The Synthesis of 19-Nor-1α, 25-dihydroxy-22-oxo-vitamin D_3

Since the last decade, there has been a growing interest in the development of analogues of 1(, 25- dihydroxyvitamin D3 1 with low calcemic effect but increased cell differentiating ability1. Among side chain and the A-ring modifications of 1, the 1(, 25- dihydroxy-22-oxo-vitamin D3 22 and 19-nor-1(, 25- dihydroxyvitamin D3 33 have shown much lower calcemic effect and stronger cell differentiating ability than 1. In this paper, we reported synthesis of 19-nor-1(, 25-dihydroxy-22-oxo-vitamin …     

AFLP在水稻线粒体DNA研究中的应用

对 Ａ Ｆ Ｌ Ｐ应用于水稻线粒体基因组研究中的问题进行了研究结果表明： Ａ Ｆ Ｌ Ｐ分析对ｍ ｔ Ｄ Ｎ Ａ 质量要求高,ｍ ｔ Ｄ Ｎ Ａ 应完整并反复抽提以达高纯度 ｍ ｔ Ｄ Ｎ Ａ 不完全酶切所造成的假阳性可经第二次酶切排除选择引物一个选择碱基最适合水稻ｍ ｔ Ｄ Ｎ Ａ Ａ Ｆ Ｌ Ｐ分析 另外,研究表明从银染后未经烘烤的新鲜银染凝胶回收的 Ｄ Ｎ Ａ 扩增效果好、产物经纯化可直接用于克隆以及探针标记     

证明策略的集成研究

讨论了ＸＹＺ／ＶＥＲＩ系统的向后推理机制,具体而言是基本策略、集成策略语言、策略的结构以及在这样的策略集成环境中的向后推理过程．     

Suppression of large intraluminal bubble expansion in shock wave lithotripsy without compromising stone comminution: refinement of reflector geometry

Using the Hamilton model [Hamilton, J. Acoust. Soc. Am. 93, 1256-1266 (1993)], the effects of reflector geometry on the pulse profile and sequence of the shock waves produced by the original and upgraded reflector of an HM-3 lithotripter were evaluated qualitatively. Guided by this analysis, we have refined the geometry of the upgraded reflector to enhance its suppressive effect on intraluminal bubble expansion without compromising stone comminution in shock wave lithotripsy. Using the original HM-3 reflector at 20 kV, rupture of a standard vessel phantom made of cellulose hollow fiber (i.d. = 0.2 mm), in which degassed water seeded with ultrasound contrast agents was circulated, was produced at the lithotripter focus after about 30 shocks. In contrast, using the upgraded reflector at 24 kV no rupture of the vessel phantom could be produced within a 20-mm diameter around the lithotripter focus even after 200 shocks. On the other hand, stone comminution was comparable between the two reflector configurations, although slightly larger fragments were produced by the upgraded reflector. After 2000 shocks, stone comminution efficiency produced by the original HM-3 reflector at 20 kV is 97.15 +/- 1.92% (mean +/- SD), compared to 90.35 +/- 1.96% produced by the upgraded reflector at 24 kV (p<0.02). All together, it was found that the upgraded reflector could significantly reduce the propensity for vessel rupture in shock wave lithotripsy while maintaining satisfactory stone comminution.     

Efficient syntheses of benzothiazepines as antagonists for the mitochondrial sodium-calcium exchanger: potential therapeutics for type II diabetes

Type II diabetes mellitus is a chronic metabolic disorder that can lead to serious cardiovascular, renal, neurologic, and retinal complications. While several drugs are currently prescribed to treat type II diabetes, their efficacy is limited by mechanism-related side effects (weight gain, hypoglycemia, gastrointestinal distress), inadequate efficacy for use as monotherapy, and the development of tolerance to the agents. Consequently, combination therapies are frequently employed to effectively regulate blood glucose levels. We have focused on the mitochondrial sodium-calcium exchanger (mNCE) as a novel target for diabetes drug discovery. We have proposed that inhibition of the mNCE can be used to regulate calcium flux across the mitochondrial membrane, thereby enhancing mitochondrial oxidative metabolism, which in turn enhances glucose-stimulated insulin secretion (GSIS) in the pancreatic beta-cell. In this paper, we report the facile synthesis of benzothiazepines and derivatives by S-alkylation using 2-aminobenzhydrols. The syntheses of other bicyclic analogues based on benzothiazepine, benzothiazecine, benzodiazecine, and benzodiazepine templates are also described. These compounds have been evaluated for their inhibition of mNCE activity, and the results from the structure-activity relationship (SAR) studies are discussed.     

Imaging theory and resolution improvement of two-photon confocal microscopy

The nonlinear effect of two-photon excitation on the imaging property of two-photon confocal microscopy has been analyzed by the two-photon fluorescence intensity transfer function derived in this paper. The two-photon fluorescence intensity transfer function in a confocal microscopy is given. Furthermore the three-dimensional point spread function (3D-PSF) and the three-dimensional optical transfer function (3D-OTF) of two-photon confocal microscopy are derived based on the nonlinear effect of two-photon excitation. The imaging property of two-photon confocal microscopy is discussed in detail based on 3D-OTF. Finally the spatial resolution limit of two-photon confocal microscopy is discussed according to the uncertainty principle.     

非碱性介质中全硅分子筛的合成与表征

在非碱性介质中,F-离子存在下,采用水热方法研究了全硅分子筛的合成。以三丙胺、胆碱、三亚乙基二胺和哌嗪为模板剂,合成出具有MFI结构(ZSM-5型)的全硅分子筛。全硅Theta-1和ZSM-39的模板剂分别为1,6-已二胺和四甲基溴化铵。~(29)Si MAS NMR研究结果表明,该体系得到的全硅分子筛具有结晶度高和缺陷少的特点。     

蛋氨酸稀土配合物构象的^13CNMR研究

本文测量了在7种不同稀土离子(La~(3 )、Pr~(3 )、Nd~(3 )、Dy~(3 )、Ho~(3 )、Er~(3 )和Tm~(3 ))的水溶液中蛋氨酸~(13)C稀土诱导位移。利用稀土诱导位移对蛋氨酸稀土配合物构象的模拟结果表明,蛋氨酸通过离子化的羧基与稀土离子配位,Ln~(3 )—O长度为2.7A在配合物中,蛋氨酸以伸展状态存在,C_0-C_α-C_β-C_γ和C_α-C_β-C_γ-S成反式构象,C_β-C_γ-S-C_δ成旁式构象。根据稀土诱导位移方法建立的构象模型符合~1H邻位质子偶合常数和~(13)C顺磁弛豫速率的结果。     

Thioglucosides from the Seeds of Raphanus sativus L.

Three new thioglucosides, (4E)‐5‐{6‐O‐[(2E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enoyl]‐β‐glucopyranosylsulfanyl}pent‐4‐enenitrile ( 1 ), (4E)‐5‐{6‐O‐[(2E)‐3‐(4‐hydroxy‐3,5‐dimethoxyphenyl)prop‐2‐enoyl]‐β‐glucopyranosylsulfanyl}pent‐4‐enenitrile ( 2 ) and its (4Z)‐isomer 3 , were isolated from the seeds of Raphanus sativus L. (radish), together with two known compounds. Their structures were determined by spectroscopic methods, including UV/VIS, 1D‐ and 2D‐NMR, FAB‐ and HR‐FAB‐MS experiments.