检索结果-南通市图书馆

Diagnostics of Ellerman bombs with high-resolution spectral data

Research in Astronomy and Astrophysics 2015年第9期15卷 1513-1524页

作者： Zhen Li cheng Fang Yang Guo Peng-fei Chen Zhi xu Wen-Da Cao School of Astronomy and Space Science Nanjing University Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education Collaborative Innovation Center of Modern Astronomy and Space Exploration Yunnan Observatories Chinese Academy of Sciences Big Bear Solar Observatory New Jersey Institute of Technology

Ellerman bombs （EBs） are tiny brightenings often observed near sunspots. The most impressive characteristic of EB spectra is the two emission bumps in both wings of the Hα and Ca II 8542 A lines. High-resolution spectral data of three small EBs were obtained on 2013 June 6 with the largest solar telescope, the 1.6 m New Solar Telescope at the Big Bear Solar Observatory. The characteristics of these EBs are analyzed. The sizes of the EBs are in the range of 0.3＂ - 0.8＂ and their durations are only 3-5 min. Our semi-empirical atmospheric models indicate that the heating occurs around the temperature minimum region with a temperature increase of 2700- 3000 K, which is surprisingly higher than previously thought. The radiative and kinetic energies are estimated to be as high as 5 × 1025 - 3.0 × 10^26 erg despite the small size of these EBs. Observations of the magnetic field show that the EBs just appeared in a parasitic region with mixed polarities and were accompanied by mass motions. Nonlinear force-free field extrapolation reveals that the three EBs are connected with a series of magnetic field lines associated with bald patches, which strongly implies that these EBs should be produced by magnetic reconnection in the solar lower atmosphere. According to the lightcurves and the estimated magnetic reconnection rate, we propose that there is a three phase process in EBs： pre-heating, flaring and cooling phases.

关键词： Sun: chromosphere -- Sun: photosphere -- line profiles -- magnetic reconnection

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Heterogeneity of chronic obstructive pulmonary disease:from phenotype to genotype

引用

Frontiers of Medicine 2013年第4期7卷 425-432页

作者： xu Chen Xiaomao xu fei Xiao Key Laboratory of Geriatrics Beijing Institute of Geriatrics Department of Respiratory Medicine Beijing HospitalMinistry of HealthBeijing 100730China

Chronic obstructive pulmonary disease(COPD)is one of the leading causes of morbidity and mortality throughout the world and is mainly characterized by persistent airflow *** that multiple systems other than the lung can be impaired in COPD patients,the traditional FEV1/FVC ratio shows many limitations in COPD diagnosis and *** heterogeneities are found in terms of clinical manifestations,physiology,imaging findings,and inflammatory reactions in COPD patients;thus,phenotyping can provide effective information for the prognosis and ***,phenotypes are often based on symptoms or pathophysiological impairments in late-stage COPD,and the role of phenotypes in COPD prevention and early diagnosis remains *** shortcoming may be overcome by the potential genotypes defined by the heterogeneities in certain *** review briefly describes the heterogeneity of COPD,with focus on recent advances in the correlations between genotypes and *** potential roles of these genotypes and phenotypes in the molecular mechanisms and management of COPD are also elucidated.

关键词： chronic obstructive pulmonary disease heterogeneity phenotype genotype prediction

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A historical review of hybrid rice breeding

引用

Journal of Integrative Plant Biology 2024年第3期66卷 532-545页

作者： Xiaoming Zheng fei Wei cheng cheng Qian Qian State Key Laboratory of Crop Gene Resources and Breeding Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijing 100081China Yazhouwan National Laboratory Sanya City 572024China

The development of germplasm resources and advances in breeding methods have led to steady increases in yield and quality of rice (Oryza sativa L.). Three milestones in the recent history of rice breeding have contributed to these increases: dwarf rice breeding, hybrid rice breeding, and super rice breeding. On the 50th anniversary of the success of three-line hybrid rice,we highlight important scientific discoveries in rice breeding that were made by Chinese scientists and summarize the broader history of the field. We discuss the strategies that could be used in the future to optimize rice breeding further in the hope that China will continue to play a leading role in international rice breeding.

