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11.
A simple method to perform selective on-line preconcentration of protein samples in capillary electrophoresis (CE) is described. The selectivity, based on protein electrophoretic mobility, was achieved by controlling electroosmotic flow (EOF). A short section of dialysis hollow fiber, serving as a porous joint, was connected between two lengths of fused silica capillary. High voltage was applied separately to each capillary, and the EOF in the system was controlled independently of the local electric field intensity by controlling the total voltage drop. An equation relating the EOF with the total voltage drop was derived and evaluated experimentally. On-line preconcentration of both positively charged and negatively charged model proteins was demonstrated without using discontinuous background electrolytes, and protein analytes were concentrated by approximately 60-200-fold under various conditions. For positively charged proteins, positive voltages of the same magnitude were applied at the free ends of the connected capillaries while the porous joint was grounded. This provided a zero EOF in the system and a non-zero local electric field in each capillary to drive the positively charged analytes to the porous joint. CE separation was then initiated by switching the polarity of the high voltage over the second capillary. For negatively charged proteins, the procedure was the same except negative voltages were applied at the free ends of the capillaries. Mobility-based selective on-line preconcentration was also demonstrated with two negatively charged proteins, i.e. beta-lactoglobulin B and myoglobin. In this case, negative voltages of different values were applied at the free ends of the capillaries with different values, which provided a non-zero EOF in the system. The direction of EOF was the same as that of the electrophoretic migration velocities of the protein analytes in the first capillary and opposite in the second capillary. By controlling the EOF, beta-lactoglobulin B, which has a higher mobility, could be concentrated over 150-fold with a 15 min injection while myoglobin, which has a lower mobility, was eliminated from the system. 相似文献
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组合导航系统初始对准的稳定性分析及其控制 总被引:1,自引:0,他引:1
针对INS/GPS组合导航系统的初始对准问题,说明当载体受到周期性激励时(由风浪、地面振动等因素引起),状态变量的估计结果也会出现周期性振荡,从而影响系统状态变量的估计精度,通过仿真说明了利用线性反馈可以消除周期性激励对系统的影响。 相似文献
14.
A new interface plate was employed in microspray ionization mass spectrometry (μESI-MS) to improve ion transmission from the
sprayer into the sampling nozzle of the mass spectrometer at atmospheric pressure. Using a time-of-flight mass spectrometer
(TOFMS), a fivefold increase in ion intensity and a sevenfold reduction in method detection limit were observed. The interface
plate attenuated the dependence of the ion intensity on the sprayer position. Even when the distance between the sprayer tip
and sampling nozzle was 15.0 mm, ion signals were still stronger than when the sprayer tip was positioned 3.0 mm in front
of the sampling nozzle with the original interface plate. This enhancement in the performance of μESI-MS was due to the improved
shapes of the equipotential lines near the sprayer tip and the long desolvation distance between the sprayer and the sampling
nozzle of the MS. 相似文献
15.
双(O,O-二乙基硫代磷酰基)二硫物(Ⅰ)及双(O,O-二正丁基硫代磷酸基)二硫物(Ⅰ)与二氯化汞于室温下在乙醇中反应,视反应物的摩尔比为1:1或1:2. 相似文献
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In this study, with combined carboxymethyl cellulose agar plate, xylan agar plate and filter paper hydrolysis assay, a novel cellulase and xylanase-producing strain identified as Bacillus sp. was isolated. Using lactose as the only carbon source, a complete and balanced lignocellulolytic enzyme system containing at least endoglucanase (9.6 U/ml), exoglucanase (0.8 U/ml), Fpase (1.4 U/ml), xylanase (3.8 U/ml) and β-glucosidase (1.2 U/ml) was produced. Interestingly, a zymogram of the crude culture supernatant displayed a multifunctional lignocellulolytic enzyme system including at least four bonds with both endoglucanase activity and xylanase activity at 21.2, 23.8, 28.9 and 31.2 kDa, respectively, indicating that these enzymes might be bifunctional. More gratifyingly, according to the binding affinity analysis and scanning electron microscopy, the crude enzyme complex produced by strain BS-5 was capable of hydrolyzing not only pure insoluble polysaccharides, but also agricultural residues such as corn cob. At 5% substrate concentration and 20 FPU/g enzyme loading, the reducing sugar was 350.8 mg/g of alkali-pretreated corn cob after 72 h enzymatic hydrolysis. These results suggested that this strain could be a good candidate for the development of a more cost-effective and efficient lignocellulolytic enzyme cocktail for the saccharification of lignocellulosic biomass. 相似文献
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