首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7篇
  免费   0篇
化学   3篇
物理学   4篇
  2023年   1篇
  2020年   2篇
  2006年   1篇
  2003年   1篇
  2002年   1篇
  1997年   1篇
排序方式: 共有7条查询结果,搜索用时 140 毫秒
1
1.
缺陷态透射率可调的三缺陷层的一维光子晶体   总被引:10,自引:9,他引:1  
利用传输矩阵方法,从理论上研究了三缺陷层一维光子晶体的光学性质.在缺陷层间距足够大以致于出现缺陷态简并的情况下,调节第一或第三个缺陷层的光学厚度,光子晶体缺陷态的透射率会发生最大程度的变化.这种结构可同时具有窄带滤波器和光开关的功能,据此提出了一种低阈值光开关的设计.把折射率可调的向列型液晶作为晶体的第三个缺陷层,并用4×4传输矩阵方法计算了其缺陷态透射率与电场电压的关系.  相似文献   
2.
Developing a bifunctional catalyst with low cost and high catalytic performance in NaBH4 hydrolysis for H2 generation and selective reduction of nitroaromatics will make a significant impact in the field of sustainable energy and water purification. Herein, a low-loading homogeneously dispersed Pd oxide-rich Co3O4 polyhedral catalyst (PdO-Co3O4) with concave structure is reported by using a metal–organic framework (MOF)-templated synthesis method. The results show that the PdO-Co3O4 catalyst has an exceptional turnover frequency (3325.6 molH2 min−1 molPd−1), low activation energy (43.2 kJ mol−1), and reasonable reusability in catalytic H2 generation from NaBH4 hydrolysis. Moreover, the optimized catalyst also shows excellent catalytic performance in the NaBH4 selective reduction of 4-nitrophenol to 4-aminiphenol with a high first-order reaction rate of approximately 1.31 min−1. These excellent catalytic properties are mainly ascribed to the porous concave structure, monodispersed Pd oxide, as well as the unique synergy between PdO and Co3O4 species, which result in a large specific surface area, high conductivity, and fast solute transport and gas emissions.  相似文献   
3.
Hydrogen is one of the most promising energy carriers to replace fossil fuels and electrolyzing water to produce hydrogen is a very effective method. However, designing highly active and stable non-precious metal hydrogen evolution electrocatalysts that can be used in universal pH is a huge challenge. Here, we have reported a simple strategy to develop a highly active and durable non-precious MoO_2-Ni electrocatalyst for hydrogen evolution reaction(HER) in a wide pH range. The MoO_2-Ni catalyst exhibits a superior electrocatalytic performance with low overpotentials of 46, 69, and 84 mV to reach-10 mA cm~(-2) in 1.0 M KOH, 0.5 M H_2SO_4,and 1.0 M PBS electrolytes, respectively. At the same time, the catalyst also shows outstanding stability over a wide pH range. It is particularly noted that the catalytic performance of MoO_2-Ni in alkaline solution is comparable to the highest performing catalysts reported. The outstanding HER performance is mainly attributed to the collective effect of the rational morphological design, electronic structure engineering, and strong interfacial coupling between MoO_2 and Ni in heterojunctions.This work provides a viable method for the synthesis of inexpensive and efficient HER electrocatalysts for the use in wide pH ranges.  相似文献   
4.
李普选  赵强  张孝林 《物理与工程》2003,13(1):17-18,11
本文介绍了安培分子电流思想在磁力对载流线圈做功方面的应用和对斯托克斯公式的几何解释。  相似文献   
5.
本文介绍了创建高水平专门系列演示实验教学基地的做法。该基地极大地丰富了理论教学,为全面提高教学质量起到了应有的作用。  相似文献   
6.
应用质心运动定理一例   总被引:6,自引:0,他引:6  
赵强  李普选 《物理与工程》2002,12(6):23-23,22
利用质心运动定理方便地求出了沿放在光滑水平面上圆弧槽运动的小球相对惯性参照系的运动轨迹。  相似文献   
7.
Dissolvable microneedles (DMNs) are an attractive alternative for vaccine delivery due to their user-friendly, skin-targeted, and minimally invasive features. However, vaccine waste and inaccurate dosage remain significant issues faced by DMNs, as the skin's elasticity makes it difficult to insert MNs completely. Here, a simple and reliable fabrication method are introduced based on two-casting micromolding with centrifugal drying to create a rapidly DMN patch made of hyaluronic acid. Ovalbumin (OVA), as the model antigens, is concentrated in the tip parts of the DMNs (60% of the needle height) to prevent antigen waste caused by skin elasticity. The time and temperature of the initial centrifugal drying significantly affect antigen distribution within the needle tips, with lower temperature facilitating antigen accumulation. The resulting DMN patch is able to penetrate the skin with enough mechanical strength and quickly release antigens into the skin tissue within 3 min. The in vivo study demonstrates that immunization of OVA with DMNs outperforms conventional vaccination routes, including subcutaneous and intramuscular injections, in eliciting both humoral and cellular immunity. This biocompatible DMN patch offers a promising and effective strategy for efficient and safe vaccination.  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号