全文获取类型
收费全文 | 6831篇 |
免费 | 272篇 |
国内免费 | 42篇 |
专业分类
化学 | 4795篇 |
晶体学 | 43篇 |
力学 | 164篇 |
数学 | 756篇 |
物理学 | 1387篇 |
出版年
2023年 | 44篇 |
2022年 | 49篇 |
2021年 | 102篇 |
2020年 | 139篇 |
2019年 | 126篇 |
2018年 | 94篇 |
2017年 | 81篇 |
2016年 | 177篇 |
2015年 | 159篇 |
2014年 | 185篇 |
2013年 | 351篇 |
2012年 | 378篇 |
2011年 | 468篇 |
2010年 | 216篇 |
2009年 | 175篇 |
2008年 | 412篇 |
2007年 | 418篇 |
2006年 | 423篇 |
2005年 | 336篇 |
2004年 | 307篇 |
2003年 | 279篇 |
2002年 | 237篇 |
2001年 | 96篇 |
2000年 | 116篇 |
1999年 | 76篇 |
1998年 | 72篇 |
1997年 | 72篇 |
1996年 | 103篇 |
1995年 | 83篇 |
1994年 | 67篇 |
1993年 | 74篇 |
1992年 | 66篇 |
1991年 | 66篇 |
1990年 | 67篇 |
1988年 | 38篇 |
1987年 | 50篇 |
1986年 | 48篇 |
1985年 | 70篇 |
1984年 | 79篇 |
1983年 | 40篇 |
1982年 | 46篇 |
1981年 | 57篇 |
1980年 | 64篇 |
1979年 | 56篇 |
1978年 | 54篇 |
1977年 | 56篇 |
1976年 | 61篇 |
1975年 | 39篇 |
1974年 | 42篇 |
1973年 | 45篇 |
排序方式: 共有7145条查询结果,搜索用时 15 毫秒
1.
Dr. Chen-Ming Lin Maritess Arancillo Jonathan Whisenant Prof. Kevin Burgess 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(24):9484-9488
Secondary structures tend to be recognizable because they have repeating structural motifs, but mimicry of these does not have to follow such well-defined patterns. Bioinformatics studies to match side-chain orientations of a novel hydantoin triazole chemotype ( 1 ) to protein-protein interfaces revealed it tends to align well across parallel and antiparallel sheets, like rungs on a ladder. One set of these overlays was observed for the protein-protein interaction uPA⋅uPAR. Consequently, chemotype 1 was made with appropriate side-chains to mimic uPA at this interface. Biophysical assays indicate these compounds did in fact bind uPAR, and elicit cellular responses that affected invasion, migration, and wound healing. 相似文献
2.
3.
4.
5.
Kevin Phelps 《Designs, Codes and Cryptography》2015,77(2-3):357-363
6.
Facile non‐lithographic route to highly aligned silica nanopatterns using unidirectionally aligned polystyrene‐block‐polydimethylsiloxane films
下载免费PDF全文
![点击此处可从《Journal of Polymer Science.Polymer Physics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zhe Qiang Maurice L. Wadley Bryan D. Vogt Kevin A. Cavicchi 《Journal of Polymer Science.Polymer Physics》2015,53(15):1058-1064
Thin films (monolayer and bilayer) of cylinder forming polystyrene‐block‐polydimethylsiloxane (PS‐b‐PDMS) were shear aligned by the swelling and deswelling of a crosslinked PDMS pad that was physically adhered to the film during solvent vapor annealing. The nanostructures formed by self‐assembly were exposed to ultraviolet‐ozone to partially oxidize the PDMS, followed by calcination in air at 500 °C. In this process, the PS segments were fully decomposed, while the PDMS yielded silica nanostructures. The highly aligned PDMS cylinders were thus deposited as silica nanolines on the silicon substrate. Using a bilayer film, the center‐to‐center distance of these features were effectively halved from 38 to 19 nm. Similarly, by sequential shear‐alignment of two distinct layers, a rhombic array of silica nanolines was fabricated. This methodology provides a facile route to fabricating complex topographically patterned nanostructures. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1058–1064 相似文献
7.
8.
9.
10.
A comparison of steady-state evoked potentials to modulated tones in awake and sleeping humans. 总被引:12,自引:0,他引:12
L T Cohen F W Rickards G M Clark 《The Journal of the Acoustical Society of America》1991,90(5):2467-2479
Steady-state evoked potential responses were measured to binaural amplitude-modulated (AM) and combined amplitude- and frequency-modulated (AM/FM) tones. For awake subjects, AM/FM tones produced larger amplitude responses than did AM tones. Awake and sleeping responses to 30-dB HL AM/FM tones were compared. Response amplitudes were lower during sleep and the extent to which they differed from awake amplitudes was dependent on both carrier and modulation frequencies. Background EEG noise at the stimulus modulation frequency was also reduced during sleep and varied with modulation frequency. A detection efficiency function was used to indicate the modulation frequencies likely to be most suitable for electrical estimation of behavioral threshold. In awake subjects, for all carrier frequencies tested, detection efficiency was highest at a modulation frequency of 45 Hz. In sleeping subjects, the modulation frequency regions of highest efficiency varied with carrier frequency. For carrier frequencies of 250 Hz, 500 Hz, and 1 kHz, the highest efficiencies were found in two modulation frequency regions centered on 45 and 90 Hz. For 2 and 4 kHz, the highest efficiencies were at modulation frequencies above 70 Hz. Sleep stage affected both response amplitude and background EEG noise in a manner that depended on modulation frequency. The results of this study suggest that, for sleeping subjects, modulation frequencies above 70 Hz may be best when using steady-state potentials for hearing threshold estimation. 相似文献