Influence of branch length on the dynamic fatigue properties of short-chain branched polyethylenes

An investigation of the influence of the short-chain branch length on the dynamic fatigue behavior of short-chain branched polyethylenes (SBPE) is reported. The number of fatigue failure cycles (N_f) increases significantly with increasing branch length at temperatures above the β-transition of SBPE polymers. In addition, an examination of the fracture surfaces of these specimens indicates a transition to a more ductile-type behavior when specimens are associated with larger branch lengths. Detailed characterization shows that these SBPEs have approximately the same molecular weight, molecular weight distribution, branch frequency, crystallinity or microstructure but different branch length. The difference in branch length is suggested to be responsible of the dramatic change in N_f and in the morphology of the fracture surface at temperatures above the β-transition of SBPEs. In contrast, no significant change in N_f and in the morphology of the fracture surface were found with increasing branch length at temperatures near or below the β-transition. This dramatic change in the effect of short-chain branches on N_f and on the morphology of the fracture surface are attributed to the change in the molecular relaxation motion at temperatures near the β-transition of SBPE polymers.     

气管与主支气管肿瘤的影像诊断（附32例报告）

作者对３２例经病理证实的气管与主支气管良、恶性肿瘤的影像学表现进行分析，归纳为３型：腔内型、壁增厚型和腔内外型。后２种类型提示恶性，而无蒂的腔内型表现者不能鉴别良，恶性。作者还评价了常规体层、ＣＴ及ＭＲＩ诊断气管与主支气管肿瘤的优、缺点，讨论了影像诊断的作用。     

胸部高分辨率CT检查技术的临床应用

笔者对５０例肺部疾病胸部常规ＣＴ和高分辨率ＣＴ（ＨＲＣＴ）图像进行了对照分析。其中特发性肺间质纤维化（ＩＦＰ）８例，肺转移癌５例，支气管扩张１５例，慢性阻塞性肺气肿１５例，周围型肺癌７例，结果表明：ＨＲＣＴ在ＩＦＰ、支气管扩张和肺气肿的显示明显优于常规ＣＴ（Ｐ＜０．００１），在对肺部原发或转移性肿瘤的显示能提供更多的诊断信息。笔者还讨论了ＨＲＣＴ的检查技术和图像后处理，分析了影响ＨＲＣＴ的若干因素，指出通过缩小视野（ＦＯＶ），减少象素做图像的重建放大显示肺部局部结构更为清楚方便，应灵活运用。     

小学教师主观幸福感与心理健康的相关研究

目的 研究小学教师主观幸福感和心理健康的关系。方法 用人脸量表和SCL－90测量了301名小学教师的主观幸福感和心理健康状况。结果 小学教师的主观幸福感呈右偏态分布趋势，主观幸福感与心理健康存在显著正相关。结论 心理健康是影响小学教师主观幸福感的因素之一。     

氟罗沙星片剂,胶囊剂的人体药物动力学和相对生物利用度研究

9名男性健康自愿受试者采用三交叉单剂口服国产氛罗沙星片剂、胶囊和进口氟罗沙星片剂各400mg的药代动力学参数比较。血、尿药浓度用HPLC检测．结果表明：体内过程符合一室模型，主要药代动力学参数分别为：AUC：82.30±14．30、81．13±8．45与83．92±14.27h·mg／L；Cmax：4．71±0．83、4．67±0．51与4．86±0．89mg／L；Tmax：1．88±0．44、1．90±0．39与1．92±0．23h；T1／2ke：11．02±0．96、10．93±0．68与10．86±0．82h；V／F（c）：79．08±13．31、78.42±8．70与76．39±12．93L；Cl／F：5．00±0．98、4．98±0．52与4．88±0．73L／h。服药48h的尿中原型药排出率分别为给药量的57．4％，55．9％和60．7％。国产氧罗沙星片剂和胶囊口服后药物动力学参数与进口片剂相仿．其相对生物利用及分别为98.07％与96．68％。     

nm23基因在前列腺癌中的表达与癌转移的关系

应用ＬＳＡＢ免疫组织化学染色方法，研究转移抑制基因ｎｍ２３表达产物二磷酸核苷激酶（ＮＤＰＫ）在前列腺癌中的表达及其意义。结果表明，ＮＤＰＫ／ｎｍ２３在前列腺癌中有较高的表达，阳性率为５００％（２０／４０）。无前列腺癌转移者其阳性率为６６７％（１２／１８），有前列腺癌转移者其阳性率为３６４％（８／２２），两者比较差异有显著性（Ｐ＜００５），并与前列腺癌分化程度和临床分期有显著相关。因此，ｎｍ２３基因可能在前列腺癌形成及转移过程中起不同的调节作用，其表达程度与前列腺癌转移呈负相关，有可能成为评价前列腺癌病人预后的一项新指标。     

