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41.
Summary Our aim is to reveal the elementary diffusion jump of Fe atoms in ordered Fe−Al single crystals (Fe contents 50.5, 55, 66
and 75 at.%) by comparing results from quasi-elastic M?ssbauer spectroscopy at57Fe with results from other methods. The mechanism obviously follows one and the same logics irrespective of the alloy composition:
Fe atoms jump into second or third nearest-neighbour sites on their own sublattice via the lying-between antistructure site
on the Al sublattice. Since the disorder increases with increasing Fe concentration, the residence time of Fe atoms on the
antistructure sites increases at the same time.
Paper presented at ICAME-95, Rimini, 10–16 September 1995. 相似文献
42.
J. J. Pohl und Aug Vogel Jr. 《Fresenius' Journal of Analytical Chemistry》1867,6(1):270-275
Ohne Zusammenfassung 相似文献
43.
44.
E. Schacht D. Bailey O. Vogl 《Journal of polymer science. Part A, Polymer chemistry》1978,16(9):2343-2351
Polyepiiodohydrin was prepared from polyepichlorohydrin by the Finkelstein reaction with sodium iodide in butanone. An 88% degree of replacement of chlorine by iodine was obtained. The reaction of iodides with polyepichlorohydrin was accompanied by a substantial drop in molecular weight. The copolymer, which contains eight epiiodohydrin units per epichlorohydrin unit, has a glass transition temperature of 1°C and a density of 2.2 g/cm3. Properties of epiiodohydrin homopolymer were estimated by extrapolation of copolymer data. 相似文献
45.
Ohne Zusammenfassung 相似文献
46.
Knobbe N Vogl J Pritzkow W Panne U Fry H Lochotzke HM Preiss-Weigert A 《Analytical and bioanalytical chemistry》2006,386(1):104-108
The stable carbon and nitrogen isotopic composition of urine and milk samples from cattle under different feeding regimes
were analysed over a period of six months. The isotope ratios were measured with isotope ratio mass spectrometry (IRMS). The
δ
13C values of milk and urine were dependent on different feeding regimes based on C3 or C4 plants. The δ
13C values are more negative under grass feeding than under maize feeding. The δ
13C values of milk are more negative compared to urine and independent of the feeding regime. Under grass feeding the analysed
milk and urine samples are enriched in 13C relative to the feed, whereas under maize feeding the 13C/12C ratio of urine is in the same range and milk is depleted in 13C relative to the diet. The difference between the 15N/14N ratios for the two feeding regimes is less pronounced than the 13C/12C ratios. The δ
15N values in urine require more time to reach the new equilibrium, whereas the milk samples show no significant differences
between the two feeding regimes. 相似文献
47.
Lubin-Germain N Baltaze JP Coste A Hallonet A Lauréano H Legrave G Uziel J Augé J 《Organic letters》2008,10(5):725-728
Indium-mediated alkynylation reaction was studied for the direct preparation of C-glycosides. Easily available starting sugar derivatives with an acetyl group at the anomeric position were tested as electrophiles toward alkynylindium reagents under Barbier conditions. Good yields and stereoselectivities were observed during the reaction. The alkynylation was applied to the synthesis of an alpha-(1-->6)-C-disaccharide analogue of isomaltoside. 相似文献
48.
Vincent Weigelt Dr. Sarah Vogl Dr. Johannes Schmidt Prof. Arne Thomas 《Angewandte Chemie (International ed. in English)》2023,62(39):e202307818
The Wittig reaction is a key step in industrial processes to synthesise large quantities of vitamin A and various other important chemicals that are used in daily life. This article presents a pathway to achieve the Wittig reaction in a solid network. A highly porous triphenylphosphine-based polymer was applied as a solid Wittig reagent that undergoes, in a multi-step cycle, in total six post-synthetic modifications. This allowed for regeneration of the solid Wittig reagent and reuse for the same reaction cycle. Of particular industrial relevance is that the newly developed material also enables a simple way of separating the product by filtration. Therefore, additional costly and difficult separation and purification steps are no longer needed. 相似文献
49.
Simone König Martin Zeller Jasna Peter-Katalinic Johannes Roth Clemens Sorg Thomas Vogl 《Journal of the American Society for Mass Spectrometry》2001,12(11):1180-1185
In this paper, analysis strategies developed for a sequencing problem concerning the identification of an S100 protein isolated from human granulocytes are discussed. The analysis of a trypsinized lyophilized sample suggested the presence of a number of peptides which are non-tryptic in origin. During purification of proteins from cell lysates nonspecific cleavage can be observed which may reflect biological processes and can become an unavoidable analytical problem. Current mass spectrometric software is evaluated for the analysis of nonspecific digests in this context. Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), high-performance liquid chromatography (HPLC)-MS/MS, and selected ion monitoring (SIM)-MS/MS have been used for peptide analysis and in addition HPLC-MS was carried out for protein analysis leading to the detection of an N-terminal modification of the protein. The success of the study is mainly due to the careful investigation of nonspecific cleavage products. Data obtained from the routine mass spectrometric analysis of an in-gel-digest allowed the identification of this protein as S100 calcium-binding protein A6-calcyclin whose expression in granulocytes has not been described so far. 相似文献
50.
C. R. Quétel J. Vogl T. Prohaska S. Nelms P. D. P. Taylor P. De Bièvre 《Analytical and bioanalytical chemistry》2000,368(2-3):148-155
The performance of four commercially available ICPMS instruments of three different types was compared by means of uranium “isotopic measurements”. Examined were two quadrupole sector (different generation, different manufacturer), one single detector double focusing magnetic sector and one multiple collector double focusing magnetic sector instruments. The same samples of the IRMM-072 series were used under routine conditions to measure the 233U/235U and the 233U/238U ratios which, in these samples, vary over almost three orders of magnitude from ~ 1 to ~ 2 · 10–3. Within expanded (k = 2) uncertainties, good agreement was observed between the certified values and the data internally corrected for mass-discrimination effects. The magnitude of the evaluated uncertainties was different for each type of instrument. With the multiple collector instrument, expanded uncertainties varied from ± 0.04% to± 0.24% for the 233U/235U ratio, and from ± 0.08% to ± 0.27% for the 233U/238U ratio. They were ~ 1 to 5 times larger with the single detector magnetic sector instrument, and ~ 10 to 25 times larger with both quadrupole sector instruments. With the multiple collector instrument, repeatability of the measurements seemed to be limited by the difficulty of correcting properly for instrumental background, whereas with the single detector magnetic sector instrument the counting statistics was the only limitation (on smallest ratios). Apparent mass-discrimination was clearly found to be larger but more reproducible (and hence easier to correct for) in the case of magnetic sector instruments than for both quadrupole sector instruments. If space charge effects were the main source of mass-discrimination for all instruments, these results are in contradiction with the hypothesis of the size of mass-discrimination decreasing with the acceleration voltage. With the single detector magnetic sector instrument in particular (when operated by changing the ion energy only), our results pointed at more than only one major source of mass-discrimination, with variable size depending on the ratios measured. 相似文献