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排序方式: 共有813条查询结果,搜索用时 78 毫秒
811.
Miao Zhou Chuanqi Cheng Cunku Dong Liyang Xiao Yao Zhao Zhanwei Liu Xueru Zhao Kotaro Sasaki Hao Cheng Xiwen Du Jing Yang 《Liver Transplantation》2023,13(1):2202595
Large-scale application of alkaline water electrolysis for high-rate hydrogen production is severely hindered by high electricity cost, mainly due to difficulties to acquire cost-effective catalytic electrodes with both extremely low overpotential and long-term durability at ultrahigh current densities (≥1 A cm−2). Here it is demonstrated that by adopting a synthetic method of laser direct writing in liquid nitrogen via a commercial laser welding machine, a remarkably efficient and durable electrode with large area and low platinum content is obtained, where PtNi nanocatalysts with dislocation network are firmly welded on a nickel foam (NF). The dense dislocation network not only improves intrinsic activity of a majority of surface-active sites induced by coupled compressive-tensile strains synergistically promoting both Volmer and Tafel steps of alkaline hydrogen evolution reaction (HER), but also well stabilizes surface dislocations for HER at ultrahigh current densities. Such a robust electrode achieves record-low overpotentials of 5 and 63 mV at 10 and 1000 mA cm−2 in alkaline medium, respectively, exhibiting negligible activity decay after 300 h chronoamperometric test at 1 A cm−2. It displays a high Pt mass activity 16 times higher than 20 wt% Pt/C loaded on NF, surpassing most of the recently reported efficient Pt-based catalysts. 相似文献
812.
We developed a novel flow particle analyzer that automatically classifies airborne pollen grains. The design of the particle
counter (model KP-1000) is based on that of a flow cytometer, applied to the measurement of airborne particles. The counter
classifies pollen species by simultaneously detecting both scattered light and the characteristic fluorescence excited by
ultraviolet light in the flow cell. We observed airborne pollen using KP-1000 pollen counters and Durham samplers to compare
their performance at three study sites in Japan during the spring pollen season. The pollen counter followed the variation
in pollen concentrations, and its daily pollen counts were significantly correlated with the results of the Durham sampling
method at all study sites. Although the counter over- or under-counted 2 target pollen species (Cryptomeria japonica and Chamaecyparis obtusa) when they coexisted, a data correction based on the Durham sampling results improved the accuracy of pollen classification
of the counter. Our results indicate that the new pollen counter has a strong potential for counting and identifying airborne
pollen grains in real time, and it requires further improvement, field trials, and tests with other common airborne pollen
grains. 相似文献
813.
Kotaro T. Yamamoto 《Journal of plant research》1990,103(4):469-491
Phytochrome is a proteinaceous pigment that acts as a photoreceptor for photomorphogenetic responses in plants. It exists
as two stable absorbing forms, Pr and Pfr, which are interconvertible reversibly by irradiation with red or far-red light. The present review discusses (i) the primary
and higher-order structures of phytochrome that permit the reversible photoreaction; (ii) the molecular properties which change
accompanying the phototransformation; and (iii) the four-leaved shape model which has recently been proposed as a model of
quaternary structure of phytochrome. 相似文献