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51.
Mow-Lowry CM Mullavey AJ Gossler S Gray MB McClelland DE 《Physical review letters》2008,100(1):010801
A series of recent articles have presented results demonstrating optical cooling of macroscopic objects, highlighting the importance of this phenomenon for investigations of macroscopic quantum mechanics and its implications for thermal noise in gravitational wave detectors. In this Letter, we present a measurement of the off-resonance suspension thermal noise of a 1 g oscillator, and we show that it can be cooled to just 70 mK. The cooling is achieved by using a servo to impose a phase delay between oscillator motion and optical force. A model is developed to show how optical rigidity and optical cooling can be interchangeable using this technique. 相似文献
52.
We report on a study of time dependence of ir laser emission at 3.41 μm in a dense Na vapor that is resonantly excited to the 32 P levels by a flashlamp, pumped dye laser. Energy-pooling collisions (excitation transfer) between excited atoms create a large population inversion among the 52 S 1/2 and 42 P 3/2 states which is destroyed by electron collisions as a result of subsequent plasma formation. The ir laser emission may serve as a new diagnostic tool to follow the time evolution of such media. 相似文献
53.
The exciton binding energy, band gap, and static dialectric constant were obtained from electromodulation measurements on the face-centered cubic (NaCl structure) phase of TlBr. An unusual electroabsorption structure has been observed in TlBr and TlCl for features which have no established assignment. 相似文献
54.
M.M. Gazzaly J.B. Carroll J.V. Geaga G. Igo J.B. McClelland M.A. Nasser H. Spinka A.L. Sagle V. Perez-Mendez R. Talaga E.T.B. Whipple F. Zarbakhsh 《Physics letters. [Part B]》1978,79(3):325-328
Single particle inclusive spectra and the associated multiplicity were obtained with a magnetic spectrometer and an azimuthal array of 30 ?erenkov counters from collisions of 1.8 GeV/nucleon 40Ar on Be and Cu targets. No change is seen in the shape of the spectra obtained by the spectrometer for various multiplicity requirements. 相似文献
55.
Mirman D Holt LL McClelland JL 《The Journal of the Acoustical Society of America》2004,116(2):1198-1207
Different patterns of performance across vowels and consonants in tests of categorization and discrimination indicate that vowels tend to be perceived more continuously, or less categorically, than consonants. The present experiments examined whether analogous differences in perception would arise in nonspeech sounds that share critical transient acoustic cues of consonants and steady-state spectral cues of simplified synthetic vowels. Listeners were trained to categorize novel nonspeech sounds varying along a continuum defined by a steady-state cue, a rapidly-changing cue, or both cues. Listeners' categorization of stimuli varying on the rapidly changing cue showed a sharp category boundary and posttraining discrimination was well predicted from the assumption of categorical perception. Listeners more accurately discriminated but less accurately categorized steady-state nonspeech stimuli. When listeners categorized stimuli defined by both rapidly-changing and steady-state cues, discrimination performance was accurate and the categorization function exhibited a sharp boundary. These data are similar to those found in experiments with dynamic vowels, which are defined by both steady-state and rapidly-changing acoustic cues. A general account for the speech and nonspeech patterns is proposed based on the supposition that the perceptual trace of rapidly-changing sounds decays faster than the trace of steady-state sounds. 相似文献
56.
McKenzie K Grosse N Bowen WP Whitcomb SE Gray MB McClelland DE Lam PK 《Physical review letters》2004,93(16):161105
We demonstrate the generation of broadband continuous-wave optical squeezing from 280 Hz-100 kHz using a below-threshold optical parametric oscillator (OPO). The squeezed state phase was controlled using a noise locking technique. We show that low frequency noise sources, such as seed noise, pump noise, and detuning fluctuations, present in optical parametric amplifiers, have negligible effect on squeezing produced by a below-threshold OPO. This low frequency squeezing is ideal for improving the sensitivity of audio frequency measuring devices such as gravitational-wave detectors. 相似文献
57.
An experimental technique to observe and accurately measure the Gouy phase evolution of Hermite-Gaussian modes is presented. Because of the unique features of spatial mode interference frequency-locking error signals, we are able to readily perform explicit measurement of the Gouy phase in a simple and highly accurate manner. We present these data and discuss the technique and its implications. 相似文献
58.
D.E. McClelland N. Mavalvala Y. Chen R. Schnabel 《Laser \u0026amp; Photonics Reviews》2011,5(5):677-696
Currently operating laser interferometric gravitational wave detectors are limited by quantum noise above a few hundred Hertz. Detectors that will come on line in the next decade are predicted to be limited by quantum noise over their entire useful frequency band (from 10 Hz to 10 kHz). Further sensitivity improvements will, therefore, rely on using quantum optical techniques such as squeezed state injection and quantum non‐demolition, which will, in turn, drive these massive mechanical systems into quantum states. This article reviews the principles behind these optical and quantum optical techniques and progress toward there realization. 相似文献
59.
Nergis Mavalvala David E. McClelland Guido Mueller D. H. Reitze Roman Schnabel Benno Willke 《General Relativity and Gravitation》2011,43(2):569-592
Third generation terrestrial interferometric gravitational wave detectors will likely require significant advances in laser
and optical technologies to reduce two of the main limiting noise sources: thermal noise due to mirror coatings and quantum
noise arising from a combination of shot noise and radiation pressure noise. Increases in laser power and possible changes
of the operational wavelength require new high power laser sources and new electro-optic modulators and Faraday isolators.
Squeezed light can be used to further reduce the quantum noise while nano-structured optical components can be used to reduce
or eliminate mirror coating thermal noise as well as to implement all-reflective interferometer configurations to avoid thermal
effects in mirror substrates. This paper is intended to give an overview on the current state-of-the-art and future trends
in these areas of ongoing research and development. 相似文献
60.
Andrews AB McClelland A Korkeila O Demidov A Krummel A Mullins OC Chen Z 《Langmuir : the ACS journal of surfaces and colloids》2011,27(10):6049-6058
Asphaltenes are an important class of compounds in crude oil whose surface activity is important for establishing reservoir rock wettability which impacts reservoir drainage. While many phenomenological interfacial studies with crude oils and asphaltenes have been reported, there is very little known about the molecular level interactions between asphaltenes and mineral surfaces. In this study, we analyze Langmuir-Blodgett films of asphaltenes and related model compounds with sum frequency generation (SFG) vibrational spectroscopy. In SFG, the polarization of the input (vis, IR) and output (SFG) beams can be varied, which allows the orientation of different functional groups at the interface to be determined. SFG clearly indicates that asphaltene polycyclic aromatic hydrocarbons (PAHs) are highly oriented in the plane of the interface and that the peripheral alkanes are transverse to the interface. In contrast, model compounds with oxygen functionality have PAHs oriented transverse to the interface. Computational quantum chemistry is used to support corresponding band assignments, enabling robust determination of functional group orientations. 相似文献