全文获取类型
收费全文 | 1440篇 |
免费 | 78篇 |
国内免费 | 10篇 |
专业分类
化学 | 1151篇 |
晶体学 | 6篇 |
力学 | 8篇 |
数学 | 148篇 |
物理学 | 215篇 |
出版年
2023年 | 20篇 |
2022年 | 11篇 |
2021年 | 37篇 |
2020年 | 43篇 |
2019年 | 28篇 |
2018年 | 33篇 |
2017年 | 18篇 |
2016年 | 81篇 |
2015年 | 35篇 |
2014年 | 56篇 |
2013年 | 81篇 |
2012年 | 120篇 |
2011年 | 146篇 |
2010年 | 72篇 |
2009年 | 57篇 |
2008年 | 112篇 |
2007年 | 82篇 |
2006年 | 75篇 |
2005年 | 87篇 |
2004年 | 68篇 |
2003年 | 58篇 |
2002年 | 45篇 |
2001年 | 9篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1998年 | 15篇 |
1997年 | 12篇 |
1996年 | 15篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1971年 | 2篇 |
1968年 | 4篇 |
1960年 | 2篇 |
1957年 | 2篇 |
1935年 | 2篇 |
排序方式: 共有1528条查询结果,搜索用时 250 毫秒
41.
42.
43.
44.
Bruno Saussereau Ion Lucretiu Stoica 《Stochastic Processes and their Applications》2012,122(4):1456-1486
We study a fractional stochastic perturbation of a first-order hyperbolic equation of nonlinear type. The existence and uniqueness of the solution are investigated via a Lax–Ole?nik formula. To construct the invariant measure we use two main ingredients. The first one is the notion of a generalized characteristic in the sense of Dafermos. The second one is the fact that the oscillations of the fractional Brownian motion are arbitrarily small for an infinite number of intervals of arbitrary length. 相似文献
45.
Christina Schmidt A. M. Sarwaruddin Chowdhury† Klaus Neuking Gunther Eggeler 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):204-210
Thermomechanical cycles including programming, cooling, unloading and heating to trigger the 1WE were examined for a shape memory polymer (SMP), Tecoflex® (TFX EG-72D). Cycles were performed at 60°C with 50% and 225% strains and the recovery time of 10 min. Strains evolving with time were estimated during the thermomechanical treatments for the total 44 cycles using 50% strains and the total 50 cycles using 225% strains. Recovery ratios for 50% strains and 225% were also estimated. It turns out that programming, cooling, unloading and heating to trigger the 1WE causes an increase of irreversible strain and is associated with a corresponding decrease of the intensity of the 1WE in particular during the first thermomechanical cycles. In parallel scanning electron microscopic study using secondary electron imaging shows a very slight wavy surface structure evolved during cycling. 相似文献
46.
Sreekar Wunnava Christina F. Dirscherl Jakub Výravský Dr. Aleš Kovařík Dr. Roman Matyášek Prof. Jiří Šponer Prof. Dieter Braun Dr. Judit E. Šponer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(70):17581-17585
The assembly of ancient informational polymers from nucleotide precursors is the central challenge of life's origin on our planet. Among the possible solutions, dry polymerization of 3’,5’-cyclic guanosine monophosphate (3’,5’-cGMP) has been proposed as a candidate to create oligonucleotides of 15–20 units in length. However, the reported sensitivity of the reaction to the presence of cations raised questions of whether this chemistry could be relevant in a geological context. The experiments in this study show that the presence of cations is not restrictive as long as the reaction is conducted in an acidic environment, in contrast to previous reports that suggested optimal conditions at pH 9. 相似文献
47.
48.
Andreea Irina Barzic Iuliana Stoica Dana-Ortansa Dorohoi 《Journal of Macromolecular Science: Physics》2016,55(6):575-590
New drug delivery systems based on hydroxypropyl cellulose (HPC) and different percents of glucose were prepared and characterized to check their suitability as UV resistant patches. The spectral absorption properties of the HPC and HPC-glucose blends before and after UV irradiation were analyzed. The surface polarity and hydrophilicity were correlated with the morphology of the films and analyzed with respect to the UV exposure time and the embedded amount of glucose. The effects of UV radiation on in vitro evaluation of glucose release from the HPC films are reported. The mechanism involved in the drug release process, evaluated using the Korsmeyer-Peppas equation, was dependent on the introduced amount of glucose and less on the UV exposure time. A more polar, smoother, and less dense surface releases the glucose over larger periods of time, making the system with lower percents of glucose more adequate for the pursued purpose. 相似文献
49.
50.