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51.
An approximate method is evaluated for calculating the second virial coefficient in a dilute macromolecular solution bounded by two interfaces. The approximation is essentially the superposition of the coefficients calculated independently for each surface. To test this approach, the depletion interaction between two particles in a solution of nonadsorbing, spherical macromolecules is calculated in systems with either hard-wall or long-range electrostatic interactions. In all systems tested, the interparticle interaction energy calculated with the approximation is found to be in good agreement with that calculated using the exact approach (e.g., error less than 2% at the smallest separations). The primary advantage of this approximation is a significant reduction in the computation time required for calculating the depletion interaction, especially in charged systems. The paper also shows that the expressions for predicting the depletion interaction in purely hard-sphere systems can be used in dilute ionic systems, provided the appropriate effective macromolecule size is used. For the attractive depletion interaction, this effective size is determined by the range of the particle-macromolecule interaction (as opposed to the macromolecule-macromolecule interaction). 相似文献
52.
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54.
Ronie?Cleverson?Cardoso Bruno?Lob?o-SoaresEmail author Marino?Muxfeldt?Bianchin Carlos?Gilberto?CarlottiJr Roger?Walz Márcio?Alvarez-Silva Andréa?Gon?alves?Trentin Mauro?Nicolau 《BMC neuroscience》2004,5(1):38
Background
While it is well known that bradykinin B2 agonists increase plasma protein extravasation (PPE) in brain tumors, the bradykinin B1 agonists tested thus far are unable to produce this effect. Here we examine the effect of the selective B1 agonist bradykinin (BK) Sar-[D-Phe8]des-Arg9BK (SAR), a compound resistant to enzymatic degradation with prolonged activity on PPE in the blood circulation in the C6 rat glioma model.Results
SAR administration significantly enhanced PPE in C6 rat brain glioma compared to saline or BK (p < 0.01). Pre-administration of the bradykinin B1 antagonist [Leu8]-des-Arg (100 nmol/Kg) blocked the SAR-induced PPE in the tumor area.Conclusions
Our data suggest that the B1 receptor modulates PPE in the blood tumor barrier of C6 glioma. A possible role for the use of SAR in the chemotherapy of gliomas deserves further study.55.
H. Abele H. J. Hauser A. Körber W. Leitner R. Neu H. Plappert T. Rohwer G. Staudt M. Straßer S. Weite M. Walz P. D. Eversheim F. Hinterberger 《Zeitschrift für Physik A Hadrons and Nuclei》1987,326(4):373-381
Differential cross sections ofα-elastic scattering have been measured for the target nuclei11B,12C,13C,14N,15N, and16O atE=48.7 and 54.1 MeV and for the nuclei17O,18O, and20Ne atE=54.1 MeV. The experimental results were analysed in terms of the optical model using different complex potentials. Special emphasis is given to the application of the double-folding approach for the real part of the potential. The imaginary part is expressed in terms of Fourier-Bessel functions. Differential cross sections for theα-16O scattering over a wide energy range and for the elasticα-scattering for nuclei in the mass rangeA=11 up toA=24 atE=54.1 MeV are analysed by this method. A close correlation between the absorptive part of the potential and nuclear deformation is observed. 相似文献
56.
Alkylation of ketones via silyl enol ethers is possible using aryl activated secondary alkyl halides or thio ketals. In case of prenyl halides the ratio fo primary to tertiary alkylation is governed by steric factors and by the nature of the Lewis acid. 相似文献
57.
We consider the problem of finding the best (uniform) approximation of a given continuous function by spline functions with free knots. Our approach can be sketched as follows. By using the Gauß transform with arbitrary positive real parameter t, we map the set of splines under consideration onto a function space, which is arbitrarily close to the spline set, but satisfies the local Haar condition and also possesses other nice structural properties. This enables us to give necessary and sufficient conditions for best approximations (in terms of alternants) and, under some assumptions, even full characterizations and a uniqueness result. By letting t 0, we recover best approximation in the original spline space. Our results are illustrated by some numerical examples, which show in particular the nice alternation behavior of the error function. 相似文献
58.
Continuous coherent radiation in the vacuum ultraviolet at 122 nm (Lyman-α) can be generated using sum-frequency mixing of three fundamental laser beams in mercury vapor. One of the fundamental beams is at 254 nm wavelength, which is close to the 61 S 0–63 P 1 resonance in mercury. Experiments have been performed to investigate the effect of this one-photon resonance on phase-matching, absorption and the nonlinear yield. The efficiency of continuous Lyman-α generation has been improved by a factor of 4.5. 相似文献
59.
Daniel Kolbe Anna Beczkowiak Thomas Diehl Andreas Koglbauer Matthias Sattler Matthias Stappel Ruth Steinborn Jochen Walz 《Hyperfine Interactions》2012,212(1-3):213-220
We demonstrate a reliable continuous-wave (cw) laser source at the 1 S–2 P transition in (anti)hydrogen at 121.56 nm (Lyman-α) based on four-wave sum-frequency mixing in mercury. A two-photon resonance in the four-wave mixing scheme is essential for a powerful cw Lyman-α source and is well investigated. 相似文献
60.
Miller MJ Walz AJ Zhu H Wu C Moraski G Möllmann U Tristani EM Crumbliss AL Ferdig MT Checkley L Edwards RL Boshoff HI 《Journal of the American Chemical Society》2011,133(7):2076-2079
Although the antimalarial agent artemisinin itself is not active against tuberculosis, conjugation to a mycobacterial-specific siderophore (microbial iron chelator) analogue induces significant and selective antituberculosis activity, including activity against multi- and extensively drug-resistant strains of Mycobacterium tuberculosis. The conjugate also retains potent antimalarial activity. Physicochemical and whole-cell studies indicated that ferric-to-ferrous reduction of the iron complex of the conjugate initiates the expected bactericidal Fenton-type radical chemistry on the artemisinin component. Thus, this "Trojan horse" approach demonstrates that new pathogen-selective therapeutic agents in which the iron component of the delivery vehicle also participates in triggering the antibiotic activity can be generated. The result is that one appropriate conjugate has potent and selective activity against two of the most deadly diseases in the world. 相似文献