全文获取类型
收费全文 | 554篇 |
免费 | 24篇 |
国内免费 | 2篇 |
专业分类
化学 | 389篇 |
晶体学 | 7篇 |
力学 | 17篇 |
数学 | 75篇 |
物理学 | 92篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 16篇 |
2021年 | 24篇 |
2020年 | 20篇 |
2019年 | 18篇 |
2018年 | 16篇 |
2017年 | 7篇 |
2016年 | 30篇 |
2015年 | 22篇 |
2014年 | 16篇 |
2013年 | 29篇 |
2012年 | 39篇 |
2011年 | 37篇 |
2010年 | 23篇 |
2009年 | 22篇 |
2008年 | 38篇 |
2007年 | 38篇 |
2006年 | 28篇 |
2005年 | 34篇 |
2004年 | 20篇 |
2003年 | 23篇 |
2002年 | 14篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
1957年 | 1篇 |
1940年 | 1篇 |
1935年 | 3篇 |
1906年 | 1篇 |
排序方式: 共有580条查询结果,搜索用时 15 毫秒
91.
92.
Using experiments and theory, we show that light scattering by inhomogeneities in the index of refraction of a fluid can drive a large-scale flow. The experiment uses a near-critical, phase-separated liquid, which experiences large fluctuations in its index of refraction. A laser beam traversing the liquid produces a interface deformation on the scale of the experimental setup and can cause a liquid jet to form. We demonstrate that the deformation is produced by a scattering-induced flow by obtaining good agreements between the measured deformations and those calculated assuming this mechanism. 相似文献
93.
Sonochemical processing techniques may be used to create fully miscible sols without the initial addition of a solvent. However,
by intentionally adding excess alcohol to a sol produced by sonication, it is possible to manipulate the porosity of the resulting
sonogel. Sonogels of systematically varied methanol content were prepared using a two-step process with subsequent drying
at 60°C. The as-prepared sol with no excess methanol produced a purely microporous solid. The addition of excess methanol
to the sol resulted in the formation of mixed microporosity and mesoporosity as revealed by nitrogen gas adsorption and transmission
electron microscopy. 相似文献
94.
The nature of the instability governing the self-sustained tones produced by a low Mach number plane jet impinging on a slotted plate, known as slot-tone, is identified experimentally. For a given Reynolds number, the natural shear-layer and the jet column mode frequencies of the free jet delimit the values of the measured slot-tone operating frequencies. The oscillations at lower frequencies are the result of the amplification of the jet column mode, and those at higher frequencies correspond to the shear layer instabilities. To cite this article: A. Billon et al., C. R. Mecanique 332 (2004). 相似文献
95.
96.
Troy N. Eichmann Timothy J. McIntyre Alexis I. Bishop Sosefo Vakata Halina Rubinsztein-Dunlop 《Shock Waves》2007,16(4-5):299-307
Flow visualization experiments were performed for supersonic and hypersonic nitrogen test gas flows over a cylinder. The results
were used to quantify the influence of three-dimensional effects on optical line-of-sight visualization measurements. Images
of cylindrical models of varying aspect ratios (length to diameter) were taken. Shock stand-off distance measurements for
the models were compared with a two-dimensional approximation and numerical simulations. For aspect ratios of two and above,
the two-dimensional approximation was acceptable within experimental uncertainty. The measured shock stand-off decreased by
less than 5% from an asymptotic value for an infinite length cylinder. For smaller aspect ratios, a correction factor for
the shock stand-off needs to be applied if comparisons between the two-dimensional approximation and experimental measurements
are to be drawn. An estimate of this correction factor has been derived from an empirical fit to the available data.
相似文献
97.
98.
Alexis F. Vasseur 《NoDEA : Nonlinear Differential Equations and Applications》2007,14(5-6):753-785
In this paper we give a new proof of the partial regularity of solutions to the incompressible Navier-Stokes equation in dimension
3 first proved by Caffarelli, Kohn and Nirenberg. The proof relies on a method introduced by De Giorgi for elliptic equations.
This work was supported in part by NSF Grant DMS-0607953. 相似文献
99.
Michèle?Thieullen Alexis?VigotEmail author 《Methodology and Computing in Applied Probability》2017,19(1):121-149
In this paper, we consider the composition of two independent processes: one process corresponds to position and the other one to time. Such processes will be called iterated processes. We first propose an algorithm based on the Euler scheme to simulate the trajectories of the corresponding iterated processes on a fixed time interval. This algorithm is natural and can be implemented easily. We show that it converges almost surely, uniformly in time, with a rate of convergence of order 1/4 and propose an estimation of the error. We then extend the well known Feynman-Kac formula which gives a probabilistic representation of partial differential equations (PDEs), to its higher order version using iterated processes. In particular we consider general position processes which are not necessarily Markovian or are indexed by the real line but real valued. We also weaken some assumptions from previous works. We show that intertwining diffusions are related to transformations of high order PDEs. Combining our numerical scheme with the Feynman-Kac formula, we simulate functionals of the trajectories and solutions to fourth order PDEs that are naturally associated to a general class of iterated processes. 相似文献
100.
Lizbeth Zamora-Mendoza Esteban Guamba Karla Mio Maria Paula Romero Anghy Levoyer Jos F. Alvarez-Barreto Antnio Machado Frank Alexis 《Molecules (Basel, Switzerland)》2022,27(22)
Healthcare-associated infections (HAI), or nosocomial infections, are a global health and economic problem in developed and developing countries, particularly for immunocompromised patients in their intensive care units (ICUs) and surgical site hospital areas. Recurrent pathogens in HAIs prevail over antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. For this reason, natural antibacterial mechanisms are a viable alternative for HAI treatment. Natural fibers can inhibit bacterial growth, which can be considered a great advantage in these applications. Moreover, these fibers have been reported to be biocompatible and biodegradable, essential features for biomedical materials to avoid complications due to infections and significant immune responses. Consequently, tissue engineering, medical textiles, orthopedics, and dental implants, as well as cosmetics, are fields currently expanding the use of plant fibers. In this review, we will discuss the source of natural fibers with antimicrobial properties, antimicrobial mechanisms, and their biomedical applications. 相似文献