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Erich Manegold 《Colloid and polymer science》1938,82(1):26-36
Ohne Zusammenfassung 相似文献
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Stochastic resonance is a statistical phenomenon that has been observed in periodically modulated, noise-driven, bistable systems. The characteristic signatures of the effect include an increase in the signal-to-noise of the output as noise is added to the system, and exponentially decreasing peaks in the probability density as a function of residence times in one state. Presented are the results of a numerical simulation where these same signatures were observed by adding achaotic driving term instead of a white noise term. Although the probability distributions of the noise and chaos inputs were significantly different, the stochastic and chaotic resonances were equal within the experimental error. 相似文献
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Zusammenfassung An feinpolierten, ölbeschichteten V2A-Oberflächen mit jeweils einer gebohrten (d=140 µm) und einer geätzten (d=47 µm) Vertiefung als Keimstelle wurde für Wasserblasen das Wachstum, der Abreißdurchmesser und die Abreißfrequenz gemessen. Für die wärmetransportgesteuerte Blasenbildung liefert der Vergleich mit Beziehungen, die für reine Metallflächen gewonnen wurden, gute Übereinstimmung, so daß keine Einfluß der Ölschicht erkennbar wurde.
Formelzeichen a Temperaturleitfähigkeit - D a Blasenabreißdurchmesser - f Blasenfrequenz - Ja Jakob-Zahl - Pr Prandtl-Zahl /a - q Wärmestromdichte - R Blasenradius - T Temperatur - dynamische Zähigkeit - Wärmeleitfähigkeit - Dichte - Oberflächenspannung - Zeit Indizes g Gas, Dampf - l flüssig - s Sättigung - w Wand Herrn Prof. Dr.-Ing. Karl Stephan zum 60. Geburtstag gewidmet 相似文献
Investigation of single vapor bubbles on surfaces covered with a thin oil film with artificial nuclei
For single vapor bubbles, the growth rates, the detachment diameter, and the frequency were measured on single artificial nuclei, either drilled (d=140 µm) or etched (d=47 µm) into a highly polished stainless steel plate which was covered with a thin oil film. For evaporation controlled by heat transport, good agreement was observed with relations from literature which were obtained for clean surfaces; thus, an effect of the oil film could not be discovered.
Formelzeichen a Temperaturleitfähigkeit - D a Blasenabreißdurchmesser - f Blasenfrequenz - Ja Jakob-Zahl - Pr Prandtl-Zahl /a - q Wärmestromdichte - R Blasenradius - T Temperatur - dynamische Zähigkeit - Wärmeleitfähigkeit - Dichte - Oberflächenspannung - Zeit Indizes g Gas, Dampf - l flüssig - s Sättigung - w Wand Herrn Prof. Dr.-Ing. Karl Stephan zum 60. Geburtstag gewidmet 相似文献
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Erich Berger 《Probability Theory and Related Fields》1990,84(2):161-201
Summary In this paper we establish an almost sure invariance principle with an error termo((t log logt)1/2) (ast) for partial sums of stationary ergodic martingale difference sequences taking values in a real separable Banach space. As partial sums of weakly dependent random variables can often be well approximated by martingales, this result also leads to almost sure invariance principles for a wide class of stationary ergodic sequences such as ø-mixing and -mixing sequences and functionals of such sequences. Compared with previous related work for vector valued random variables (starting with an article by Kuelbs and Philipp [27]), the present approach leads to a unification of the theory (at least for stationary sequences), moment conditions required by earlier authors are relaxed (only second order weak moments are needed), and our proofs are easier in that we do not employ estimates of the rate of convergence in the central limit theorem but merely the central limit theorem itself. 相似文献
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Erich N. Grossman 《International Journal of Infrared and Millimeter Waves》1989,10(7):803-820
A new device for the gigahertz modulation of far-infrared radiation is analytically and numerically analyzed. It consists of a thin layer of a high-mobility, direct-bandgap semiconductor, such as GaAs, in which a high-density electron-hole plasma is rapidly created and destroyed, thereby rapidly changing the free-carrier reflectivity of the active layer. Illumination by a high-power, near-infrared laser diode array generates the plasma through intrinsic photoconduction. It is shown that this device acis primarily as an amplitude modulator, and that its efficiency increases sharply with increasing far-IR frequency, in contrast to a Schottky diode, which acts primarily as a phase modulator, and whose efficiency falls off sharply with far-IR frequency. The breakeven frequency lies at about 1.5 THz, depending slightly on the assumed device parameters. The relative advantage of the new device increases rapidly with increasing far-infrared frequency. At an operating frequency of 2.5 THz (119 m), for example, a 1 GHz modulation bandwidth may be achieved with a single-sideband conversion loss of only-21 db, versus a Schottky's loss of-39 db, assuming a laser diode power of 1 W, which is readily available from recently developed laser diode arrays. 相似文献