全文获取类型
收费全文 | 1577篇 |
免费 | 21篇 |
国内免费 | 22篇 |
专业分类
化学 | 1005篇 |
晶体学 | 12篇 |
力学 | 51篇 |
数学 | 307篇 |
物理学 | 245篇 |
出版年
2021年 | 17篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 19篇 |
2017年 | 21篇 |
2016年 | 38篇 |
2015年 | 20篇 |
2014年 | 45篇 |
2013年 | 81篇 |
2012年 | 80篇 |
2011年 | 76篇 |
2010年 | 59篇 |
2009年 | 67篇 |
2008年 | 81篇 |
2007年 | 108篇 |
2006年 | 100篇 |
2005年 | 84篇 |
2004年 | 76篇 |
2003年 | 58篇 |
2002年 | 42篇 |
2001年 | 24篇 |
2000年 | 18篇 |
1999年 | 18篇 |
1998年 | 17篇 |
1997年 | 16篇 |
1996年 | 24篇 |
1995年 | 25篇 |
1994年 | 20篇 |
1993年 | 23篇 |
1992年 | 19篇 |
1991年 | 16篇 |
1990年 | 21篇 |
1989年 | 16篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 15篇 |
1985年 | 23篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1982年 | 24篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1977年 | 18篇 |
1976年 | 10篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1965年 | 8篇 |
1960年 | 4篇 |
排序方式: 共有1620条查询结果,搜索用时 15 毫秒
1.
Dariusz Marek Adam Domaski Joanna Domaska Jakub Szygua Tadeusz Czachrski Jerzy Klamka 《Entropy (Basel, Switzerland)》2021,23(5)
In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature. 相似文献
2.
Jan Ingo Flege Jan Höcker Jerzy T. Sadowski Sanjaya D. Senanayake Jens Falta 《Surface and interface analysis : SIA》2019,51(1):110-114
The early stages of ceria growth on Rh(111) at high temperature have been investigated by low-energy electron microscopy and photoemission electron microscopy. Ceria was deposited by reactive Ce deposition at substrate temperatures between 700°C and 900°C in an oxygen ambient of 5 × 10−7 Torr. At 700°C, we observe a high nucleation density of 100-nm-sized islands. With elevated temperature, the average island size increases, and the nucleation density decreases. Triangularly shaped islands nucleate preferentially at step edges, with seemingly abrupt interfaces between Ce and Rh. At 900°C, the island edges are still straight, but during growth the islands lose their triangular form. Instead, growth along the substrate step edges becomes favorable, leading to a maze-like morphology. Atomic force microscopy reveals islands of 0.3 to 0.6-nm height, consistent with ceria islands formed by one or two trilayers (O―Ce―O) of ceria. Moreover, the second layer of the islands is also triangularly shaped, with lateral dimensions of 50 nm and similar step heights. IV-LEEM analysis leads to the conclusion that the rhodium surface is covered by a layer of reduced cerium oxide, which is partially overgrown by smaller islands of CeO2. 相似文献
3.
Gorzkiewicz Krzysztof Mietelski Jerzy Wojciech Kierepko Renata Brudecki Kamil 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(3):1311-1321
Journal of Radioanalytical and Nuclear Chemistry - This paper presents results of the development process of low-background, digital gamma-rays spectrometer equipped with Broad Energy Germanium... 相似文献
4.
Litak Grzegorz Margielewicz Jerzy Gąska Damian Yurchenko Daniil Dąbek Krzysztof 《Nonlinear dynamics》2020,102(4):2125-2142
Nonlinear Dynamics - This paper examines the oscillations of a spherical pendulum with horizontal Lissajous excitation. The pendulum has two degrees of freedom: a rotational angle defined in the... 相似文献
5.
For wide classes of locally convex spaces, in particular, for the space of continuous real‐valued functions on a Tychonoff space X equipped with the pointwise topology, we characterize the existence of a fundamental bounded resolution (i.e., an increasing family of bounded sets indexed by the irrationals which swallows the bounded sets). These facts together with some results from Grothendieck's theory of ‐spaces have led us to introduce quasi‐ ‐spaces, a class of locally convex spaces containing ‐spaces that preserves subspaces, countable direct sums and countable products. Regular ‐spaces as well as their strong duals are quasi‐ ‐spaces. Hence the space of distributions provides a concrete example of a quasi‐ ‐space not being a ‐space. We show that has a fundamental bounded resolution if and only if is a quasi‐ ‐space if and only if the strong dual of is a quasi‐ ‐space if and only if X is countable. If X is metrizable, then is a quasi‐ ‐space if and only if X is a σ‐compact Polish space. 相似文献
6.
Ojha Probir Kumar Kar Supratik Krishna Jillella Gopala Roy Kunal Leszczynski Jerzy 《Molecular diversity》2021,25(1):625-659
Molecular Diversity - After the 1918 Spanish Flu pandemic caused by the H1N1 virus, the recent coronavirus disease 2019 (COVID-19) brought us to the time of serious global health catastrophe.... 相似文献
7.
8.
9.
Self-maps of <Emphasis Type="Italic">S</Emphasis><Superscript>2</Superscript> homotopic to a smooth map with a single <Emphasis Type="Italic">n</Emphasis>-periodic point 下载免费PDF全文
Jerzy Jezierski 《数学学报(英文版)》2017,33(8):1073-1082
We show for which (d,n) ∈ Z×N there exists a smooth self-map f:S2 → S2 so that deg(f)=d and Fix(fn) is a point. 相似文献
10.