检索结果-南通市图书馆

催化学报 2015年第10期36卷 1656-1661页

作者： Oleksiy v.Khavryuchenko volodymyr D.Khavryuchenko 苏党生计算化学集团乌克兰基辅UA-02091 中国科学院金属研究所沈阳材料科学国家(联合)实验室辽宁沈阳110016 马克斯普朗克协会弗里茨·哈伯研究所无机化学系德国柏林Faradayweg 4-6 D-14195

当初始态和过渡态之间存在能量差时,通常会考虑用催化的方法来增加反应速率,即经由能量更低过渡态的反应路径,或增加反应物初始态能量,如改变溶剂或在特殊表面吸附分子.然而,对于某些类型的反应,如H2和O2反应生成水,NO的氧化等,仅仅采... 详细信息

当初始态和过渡态之间存在能量差时,通常会考虑用催化的方法来增加反应速率,即经由能量更低过渡态的反应路径,或增加反应物初始态能量,如改变溶剂或在特殊表面吸附分子.然而,对于某些类型的反应,如H2和O2反应生成水,NO的氧化等,仅仅采用这些方法还不够,因为反应物和产物具有不同的自旋态,而自旋守恒定律一般会禁止该过程的发生.即使克服了能垒,该体系也不能转化成稳定的产物,且不改变其电子自旋多重态.但在特殊的非热力学条件下,该类反应仍可发生.这通常指自旋不守恒的过程.改变体系电子自旋最直接的方法是与原子核自旋有作用的电子自旋翻转.它可由自旋-轨道耦合来实现,因此,其实现的几率取决于元素的原子数.从3d金属开始,发生这种情况的可能性甚至更大.这是由于与d轨道耦合的效率更高所致,所以采用自旋交叉就能方便地解释自旋禁止反应发生的原因.然而,轻原子发生自旋翻转的可能性很低,因此,当面对无金属化学时,我们应该考虑自旋禁止反应发生的第二个方法—自旋催化.通过帮助克服自旋禁止的物质以促进化学反应,或通过顺磁催化剂诱导自旋解耦以降低活化能垒,这类现象就可定义为自旋催化.简而言之,为了得到想要的和热力学更有利的自旋态,一个反应粒子可以与自旋催化剂交换磁矩;该自旋催化剂需有拟自旋-简并基态或低激发态.因此,体系整个的自旋仍守恒,但可发生反应.值得强调的是,自旋"催化剂"指的是分子状态和固体状态,通常后者应用于工业中则方便得多.自旋催化是作为自旋化学的范例来研究的,或在外磁场中化学诱导动态核极化和反应,主要是指采用EPR光谱研究以液相为主的过程.本文简略介绍了自旋催化的理论.实际上,自旋催化与常规催化之间并不相互抵触—相同的材料既可作为自旋催化剂,也可用作常规催化剂,都起着降低反应能垒和提供自旋交换的自由基中心的作用.另外,许多现代材料包含着常规催化剂和自旋催化剂的特性.有些发生在多核磁性金属中心上的过程可能本身就包含着常规催化(活化底物)、自旋交叉(与d金属相互作用)和自旋催化(金属-氧簇合物中低能的铁磁-反铁磁转化)效应.气相自旋催化在实际应用中产生的主要问题是在稀释的体系中三粒子碰撞几率低,常规催化在这方面则有很多优势.我们首先列出固体成为自旋催化剂的条件:(1)活性中心中至少2个自旋态的能量差要小于反应温度下热运动的能量,这样无需额外的能量活化催化剂;(2)较大的比表面积以提供更多的自旋中心用于相互作用;(3)最好能够自旋导电,在此情况下反应无需三粒子碰撞即可发生.这是因为自由基可通过催化剂的电子系统交换自旋,使得自旋-自旋相互作用的几率迅速增加,从而有利于自旋催化反应的进行.另外,如果固体或载体具有自旋导电性,则无需外加电场或磁场,即有可能遥控催化中心的电荷和自旋态,从而避免使用外电场或磁场.实际上,许多反应过程本身就包含着自旋催化,它还可使反应过程的许多不足变成优势,如对于不需要的链式自由基反应;通过引入自旋捕获剂使得自旋禁止反应成为有用的自旋催化;磁性粒子的浓度以及外加磁场和电场均可导致自旋催化/禁止反应.由于均相自旋催化的研究较早,在此不再赘述.本文详细介绍了多相体系中的自旋催化的应用,如燃烧、温和氧化、环化、开环、非极性小分子的活化和不稳定自由基的耦合等.可能用作自旋催化剂的材料有:含有不同顺磁性的金属离子的磁性氧化物或多核磁性簇合物;嫁接在一些载体上的多核络合物或过渡金属(低温催化);带有非整数氧化价态的导电金属;各种具有半金属性和导电性的碳材料.研究自旋催化反应的一个突出问题就是这些过程大部分是自由基式的,趋于非线性区域,因而很难预测,也没有一个便利的工具用以描述,甚至预测自旋催化反应,但也许这些研究的特点就是不可预测性.自旋催化除了可调变反应的进行,我们还可从中获得一个独特的调节手段:通过外加磁场或电场触发基元过程,在非热力学上控制反应的进行.该手段在控制化学反应方面具有明显优势,因为现在大都是通过调节温度、压力和流量等参数来实现对化学反应的控制,且滞后严重.同时,通过添加外加磁场可立刻改变反应速率.另外,通过降温可精细控制基元反应,从而开辟了一种抑制副反应的方法,因而也使得反应的随机性降低.

