检索结果-南通市图书馆

The association of aromatase （CYP19） gene variants wil sperm concentration and motility

Asian Journal of Andrology 2011年第2期13卷 292-297页

作者： Leandros Lazaros Nectaria Xita Apostolos Kaponis Elissavet Hatzi nicolaos Plachouras nicolaos sofikitis Konstantinos Zikopoulos Ioannis Georgiou Genetics and IVF Unit Department of Obstetrics and Gynaecology Medical School University of Ioannina Ioannina 45110 Greece Department of Endocrinology MedicalSchool University of Ioannina Ioannina 45110 Greece Department of Urology Medical School University of Ioannina Ioannina 45110 Greece

The irreversible transformation of androgens into oestrogens is catalysed by cytochrome P450 aromatase. In the present study, we explored the contribution of the （TTTA）n polymorphism in the aromatase gene （CYP19） to sperm concentration and motility. Ninety normozoospermic and 60 oligospermic men were examined during infertility examinations. DNA was extracted from spermatozoa, and the CYP19（TTTA）n polymorphism was genotyped by PCR. Genotype analysis revealed six CYP19（TTTA）n alleles with 7-12 repeats. The allelic distribution of the CYP19（TTTA）n polymorphism differed between normozoospermic and oligospermic men （P〈0.01）. Oligospermic men less frequently had long CYP19 alleles than did normozoospermic men （25 and 37.8%, respectively; P〈0.02）. The higher frequency of short CYP19alleles in oligospermic men compared to normozoospermic men （43.3 and 28.3%, respectively; P〈0.01） was primarily due to the distribution of the CYP19 （TTTA）7 allele. The CYP19 （TTTA）7 allele was associated with lower sperm concentration in normozoospermic men {P〈0.01） and in the total study population {P〈0.01）; it was also associated with lower sperm motility in normozoospermic men （P〈0.05） and in the total study population （P〈0.01）. In conclusion, the CYP19 （TTTA）7 allele probably impairs aromatase activity, which in turn alters aromatase and oestrogen levels in the testis, leading to decreased sperm concentration and motility. These findings support the significance of cytochrome P450 aromatase in human spermatogenesis and consequently in semen quality.

关键词： androgen male infertility oestrogen semen quality spermatogenesis

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frequency Stability of Power System with Large Share of Wind Power Under Storm Conditions

引用

Journal of Modern Power Systems and Clean Energy 2020年第2期8卷 219-228页

作者： Kaushik Das Feng Guo Edgar Nuno nicolaos A.Cutululis the Department of Wind Energy Technical University of Denmark(DTU)RiseDenmark Suzlon Energy Limited RostockGermany

The operation of transmission systems with large share of wind power is specially challenging under storm *** the stormy wind speed conditions,wind turbine protection system is designed to shut down the turbine to avoid excessive mechanical *** sudden loss of wind power from large offshore plants is difficult to forecast accurately,which results in a large amount of power *** severity of such a wind power imbalance towards frequency stability needs to be studied for the future power *** addition,the overhead transmission lines can also be affected during storms,thereby increasing their probability of failure in the operation of power system under the islanded *** paper investigates how the stormy weather can threaten the frequency stability of future Danish power system with large share of wind power and how to avoid the frequency instability through proper control and defence strategies such as high-voltage direct current(HVDC)control and load *** studies are performed for ramp rates of HVDC control,load shedding strategies,inertia of the system with different volumes of disturbances to understand their impact on frequency stability.

