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1.
世界耐除草剂转基因作物的发展及问题   总被引:4,自引:0,他引:4  
介绍了耐除草剂转基因作物的发展概况及存在问题,以及它们的解决措施。  相似文献   
2.
Sensing from the ultraviolet–visible to the infrared is bringing more attentions recently. Here, we report the effects of optically generated dipoles within PTB7 layer on photocurrent and photoresponse in single wall carbon nanotube-based photodetectors. The observations in this work provide the direct evidence that optically generated dipoles within the PTB7 layer can be aligned by a built-in field, and then consequently affect dissociation of photo-excited electron-hole pairs in single wall carbon nanotubes. Additionally, PL (photoluminescence) of single wall carbon nanotubes can be appreciably quenched by optically generated dipoles in PTB7 layer. This quenched PL provides further information to back up photodetectivity increasing through dipoles alignment in PTB7 layer.  相似文献   
3.
本文通过比较观察几种常见抗体介导的肾小球肾炎的免疫荧光和超微结构的特征,以进一步提高对其识别能力和诊断水平。结果显示,一些常见抗体介导的肾小球病,如IgA肾病(包括紫癜性肾炎)、膜性肾病、急性弥漫增生性肾小球肾炎、膜性增生性肾小球肾炎(Ⅰ型)、狼疮性肾炎(Ⅳ型)的免疫荧光和电镜检查所显示的抗体或免疫反应产物有较好的可比性和一致性。提高对抗体介导的肾小球肾炎典型肾小球超微结构形态特征的认识和鉴别能力将十分有助于对肾小球疾病作出正确的病理学诊断。  相似文献   
4.
Systematic studies on a family of photovoltaic molecules are important for fundamentally understanding the basic principles and the key structural factors that govern their photovoltaic performance. In this work, a series of D2-A-D1-A-D2 type small molecules with isoindigo as acceptor (A), oligothiophene as donor (D1), and 5-hexyl thiophene as D2 were designed, synthesized and studied. The number of thiophene unit in oligothiophene segment is systematically varied from 0 to 4. It has been found this structural parameter have significant influence on their phase transition behaviours, light absorption properties, frontier orbital energy levels, molecular packing structures in both neat and blending films with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM), charge mobility, phase separation morphology, and as well as photovoltaic performances. The compounds bearing odd number of thiophene unit displayed much better photovoltaic performance than those having even number, while the best performance was given by that having terthiophene as D1 unit.  相似文献   
5.
6.
The inhibitory effects of dietary polyphenols against α-amylase have attracted great interest among researchers. The aim of this review is to give an overview of the research reports on the structure–activity relationship of polyphenols inhibiting α-amylase. The molecular structures that influence the inhibition are the following: (1) The hydroxylation of flavonoids improved the inhibitory effect on α-amylase; (2) Presence of an unsaturated 2,3-bond in conjugation with a 4-carbonyl group has been associated with stronger inhibition; (3) The glycosylation of flavonoids decreased the inhibitory effect on α-amylase depending on the conjugation site and the class of sugar moiety; (4) The methylation and methoxylation of flavonoids obviously weakened the inhibitory effect; (5) The galloylated catechins have higher inhibition than nongalloylated catechins; the catechol-type catechins were stronger than the pyrogallol-type catechins; the inhibition activities of the catechins with 2,3-trans structure were higher than those of the catechins with 2,3-cis structure; (6) Cyanidin-3-glucoside showed higher inhibition against than cyanidin and cyanidin-3-galactoside and cyanidin-3,5-diglucoside had no inhibitory activity; (7) Ellagitannins with β-galloyl groups at glucose C-1 positions have higher inhibitory effect than the α-galloyl and nongalloyl compounds and the molecular weight of ellagitannins is not an important element.  相似文献   
7.
High-amylose cereal starch has a great benefit on human health. Acid modification is very helpful for application of high-amylose starch in food and non-food industries. In this study, the ordered structure of acid-modified high-amylose rice starch was investigated by GPC, HPAEC, 13C CP/MAS NMR and XRD. Acid preferentially degraded the amylose, then A chain and short B chain of amylopectin. Relative double helix content and crystallinity both initially increased sharply and then progressively with acid hydrolysis. The relative crystallinity of starches obtained from 13C CP/MAS NMR was higher than that from XRD. The onset gelatinisation temperature decreased, while the peak and conclusion temperatures increased with increasing hydrolysis time. The endothermic value initially increased and then decreased with acid hydrolysis. The swelling power decreased while solubility increased after acid hydrolysis. These results add to our understanding of the effect of acid hydrolysis on the high-amylose rice starch.  相似文献   
8.
烟草挥发性成分的谱图检索结合保留指数和准确质量定性   总被引:1,自引:0,他引:1  
为更准确地给烟草中挥发性成分定性,采用同时蒸馏萃取和GC/MS,GC/TOFMS对烟草中的挥发性成分进行了分离,并采用谱库检索,结合保留指数和准确质量进行定性。结果显示:GC/MS谱库检索,结合保留指数和由GC/TOFMS得到的准确分子质量定性,可以明显提高烟草中挥发性成分定性分析的准确性和可靠性,尤其是同分异构体。  相似文献   
9.
Polaritons are arousing tremendous interests in physics and material sciences for their unique and amazing properties,especially including the condensation,lasing without inversion and even room-temperature superfluidity.Herein,we propose a cell vibron polariton(cell-VP):a collectively coherent mode of a photon and all phospholipid molecules in a myelin sheath formed by glial cells.Cell-VP can be resonantly self-confined in the myelin sheath under physiological conditions.The observations benefit from the specifically compact,ordered and polar thin-film structure of the sheath,and the relatively strong coupling of the mid-infrared photon with the vibrons of phospholipid tails in the myelin.The underlying physics is revealed to be the collectively coherent superposition of the photon and vibrons,the polariton induced significant enhancement of myelin permittivity,and the resonance of the polariton with the sheath.The captured cell-VPs in myelin sheaths may provide a promising way for super-efficient consumption of extra-weak bioenergy and even directly serve for quantum information.These findings further the understanding of nervous system operations at cellular level from the view of quantum mechanics.  相似文献   
10.
国民经济“十一五规划”以来,上海基本建设进入新的历史性跨越,上海世博园区、上海中心项目、虹桥交通枢纽项目等一大批特大型的地标项目接踵开工。特大型工程体量大,难度高,技术尖端,专业门类多,施工人员空前集中,质量安全要求高,对周边环境影响突出,政府、民生关注度特别敏感,也给工程监督带来新的挑战。  相似文献   
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