关键词：催化自旋化学化学键均裂氧化过程自由基耦合

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 insights into the pathogenesis of Peyronie’s disease:A narrative review

引用

Chronic Diseases and Translational Medicine 2020年第3期6卷 165-181页

作者： Denis v.Krakhotkin volodymyr A.Chernylovskyi Alexandre Mottrie Francesco Greco Ruslan A.Bugaev Outpatient Department Central District HospitalKamenolomniRostov Region.Russia Department of Urology 1 City Clinical Hospital No-4DniproUkraine Department of Urology Onze Li eve Vrouw HospitalAalstBelgium ORSI Academy Me lieBelgium Department of Urology Humanitas GcivazzeniBergamoItaly

Peyronie’s disease(PD)is a benign,progressive fibrotic disorder characterized by scar or plaques within the tunica albuginea(TA)of the *** study provides new insights into the pathogenesis of PD based on data from different studies regarding the roles of cytokines,cell signaling pathways,biochemical mechanisms,genetic factors responsible for fibrogenesis.A growing body of literature has shown that PD is a chronically impaired,localized,wound healing process within the TA and the Smith *** is caused by the influence of different pathological stimuli,most often the effects of mechanical stress during sexual intercourse in genetically sensitive individuals with unusual anatomical TA features,imbalanced matrix metalloproteinase/tissue inhibitor of metalloproteinase(MMP/TIMP),and suppressed antioxidant systems during chronic *** intracellular signal cascades are activated during fibrosis along with low expression levels of their negative regulators and transforming growth factor-β1 *** development of multikinase agents with minimal side effects that can block several signal cell pathways would significantly improve fibrosis in PD tissues by acting on common downstream mediators.

关键词： Peyronie’s disease Cell signal pathway Penile curvature Myofibroblast Extracellular matrix

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

Synthesis of ferromagnetic La1-xSrxMnO3 nanoparticles by precipitation from diethylene glycol solution and their properties

引用

Journal of Advanced Ceramics 2016年第3期5卷 197-203页

作者： Yulia SHLAPA Sergii SOLOPAN Oleksandr YELENICH volodymyr TRACHEvSKII Anatolii BELOUS v.I.vernadsky Institute of General and Inorganic Chemistry NAS of Ukraine32/34 Palladina Avenue 03680 Kyiv 142 Ukraine Technical Center NAS of Ukraine

La1−x Sr x MnO3 nanoparticles were synthesized by precipitation from diethylene glycol solution. Features of synthesis were studied using 1Н, 13С, 139La... 详细信息

La1−x Sr x MnO3 nanoparticles were synthesized by precipitation from diethylene glycol solution. Features of synthesis were studied using 1Н, 13С, 139La nuclear magnetic resonance (NMR) investigations. The obtained results showed that the complexation reaction between diethylene glycol and metal cations takes place during the synthesis. These complexes decomposed at 200 °C and an amorphous precursor (La,Sr)MnO3 was formed. According to X-ray results, the crystallization of the perovskite structure began at 600 °C and finished at 800 °C. Microstructural studies showed that obtained nanoparticles are weakly agglomerated and have small sizes. Based on these nanoparticles, magnetic fluid was prepared which was effectively heated under an alternating magnetic field.

