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排序方式: 共有151条查询结果,搜索用时 15 毫秒
1.
报道声表面波可程序抽头延迟线的研制情况。对该器件的总体结构,电路原理框图、声表面波可程序抽头延迟线结构作了一个扼要的概念。同时分别报道了我所研制的各类声表面波可程序抽头延迟线器件性能指标及相应的图片说明,最后对该器件仍存在的一些问题作了探讨。 相似文献
2.
Xiao Zhangru Qiao Jingsi Lu Wanglin Ye Guojun Chen Xianhui Zhang Ze Ji Wei Li Jixue Jin Chuanhong 《Nano Research》2017,10(7):2519-2526
Phosphorus atomic chains,the narrowest nanostructures of black phosphorus (BP),are highly relevant to the in-depth development of BP-based one-dimensional (1D) nano-electronics components.In this study,we report a top-down route for the preparation of phosphorus atomic chains via electron beam sculpturing inside a transmission electron microscope (TEM).The growth and dynamics (i.e.,rupture and edge migration) of 1D phosphorus chains are experimentally captured for the first time.Furthermore,the dynamic behavior and associated energetics of the as-formed phosphorus chains are further investigated by density functional theory (DFT) calculations.It is hoped that these 1D BP structures will serve as a novel platform and inspire further exploration of the versatile properties of BP. 相似文献
3.
Shengxian Li Xiangru Feng Jixue Wang Liang He Chunxi Wang Jianxun Ding Xuesi Chen 《Nano Research》2018,11(11):5769-5786
Immunotherapy is a promising strategy to inhibit cancer progression via activation of the immune system. In immunotherapy, adjuvants as immunologic stimulants or delivery systems play a critical role in inducing the antitumor immune response and decreasing the side effects of immune stimulants. Polymer nanoparticles have attracted increasing attention as an indispensable component of immunotherapy, owing to their favorable properties, such as excellent biocompatibility and biodegradability, flexible size, high activity as immune stimulants, large surface area for binding multivalent immune ligands, and high loading capacity for immune-related components. In cancer immunotherapy, polymer nanoparticles can protect cargo from the surrounding milieu, deliver the antigens and immunostimulatory molecules to antigen-presenting cells, or stimulate robust T cell response. This review summarizes the current advancements in polymer nanoparticle adjuvants for cancer immunotherapy and predicts their prospects in fundamental and clinical studies. 相似文献
4.
基于Pro/E软件的建模和仿真模块,构建曲柄滑块机构的机械模型,并进行运动仿真。结合机械原理,对曲柄活塞机构的运动进行研究;并从理论角度运用数理方法建立运动方程,借助MATLAB函数编辑器绘制函数曲线。对比两者结果表明,运用Pro/E进行模拟比用数值理论方法更具优越性。 相似文献
5.
碱法麦草浆木聚糖酶处理后木质素及碳水化合物的变化 总被引:8,自引:0,他引:8
采用UV光谱、凝胶色谱、X—射线衍射及扫描电镜等技术对碱法麦草浆的酶解浆和酶解液进行分析,探讨了木聚糖酶对碱法麦草浆处理后浆中木质素和碳水化合物的变化情况。研究认为,木聚糖酶对碱法麦草浆漂白作用主要是因为木聚糖酶降解了浆中部分木聚糖和残余木质素中的LCC结构,从而使后序漂白中漂液更易渗透,木质素的溶出更多、更易。 相似文献
6.
View materialization is an important way of improving the performance of query
processing. When an update occurs to the source data from which a materialized view is
derived, the materialized view has to be updated so that it is consistent with the source
data. This update process is called view maintenance. The incremental method of view
maintenance, which computes the new view using the old view and the update to the
source data, is widely preferred to full view recomputation when the update is small in
size. In this paper we investigate how to incrementally maintain views in object-relational
(OR) databases. The investigation focuses on maintaining views defined in OR-SQL, a
language containing the features of object referencing, inheritance, collection, and aggregate
functions including user-defined set aggregate functions. We propose an architecture and
algorithms for incremental OR viewmaintenance. We implement all algorithms and analyze
the performance of them in comparison with full view recomputation. The analysis shows
that the algorithms significantly reduce the cost of updating a vieww hen the size of an
update to the source data is relatively small.
Received 23 May 2000 / Revised 27 March 2001 / Accepted in revised form 30 April 2001
Correspondence and offprint requests to: Jixue Liu, School of Computer and Information Science, University of South Australia, Mawson Lakes, Adelaide SA5084, Australia.
Email: jixue.liu@unisa.edu.auau 相似文献
7.
Irrelevant updates in a database are updates to source data that do not affect a view defined over the source data. Self-maintainable updates are ones for which the view can be updated, without having to access source data, when the source data from which the view is derived is updated. In this paper we derive necessary and sufficient conditions for an update to be irrelevant or self-maintainable when the source data is a graph and the view is defined to be the transitive closure of the graph. 相似文献
8.
9.
加入微量Sr(0.01%-0.1%,质量分数)可明显细化AZ91D镁合金晶粒,随Sr含量增加,初生相α-Mg尺寸逐渐减小,而二次枝晶间距变化不大,同时β-Mg17Al12析出相增多.Sr添加量为0.1%时,针状或块状Al4Sr相依附在枝晶间的β-Mg17Al12相上析出.Sr在AZ91D合金凝固固-液界面前沿富集,并且优先在曲率较大的枝晶端面富集,从而抑制晶粒长大,细化了合金中初生相α-Mg;同时,Sr在枝晶的尖端富集降低了初生相α-Mg的尖端生长优势,改变了初生相形貌. 相似文献
10.
Guanghui Zhao Xinghong Zhang Zhenju Shen Dejiong Zhang Changqing Hong Jixue Li Ze Zhang 《Journal of the American Ceramic Society》2014,97(8):2360-2363
The oxidation of ZrB2 nanoparticles was observed at high temperature of 1500°C under low oxygen partial pressure of 5 × 10?2 Pa by an environmental transmission electron microscope. The results demonstrate that the oxidation starts on the surface of ZrB2 nanoparticles with decomposition of ZrB2 into ZrO2 and B2O3. The nucleation and growth of ZrO2 on the surface of ZrB2 proceed with B2O3 being evaporated. 相似文献