胃癌病人天然杀伤细胞活性监测

报道微量细胞毒试验——LDH 释放法用于对胃癌病人临床免疫的监测.测定100例正常人和50例胃癌病人外周血 NK 细胞毒.结果:正常人值为36.10±5.68,胃癌组中,10例早期胃癌为28.76±4.70,25例进展期胃癌为14.51±5.80,15例晚期胃癌为11.86±4.43,与正常人值比较,P 值分别>0.05,<0.01和<0.01.NK 细胞毒活性随胃癌病变的进展和肿瘤体积的增大而逐渐降低,手术切除肿瘤后可有不同程度回升,甚至恢复到正常水平。长期化疗能损伤 NK 活性.     

CT造影剂碘海醇注射液的制备及动物实验

本文报道了非离子型Ｘ－ＣＴ造影剂碘海醇注射液的制备及动物实验结果。磺海醇的最大吸收波长λ＿（ｍａｘ）为２４４ｎｍ。讨论了温度、浓度对磺海醇溶液粘度的影响：粘度随温度的升高而下降，呈负线型相关；粘度随浓度（Ｃ）升高而激剧升高，与浓度的四次方呈线性相关：Ｖ＿（３７℃）＝４７２．５８９［Ｃ］￣４＋１．１２１（ｒ＝０．９９７７）Ｖ＿（３０℃）＝６６３．８１３［Ｃ］￣４＋１．１５２（ｒ＝０．９９９６）Ｖ＿（２０℃）＝１０８２．９５３［Ｃ］￣４＋１．４３３（ｒ＝０．９９８２）使用该注射液进行狗的造影实验，获得了清晰的造影图像。     

苯作业工人白细胞降低者的总估校正现患率

选择乡镇工业苯作业工人４次外周血白细胞计数中的间隔半年的两次数据，应用俘获再俘获法，计算其白细胞降低者的总估校正现患率（ＡＣＰＲ）。结果苯接触组为３６．８ｌ％（２９．１４％～４４．４８％），对照组为１２．７１％（７．２０％～１８．２２％）具有显著差异，其相对危险度为２，９。用常规法求得的４次检出率分别是：苯接触组为２６．３７％，１８．７３％，２７．９３％，３６．７６％；对照组为６。８５％，７．３８％，７．９４％，１５．００％。均在其ＡＣＰＲ之９５％可信限内，可见ＡＣＰＲ计算方法简便、结果准确，值得推广。对于稳定的人群，可用其每年一次的健康监护资料计算ＡＣＰＲ。     

Coplanar PCBs in fish and mussels from marine and estuarine waters of New York State.

Thirty samples of striped bass from marine and estuarine waters of New York State, six samples of mussels from Long Island Sound, and one composite sample of freshwater mussels from Troy were analyzed by a recently developed method which combines sulfuric acid cleanup, carbon chromatography, and high-resolution gas chromatography for the determination of non-ortho- and mono-ortho-substituted polychlorinated biphenyls (PCBs), which are biologically active congeners of PCBs and approximate isostereomers of 2,3,7,8-tetrachlorodibenzo-P-dioxin of (2,3,7,8-TCDD). Non-ortho coplanar PCBs ranged from 0.2 to 37.1 ppb in fish. The highest concentrations of 37.1 ng/g of 3,3',4,4'-tetrachlorobiphenyl (77) and 7.5 ng/g of 3,3',4,4',5-pentachlorobiphenyl (126) were detected in a fish caught near Troy/Albany, New York. Mono-ortho-substituted PCBs ranged from 0.4 to 790 ppb in fish, with the major components identified as 2,3',4,4',5-penta-(118) and 2,3,3',4,4'-pentachlorobiphenyls (105). When concentrations were converted to 2,3,7,8-TCDD picogram equivalents, 99% of the equivalents were derived from three congeners (77, 105, and 126), 3,3',4,4',5-pentachlorobiphenyl (126) accounting for approximately 80% of the activity. At Troy pg/g TCDD equivalents derived from PCB were approximately 3000, whereas the actual 2,3,7,8-TCDD concentration was only 20 pg/g; hence, accurate coplanar PCB measurement is important.