关键词： Emergency control frequency stability storm security wind power

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

Determining the type of orbits in the central regions of barred galaxies

引用

Research in Astronomy and Astrophysics 2016年第2期16卷 45-62页

作者： Euaggelos E.Zotos nicolaos D.Caranicolas Department of Physics Section of AstrophysicsAstronomy and MechanicsAristotle University of ThessalonikiGR-54124

We use a simple dynamical model which consists of a harmonic oscillator and a spherical com- ponent, in order to investigate the regular or chaotic character of orbits in a barred galaxy with a central spherically symmetric nucleus. Our aim is to explore how the basic parameters of the galactic system in- fluence the nature of orbits, by computing in each case the percentage of chaotic orbits, as well as the percentages of different types of regular orbits. We also give emphasis to the types of regular orbits that support either the formation of nuclear rings or the barred structure of the galaxy. We provide evidence that the traditional xl orbital family does not always dominate in barred galaxy models since we found several other types of resonant orbits which can also support the barred structure. We also found that sparse enough nuclei, fast rotating bars and high energy models can support the galactic bars. On the other hand, weak bars, dense central nuclei, slowly rotating bars and low energy models favor the formation of nuclear rings. We also compare our results with previous related work.

关键词： galaxies kinematics and dynamics

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

Dark halos acting as chaos controllers in asymmetric triaxial galaxy models

引用

Research in Astronomy and Astrophysics 2011年第7期11卷 811-823页

作者： nicolaos D.Caranicolas Euaggelos E.Zotos Department of Physics Section of AstrophysicsAstronomy and MechanicsAristotle University of Thessaloniki 541 24ThessalonikiGreece

We study the regular or chaotic character of orbits in a 3D dynamical model,describing a triaxial galaxy surrounded by a spherical dark halo *** numerical experiments suggest that the percentage of chaotic orbits decreases exponentially as the mass of the dark halo increases.A linear increase of the percentage of the chaotic orbits was observed as the scale length of the halo component increases. In order to distinguish between regular and chaotic motion,we chose to use the total angular momentum Ltot of the 3D orbits as a new *** with other,previously used,dynamical indicators,such as the Lyapunov Characteristic Exponent or the P（f） spectral method,shows that the Ltot indicator gives very fast and reliable results for characterizing the nature of orbits in galactic dynamical models.

关键词： galaxies:kinematics and dynamics—dynamical indicators

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

The nature of orbits in a prolate elliptical galaxy model with a bulge and a dense nucleus

引用

Research in Astronomy and Astrophysics 2011年第12期11卷 1449-1456页

作者： nicolaos D.Caranicolas Euaggelos E.Zotos Department of Physics Section of AstrophysicsAstronomy and MechanicsAristotle University of Thessaloniki 541 24ThessalonikiGreece

We study the transition from regular to chaotic motion in a prolate elliptical galaxy dynamical model with a bulge and a dense nucleus. Our numerical investigation shows that stars with angular momentum Lz less than or equal to a critical value Lzc, moving near the galactic plane, are scattered to higher z, when reaching the central region of the galaxy, thus displaying chaotic motion. An inverse square law relationship was found to exist between the radius of the bulge and the critical value Lzc of the angular momentum. On the other hand, a linear relationship exists between the mass of the nucleus and Lzc. The numerically obtained results are explained using theoretical arguments. Our study shows that there are connections between regular or chaotic motion and the physical parameters of the system, such as the star＇s angular momentum and mass, the scale length of the nucleus and the radius of the bulge. The results are compared with the outcomes of previous work.

关键词： galaxies: kinematics and dynamics

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

Neurotherapeutic potential of erythropoietin after ischemic injury of the central nervous system

引用

Neural Regeneration Research 2019年第8期14卷 1309-1312页

作者： Florian Simon nicolaos Floros Wiebke Ibing Hubert Schelzig Artis Knapsis Department of Vascular and Endovascular Surgery Heinrich-Heine-University of Düsseldorf