关键词： Chinese experience dwarf breeding hybrid rice breeding super rice breeding

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Heteroatom-substituted rhodamine dyes: Structure and spectroscopic properties

引用

Chinese Chemical Letters 2019年第10期30卷 1667-1681页

作者： fei Deng Zhaochao xu CAS Key Laboratory of Separation Science for Analytical Chemistry Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China

Rhodamine is one class of most popular dyes used in fluorescence imaging due to the outstanding photoproperties including high brightness and photostability. In recent years, replacement the xanthene oxygen with other elements, especially silicon, has attracted great attentions in the development of new rhodamine derivatives. This review summarized the structures and photophysical properties of heteroatom-substituted rhodamines. We hope this review can help to understand the structure-property relationships of rhodamine dyes and then elucidate the way to create derivatives with improved photoproperties.

关键词： Rhodamine Heteroatom Si-rhodamine Optical properties Fluorescent dyes

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Protection zone in a diffusive predator-prey model with Ivlev-type functional response

引用

Applied Mathematics(A Journal of Chinese Universities) 2020年第4期35卷 437-451页

作者： ZHANG Li-na xu fei Department of Mathematics and statistics Northwest Normal UniversityLanzhou 730070China

The effect of a protection zone on a diffusion predator-prey model with Ivlev-type functional response is *** discuss the existence and non-existence of positive steady state solutions by using the bifurcation *** is shown that the protection zone for prey has beneficial effects on the coexistence of the two species when the growth rate of predator is ***,we examine the dependence of the coexistence region on the efficiency of the predator capture of the prey and the protection zone.

关键词： Ivlev-type functional response protection zone bifurcation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

New lobane-type diterpenoids from the Xisha soft coral Sinularia polydactyla

引用

Chinese Journal of Natural Medicines 2020年第11期18卷 839-843页

作者： YE fei CHEN Zi-Hui GU Yu-cheng GUO Yue-Wei LI xu-Wen State Key Laboratory of Drug Research Shanghai Institute of Materia MedicaChinese Academy of SciencesShanghai 201203.China Open Studio for Druggability Research of Marine Natural Products Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237.China University of Chinese Academy of Sciences Beijing 100049China Syngenta Jealott's Hill International Research CentreBracknellBerkshire RG426EYUnited Kingdom

Lobane-type diterpenoids are not frequently discovered from marine soft corals. In this paper, three new lobane type diterpenes, 13-methoxyloba-8,10,15(16),17(18)-tetraene(1), 8,10,13(15)Z,16 E-lobatetraene(2) and 19-hydroxy-lobatetraene(3), and a new natural compound, 17,18-epoxyloba-16-acetoxy-8,10,13(15)-trien(4), co-occurring with a known related diterpenoid, 18-methoxyloba-8,10,13(15),16(17)-tetraene(5), were isolated from the South China Sea soft coral Sinularia polydactyla. The structures of new compounds were determined by extensive spectroscopic analysis and by comparison with those reported in the literature. In bioassay, all the isolates were inactive on antibacterial, PTP1 B inhibitory, and immunological activities. This study increased the chemical diversity of marine diterpenoids.

关键词： Soft coral Sinularia polydactyla Lobane Diterpenes

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Data-driven fault diagnosis method for analog circuits based on robust competitive agglomeration

引用

Journal of Systems Engineering and Electronics 2013年第4期24卷 706-712页

作者： Rongling Lang Zheping xu fei Gao School of Electronic and Information Engineering Beihang University

The data-driven fault diagnosis methods can improve the reliability of analog circuits by using the data generated from it. The data have some characteristics, such as randomness and incompleteness, which lead to the diagnostic results being sensitive to the specific values and random noise. This paper presents a data-driven fault diagnosis method for analog circuits based on the robust competitive agglomeration （RCA）, which can alleviate the incompleteness of the data by clustering with the competing process. And the robustness of the diagnostic results is enhanced by using the approach of robust statistics in RCA. A series of experiments are provided to demonstrate that RCA can classify the incomplete data with a high accuracy. The experimental results show that RCA is robust for the data needed to be classified as well as the parameters needed to be adjusted. The effectiveness of RCA in practical use is demonstrated by two analog circuits.

