排序方式: 共有38条查询结果,搜索用时 15 毫秒
1.
分散染料溶解度参数的计算及应用 总被引:1,自引:0,他引:1
用Small、Hoy、Krevelen和Fedors基团增量法,对50只蒽醌、偶氮分散染料的溶解度参数进行了计算,并作了比较。对Small法中—NH_2、—NO_2、—NH—、—N—基团的吸引力常数作了补充。确认用于计算分散染料及涤纶纤维溶解度参数的较好方法是Hoy法。且发现:①当染料的溶解度参数与涤纶的溶解度参数接近时,染料的耐升华牢度可达4—5级;②分散染料摩尔体积与其匀染性几乎呈反比关系,当摩尔体积为210—340cm~3/mol时,匀染性能可达3—4级;③分散染料的扩散系数随着其摩尔体积的增大而减小,其减小趋势逐渐变缓。 相似文献
2.
Genomic islands, such as pathogenicity islands, contribute to the evolution and diversification of microbial life. Here we report on the Widespread Colonization Island, which encompasses the tad (tight adherence) locus for colonization of surfaces and biofilm formation by the human pathogen Actinobacillus actinomycetemcomitans. At least 12 of the 14 genes at the tad locus are required for tenacious biofilm formation and synthesis of bundled Flp pili (fibrils) that mediate adherence. The pilin subunit, Flp1, remains inside the cell in tad-locus mutants, indicating that these genes encode a secretion system for export and assembly of fibrils. We found tad-related regions in a wide variety of Bacterial and Archaeal species, and their sequence characteristics indicate possible horizontal transfer. To test the hypothesis of horizontal transfer, we compared the phylogeny of the tad locus to a robust organismal phylogeny using statistical tests of congruence and tree reconciliation techniques. Our analysis strongly supports a complex history of gene shuffling by recombination and multiple horizontal transfers, duplications and losses. We present evidence for a specific horizontal transfer event leading to the establishment of this region as a determinant of disease. 相似文献
3.
ZHANG Jie Yang Ke TAN DeYong ZENG JunYing Alan FINE 《科学通报(英文版)》2007,52(16):2210-2215
Constitutively expressed Fas ligand (FasL) in several distinct epithelial cell types appears to protect tissues by inducing apoptosis of Fas immune cells during inflammatory reactions. To study the rela-tionship of FasL and inflammation process in cornea,we examined the effects of inflammatory cytokine IL-1β on the FasL production,expression and cytotoxic function in corneal endothelial cells. In this paper,we demonstrate that IL-1β inhibits the FasL production and expression in corneal endothelial cells. The promoter activities of FasL in these cells are reduced by IL-1β in a dose-dependent manner. Finally,we also find that IL-1β block the cytotoxic effects of FasL derived from corneal endothelial cells to the Fas target cells. These data support the view that FasL derived from corneal endothelial cells modulate inflammation within cornea. 相似文献
4.
6.
7.
8.
推帚式TDI-CCD相机应用分析 总被引:8,自引:0,他引:8
简要介绍了推帚式TDI-CCD相机及TDI-CCD像感器的工作原理,对引起相机调制传递函数退化的几个因素进行了详细分析,这些因素包括几何尺寸、电荷转移损失、速度失配、电荷分立运动,而且对离散空间域的线阵静态扫描MTF进行了分析研究,阐述了TDI-CCD级数与速度同步性、信噪比、动态范围的关系。 相似文献
9.
JIANG Hui |lin YANG Hua |min XI Hao Changchun Institute of Optics Fine Mechanics Changchun China 《系统科学与系统工程学报(英文版)》2000,(3)
1 TheEvaluationIndicesofPhotoelectricSystem(PS)′sOverallPerformanceTherearemanykindsofphotoelectricinstrumentsusedforvariouspurposeswithdifferentoverallperformance ,buttheystillhavelotsofcommoncharacteristics .IntermsoftheessenceofPS ,PS′spurposeismostly… 相似文献
10.
苯并氧杂蒽-3,4-二酸酐型染料的合成研究 总被引:2,自引:0,他引:2
以1,8-萘酐为原料,经过氯化(重量产率82%)、缩合(71%)、还原(90%)、环构(98%)、亚酰胺化等反应步骤,合成了苯并氧杂蒽-3,4-二酸酐及其八种衍生物。提出了引入不同基团时,衍生物色光的变化趋势,并研究了其衍生物在聚酯纤维上的染色应用性能。结果表明:所得的染样具有强烈的绿色荧光,且色泽鲜艳,耐升华牢度一般为4—5级,耐晒牢度最好的可达5级。 相似文献