关键词： manganite perovskite precipitation complexation reaction diethylene glycol nuclear magnetic resonance (NMR)

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

One-pot Synthesis and X-ray Structure Determination of 7-(Diethylamino)-3-(4-aminophenyl)coumarin

引用

Chinese Journal of Structural Chemistry 2015年第12期34卷 1841-1844页

作者： KULAI Ihor MALLET-LADEIRA Sonia KOvTUNENKO volodymyr vOITENKO Zoia IMRCP CNRS UMR 5623 University of Toulouse Department of Chemistry Taras Shevchenko National University of Kyiv ICT FR CNRS 2599 University of Toulouse

7-（Diethylamino）-3-（4-aminophenyl）coumarin has been synthesized in a new one-pot synthesis by a three-step process starting from 4-（diethylamino）salicylaldehyde and 4-nitrophenylacetonitrile. The product was obtained in a good yield with a high degree of purity and characterized by NMR, IR and HR-MS. The orange crystals of the title compound were grown from ethyl acetate solution. The solid state structure was established by X-ray crystallography analysis. The crystal belongs to the orthorombic system, space group Pccn with a = 11.1095（5）, b = 33.0187（15）, c = 17.2865（7） A, v= 6341.1（5） A3, C19H20N2O2, Mr = 308.37, ρcalc = 1.292 g·cm^-3, = 0.085 mm^-1, F（000） = 2624, the final R = 0.0480 and wR = 0.1265 （I〉 2σ（I））.

关键词： coumarin dye crystal structure fluorescence one-pot synthesis

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 method for optimization of time intervals between rolling cuts on sorting humps

引用

Journal of Modern Transportation 2018年第3期26卷 189-199页

作者： Dmytro Kozachenko volodymyr Bobrovsky Yevhen Demchenko Research and Development Department Dnipropetrovsk National University of Railway Transport Named After Academician V.LazaryanDnipro 49010Ukraine Stations and Junctions Department Dnipropetrovsk National University of Railway Transport Named After Academician V.LazaryanDnipro 49010Ukraine

Sorting humps are the main technical means providing the breaking- and making-up of freight trains. Automation of sorting process by implementing microprocessor control systems is the main direction ofincreasing hump yard capacity, enhancement of safety in trains breaking-up, improvement of working conditions on hump yards. However, for wider introduction of such systems at the humps, it is necessary to reduce their cost. One of the main tasks of hump control systems is the determination of the optimal cars exit speeds from the retarders. Its solution is significantly complicated because of the uncertainty of cars rolling resistance coefficient, wind velocity and direction, retarder control errors. The paper is aimed at solving the problem of searching for such cars exit speeds from the retarders that provide the longest time intervals between them at the switches. Implementation of this method will make it possible to improve the quality of sorting process as a whole by improving the software of microprocessor control systems for automatic humping, rather than by increasing their technical facilities, which as a result will reduce the cost of their construction and operation. The research results, when solving the problem of searching for cars exit speeds from the retarders, allow us to move from searching for the maximum of a nonlinear non-smooth function of two variables to solution of an equation with one variable, which significantlyaccelerates and simplifies the solution to the problem.

关键词： Railways Sorting hump Optimization Marshalling yard

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

Diagnostic value ultrasound signs of stones less than or equal to 10 mm and clinicoradiological variants of ureteric colic

引用

Asian Journal of Urology 2023年第1期10卷 39-49页

作者： Denis v.Krakhotkin volodymyr A.Chernylovskyi Kemal Sarica Arman Tsaturyan Evangelos Liatsikos Jurijus Makevicius Nikolay Yu Iglovikov Dmitry N.Pikhovkin Central District Hospital Outpatient ClinicSadovaya Lane 23KamenolomniRostov RegionRussia Private Urological Practice DniproUkraine Department of Urology Biruni University HospitalInstanbulTurkey Department of Urology University Hospital of PatrasPatrasGreece Department of Urology Medical University of ViennaViennaAustria Institute for Urology and Reproductive Health Sechenov UniversityMoscowRussia Institute of Clinical Medicine Faculty of MedicineVilnius UniversityVilniusLithuania Department and Clinic of Urology S.M.Kirov Military Medical Academy of the Ministry of Defense of the Russian FederationSt.PetersburgRussia Central District Hospital Department of SurgeryLenina Avenue 28AksayRostov RegionRussia