关键词： data-driven fault diagnosis analog circuit robust competitive agglomeration (RCA).

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A platform of digital brain using crowd power

引用

Frontiers of Information Technology & Electronic Engineering 2018年第1期19卷 78-90页

作者： Dongrong xu fei DAI Yue LU Columbia University & New York State Psychiatric Institute NY 10032 USA Shanghai Key Laboratory of Multidimensional Information Processing East China Normal University Shanghai 200062 China

A powerful platform of digital brain is proposed using crowd wisdom for brain research,based on the computational artificial intelligence model of synthesis reasoning and multi-source analogical *** design of the platform aims to make it a comprehensive brain database,a brain phantom generator,a brain knowledge base,and an intelligent assistant for research on neurological and psychiatric diseases and brain *** big data,crowd wisdom,and high performance computers may significantly enhance the capability of the *** achievements along this track are reported.

关键词： Artificial intelligence Digital brain Synthesis reasoning Multi-source analogical generating Crowd wisdom Deducing Neuroimaging

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Efficient prediction of ground noise from helicopters and parametric studies based on acoustic mapping

引用

Chinese Journal of Aeronautics 2018年第2期31卷 273-284页

作者： fei WANG Guohua xu Yongjie SHI National Key Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics and Astronautics

Based on the acoustic mapping, a prediction model for the ground noise radiated from an in-flight helicopter is established. For the enhancement of calculation efficiency, a high-efficiency second-level acoustic radiation model capable of taking the influence of atmosphere absorption on noise into account is first developed by the combination of the point-source idea and the rotor noise radiation characteristics. The comparison between the present model and the direct computation method of noise is done and the high efficiency of the model is validated. Rotor free-wake analysis method and Ffowcs Williams-Hawkings（FW-H） equation are applied to the aerodynamics and noise prediction in the present model. Secondly, a database of noise spheres with the characteristic parameters of advance ratio and tip-path-plane angle is established by the helicopter trim model together with a parametric modeling approach. Furthermore, based on acoustic mapping, a method of rapid simulation for the ground noise radiated from an in-flight helicopter is developed. The noise footprint for AH-1 rotor is then calculated and the influence of some parameters including advance ratio and flight path angle on ground noise is deeply analyzed using the developed *** results suggest that with the increase of advance ratio and flight path angle, the peak noise levels on the ground first increase and then decrease, in the meantime, the maximum Sound Exposure Level（SEL） noise on the ground shifts toward the advancing side of rotor. Besides, through the analysis of the effects of longitudinal forces on miss-distance and rotor Blade-Vortex Interaction（BVI） noise in descent flight, some meaningful results for reducing the BVI noise on the ground are obtained.

关键词： Acoustic mapping Helicopter Noise footprint Rotor noise Second-level acoustic radiation model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Optimal production lot size with process deterioration under an extended inspection policy

引用

Journal of Systems Engineering and Electronics 2009年第4期20卷 768-776页

作者： Hu fei xu Genqi Ma Lixia Dept. of Mathematics Tianjin Univ. Tianjin 300072 P. R. China

A mathematical model to determine the optimal production lot size for a deteriorating production system under an extended product inspection policy is developed. The last-K product inspection policy is considered so that the nonconforming items can be reduced, under which the last K products in a production lot are inspected and the nonconforming items from those inspected are reworked. Consider that the products produced towards the end of a production lot are more likely to be nonconforming, is proposed an extended product inspection policy for a deteriorating production system. That is, in a production lot, product inspections are performed among the middle K1 items and after inspections, all of the last K2 products are directly reworked without inspections. Our objective here is the joint optimization of the production lot size and the corresponding extended inspection policy such that the expected total cost per unit time is minimized. Since there is no closed form expression for our optimal policy, the existence for the optimal production inspection policy and an upper bound for the optimal lot size are obtained. Furthermore, an efficient solution procedure is provided to search for the optimal policy. Finally, numerical examples are given to illustrate the proposed model and indicate that the expected total cost per unit time of our product inspection model is less than that of the last-K inspection policy.

关键词： production lot size product inspection policy deteriorating production system economic manufacturing quantity.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：