40 resultados para Cisma de 1130


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Two new ultrathin multiplayer films have been successfully prepared fi-om Keggin-type heteropoly acids H-4[SiW12O40] and H-3[PMo12O40] with polyelectrolytes PEI, PSS, and PAH, using the electrostatic layer-by-layer self-assembly, technique. The XR results reveal their film thickness at nanoscale (similar to 20 nm). According to the AFM images, it is believed that the surface roughness (rough degree of film surface) of the polyelectrolyte-polyoxometalate film greatly depends on the kind of polyoxometalates.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The elucidation of key influence factors for electrostatic adsorption is very important to control protein nonspecific adsorption on modified surfaces. In this study, real-time surface plasmon resonance technique is used to characterize the electrostatic adsorption of two proteins (mouse IgG and protein A) on carboxymethyldextran-modified surface. The results show that protein solution pH and ionic strength are key influence factors for efficient electrostatic adsorption. The influence of protein, solution pH on the amount of electrostatic adsorption depends on the type of the charge and the charge density of both protein and modified matrix on the surface. The electrostatic adsorption process involves a competition between the positively charged protein and other positively charged species in the buffer solution. A decrease of ionic strength leads to an increasing electrostatic adsorption. The kinetic adsorption constants of protein A at different pH values were also calculated and compared.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

琼脂(agar,又称琼胶)作为世界三大工业海藻胶之一,被广泛应用于食品、医药、生物技术、造纸等领域。本文首先研究了琼脂的分级方法,用DEAE-Cellulose将石花菜琼脂分级,得到四个级分,即水级分、0.5mol/L NaCl级分、1.0mol/L NaCl级分、2.5mol/L NaCl级分。分析了各级分的理化性质,并通过IR和~(13)C-NMR光谱研究其化学结构。石花菜琼脂分级得到的四个级分中,水级分的硫酸基含量为0.16%,凝胶强度为1130 g/cm~2(1%浓度),电内渗(EEO)为0.12,主要质量标准为Sigma公司的低电内渗琼脂糖(agarose)产品接近,符合低电内渗琼脂糖产品的质量要求。1.0mol/L NaCl级分和2.5mol/L NaCl级分的硫酸基含量较高,分别为22.8%和32.5%,合称为硫琼脂(agaropectin)。在琼脂糖的应用中,特别是现代生物技术研究中,需要低凝固温度琼脂糖。本文以石花菜琼脂分级得到的水级分为原料,采用甲基化反应制备低凝固温度琼脂糖。实验产品的凝固温度为30.1 ℃(1.5%浓度),融化温度为64.8 ℃(1.5%浓度),凝胶强度为264 g/cm~2(1%浓度),主要质量标准与Sigma公司的低凝固温度琼脂糖产品接近,符合低凝固温度琼脂糖产品的质量要求。随着对多糖生物学功能的深入,海藻硫酸多糖表现出多种生物活性,其活性研究已经成为目前新药研究的一个热点。到目前为止,有关琼脂分级产物的生物活性研究较少。本文在研究石菜硫琼脂的组成和主要理化特性的基础上,对基体内外抗凝血活性进行了较系统的研究。新西兰兔腹主动脉血体外抗凝实验结果表明,石花菜硫琼脂具有明显的体外抗凝血活性,在3.125mg/ml ~ 25mg/ml剂量范围内呈现量效关系;大鼠体内抗凝血实验的结果表明其口服可以吸收,在体内产生抗凝血作用,在100 mg/kg·d ~ 400 mg/kg·d剂量范围内,与全血凝血时间(CT)、凝血酶时间(TT)、凝血酶原时间(PT)、部分凝血活酶时间(KPTT)的延长及血浆纤维蛋白原(Fib)含量的降低均呈剂量依赖关系。就其抗凝血机制而言,石花菜硫琼脂的抗凝血作用既影响凝血系统,又影响纤溶系统。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

黄河三角洲存在着不可忽视的地面沉降现象,并在一定程度上阻碍着三角洲的快速发展。对黄河三角洲地面沉降的研究在黄河三角洲防灾减灾、土地利用、河口河道治理等方面具有理论与实践指导意义。 本文收集了黄河三角洲地区1956年、1967年、1980年和1995年四个时期的1:5万地形图,提取高程信息,应用地理信息系统(GIS)软件生成数字高程模型并展开了相应的空间分析,得到各个时间段内黄河三角洲的地面沉降速率图,通过对各沉降速率图的统计分析得出了三角洲地区地面沉降的时空变化规律。文章继而分析了引发黄河三角洲地面沉降的三个主要诱导因子、它们在影响范围、作用时间、作用强度等方面的特点,以及在不同时间段内各诱导因子在引发地面沉降方面所发挥作用的主次。随后,在列举地面沉降对黄河三角洲产生的影响之后,归纳总结了防治地面沉降及其引发灾害的对策。最后,基于采用常规水准测量方法进行地面沉降监测费时费力,提出利用InSAR技术对黄河三角洲地面沉降进行监测的设想,并简要分析了其可行性。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The three-dimensional fluorescence spectrum was used to detect the changes in dissolved organic substances from the cultured Skeletonema costatum, Alexandrium tamarense, Alexandrium mimutum, Scrippsiella trochodea, Prorocentrum donghaiense and Prorocentrum micans. The result indicates that all of the microalgaes can produce FDOM in the growth courses. Diatom such as Skeletonema costatum can produce humic-like FDOM. However dinoflagellate can produce protein-like FDOM at exponential growth phase. When the algae grows into decadency phase, the intensity of humic-like and protein-like fluorescence augments rapidly, which may be due to a mass of FDOM realeased by the old or dead cell fragmentation and the degradation of bacteria by using non-FDOM. The fluorescent intensity of Alexandrium tamarense, Alexandrium mimutum, Prorocentrum donghaiense and Prorocentrum micans can reduce at anaphase of decadency phase because of the degradation of bacteria and light. The same genus of algae can produce similar FDOM, for example: Alexandrium tamarense, and Alexandrium mimutum, Prorocentrum donghaiense and Prorocentrum micans, but the positions of the fluorescence peaks are different.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

