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1.
Tegos GP Demidova TN Arcila-Lopez D Lee H Wharton T Gali H Hamblin MR 《Chemistry & biology》2005,12(10):1127-1135
Fullerenes are soccer ball-shaped molecules composed of carbon atoms, and, when derivatized with functional groups, they become soluble and can act as photosensitizers. Antimicrobial photodynamic therapy combines a nontoxic photosensitizer with harmless visible light to generate reactive oxygen species that kill microbial cells. We have compared the antimicrobial activity of six functionalized C(60) compounds with one, two, or three hydrophilic or cationic groups in combination with white light against gram-positive bacteria, gram-negative bacteria, and fungi. After a 10 min incubation, the bis- and tris-cationic fullerenes were highly active in killing all tested microbes (4-6 logs) under conditions in which mammalian cells were comparatively unharmed. These compounds performed significantly better than a widely used antimicrobial photosensitizer, toluidine blue O. The high selectivity and efficacy exhibited by these photosensitizers encourage further testing for antimicrobial applications. 相似文献
2.
3.
Richard E. Smalley Lennard Wharton Donald H. Levy Dean W. Chandler 《Journal of Molecular Spectroscopy》1977,66(3):375-388
The fluorescence excitation spectrum of the transition in s-tetrazine has been observed and measured. The sample was cooled to a rotational temperature of <1 K by expansion in a supersonic free jet. In this way the rotational structure arising from asymmetry split low J lines could be observed. The rotational A and B axes of the 2H112C214N4 isotope were observed to interchange upon electronic excitation and a theory describing the effect of this interchange upon the optical selection rules has been developed. Analysis of the resolved rotational structure suggests that the geometry change upon electronic excitation is smaller than that deduced from previous analysis of the room temperature optical spectrum. 相似文献
4.
Butler J.M. Wharton C.B. Furukawa S. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1990,18(3):490-496
The operation of a backward wave oscillator (BWO) is shown to be critically dependent on the energy of the slow space-charge wave of the electron beam. Experimental work parameterizing the dependence of microwave frequency on effective beam energy, γbeam, reveals that through an understanding of electron-beam dynamics, a BWO could be systematically tuned through a desired frequency range while maintaining a high power of a few hundred megawatts and narrow frequency bandwidth, which was 400 MHz. Through variation of γbeam, 1.2 to 1.5 for the experiment, the lack of scaling of peak microwave power with the kinetic energy of the electron beam for γbeam >1.32 was observed. This effect was previously found in numerical simulation. In order to explain this effect, the relationship of the beam current to the space-charge-limiting current for increasing γbeam is examined. Dramatic evidence of pulse shortening, a phenomenon known to relativistic oscillators, was also seen 相似文献
5.
Levels of recrystallization have been measured by two distinct techniques; a splat cooling assay and a new device, an optical recrystallometer, which measures the change in light transmittance through a frozen sample. Both techniques indicate the presence of recrystallization inhibitors in a grass extract and in other samples. The advantages of each method of measuring recrystallization are discussed. 相似文献
6.
The overwintering strategy of Litoria ewingii in Otago, New Zealand, was studied under laboratory and field conditions. Microhabitat temperature measurements showed that the frogs were often exposed to subzero temperatures. In the laboratory, Litoria ewingii tolerated freezing for up to 6 hrs at -1 degrees C, and after the completion of the freezing event (about 1 hr) at -2 degrees C. Frogs frozen with insulation survived freezing for 12 hrs at -1 degrees C. Frogs supercooled to -1.2 +/- 0.1 degrees C and -1.7 +/- 0.3 degrees C on wet and dry substrates respectively. L. Ewingii tolerated up to 47.5% of its body water frozen. Plasma glucose levels and osmolality were not increased during freezing. It is concluded that l. Ewingii cannot avoid freezing and is sufficiently freeze tolerant to survive the subzero temperatures encountered during winter in Otago. 相似文献
7.
In this study, experiments were performed on a two-section porous burner operated on propane and air. The burner consisted of an upstream section of reticulated yttria stabilized zirconia with 23.6 pores per centimeter (ppc) followed by a downstream section of 3.9 ppc, composed of the same material. The velocity and turbulence intensity of the exit flow for reacting and non-reacting conditions were measured. The velocity profiles for both reacting and non-reacting flow were very non-uniform. The turbulence intensity for the reacting flow increased with distance due to turbulence created by the non-uniformities. Blow-off occurred first on one side of the burner, but otherwise the flame in this burner was stable. 相似文献
8.
Open-framework materials synthesized in the TMA+/TEA+ mixed-template system: the new low Si/Al ratio zeolites UZM-4 and UZM-5. 总被引:1,自引:0,他引:1
C Scott Blackwell Robert W Broach Michael G Gatter Jennifer S Holmgren Deng-Yang Jan Gregory J Lewis Beckay J Mezza Thomas M Mezza Mark A Miller Jaime G Moscoso R Lyle Patton Lisa M Rohde Michael W Schoonover Wharton Sinkler Ben A Wilson Stephen T Wilson 《Angewandte Chemie (International ed. in English)》2003,42(15):1737-1740
9.
Barreto G. Wharton C.B. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(5):493-498
A relativistic backward wave oscillator (BWO) in tandem with a traveling wave tube (TWT) amplifier has been used to generate relatively long pulses of high-power X -band microwaves. In these experiments, a BWO is used to modulate the annular relativistic electron beam, which subsequently drives a TWT producing high-power microwave radiation. A special RF sever located between the two structures cuts off microwaves generated in the BWO from the TWT. Peak powers in excess of 100 MW are observed with overall beam-to-microwave efficiencies as high as 35%. By operating the BWO below saturation levels, pulse-shortening effects are minimized so that microwave pulses of duration comparable to that of the beam (100 ns) are possible. The operating frequency of the tandem system is tuned from 11 to 12 GHz by varying the effective energy of the beam 相似文献
10.
Summary Based on a random sample from the normal cumulative distribution function ϕ(x; μ, σ) with unknown parameters μ and σ, one-sided confidence contours for ϕ(x; μ, σ), −∞<x<∞, and simultaneous confidence intervals for ϕ(y; μ, σ)−ϕ(x; μ, σ), −∞<x<y<∞, are constructed using the method outlined in [3]. Small sample and asymptotic distributions of the relevant statistics
are provided so that the construction could be completely carried out in any practical situation. 相似文献