全文获取类型
收费全文 | 102篇 |
免费 | 0篇 |
专业分类
化学 | 24篇 |
力学 | 4篇 |
数学 | 2篇 |
物理学 | 72篇 |
出版年
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1969年 | 2篇 |
1939年 | 1篇 |
排序方式: 共有102条查询结果,搜索用时 78 毫秒
91.
I. V. Hertel M. H. Kelley J. J. McClelland 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1987,6(2):163-183
A general framework using density matrices is developed for the analysis of atomic excitation by spin-polarized electrons. This framework is applied to the specific case of the 3S 1/2→3P 3/2 transition in Na, as studied by the time-reversed, superelastic process. The scattering is characterized in terms of physical parameters describing the collisionally excitedp-state, i.e., its angular momentum (L ⊥), linear polarization (P lin), and alignment angle (γ), with these parameters defined separately for singlet and triplet excitation. An expression for the scattering intensity is derived which is valid for arbitrary electron polarization and atomic state preparation. Specific examples are discussed with a view toward complete determination of the relevant scattering amplitudes and phases. Recent experimental results are reevaluated for comparison with theoretical calculations, and suggestions are made for future experiments. 相似文献
92.
93.
R. Breckpot A. Gatterer W. Gerlach G. Scheibe F. Twyman H. Kaiser J. A. C. McClelland H. K. Whalley J. Junkes J. Martin W. Rollwagen A. Mittasch W. Kordatzki P. Wessel G. M. Ott Remsen-Reihlen A. Thiel und Union Internationale de Chimie 《Fresenius' Journal of Analytical Chemistry》1939,118(3-4):102-106
Ohne Zusammenfassung 相似文献
94.
95.
96.
Bram?J.?J.?SlagmolenEmail author Mark?Barton Conor?Mow-Lowry Glenn?de?Vine David?S.?Rabeling Jong?H.?Chow Albert?Romann Chunnong?Zhao Malcolm?B.?Gray David?E.?McClelland 《General Relativity and Gravitation》2005,37(9):1601-1608
In this paper we report on the alignment locking of an in vacuum 77 m long suspended mirror Fabry-Perot cavity. Lock was achieved
by mode-matching a 500 mW Nd:YAG NPRO onto a pre-mode cleaner, the output of which was then mode-matched to the suspended
cavity. The longitudinal locking was achieved by feeding back to the laser frequency actuator to follow the cavity resonance.
Subsequent implementation of a hybrid auto-alignment system enhanced the stability of the circulating power inside the cavity.
Preliminary results are presented. 相似文献
97.
The reaction between adsorbed oxygen and segregated carbon on a cylindrical nickel single-crystal has been examined with Auger electron spectroscopy (AES) and temperature programmed desorption (TPD), for a range of surface orientation, oxygen exposure, and sulfur coverage. It was found that for small oxygen exposures, surface carbon and surface oxygen react during TPD to form a CO desorption peak, labeled β1. The β1 CO peak temperature and peak shape vary with orientation. At higher oxygen coverages, the CO desorption peak split into low-temperature and high-temperature peaks. The behavior of the β1 CO desorption peak for large oxygen exposures is consistent with a model of the carbon-oxygen recombination reaction in which the morphologies of the initial carbon and oxygen phases change during oxygen exposure as a result of repulsive lateral interactions. High oxygen exposures result in the formation of large regions of contact between the two phases; this is believed to produce the low-temperature β1 CO desorption peak. Small segregated-sulfur coverages, and low oxygen exposures, caused the β1 CO peak to shift to lower temperatures for all orientations. Sulfur is believed to cause more frequent contact between carbon and oxygen for small oxygen exposures because it compresses the adsorbed oxygen and segregated carbon into the sulfur-free areas of the surface. Large coverages of segregated sulfur inhibited carbon segregation on some, and oxygen adsorption on most, orientations. The absence of reactant species explains the disappearance of the β1 CO peak during TPD from orientations which had a high sulfur coverage. 相似文献
98.
J.C. Kahane N.S. Beckford L.B. Chorna J.C. Teachey D.K. McClelland 《Journal of voice》2006,20(2):297-307
The bassoon is a demanding double-reed woodwind instrument requiring exquisite control of airflow and air pressure to the reed to produce desired tonal characteristics. Little information is available from direct visualization of the vocal tract and larynx of the bassoonist while playing. Of particular interest is the mechanism(s) of vibrato. This study was undertaken to understand more fully the mechanics of the upper airway in bassoonists during music production. Four adult bassoon players served as subjects. Three players were studied with both sound-synchronized videofluoroscopy and fiber-optic nasal endoscopy. The other subject was studied only by fiber-optic endoscopy. All subjects were evaluated while playing various scales and standard passages common in music pedagogy. The results from this study revealed several findings on the mechanics of upper airway activity during playing: (1) firm velopharyngeal closure was a prerequisite for maximal containment of air pressure and regulation of airflow in the oropharyngeal regions; (2) changes in the pitch and intensity were associated with differential expansion of the pharynx; (3) tongue activity was notable because of its shaping the size and shape of the airway, its role in regulating airflow to the reed, and its contributions to conditioning airflow in vibrato; and (4) slight vocal fold displacements from subglottal airflow and epiglottic movements from tongue base activity contributed to airway changes during vibrato. These seemed to further condition subglottal pressure trains derived primarily from expiration. 相似文献
99.
The eels of LiF has been measured in the range 0–18 eV with primary beam energies 50 eV and 1.5 keV. Four peaks are clearly resolved in the band gap region at room temperature. The amplitude of the three lower energy loss peaks was found to depend on beam exposure and temperature. It is concluded that the lowest energy peak arises at a beam induced defect, that the next two peaks arise in lithium metal liberated by the electron beam and that the peak nearest to the band edge is due to an intrinsic surface excitation. 相似文献
100.
A. C. Hopkinson R. A. McClelland K. Yates I. G. Csizmadia 《Theoretical chemistry accounts》1969,13(1):65-78
The semi-empirical extended Hückel molecular orbital (EHMO) and non-empirical self consistent field molecular orbital (SCF-MO) methods have been used to study protonation reactions of acids, amides and esters. The work has been extended to the charged intermediates and subsequent products in their hydrolysis reactions.
Contribution from the Department of Chemistry, University of Toronto, Toronto 5, Ontario, Canada. 相似文献
Zusammenfassung Ein semiempirisches, erweitertes Hückel-Verfahren sowie ab initio SCF-MO-Rechnungen wurden zur Untersuchung der Protonierung von Säuren, Amiden und Estern, deren ladungstragender Ab-kömmlinge und ihrer Folgeprodukte herangezogen.
Résumé La méthode de Hückel étendue semi-empirique (EHMO) et la méthode du champ selfconsistant non empirique (SCF MO) ont été utilisées pour l'étude des réactions de protonation des acides, des amides et des esters. Ce travail a été étendu aux intermédiaires chargés et aux produits résultants lors de leur «hydrolyse».
Contribution from the Department of Chemistry, University of Toronto, Toronto 5, Ontario, Canada. 相似文献