检索结果-南通市图书馆

Ab initio studies on reaction H_2C═C(OH)Li+CH_3^+(CH_3^-)

Science China Chemistry 1998年第6期41卷 587-595页

作者：王义贵孙昌俊邓从豪 Institute of Theoretical Chemistry Shandong University Jinan China

The possible structures and isomerizations of H 2C C（OH）Li are studied theoretically by the gradient analytical method at RHF/631+G* level. According to these results, reactions of H 2C C（OH）Li with CH 3 + and CH 3 - are investigated thoroughly. When H 2C C（OH）Li reacts with CH 3 +, H 2C C（OH）Li firstly changes from structure 1 to structure 4, and then combines with CH 3 +. In this reaction, the configuration of central carbon is retained. When H 2C C（OH）Li reacts with CH 3 -, structure 1 firstly breaks its CO bond to give contact ionpair. Then through transition state 16 which is similar to structure 2, the attack of CH 3 - from the opposite side of -OH replaces -OH group and inverts the configuration of carbenoid carbon atom. All the results show that the ambident reactivity of carbenoid has close relationship with the stability of special structures.

关键词： carbenoid structure isomerization ambident reactivity acyl anion equivalent.

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

Retinal Vessels Diameter Changes during Pregnancy in Type 1 Diabetes

引用

Open Journal of Ophthalmology 2013年第2期3卷 27-32页

作者： Aurore Mensah Afrouz Ahmadzadeh Ann-Sofie Svanbom Lene Ringholm Birgit Sander Henrik Lund-Andersen Elisabeth Mathiesen Michael Larsen Department of Endocrinology Rigshospitalet Copenhagen Denmark Department of Ophthalmology Glostrup Hospital Glostrup Denmark Faculty of Health Sciences University of Copenhagen Copenhagen Denmark

Objective: Investigate how pregnancy-induced hormonal and hemodynamic changes affect retinal vessels caliber dynamic and the course of diabetic retinopathy. Methods: Retinopathy grading and vessel diameter measurement using digital fundus photographs in women with diabetes type 1 taken no more than one year before conception, during week 10 and/or 22, week 34, and within one year after delivery. Calibers were measured using a custom-developed semi-automated computer algorithm which identified the six largest arteries and six largest veins and calculated the central retinal artery equivalent.(CRAE) and central vein equivalent.(CRVE) diameters. Glycemic control was assessed quarterly by HbA1c. Systolic and diastolic blood pressure was assessed at week 10, 22 and 34. Results: Photographs at baseline, weeks 10, 22, 34 and after delivery were available in 28 patients, of whom 24 did not progress in retinopathy. For those whose level of retinopathy remained stable CRAE constricted from 138.80 ± 21.27 μm at baseline to 129.88 ± 13.97 μm at week 10 (p = 0.0379) CRVE constricted from 195.16 ± 24.98 μm at baseline to 185.97 ± 21.96 μm at week 10 (p = 0.0400). The patients with retinopathy progression had a CRAE of 131.67 ± 13.37 μm at baseline and 132.08 ± 11.07 μm at week 10 (p = 0.34) while CRVE was 195.33 ± 24.92 μm at baseline and 204.27 ± 10.18 μm at week 10 (p = 0.16). Progressors had higher blood pressures at week 10. Conclusion: Retinal vessels constricted between prepregnancy and first trimester in women who did not experience diabetic retinopathy progression. The study suggests that the vessels constriction seen in early pregnancy contributes to reduce the risk of gestational microvascular complications and progression of diabetes in the eye.

关键词： Pregnancy and Diabetes Type 1 Diabetic Retinopathy Central Retinal Artery equivalent Central Retinal Vein equivalent.

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

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

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：