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61.
Fluorescent probe for monosaccharides based on a functionalized boron-dipyrromethene with a boronic acid group 总被引:4,自引:0,他引:4
A new highly fluorescent probe based on a boron-dipyrromethene functionalized with a phenylboronic acid group was synthesized from 2,4-dimethylpyrrol and 4-formylphenylboronic acid. Spectral changes in both absorption and emission spectra were observed in the presence of sugars. 相似文献
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本文报导了采用氩离子激光器来泵浦Pr3+:YLF晶体,应用声光调制器实现了主动锁模;同时应用振动─高反射平面镜也实现了被动锁模,两种锁模均得到了ps光脉冲.据作者了解这是这种晶体材料的第一次锁模运转. 相似文献
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Henryk Malak Ignacy Gryczynski Joseph R. Lakowicz Gerald J. Meyers Felix N. Castellano 《Journal of fluorescence》1997,7(2):107-112
We examined the intensity and anisotropy decays of DNA labeled with two ruthenium metalligand complexes, [Ru(bpy)2(dppz)]2+ and [Ru(phe)2(dppz)]2+. Both complexes display high emission anisotropies in the absence of rotational diffusion, making them suitable probes for
rotational motions. When bound to DNA, these complexes display decay times as long as 294 ns, providing long-lived probes
of DNA dynamics. The decay times of both complexes were rather insensitive to dissolved oxygen. We examined anisotropy decays
of these complexes bound to B-form DNA. The anisotropy decays revealed correlation times near 10, 50, and several hundred
nanoseconds, suggesting that these probes are sensitive to a wide range of DNA motions. The use of metalligand complexes should
allow resolution of both the torsional and bending motions of DNA, the latter of which has been mostly inaccessible using
shorter-lived fluorescent probes bound to DNA.
Dedicated to Professor Robert F. Steiner upon his retirement 相似文献
66.
Joseph R. Lakowicz Ewald Terpetschnig Zakir Murtaza Henryk Szmacinski 《Journal of fluorescence》1997,7(1):17-25
Metal-ligand complexes containing ruthenium, osmium, or rhenium display a high photostability, with polarized emission and
decay times from 100 ns to 100 Μs. Such probes have considerable potential in biophysics, clinical chemistry, and fluorescence
microscopy. In this review we sumrecent developments from this laboratory on the spectral properties of conjugatable metalligand
complexes. We also suggest how improved probes can be developed based on the selection of organic ligands. 相似文献
67.
Joseph R. Lakowicz Bogumil Zelent Ignacy Gryczynski Józef Kuba Michael L. Johnson 《Photochemistry and photobiology》1994,60(3):205-214
Abstract We used GHz frequency-domain fluorometry to investigate the time-dependent intensity decays of N -acetyl -L-trytophanamide (NATA) when collisionally quenched by acrylamide in propylene glycol at 20°C. The intensity decays of NATA became increasingly heterogeneous in the presence of acrylamide. The NATA intensity decays were not consistent with the Collins-Kimball radiation boundary condition (RBC) model for quenching. The steady-state Stern-Volmer plots show significant upward curvature. At low temperature in vitrified propylene glycol (-60%), where translational diffusion cannot occur during the lifetime of the excited state, quenching of NATA by acrylamide was observed. The Smoluchowski and RBC quenching models do not predict any quenching in the absence of translational diffusion. Hence, these frequency-domain and steady-state data indicate a through-space quenching interaction between NATA and acrylamide. The rate for quenching of NAT A by acrylamide appears to depend exponentially on the fluorophore-quencher separation distance. Comparison of the time-resolved and steady-state data provides a sensitive method to determine the distance dependence of the fluorophore-quencher interaction. The distance-dependent rate of quenching also explains the upward curvature of the Stern-Volmer plot, which is often observed for quenching by acrylamide. These results suggest that the distance-dependent quenching rates need to be considered in the interpretation of quenching data of proteins by acrylamide. 相似文献
68.
Wieslaw Wiczk Peggy S. Eis Mayer N. Fishman Michael L. Johnson Joseph R. Lakowicz 《Journal of fluorescence》1991,1(4):273-286
The end-to-end distance distribution of a flexible molecule was recovered from steady-state fluorescence energy transfer measurements using the method suggested by Cantor and Pechukas (Proc. Natl. Acad. Sci. USA
68, 2099–2101, 1971). In this method, the Förster distance (R
0) is varied by attaching different donor-acceptor (D-A) pairs to the flexible linker of interest. Distance distributions are then recovered from energy transfer efficiency measurements on the set of D-A pairs with differentR
0 values. Thirteen D-A pair compounds were synthesized withR
0 values ranging from 6 to 32 Å. Each compound contained a tryptamine donor linked by an alkyl chain (10 carbons) to 1 of 13 acceptors. Using these compounds, we have experimentally confirmed the Cantor and Pechukas method for recovering distance distributions. The measured transfer efficiencies, as a function ofR
0, were fit to the transfer efficiencies predicted for both Gaussian and skewed Gaussian distance distributions. The data support the existence of a skewed Gaussian distribution, and we believe that this is the first experimental observation of an asymmetric distribution for a flexible molecule using fluorescence resonance energy transfer measurements. Finally, the experimentally recovered distance distribution was found to be in good agreement with the distribution predicted from the rotational isomeric state model of Flory (Statistical Mechanics of Chain Molecules, John Wiley & Sons, New York, 1969, Chaps. 1, 3, and 5) but not with the predicted distribution for a freely rotating or freely jointed chain. 相似文献
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