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21.
H. Dougan D. M. Lyster J. S. Vincent 《Journal of Radioanalytical and Nuclear Chemistry》1985,89(1):71-78
A simple approach is presented whereby omega halogenated fatty acids can be obtained from macrocyclic musk lactones which are industrially available. While providing a secure source of 16-iodo-hexadecanoic acid and 17-iodo-heptadecanoic acid, the scheme allows ready access to a large number of untried fatty acid analogs. Examples presented are 16-iodo-hexadecanoic acid. 16-iodo-7-hexadecenoic acid. 16-iodo-12-oxa-hexadecanoic acid, 15-iodo-pentadecanoic acid, and 15-iodo-12-keto-pentadecanoic acid. 相似文献
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23.
Jennifer A. Dougan 《Tetrahedron letters》2010,51(44):5787-5790
The H-phosphonate of a derivative of thioctic acid (TA) was synthesised and used to introduce a disulfide moiety at the 5′-end of oligonucleotides. This method overcomes the difficulties experienced with the phosphoramidite approach when employing a cyclic disulfide in the starting alcohol. The disulfide-modified oligonucleotides are subsequently used in metallic nanoparticle (Au and Ag) and surface functionalisation for sensitive, sequence specific analytical detection strategies. 相似文献
24.
Lifetime of levels up to 22+, have been measured in 78Kr and an oblate shape is assigned to the ground state using the CSM and the configuration dependent shell correction calculations.
Calculations further show that 78Kr is highly γ-soft nucleus. The experimental Q
t values coupled with theoretical calculations indicate an oblate shape for 78Kr at low spins and triaxial shape at higher spins 相似文献
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Stable isotope methods are potentially quite useful for validating natural or enhanced mineral degradation of contaminants. For this reason, a continuous flow gas chromatograph (GC), isotope ratio mass spectrometer (IRMS) has been coupled with a quadrupole mass selective detector (MSD) to allow simultaneous mass spectral and stable carbon isotope ratio data to be obtained from a single chromatographic analysis. This allows the target contaminant and any extra-cellular degradation intermediates to be both qualified and quantified. Previously acceptable limits of precision (0.3 parts per mil) are undesirable given the small fractionation observed during aerobic degradation. To further understand the fate of organic contaminants and to gain information about the metabolic degradative pathway employed by a microorganism, routine isotopic analyses on a range of analytes have been performed. Quantities of sample producing mass-44 ion beam signal (I(44)) of 2 x 10(-10) to 1 x 10(-8) A were analysed. When the IRMS was tuned for high sensitivity, ion source nonlinearities were overcome by peak height correction from an algorithm that was produced using known isotopic standards of varying concentrations. This led to sample accuracy of <0.01 per thousand and sample precision of 0.1 per thousand. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
28.
Recent measurements of the differential cross-sections for deuteron photo-disintegration have been extended to lower photon energies at selected c.m. angles. The new results agree with earlier values from this laboratory and confirm the large discrepancy with data from Bonn and Orsay noted in the 100–250 MeV energy-range. They are in good agreement with the results of theoretical calculations including isobar configurations and meson-exchange currents below 150 MeV. 相似文献
29.
Lifetimes of high spin states up to {
}=22+ in the yrast positive parity bands have been measured to investigate the shape evolution with increasing spin in 72, 74Se. The Q
t values derived from these measurements indicate that prolate shape stabilizes for 72Se, while a triaxial shape develops for 74Se at higher spins. Comparison of the observed trend in Q
t with spin for 72, 74Se with that of the corresponding kryptones isotones emphasizes the stability provided by N=38 prolate shell gap even at high rotational frequency. 相似文献
30.
Lorna Dougan Dr. Ainavarapu Sri Rama Koti Dr. Georgi Genchev Hui Lu Prof. Julio M. Fernandez Prof. 《Chemphyschem》2008,9(18):2836-2847
We present an array of force spectroscopy experiments that aim to identify the role of solvent hydrogen bonds in protein folding and chemical reactions at the single‐molecule level. In our experiments we control the strength of hydrogen bonds in the solvent environment by substituting water (H2O) with deuterium oxide (D2O). Using a combination of force protocols, we demonstrate that protein unfolding, protein collapse, protein folding and a chemical reaction are affected in different ways by substituting H2O with D2O. We find that D2O molecules form an integral part of the unfolding transition structure of the immunoglobulin module of human cardiac titin, I27. Strikingly, we find that D2O is a worse solvent than H2O for the protein I27, in direct contrast with the behaviour of simple hydrocarbons. We measure the effect of substituting H2O with D2O on the force dependent rate of reduction of a disulphide bond engineered within a single protein. Altogether, these experiments provide new information on the nature of the underlying interactions in protein folding and chemical reactions and demonstrate the power of single‐molecule techniques to identify the changes induced by a small change in hydrogen bond strength. 相似文献