Objective:To determine the diagnostic value of ultrasound signs of urinary stones less than or equal to 10 mm and to determine clinico-radiological variants of ureteric ***:A total of 455 ultrasound investigations were performed in patients referring to emergency department with urolithiasis and symptoms suspected of ureteric colic between January 2021 and May *** addition to microscopic evaluation of urine sediment to detect different crystals and non-contrast spiral computed tomography to detect stones,B-mode and color Doppler sonography was performed to assess the presence of acoustic shadow(AS)and twinkle artifacts(TA)as possible signs of stone(s)in ***:While the sensitivity and specificity of AS and TA were higher than 90%in patients with stones greater than 5 mm;positive prognostic values of these parameters were found to be extremely low for stones with sizes of 1-3 mm with specificity and sensitivity values not exceeding 53%.The sensitivity and specificity of AS and TA in the upper and lower ureters were higher for stones greater than or equal to 5 than for compared to those less than 5 *** the same time,the diagnostic values of TA and AS for middle ureter stones were very *** most prevalent clinico-radiological variants of ureteric colic were types I,III,and v being observed in 39%,28% and 21% cases,***:Our results demonstrate that TA and AS parameters seem to have a very low sensitivity and specificity in the diagnosis of urinary stones less than 5 *** diagnostic value of TA and AS increase significantly in stones greater than or equal to 5 ***,clinicians need to be very careful for overestimating the diagnostic values of TA and AS for stones less than 5 mm and non-contrast spiral computed tomography must be the method of choice for patients presenting to emergency department with ureteric colic.

关键词： Ureteric colic Urolithiasis Ultrasound Twinkle artifact Non-contrast computed tomography

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

Zingiber officinale extends Drosophila melanogaster life span in xenobiotic-induced oxidative stress conditions

引用

Frontiers in Biology 2018年第2期13卷 130-136页

作者： volodymyr Padalko viktoriya Dzyuba Olena Kozlova Hanna Sheremet Olena Protsenko School of Medicine V.N. Karazin Kharkiv National University 4 Svobody Sq. Kharkiv 61022 Ukraine Department of Membrane Biophysics Research Institute of Biology V.N. Karazin Kharkiv National University 4 Svobody Sq. Kharkiv61022 Ukraine

BACKGROUND： The possibility of dietary ginger to enhance oxidative stress resistance and to extend life span was studied on Drosophila melanogaster. METHODS： Oxidative stress was induced by a reducing agent dithiothreitol. Experimental groups of male D. melanogaster were cultured on media containing： 1） no additive; 2） dithiothreitol, added into the nutritional mixture to the final concentration of 10 mM; 3） 25 mg of ginger powder g^-1 of the nutritional mixture; and 4） 10 mM ofdithiothreitol and 25 mg of ginger powder g l of the nutritional mixture. The number of alive fruit flies was inspected daily, and mean life span was determined for each experimental group. RESULTS： The addition of dithiothreitol to D. melanogaster nutritional mixture was established to result in an increase in concentration of two markers of oxidative stress conditions （thiobarbituric acid reactive substances as products of lipid peroxidation and carbonylated proteins as products of protein oxidation） in fly tissues. It was followed by significant reduction of mean life span and maximum life span of the last 10% of flies. Plant preparation, being added simultaneously with dithiothreitol, significantly diminished the negative effects of this xenobiotic. In conditions of additional stress load induced by hydrogen peroxide or high temperature, survival of insects treated with dithiothreitol on the background of ginger powder was the highest. CONCLUSIONS： Thus, the presented data give the evidence that ginger preparations can reduce oxidative stress outcomes and significantly increase the life expectancy of fruit flies in stress conditions.

关键词： ginger oxidative stress Drosophila melanogaster

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

Influence of Temperature on the Measuring Accuracy of Devices Based on Surface Plasmon Resonance Phenomenon

引用

Modern Instrumentation 2018年第1期7卷 1-10页

作者： Hanna v. Dorozinska Tatyana A. Turu Olga M. Markina Glib v. Dorozinsky volodymyr P. Maslov National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” Kyiv Ukraine v. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine Kyiv Ukraine

The main reasons for the occurrence of temperature error and perspective directions of decreasing of its value are presented by improving the device design based on the phenomenon of surface plasmon resonance (SPR) and numerical methods of processing the results of measurements by this device. The most essential influence on changes in results of measurements can be rendered by temperature changes in the analyte refractive index. It is shown that the application of the integrated temperature stabilization of the device with the test substance, and numerical processing of the measurement results for compensation of temperature changes of the test substance and the use of film heaters it is possible to reduce the measurement error of the refractive index of the analyte at least 30 times from 2.4 × 10-4 to 7.6 × 10-6.

关键词： Surface Plasmon Resonance Temperature Factor Measuring Accuracy

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

Microstructure and hydrogen storage properties of as-cast and rapidly solidified Ti-rich Ti-v alloys

引用

Transactions of Nonferrous Metals Society of China 2012年第8期22卷 1831-1838页

作者： Suwarno SUWARNO Jan Ketil SOLBERG Jan Petter MAEHLEN Bente KROGH Bφrre Tore BφRRESEN Esther OCHOA-FERNANDEZ Erling RYTTER Mario WILLIAMS Roman DENYS volodymyr A.YARTYS Department of Materials Science and Engineering Norwegian University of Science and TechnologyNO-7491TrondheimNorway Institute for Energy Technology P.O.Box 40NO-2027KjellerNorway Statoil Research Centre RotvollN-7005TrondheimNorway University of the Western Cape Private Bag X17Bellville7535South Africa

The goal of the present work was to optimize the phase-structural composition and microstructure of binary Ti0.8-0.9v0.2-0.1 alloys with respect to their hydrogen sorption properties. Application of these alloys is for hydrogen absorption from gaseous mixtures containing substantial amounts of carbon monoxide （CO） at high temperatures. Irrespective of alloy composition, both α（HCP） and β（BCC） phases in Ti0.8-0.9v0.2-0.1 formed single phase FCC hydrides upon hydrogenation in pure H2. An in situ synchrotron X-ray diffraction study showed that only the β-phase transformed to the corresponding hydride when the alloy was hydrogenated in a mixture of H2＋10%CO. Rapid solidification （RS） of the alloy resulted in refined grain sizes both in the Ti0.8v0.2 and Ti0.9v0.1 alloys. Furthermore, RS was found to increase the β-phase fraction in Ti0.9v0.1, being twice larger than that of the as-cast alloy. Ti0.9v0.1 had a platelike microstructure as observed by scanning electron microscopy （SEM）, the plates were about 300 nm thick. The microstructure refinement resulted in a faster kinetics of H desorption as observed by temperature desorption spectroscopy （TDS）.

关键词： hydrogen storage Ti-v alloys rapid solidification synchrotron X-ray diffraction carbon monoxide

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 new fibrinogenase from Echis multisquamatis venom is a perspective agent for limited proteolysis and defibrinogenation

引用

Advances in Bioscience and Biotechnology 2010年第2期1卷 91-96页

作者： volodymyr O. Chernyshenko Olha v. Gornytska Tetyana M. Platonova Liudmyla I. Sokolovska 不详

A serine proteinase with a fibrinogenase activity was isolated from the venom of viper Echis multisquamatis. Isolation was performed by the combination of Q-sepharose and Heparine-agarose chromatography. The enzyme has apparent molecular weight 35 ± 1 kDа. It posesses strong fibrinogen β-chain, moderate αchain proteolytic activity, arginine-amidase activity as the majority of serine fibrinogenases. The Km value was determined for β-chain fibrinogenolytic activity: Km = 8.3 μM. Kinetic parameters for amidase activity were also determined. Amino-acid composition was revealed. Limited hydrolysis of fibrinogen by the obtained fibrinogenase allowed us to detemine stable hydrolytic subproducts with definite molecular weights. The manner of the proteolytic processes suggests possible use of this fibrinogenase in probing fibrinogen structure dinamics by limited proteolysis. Applicability of the obtained fibrinogenase in therapeutic practice is speculative, but presented data about its nature are encouraging and require additional investigation.

关键词： Fibrinogenase Serine Proteinase Snake venom Fibrinogen

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

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：