聚丙烯熔体的零切变粘度与粘均分子量的关系

<正> 零切变粘度η_0是聚丙烯熔体流变性能的一个基本物理量,零切变粘度-分子量关系不仅具有理论上的兴趣,而且也有较大的实用意义。在文献中零切变粘度通常都是用毛细管粘度计数据外推求得的,但是由于聚丙烯熔体有较强的非牛顿性,即使在毛细管粘度计测量下限测得的粘度仍表现出明显的切变速率依赖性。因此,难于用外推的方法     

粘度法研究高分子溶液行为的实验改进(Ⅱ)

高分子在粘度计毛细管管壁上的吸附不仅会导致毛细管有效管径减小，而且可以导致毛细管界面性质发生显著改变，具体表现为测定高分子溶液流过时间t之前和之后纯溶剂的流过时间t0和t0′与高分子溶液流过时间t对浓度作图外推到浓度为零时的值t0^*并不一致。不同温度时聚乙烯吡咯烷酮（PVP）水溶液粘度测定结果表明，当吸附讷发子显著改变了毛细管界面性质时，需要将高分子溶液粘度测定方法由t/t0′改为t/t0^*。经过改进的粘度测定方法不仅更加普适合理，而且更加简单有效。     

邻苯二胺合钴氧合反应的研究Ⅰ 水溶液中配合物及其氧合配合物稳定常数的测定

自１９３８年Tsumaki报道犤１犦氧载体以来，这方面的研究已有很大进展犤２犦，只是理论研究居多。氧载体的氧合常数是氧载体研究中的一个重要参数，它的测定是氧载体研究中的一项重要内容，用pH电位法测定氧载体的氧合常数已有研究报道犤２～４犦，作者在研究中发现，邻苯二胺合钴（o－Phdn－Co）配合物在固相和水溶液中与O２反应时表现出很大差异，其反应产物的组成比分别为液相配合物Co∶O２＝２∶１，而固相配合物Co∶O２＝１∶２，为究其成因和进行理论探讨，有必要先测定其氧合常数。由于o－Phdn－Co配合物的配位常数也未见文献…     

螺［异苯并呋喃－1（3H），9＇－（9H）－2＇－N，N－二苄胺基－6＇－二乙胺基占吨］－酮－3的合成及晶体结构研究

合成了螺［异苯并呋喃－１（３Ｈ），９＇－（９Ｈ）－２＇－Ｎ，Ｎ－二苄胺基－６＇－二乙胺基占吨］－酮－３，Ｃ＿（３７）Ｈ＿（３４）Ｎ＿２Ｏ＿３，单斜晶系，空间群Ｃｃ，晶体学参数为ａ＝１６．８２６（４），ｂ＝１０．６４８（４），ｃ＝１７．６１８（７），β＝９２．２５（２）°，Ｖ＝３１５４（２），Ｚ＝４，Ｍ＿ｒ＝５６６．７，Ｄ＿ｘ＝１．１９ｇ／ｃｍ３，Ｆ（０００）＝１２００。结构由直接法解出，偏离因子Ｒ＝０．０８０。分子由占吨和异苯并呋喃两部分组成Ｙ形结构，占吨部分相连的苄基的两个苯环位于占吨部分的两侧。     

Toward the most versatile fluorophore: Direct functionalization of BODIPY dyes via regioselective C—H bond activation

BODIPY dyes are privileged fluorophores that are now widely used in highly diverse research fields. An overview of BODIPY dyes and a summarization of the different synthetic methodologies reported for direct C-H functionalization of the BODIPY framework have been provided.     

Sensitive high-performance liquid chromatography/mass spectrometry method for determination of steviol in rat plasma

The main toxicological concern of stevioside, a highly potent sweetener from S. rebaudiana, is its main metabolite, steviol. To determine very low levels of steviol in in vivo experiments, a sensitive liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-MS) method was developed for quantifying steviol in rat plasma after oral administration of a single dose of stevioside (0.5 g/kg). The sample preparation uses liquid-liquid extraction with tert-butyl methyl ether in an acidic environment. The retention time of steviol was 10.5 min. The assay was linear over the range 2-1000 ng/mL with a lower limit of detection of 1 ng/mL. The intra- and inter-day precision were <5 and <7%, respectively, and the accuracy was in the range 95-108%. The steviol concentration profile in rat plasma was determined.     

一种基于流动注射梯度技术识别异常峰及校正的方法

基于流动注射梯度信息提出了一种利用梯度比均值进行定量的校正方法。方法具有在线自动判别和修复异常峰并自行校正的功能，和通用的标准系列定量方法相比，两者测定精度相当。但本文提出的方法抗干扰能力明显优于后者，可适用于在线过程监测。     

Poly(methacrylic acid-ethylene glycol dimethacrylate) monolith in-tube solid-phase microextraction applied to simultaneous analysis of some amphetamine derivatives in urine by capillary zone electrophoresis

A method based on in-tube solid-phase microextraction and capillary zone electrophoresis (CZE) was proposed for simultaneously determining four amphetamines (amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, and 3,4-methylenedioxymethamphetamine) in urine. A poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column, which can provide sufficient extraction efficiency, was introduced for the extraction of amphetamines from urine samples. The hydrophobic main chains and acidic pendant groups of the monolithic column make it a superior material for extraction of basic analytes from aqueous matrix. After extraction, the samples were analyzed by CZE. The best separation was achieved using a buffer composed of 0.1 M disodium hydrogen phosphate (adjusted to pH 4.5 with 1 M hydrochloric acid) and 20% methanol v/v, with a temperature and voltage of 25 degrees C and 20 kV, respectively. By applying electrokinetic injection with field-amplified sample stacking, detection limits of 25-34 microg/L were achieved. Excellent method of reproducibility was found over a linear range of 0.1-5 mg/L. Determination of these analytes from abusers' urine sample was also demonstrated.     

Enzymatic surface modification of Kevlar fibers

Horseradish peroxidase catalyzed grafting of acrylamide (AM) onto Kevlar fibers has been studied. The modified fiber has been characterized with scanning electron microscopy (SEM), elemental analysis and the grafting yield. From the SEM micrographs, the surface of the grafted Kevlar fiber is rougher than that of the untreated fiber, and the elemental analysis indicated that the nitrogen content of the treated fibers is higher than that of the untreated fiber. All the results suggested that AM must have been grafted onto the Kevlar surface through HRP-mediated radical initiated grafting reaction. The probably mechanism of HRP catalyzed grafting of AM onto Kevlar surface is proposed.