Erythropoietin (EPO) is one of the most successful biopharmaceuticals in history and is used for treating anemia of different origins. However, it became clear that EPO could also work in a neuroprotective, antiapoptotic, antioxidative, angiogenetic and neurotropic way. It causes stimulation of cells to delay cell apoptosis, especially in the central nervous system. In rodent models of focal cerebral ischemia, EPO showed an impressive reduction of infarct size by 30% and improvement of neurobehavioral outcome by nearly 40%. A large animal model dealing with ischemia and reperfusion of the spinal cord showed that EPO could reduce the risk of spinal cord injury significantly. In addition, some clinical studies tested whether EPO works in real live clinical settings. One of the most promising studies showed the innocuousness and improvements in follow-up, outcome scales and in infarct size, of EPO-use in humans suffering from ischemic stroke. Another study ended unfortunately in a negative outcome and an increased overall death rate in the EPO group. The most possible reason was the involvement of patients undergoing simultaneously systemic thrombolysis with recombinant tissue plasminogen activator. An experimental study on rats demonstrated that administration of EPO might exacerbate tissue plasminogen activator-induced brain hemorrhage without reducing the ischemic brain damage. This case shows clearly how useful animal models can be to check negative side effects of a treatment before going into clinical trials. Other groups looked in human trials at the effects of EPO on the outcome after ischemic stroke, relation to circulating endothelial progerdtor cells, aneurysmal subarachnoid hemorrhage, traumatic brain injury, hemoglobin transfusion thresholds and elective first-time coronary artery bypass surgery. Most of the results were pos-让ive, but are based mostly on small group sizes. However, some of the most neglected facts when focusing on experimental setups of is

关键词： erythropoietin apoptosis central nervous system cerebral ischemia animal model stroke human trials age comorbidity spinal cord ischemia

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

Measuring clock jumps using pulsar timing

引用

Science China(Physics,Mechanics & Astronomy) 2020年第1期63卷 112-117页

作者： ZhiXuan Li KeJia Lee Ricardo nicolaos Caballero YongHua Xu LongFei Hao Min Wang JianCheng Wang Yunnan Observatories Chinese Academy of SciencesKunming 650216China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China

In this paper,we investigate the statistical signal-processing algorithm to measure the instant local clock jump from the timing data of multiple *** algorithm is based on the framework of Bayesian *** order to make the Bayesian algorithm applicable with limited computational resources,we dedicated our efforts to the analytic marginalization of irrelevant *** found that the widely used parameter for pulsar timing systematics,the"Efac"parameter,can be analytically *** reduces the Gaussian likelihood to a function very similar to the Student’s *** iterative method to solve the maximum likelihood estimator is also explained in the *** pulsar timing data from the Yunnan Kunming 40-m radio telescope,we demonstrate the application of the method,where 80-ns level precision for the clock jump can be *** a precision is comparable to that of current commercial time transferring service using *** expect that the current method could help developing the autonomous pulsar time scale.

关键词： pulsars time series analysis clocks and frequency standards

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

Genetic and epigenetic risks of intracytoplasmic sperm injection method

引用

Asian Journal of Andrology 2006年第6期8卷 643-673页

作者： Ioannis Georgiou Maria Syrrou nicolaos Pardalidis Konstantinos Karakitsios Themis Mantzavinos Nikolaos Giotitsas Dimitrios Loutradis Fotis Dimitriadis Motoaki Saito Ikuo Miyagawa Pavlos Tzoumis Anastasios Sylakos Nikolaos Kanakas Theodoros Moustakareas Dimitrios Baltogiannis Stavros Touloupides Dimitrios Giannakis Michael Fatouros Nikolaos sofikitis Laboratory of Molecular Urology and Genetics of Human Reproduction Department of Urology loannina University School of Medicine loannina 45110 Greece Cytogenetics Unit Laboratory of General Biology Medical School University of loannina loannina 45110 Greece Department of Urology Tottori University School of Medicine Yonago 683 Japan Department of Molecular Pharmacology Tottori University School of Medicine Yonago 683 Japan

Pregnancies achieved by assisted reproduction technologies, particularly by intracytoplasmic sperm injection （ICSI） procedures, are susceptible to genetic risks inherent to the male population treated with ICSI and additional risks inherent to this innovative procedure. The documented, as well as the theoretical, risks are discussed in the present review study. These risks mainly represent thatconsequences of the genetic abnormalities underlying male subfertility （or infertility） and might become stimulators for the development of novel approaches and applications in the treatment of infertility. In addition, risks with a polygenic background appearing at birth as congenital anomalies and other theoretical or stochastic risks are discussed. Recent data suggest that assisted reproductive technology might also affect epigenetic characteristics of the male gamete, the female gamete, or might have an impact on early embryogenesis. It might be also associated with an increased risk for genomic imprinting abnormalities.

