正电子湮没技术在研究合金形状记忆性能中的应用

本文用正电子湮没技术测试了Cu-Zn-Al形状记忆合金100℃母相时效过程中空位的变化。结果发现,随着时效时间的延长,空位浓度不断降低,空位尺寸不断增大。这一结果很好地解释了记忆合金马氏体逆转变温度As的变化规律,从而证明过饱和空位是Cu-Zn-Al形状记忆合金马氏体稳定化的一个主要原因。     

NCD－环上模的理论探讨

研究了ＮＣＤ－环上模Ｍ，在模半理想的条件下，可得到一些有趣的结果。     

Decreased drug accumulation without increased drug efflux in a novel MRP-overexpressing multidrug-resistant cell line

KB/7D cells represent a multidrug-resistant subclone of human nasopharyngeal carcinoma KB cells generated by continuous exposure to the topoisomerase II inhibitor VP-16 (etoposide). KB/7D cells also show cross-resistance to doxorubicin and vincristine. Phenotypic traits of the cell line include a 2-fold decrease in topoisomerase II levels and a decrease in the uptake of VP-16 without an increase in the rate of drug efflux or expression of P-glycoprotein, suggesting a novel mechanism associated with the uptake of anticancer drugs. This study demonstrated that the multidrug-resistance associated protein (MRP) is overexpressed in KB/7D cells, and that the loss of resistance in revertant cells correlates with the loss of MRP. The resistance to VP-16 and doxorubicin could be overcome, partially, and resistance to vincristine could be overcome completely, by the L-enantiomer of verapamil, but not by the D-enantiomer or by BIBW 22 (4-[N-(2-hydroxy-2-methyl-propyl)-ethanolamino]-2,7-bis[cis-2,6-++ +dimethylmorpholino)-6-phenylpteridin), an inhibitor of MDR-1. L-Verapamil was shown to be significantly more potent than D-verapamil in modulating the accumulation defect in KB/7D cells towards doxorubicin, as measured by flow cytometry and confocal microscopy, and towards VP-16, as measured by increases in protein-linked DNA strand breaks. This suggests that KB/7D cells are multidrug resistant due to decreases in topoisomerase II levels and the overexpression of MRP, that MRP leads to a decrease in drug accumulation, and that L-verapamil can modulate the MRP-associated accumulation defect and drug-resistance phenotype. This contrasts with previous studies that suggest that MRP causes multidrug resistance by exporting cytotoxic drugs out of the cell and that did not show modulation of MRP by verapamil.     

Uterine relaxation responses to calcitonin gene-related peptide and calcitonin gene-related peptide receptors decreased during labor in rats

OBJECTIVES: Our purpose was to investigate (1) whether uterine relaxation responses to calcitonin gene-related peptide are differentially regulated during pregnancy and labor, (2) the involvement of nitric oxide in smooth muscle relaxant action of calcitonin gene-related peptide in the rat uterus, (3) whether receptors for calcitonin gene-related peptide are expressed in rat uterus, and if so (4) whether the concentrations of these receptors are differently regulated during pregnancy and labor. STUDY DESIGN: Rats were killed on day 18 of gestation, at the time of spontaneous labor, or postpartum day 2. The uteri were removed for in vitro contractility measurements, nitric oxide production, and calcitonin gene-related peptide receptor binding assay. RESULTS: (1) Calcitonin gene-related peptide induced a dose-dependent relaxation in spontaneously contracting uterine strips from pregnant rats on day 18 of gestation; (2) the relaxation effects of calcitonin gene-related peptide on the uterus were decreased during spontaneous delivery at term and post partum compared with that during pregnancy; (3) calcitonin gene-related peptide-induced relaxation was inhibited by pretreatment of the uterine tissue with a calcitonin gene-related peptide receptor antagonist, calcitonin gene-related peptide(8-37); (4) nitric oxide synthesis inhibitor (N(G)-nitro-L-arginine methyl ester) and soluble guanylate cyclase inhibitor (LY83583) significantly decreased calcitonin gene-related peptide-induced relaxation of the rat uterus during pregnancy; (5) calcitonin gene-related peptide increased the uterine nitric oxide production in pregnant rats, and this increase was obliterated in the presence of calcitonin gene-related peptide(8-37); and (6) calcitonin gene-related peptide receptors are present in rat uterus, and the concentration of these receptors dramatically increases during pregnancy and decreases during labor at term. CONCLUSIONS: Calcitonin gene-related peptide inhibits uterine spontaneous contractions in rats during pregnancy but not during labor and post partum. The inhibitory effects of calcitonin gene-related peptide on uterine contractility appear to be modulated, at least in part, by the activation of nitric oxide generation in the rat uterus. Changes in calcitonin gene-related peptide receptors could contribute to the changes in calcitonin gene-related peptide-mediated uterine relaxation during pregnancy and labor.     

Synthesis and characterization of block copolymers from D,L-lactide and poly(tetramethylene ether glycol)

The copolymer from D ,L -lactide and poly(tetramethyene ether glycol) (PTMG) was prepared in bulk with an isotributyl aluminum–water–phosphoric acid complex catalyst as the initiator and characterized by H-NMR, GPC, and DSC. The effects of the temperature and the amount of PTMG on the polymerization rate and the molecular weight of copolymers were studied. The behavior of the degradation and delivery rate of Levonorgestrel microspheres in vitro was observed. The results show that the degradation and the delivery rate can be controlled by adjusting the molar rate of hydrophilic and hydrophobic segments of the copolymer © 1995 John Wiley & Sons, Inc.     

聚乙烯接枝改性及其与铝的粘结性

聚乙烯在过氧化二异丙苯存在下分别与丙烯酸，顺丁烯酸酐，顺丁烯二酸，顺丁烯二酸钠，丙烯酸羧丙酯，甲基丙烯酸环丙酯等单体熔融挤出，产物的红外光谱表明聚乙烯不同程度地接了各种极性基团。     

确定型存贮模型的系统动态描述

本文尝试用系统动态学的研究方法于存贮理论，建立确定型存贮问题的系统动态优化模型，并对模型作了数学推导。     

面向对象方法在7号信令软件设计中的应用

随着交换技术的飞速发展，程控交换软件的规模越来越大，改动也越来越频繁，如何使代码对数据的改动具有相对的稳定性成为程控软件设计的一个首要问题。本文以ＣＣＳ７（７号公共信道信令）为例，从对象模型、动态模型、功能模型３个方面阐述了ＯＯ（面向对象）方法在ＣＣＳ７软件设计中的应用。这一方法，也可应用于程控软件的设计。     

天津市正常人全血和血清微量元素含量分析

人体内微量元素含量平衡与否与人体健康状态有着密切关系已为大量实践所证实。人体血液中微量元素的正常值测定是研究人体健康与微量元素关系的一项基础性工作,本文提供了天津市正常人全血及血清中几种微量元素含量的数据。     

“双驱动足”回转式压电马达初步研究

提出一种“双驱动足”回转式压电马达，分析了其工作原理，并根据工作原理，设计，研制了样机，进行了初步的试验研究，证明工作原理基本正确，为今后进一步研究提供了参考依据。