排序方式: 共有3条查询结果,搜索用时 62 毫秒
1
1.
Phosphorus is selectively extracted as molybdovanadophosphoric acid (MVPA) and determined indirectly using52V. Silicon, germanium, arsenic, fluoride and tannic acid do not interfere. The sensitivity for phosphorus was 1421±13 counts52V per ng P ml–1 with a detection limit of 0.2 ng P ml–1. The precision is ±10% over the range 0.7±70 ng P ml–1. The sensitivity is four orders of magnitude greater than for conventional neutron activation analysis (NAA) using the31P(n, )28 Al reaction and a SLOWPOKE II reactor. Greater selectivity for phosphorus is obtained than by direct measurement of32P by beta ray spectroscopy. 相似文献
2.
Roland J. Caubergs Han H. Asard Jan A. DeGreef Frans J. Leeuwerik Fred L. Oltmann 《Photochemistry and photobiology》1986,44(5):641-649
Sucrose density gradient centrifugation of a microsomal membrane fraction of cauliflower inflorescences showed a strong correlation between a blue light mediated cytochrome b reduction (LIAC) and an ion stimulated nitrate-insensitive but a vanadate-sensitive ATPase activity at 38-40% sucrose. LIAC activity and vanadate-sensitive ATPase might be assigned to the same type of membrane different from ER, Golgi, tonoplast and mitochondria. The Mg2+ -dependent ATP-hydrolytic activity obtained after purification of the microsomal fraction on an aqueous polymer two phase system was partially characterized. Temperature optimum (40°C), pH optimum (pH 7.0), vanadate inhibition (I50 at 20 μ M ), substrate kinetics ( K m = 1.37 m M Mg.ATP) and inhibitor studies all point to the presence of the frequently described plasma membrane ATPase. Potassium and Na+ stimulated the enzyme activity (20-40%). In general our data arc strongly in favour of the hypothesis that LIAC activity is localized on the plant plasma membrane. The cytochrome b involved in the light reaction has a midpoint potential near +150 mV. This cytochrome which has been previously shown in a cauliflower microsomal fraction is a constituent of the plasma membrane. 相似文献
3.
Single-shot measurement of soot aggregate sizes by wide-angle light scattering (WALS) 总被引:1,自引:0,他引:1
The wide-angle light scattering (WALS) approach has been utilized for the measurement of soot aggregate sizes (radii of gyration)
in flames on a single-shot basis. Key elements are a pulsed laser and an ellipsoidal mirror, which images the light scattered
within a plane onto an intensified CCD camera, thus allowing for an instantaneous acquisition of a full scattering diagram
with high resolution. Results for a laminar premixed flame exhibit good agreement with averaged data and demonstrate the feasibility
of the method. The applicability of the technique to unsteady combustion processes is demonstrated by measuring aggregate
sizes in a weakly turbulent jet-diffusion flame. In both cases light scattering results are verified by data obtained from
electron microscopy analysis of sampled soot. 相似文献
1