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981.
Female offspring from mice injected with androstenedione during late pregnancy showed lengthened vaginal cycles, persistent estrus and decreased incidence of pro-estrus and diestrus, whilst offspring from mice injected with corticosterone showed increased incidence of diestrus. These observations give qualified support to the hypothesis that stress during pregnancy alters the female offspring reproductive system through the action of adrenal steroids.  相似文献   
982.
Summary AnAspergillus niger mutant strain (hpp) produces an average of 4.1% of conidiophores with phialide proliferations. Increased frequency of proliferations could be induced on all studied strains by growth on potato dextrose agar. The characteristic is recessive and seems to be due to a pleiotropic effect of the mutation for olive conidia color.Acknowledgments. The authors are indebted to CNPq for financial assistance provided with grant PIG/SIP 04/053 as well as the scholarships Pesquisador Científico (R.B.Jr) and Iniciação Científica and Aperfeiçoamento (G.U.V.).  相似文献   
983.
Carcinoma of the human uterine cervix has been associated with several infectious agents including papillomavirus. Papillomavirus group-specific antigen (GSA) and viral particles have been demonstrated in human condylomata acuminata (CA) and flat warts of the uterine cervix. Cell alterations consisting of nuclear enlargement, hyperchromasia, irregularity, binucleation and cytoplasmic clearing (koilocytosis) are often interpreted as mild to moderate dysplasia. Present evidence that human papillomavirus (HPV) is responsible for the development of these lesions relies on the association of GSA and virus particles in the affected tissue, fulfilling the first two of Koch's postulates. Direct proof of an aetiological relationship, however, requires induction of the CA change in normal, human uterine cervix after exposure to papillomavirus. Infecting human subjects with HPV is ethically unacceptable and no satisfactory alternative systems have been defined. Also, human cell cultures do not support growth or transformation by HPV. Here we report the first demonstration of the morphological transformation of human tissues with a human papillomavirus under controlled, experimental conditions. 'Transformation' is used here in its literal sense to refer to a heritable morphological alteration in the appearance of the cells. The use of this term does not indicate that the changes described are neoplastic, but they are identical to the dysplastic changes found in biopsies of uterine cervical CA. Our results demonstrate the direct involvement of CA virus in dysplastic change of human cervical tissue and indicate that the experimental system described may be useful in elucidating the contribution of human papillomaviruses to the pathogenesis of human cervical cancer.  相似文献   
984.
Human T-cell lymphotropic retrovirus type III (HTLV-III), also called lymphadenopathy-associated virus (LAV), has been identified as the aetiological agent of acquired immune deficiency syndrome (AIDS). The sera of most patients with AIDS or AIDS-related complexes, and of asymptomatic individuals infected with HTLV-III, contain antibodies against antigens of HTLV-III. The characterization of these antibodies and their corresponding viral antigens is important not only for understanding immunity against HTLV-III and the pathology of AIDS, but also for the development of diagnostic methods and preventive vaccine for AIDS. Following the successful establishment of a long-term T-cell line permissive for HTLV-III replication, large quantities of virus have been produced, facilitating the purification of viral proteins and the development of mouse monoclonal antibodies against several viral antigens. More recently, the structure of HTLV-III proviral DNA has been elucidated. We now report the production, by genetic engineering methods, of a peptide encoded by a gene segment of HTLV-III. A 1.1-kilobase (kb) EcoRI DNA segment from an isolate of HTLV-III was inserted into a lpp and lac promoter-coupled expression vector, pIN-III-ompA. Escherichia coli transformants of this plasmid produced a peptide of relative molecular mass (Mr) 15,000 (15K) which was strongly immunoreactive with anti-HTLV-III antibodies present in sera from AIDS patients. Lysates of the clones expressing this 15K peptide inhibited the reactivity of the p31 virion protein with AIDS sera, suggesting that it is a fragment of the viral p31 protein. The peptide reacted with sera from all 20 AIDS patients but none of the 8 normal controls tested. These results suggest that the peptide may be useful for detecting anti-HTLV-III antibodies in blood samples.  相似文献   
985.
This paper has developed a single mathematical measure for the evaluation of the shape conformity of the curved garment objects such as moulded brassiere cups. The measurements are based on the sectional analysis of the fringe pattern generated by means of moire topography. They include the area ratio, shape ratio and root mean square (RMS) of the height deviation of the moulded cup from the standard shape profile. Ultimately, the RMS was found to be a satisfactory method of assessing the shape conformity and a guideline for determining a good fit from the RMS value was then derived.  相似文献   
986.