关键词： genetic risks epigenetic risks intracytoplasmic sperm injection testis male infertility

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

钠和钾在高血压发病机制中的作用（1）

引用

丹东医药 2007年第3期 52-54页

作者： Horacio J. Adrogué nicolaos E. Madias 于健蔚（摘） Sodium and Potassium in the Pathogenesis of Hypertension 不详

全世界近25％的成年人罹患高血压，而且有人预言，到2025年其患病率将增加60％，届时，总患病人数有可能达到15．6亿。高血压是心血管病的主要危险因素，是全世界多数死亡病例的病因。原发性高血压，也被称为特发性高血压，占高血压总... 详细信息

全世界近25％的成年人罹患高血压，而且有人预言，到2025年其患病率将增加60％，届时，总患病人数有可能达到15．6亿。高血压是心血管病的主要危险因素，是全世界多数死亡病例的病因。原发性高血压，也被称为特发性高血压，占高血压总病例数的95％。

关键词：原发性高血压发病机制特发性高血压患病人数危险因素心血管病死亡病例钾

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

使用活动形态模型对功能性肺SPECT图像进行自动分割及与相关肺CT图像的比较

引用

中华核医学与分子影像杂志 2018年第8期38卷 582-582页

作者：唐军 Grigorios-Aris Cheimariotis Mariam Al-Mashat Kostas Haris Anthony H.Aletras Jonas J?gi Marika Bajc nicolaos Maglaveras Einar Heiberg 上海交通大学医学院附属苏州九龙医院核医学科 Laboratory of Computing Medical Informatics and Biomedical-Imaging TechnologiesSchool of MedicineAristotle University of Thessaloniki Department of Clinical Sciences Lund Clinical PhysiologySkane University HospitalLund University Department of Biomedical Engineering Faculty of Engineering Lund University Department of Clinical Physiology Lund University Hospital

目的图像分割对于定量分析肺功能降低、无肺功能区域的范围和程度是必需的。该研究的目的是建立和验证一种肺通气和灌注SPECT图像自动分割方法,并比较自动、手动SPECT图像分割结果与相关CT参考容积的差别。方法 77例患者(69例阻塞性肺... 详细信息

目的图像分割对于定量分析肺功能降低、无肺功能区域的范围和程度是必需的。该研究的目的是建立和验证一种肺通气和灌注SPECT图像自动分割方法,并比较自动、手动SPECT图像分割结果与相关CT参考容积的差别。方法 77例患者(69例阻塞性肺病患者、8例无明显通气、灌注功能受损患者)先行低剂量CT检查,随后行通气/灌注(V/P) SPECT显像。使用57例患者的低剂量CT图像构建2个用于SPECT图像自动分割的活动形态肺模型(右肺和左肺)。在20例患者的SPECT图像中验证相关分割算法,并将其结果与相应的CT图像分割结果进行比较,同时比较SPECT图像自动分割与手动分割的差别。结果左、右肺自动分割与手动分割的Dice系数(一种相似性度量系数)分别为(0.82±0.05)%和(0.83±0.04)%。SPECT图像自动分割的结果与相关CT参考容积比较,左肺(R=0.69, P<0.001)与右肺(R=0.53, P=0.02)差异有统计学意义。SPECT图像手动分割与相关CT参考容积比较的统计结果与自动分割相似,左肺[偏差(-10±491) ml; R=0.60,P=0.005]、右肺[偏差(36±524) ml; R=0.62, P=0.004]。结论 SPECT图像自动分割与手动分割的结果基本一致。SPECT图像手动分割结果与相关CT参考容积间有较大的容积差别,表明功能性SPECT图像的分割是一项具有挑战性的工作。目前的算法只是实现大范围自动定量测定分析的第一步。

关键词：图像分割 V/P SPECT CT 活动形态模型

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

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：