventricle model.
相似文献
52.
The main result of the paper is a decomposition theorem of the left regular ordered semigroups into left regular and left simple semigroups. 相似文献
53.
无挠左(右)Artin环是拟Frobenius环乌成伟(吉林工学院基础部,长春130012)关键词内积,左(右)内零化子,自内射环.分类号AMS(1991)16D50/CCLO153.3设R为有1的左(右)Artin环,如果对于任一整数洲与r∈R,m... 相似文献
54.
Yaping Jiang 《Mathematische Nachrichten》1996,181(1):231-244
This paper reveals that the sub-Laplacian L0 on two step stratified Lie groups has a similar behavior like elliptic operators on the Euclidean space, that is, the sub - Laplacian satisfies a group-elliptic estimate, called the G- elliptic estimate (or the Lp regularity), and the general left Invariant operator Lλ has such a behavior if and only if λ is admissible. 相似文献
55.
We show that CH implies that , when equipped with the Vietoris topology, has a subspace which is an L-space and a subspace which is an S-space. This is an immediate consequence of the following purely combinatorial result: CH implies the existence of an ω1-sequence 〈xα: α < ω1〉 in such that (1) if α<β<ω1, then ; (2) if I ?ω1 is unaccountable, then there are distinct α, β ∈ I with Xβ ?Xα. 相似文献
56.
Rebecca Finley Detweiler 《Journal of voice》1994,8(4):303-313
Since its introduction, the Sundberg model of the laryngeal system as the resonance source of the singer's formant has gained wide acceptance. However, no studies directly testing this hypothesis in vivo have previously been reported. Thus, the present study was undertaken to test this hypothesis on three classically trained professional male singers. The vocal behaviors of the singer-subjects were evaluated during modal and pulse register phonation via magnetic resonance imaging, strobolaryngoscopy, and acoustic analysis. Results indicated the subjects did not achieve the laryngopharyngeal/laryngeal outlet cross-sectional area ratio requisite to the model and that the formant remained robust in pulse register phonation. It was concluded that these subjects' behaviors were not consistent with Sundberg's model and that the model was inadequate to account for the generation of the singer's formant in these three subjects. 相似文献
57.
Avi BickWalter Willinger 《Stochastic Processes and their Applications》1994,50(2):349-374
The paper presents a non-probabilistic approach to continuous-time trading where, in analogy to the binomial option-pricing model, terminal payoffs resulting from a given trading strategy are meaningful ‘state-by-state’, i.e., path-by-path. In particular, we obtain results of the form: “If a certain trading strategy is applied and if the realized price trajectory satisfies a certain analytical property, then the terminal payoff is.…” This way, derivation of the Black and Scholes formula and its extension become an exercise in the analysis of a certain class of real functions. While results of the above forms are of great interest if the analytical property in question is believed to be satisfied for almost all realized price trajectories (for example, if the price is believed to follow a certain stochastic process which has this property with probability 1), they are valid regardless of the stochastic process which presumably generates the possible price trajectories or the probability assigned to the set of all paths having this analytical property. 相似文献
58.
Let S be topological semigroup, we consider an appropriate semigroup compactification of S. In this paper we study the connection between subgroups of a maximal group in a minimal left ideal of , which arise as equivalence classes of some closed left congruence, and the minimal ow characterized by the left congruence. A particular topology is defined on a maximal group and it is shown that a closed subgroup under this topology is precisely the intersection of an equivalence class with the maximal group for some left congruence on . 相似文献
59.
关于光学实验中望远镜与光杠杆的调节探讨 总被引:2,自引:0,他引:2
在关于望远镜的光杠杆调节中通常只给出了对光杠杆及望远镜的上下位置的调节,而忽视了望远镜和光杠杆的左右调节。给出了望远镜和光杠杆的调节中左右位置的调节原理和调节操作方法,从而使望远镜和光杠杆的调节更具有目的性,使实验进行的更加快速和准确。 相似文献
60.