文中研究离子液体应用于电润湿显示器件的导电流体性能. 选取极性较大的乙基咪唑为离子液体的阳离子,改变阴离子的亲疏水性,对比了几种离子液体的温度窗口、粘度等物理性质,并重点研究了离子液体亲疏水性对电润湿特性、油墨萃取、器件响应等方面的影响. 同时,在1-乙基-3-甲基咪唑四氟硼酸盐离子液体的阳离子上添加羟基基团,得到具有更强亲水性的离子液体. 结果表明:亲水性高的离子液体在介电材料含氟聚合物表面的初始接触角比较大,对油墨中染料的萃取程度比疏水性离子液体弱,证明了电润湿器件更适合选取亲水性高的离子液体作为导电流体. 最后,以1-乙基-3-甲基咪唑二腈胺盐离子液体作为导电流体制备的电润湿器件得到了较佳的电学和光学响应性能.  相似文献   
987.
将巯基丙酸修饰的CdTe量子点和植物激素茉莉酸通过一步法偶联到表面修饰氨基的Fe3O4纳米颗粒表面,合成了一种同时具有荧光信号、磁响应性能和特异性标记植物原生质体中茉莉酸受体的多功能磁性荧光纳米探针. 荧光光谱测试表明该探针保持了CdTe量子点荧光性能,具有荧光强度高,适用体系的pH范围宽,抗光漂白性能好等优点. 磁响应及磁滞回线测试充分说明该探针具有良好的超顺磁性. 使用该探针对绿豆原生质体中茉莉酸受体进行成像,结果表明,该探针对茉莉酸受体具有选择性标记的功能,茉莉酸受体主要存在于原生质体膜上. 该标记方法简单方便,能为茉莉酸信号转导研究提供可视化的信息.  相似文献   
988.
基于空间句法理论中较前沿的NAchoice算法,着眼于我国第一座城市高架桥广州市人民路高架桥拆除问题进行案例分析,为空间句法在中国城市交通预测中的应用提供实证,探寻一种较好拟合实际交通流的预测模型,为路网优化提供参考依据. 论证分析从广州人民南路段交通堵塞原因、拆桥与否对桥下路段车流的影响、人民路段周边主干道交通疏导能力评估等3个方面展开,研究发现:(1)车流量偏大是人民南路段交通堵塞问题频发的原因之一;(2)高架桥的拆除会小幅增加桥底路段车流,但不一定会造成车流量的叠加式剧增;(3)人民路段及其周围主干道分流能力受到质疑,建议等到有较强疏导能力路段建成后,再拆除人民路高架桥;(4)空间句法NAchoice模型与广州市交通流数据具有较好拟合程度,运用该模型进行城市道路交通预测具有可行性.  相似文献   
989.
摘要:纳米材料的研究在近年来是材料科学中研究的重点方向,而纳米硫化铅作为新型的具有特殊光学性能的材料在各个领域都受到广泛应用。我们通过实验以求控制其量子点的颗粒变化,从而进一步研究其本身性质的改变。文中我们采用化学液相法,使用溶液混合反应共沉淀制备硫化铅量子点,并通过X射线衍射(XRD)、透射电子显微镜(TEM)和紫外可见分光光度计(UV-vis)进行表征分析。实验过程中我们成功的通过调制反应溶液的浓度和添加表面活性剂的方法改变了硫化铅量子点的颗粒尺寸,制备了粒径由7nm到20nm的硫化铅量子点。颗粒尺寸的变化也导致了量子点光学特性和能带的改变。从实验的结果上可看出,实验成功制备了结晶性良好的纯硫化铅量子点,再通过形貌及性能的表征分析后,发现量子点的能带岁颗粒尺寸大小变化的规律。通过对量子点本身光学性能的研究,我们可以使其在太阳能电池等领域获得更好的应用,同时对新型材料的发展起到促进作用。关键词:硫化铅;量子点;能带;调控  相似文献   
990.
Alloxan diabetes caused a decrease in cyclic AMP phosphodiesterase in all affected rat tissues. Cyclic GMP phosphodiesterase activity was, however, decreased in adipose and liver, but increased increased in heart and uterus.  相似文献   
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