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51.
Glucose is an important regulator of cell growth and metabolism. Uridine diphosphate sugars (UDP-sugars), as the intermediate products of metabolism, play pivotal roles as precursors in the synthesis of complex carbohydrates and glycolipids as well as lectose. It is very important to study their metabolism in cells in clinical biochemistry. A capillary electrophoretic method has been developed for the analysis of UDP-sugars and nucleotides. By using an uncoated capillary (70cm×50μm) and 20 mmol/L borax buffer (pH 9), 4 important UDP-sugars can be analyzed in 15 min at 22 kV with satisfactory precision and sensitivity. The developed method has been applied to analyze UDP-sugars concentrations in lymphocytes, fibroblasts and mesangial cells, and the results show it not only is much better than HPLC method, but also can be used to measure the energy charge of cells. 相似文献
52.
Hans Günther Wahl Hartmut M. Liebich Andreas Hoffmann 《Journal of separation science》1994,17(5):308-311
The separation and analysis of furan fatty acids and other minor component fatty acids present at very low concentrations in complex sample matrices, such as fish oil or lipids derived from liver and testes, require several pre-analytical separation steps if single column gas chromatography is to furnish sufficient resolution: after extraction and transesterification hydrogenation, urea complex precipitation and argentation TLC have been applied prior to GC analysis of furan fatty acids. By using multidimensional GC-MSD with cooled injection and flow-controlled column switching with intermediate cold trapping, it has been possible to identify directly the methyl esters of furan fatty acids without further pre-analytical separation. The most common of the furan fatty acids can be subdivided into two groups depending on whether they bear a propyl or pentyl side group in the 5-position of the furan ring. In addition to the eight furan fatty acids known to be present in fish oil, six new ones were identified, four with propyl substitution and two with pentyl substitution. Four have earlier been reported to be present in the hepatopancreas of crayfish and in fish tissue, whereas the propyl-substituted 16,19-epoxy-17,18-dimethyldocosa-16,18-dienoic acid and the pentyl-substituted furan fatty acid 6,9-epoxy-7-methyltetradeca-6,8-dienoic acid were hitherto unknown. 相似文献
53.
Trimethyloxonium tetrafluoroborate (TMO) is applied as derivatising reagent to transform urinary organic acids into their methyl esters. The method is suggested as an alternative to the use of diazomethane which is carcinogenic and explosive. In contrast to other methods avoiding diazomethane, such as derivatizations with acetyl chloride-methanol and boron trifluoride-methanol, which require an organic reaction medium and therefore an extraction of the organic acids from the urine, TMO efficiently reacts with the acids in an aqueous solution and can therefore be directly applied to native urine. The use of TMO simplifies and improves the sample preparation in the profile analysis of urinary organic acids by capillary GC-MS and hereby increases the speed of analysis. The method gives reproducible results which are comparable with the data obtained using conventional solid-phase extraction with strong anion-exchange cartridges prior to derivatisation. 相似文献
54.
D. Monnier B. Liebich M. Marcantonatos 《Analytical and bioanalytical chemistry》1969,247(3-4):188-191
The method is proposed for the direct determination of submicrotraces of boron in as little as about 0.2 to 1 mg of plant material. A mixture of concentrated sulphuric acid and hydrogen peroxide (30 %) at 200°C is employed for the mineralisation. There is no loss of boron even for quantities in the nanogram range. For 30 ng of boron fluorine interferes only for ratios F/B (w/w) 100, but analytical curves—while less sensitive—are even satisfactory for higher ratios. Several applications are given. 相似文献
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56.
D. Monnier B. Liebich et M. Marcantonatos 《Fresenius' Journal of Analytical Chemistry》1969,247(3-4):188-191
Résumé La méthode fluorimétrique à l'hydroxy-2-méthoxy-4-chloro-4-benzophénone (HMCB) est appliquée au dosage direct de traces de bore dans des échantillons végétaux de 0,2 à 1 mg. La minéralisation d'effectue par un mélange d'acide sulfurique concentré et de perhydrol (30%) à 200° C. Pour des quantités de bore de l'ordre du nanogramme, ce procédé n'entraîne pas de pertes. Pour 30 ng de bore, les fluorures n'interfèrent que pour F/B (P/P) > 100. Pour des rapports supérieurs, les résultats, quoique moins sensibles, permettent toutefois d'établir des courbes d'étalonnage satisfaisantes. Des exemples d'applications sont donnés.
Direct microdetermination of boron in plants by a fluorimetric method using hydroxy-2-methoxy-4-chloro-4-benzophenone (HMCB)
The method is proposed for the direct determination of submicrotraces of boron in as little as about 0.2 to 1 mg of plant material. A mixture of concentrated sulphuric acid and hydrogen peroxide (30 %) at 200°C is employed for the mineralisation. There is no loss of boron even for quantities in the nanogram range. For 30 ng of boron fluorine interferes only for ratios F/B (w/w) 100, but analytical curves—while less sensitive—are even satisfactory for higher ratios. Several applications are given.相似文献
57.
Klaus Doerffel Günther Herfurth Volker Liebich Editha Wendlandt 《Fresenius' Journal of Analytical Chemistry》1991,341(9):519-523
Summary CUSUM (cumulative sum) can be seen as integral of the attached time series. Therefore the shape of CUSUM allows conclusions as to the type of an instationarity inherent in the time series to be made. This indirect way is advantageous for the evaluation of time series with high random fluctuations. The theoretical background for the information to be derived from the shape of CUSUM as well as examples for application (time series, distribution analysis) are shown in this paper. 相似文献
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60.
Hartmut M. Liebich Norbert Schmieder Hans Günther Wahl Josef Wll 《Journal of separation science》1994,17(7):519-521
Fatty acids from blood serum lipids and fish oil preparations are derivatized with 2-amino-2-methyl-1-propanol to form 2-substituted 4,4-dimethyloxazolines. The derivatives are separated on a 25 m × 0.25 mm FFAP column and identified by mass spectrometry using electron impact ionization. The positions of the double bonds of mono- and polyunsaturated fatty acids can be easily and reliably recognized from a characteristic fragmentation feature of the oxazolines. Several unsaturated C16 to C22 fatty acid isomers are identified whose exact structure has not been derived from the commonly used methyl esters. 相似文献