全文获取类型
收费全文 | 522篇 |
免费 | 16篇 |
国内免费 | 2篇 |
专业分类
化学 | 330篇 |
晶体学 | 5篇 |
力学 | 24篇 |
数学 | 54篇 |
物理学 | 127篇 |
出版年
2023年 | 6篇 |
2022年 | 20篇 |
2021年 | 12篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 9篇 |
2017年 | 11篇 |
2016年 | 30篇 |
2015年 | 27篇 |
2014年 | 19篇 |
2013年 | 35篇 |
2012年 | 44篇 |
2011年 | 48篇 |
2010年 | 21篇 |
2009年 | 12篇 |
2008年 | 27篇 |
2007年 | 27篇 |
2006年 | 31篇 |
2005年 | 27篇 |
2004年 | 12篇 |
2003年 | 18篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有540条查询结果,搜索用时 15 毫秒
91.
Paradoxical vocal fold motion is a rare disorder in which adduction of the folds occurs on inspiration. The disorder presents with signs of airway obstruction and often airway distress, so proper diagnosis by the otorhinolaryngologist is critical to subsequent management. We present a retrospective review of 10 patients with the diagnosis of paradoxical vocal fold motion seen over a 6-year period. Eight patients were females, and 6 required an acute airway intervention at presentation; 3 patients eventually underwent tracheotomy for respiratory decompensation. Six patients had a prior diagnosis of asthma, and this was determined to contribute to their respiratory status. Five patients were treated with botulinum toxin and 2 with flexible nasolaryngoscopic biofeedback, which improved the outcome. A review of the literature confirms a female predominance of patients presenting with paradoxical adduction and airway distress, often with a history of asthma and psychopathology. Our experience with botulinum toxin and biofeedback suggests that these procedures are viable treatment options in the management of patients with this disorder. 相似文献
92.
93.
94.
Butylated hydroxytoluene enediyne: access to diradical and electrophilic quinone methide intermediates 下载免费PDF全文
Edyta M. Greer Cesar S. Quezada Christopher V. Cosgriff 《Journal of Physical Organic Chemistry》2015,28(5):365-369
A theoretical study was carried out on the unimolecular reaction of an enediyne with a fused butylated hydroxytoluene to internally scavenge the p‐benzyne diradical sites formed after the Bergman cyclization. The calculations revealed that the conversion of the p‐benzyne diradical (2‐tert‐butyl‐4‐methyl‐5,8‐didehydro‐1‐naphthalenol) to p‐quinone methide is favored over the conversion to a phenoxy/benzene diradical 4 in an approximate 95:5 ratio. Based on this model, the Bergman cyclization leads in a bifunctional manner to intermediates for competing reactivity with intermolecular H‐atom abstraction. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
95.
N. Zurlo M. Amoretti C. Amsler G. Bonomi C. Carraro C. L. Cesar M. Charlton M. Doser A. Fontana R. Funakoshi P. Genova R. S. Hayano L. V. Jørgensen A. Kellerbauer V. Lagomarsino R. Landua E. Lodi Rizzini M. Macrì N. Madsen G. Manuzio D. Mitchard P. Montagna L. G. Posada H. Pruys C. Regenfus A. Rotondi G. Testera D. P. Van der Werf A. Variola L. Venturelli Y. Yamazaki 《Hyperfine Interactions》2006,172(1-3):97-105
We descrbe how protonium, the quasi-stable antiproton-proton bound system, has been synthesized following the interaction
of antiprotons with the molecular ion in a nested Penning trap environment. From a careful analysis of the spatial distributions of antiproton annihilation events
in the ATHENA experiment, evidence is presented for protonium production with sub-eV kinetic energies in states around n = 70, with low angular momenta. This work provides a new two-body system for studies using laser spectroscopic techniques.
相似文献
96.
97.
Ana E. Tufo Karen E. García Cesar A. Barrero Elsa E. Sileo 《Hyperfine Interactions》2014,224(1-3):239-250
The structural and hyperfine properties of pure and substituted akaganeites prepared in the presence of Mn, Co and urea are presented and discussed. In all samples, the chloride content increased with the increase in the urea concentration of the parent solution, and a small Mn-for-Fe or Co-for-Fe substitution occurred. In pure akaganeites, the increase of urea concentration provoked an enlargement of the unit cell volume and a decrease of the crystallinity of the synthesised oxides. The incorporation of Mn and Co provoked changes in cell parameters and an increase in the crystallinity of the samples. The hyperfine parameters for both iron sites of the akaganeites remained practically unchanged, and the spectral areas of the iron sites located close to the chlorides decreased for the doped samples. The recoilless f-factor increased for the substituted akaganeites, indicating an increase in the strength of the atomic bonding of the iron ions. 相似文献
98.
99.
The Method of Images poses an important difficulty when used to solve the problem of a charge in the presence of a grounded conducting sphere. This arises from the fact that the sum of the inducing charge and the image charge is different from zero. As a consequence, there is a monopole field far from the system, and any ground wire physically connected to the sphere will carry an electric current, changing the initial balance of charges until a new equilibrium is reached. The approach taken in this paper assumed an infinite straight wire connecting the sphere to ground. The charge distribution over the surface of the conductors was calculated, and the results analyzed. It was shown that the thinner the wire, the lower will be its total charge, and the closer will be the calculated charge density at the surface of the sphere to the conventional solution by the Method of Images. 相似文献
100.
A Mayoral C Magen M Jose-Yacaman 《Chemical communications (Cambridge, England)》2012,48(69):8667-8669
The optical response of multibranched gold nanoparticles is studied by means of electron energy-loss spectroscopy (EELS) in aberration corrected STEM mode. In every case the plasmon response is constant and variations in the maxima positions were found to be dependent on the branches aspect ratio. The good spatial resolution combined with the high energy resolution (0.18 eV) of the monochromated electron beam allows mapping the different plasmonic modes along the entire nanoparticles ranging from 0.7 eV up to 2.25 eV. 相似文献