系统报道黑边假龙胆(Gentianella azurea (Bunge) Holub)的胚胎发育过程,用以讨论假龙胆属长期存在争议的分类和系统发育问题。黑边假龙胆花药4室;药壁发育属双子叶型;绒毡层单型起源,细胞单核,属腺质绒毡层;花药壁表皮层宿存,药室内壁减缩。小抱子母细胞减数分裂为同时型,四分体的排列为四面体型;成熟花粉3-细胞型。子房为2心应,1室,减编的侧膜胎座,胚珠4列。薄珠心,单珠被,横生胚珠,大抱子母细胞减数分裂形成的4个大抱呈直列式排列,其中合点端的大抱子具功能。胚囊发育为蓼型。珠心冠原存在。极核在受精前融合为次生核,反足细胞宿存、分裂为8~12个、每个细胞均多核和异常膨大,反足细胞形成的吸器明显。雄蕊先熟。异花传粉,珠孔受精。花粉管进入胚囊时不破坏助细胞,助细胞宿存;一个精核和次生核的融合几乎发生在另一个精核和卵细胞核融合的同时。受精作用属于有丝分裂前配子体融合类型。胚乳为核型,胚乳核分裂同步,每核含2~3个核仁。胚胎发育为茄型酸浆Ⅰ变型。成熟种子中胚只发育至球形胚阶段。反足细胞在合子分裂之后才开始退化;在胚的发育过程中反足细胞在胚乳层之外形成一层染色深类似“外胚乳”的结构。和龙胆属比较,假龙胆属具有如下不同的特征:绒毡层单型起源,典型的腺质绒毡层,无“类胎座”和“横格”,单层;减缩侧墨胎座,胚珠4列,横生胚珠;珠心冠原存在;反足细胞异常膨大,形成内多倍体和多核,并在胚乳核之外形成一层类似“外胚乳”的结构;花粉管进入胚囊时不破坏助细胞;胚胎发育为茄型酸浆Ⅰ变型等。胚胎学研究结果表明假龙胆与龙胆属的亲缘关系较远,分类等级上作为一独立的属较合适,在系统位置上它与龙胆属可能不在同一条进化线上。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Compared with the conventional P wave, multi-component seismic data can markedly provide more information, thus improve the quality of reservoir evaluation like formation evaluation etc. With PS wave, better imaging result can be obtained especially in areas involved with gas chimney and high velocity formation. However, the signal-to-noise of multi-component seismic data is normally lower than that of the conventional P wave seismic data, while the frequency range of converted wave is always close to that of the surface wave which adds to the difficulty of removing surface wave. To realize common reflection point data stacking from extracted common conversion point data is a hard nut to crack. The s wave static correction of common receiver point PS wave data is not easy neither. In a word, the processing of multi-component seismic data is more complicated than P wave data. This paper shows some work that has been done, addressing those problems mentioned above. (1) Based on the AVO feature of converted wave, this paper has realized the velocity spectrum of converted waves by using Sarkar’s generalized semblance method taking into account of AVO factor in velocity analysis. (2)We achieve a method of smoothly offset division normal method.Firstly we scan the stacking velocities in different offset divisions for a t0, secondly obtain some hyperbolas using these stacking velocities, then get the travel time for every trace using these hyperbolas; in the end we interpolate the normal move out between two t0 for every trace. (3) Here realize a method of stepwise offset division normal moveout.It is similar to the method of smoothly offset division normal moveout.The main difference is using quadratic curve, sixth order curve or fraction curve to fit these hyperbolas. (4)In this paper, 4 types of travel time versus distance functions in inhomogeneous media whose velocity or slowness varies with depth and vertical travel time have been discussed and used to approximate reflection travel time. The errors of ray path and travel time based on those functions in four layered models were analyzed, and it has shown that effective results of NMO in synthetic or real data can be obtained. (5) The velocity model of converted PS-wave can be considered as that of P -wave based on the ghost source theory, thus the converted wave travel time can be approximated by calculation from 4 equivalent velocity functions: velocity or slowness vary linearly with depth or vertical travel time. Then combining with P wave velocity analysis, the converted wave data can be corrected directly to the P-wave vertical travel time. The improvements were shown in Normal Move out of converted waves with numerical examples and real data. (6) This paper introduces the methods to compute conversion point location in vertical inhomogeneous media based on linear functions of velocity or slowness versus depth or vertical travel time, and introduce three ways to choose appropriate equivalent velocity methods, which are velocity fitting, travel time approximation and semblance coefficient methods.

Relevância:

10.00% 10.00%

Publicador: