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排序方式: 共有163条查询结果,搜索用时 15 毫秒
71.
选择典型的竖井建筑结构形式,重点研究不同风速下烟气从燃烧室向竖井中迁移的规律。结果表明,在燃烧室内,风速大于0.5 m/s时CO体积分数和温度变化均非常小;风速小于0.5 m/s时,CO体积分数和温度骤降,形成明显的梯度差;在竖井中,CO浓度先上升后下降,温度逐渐下降,风速对CO的影响和燃烧室内的相同。建议该模型的最佳机械排烟风速为0.5 m/s,可以保证安全,同时实现最佳的经济效益。  相似文献   
72.
鞠军  李聪  齐程远  于世钧 《辽宁化工》2011,40(2):115-117
以间二苯甲酸为原料,经多步反应合成5-[4-(羟乙氧基苯基)偶氮]-1,3-苯二甲酸;进一步与均苯三甲酰氯反应得到新型含偶氮苯结构树枝状化合物,通过FT—IR、UV—vis和。HNMR对中间体及树枝状产物进行了结构表征。TGA分析显示,5%失重温度为225℃,DSC测得树枝状化合物的玻璃化转变温度(嗜)为95.7℃。  相似文献   
73.
Abstract

A study of liquid metal magnetohydrodynamic (MHD) flows is important for analyzing flows in the Test Blanket Module of the proposed International Thermonuclear Experimental Reactor. Possible accident scenarios involve the leakage of coolant into the liquid metal flow. To address this situation, the present article considers the simplified case of two-dimensional isothermal flow of two fluids of different viscosities and electrical conductivities. We present analytical solutions to the fully developed flows and a solver based on OpenFOAM. We validate the solver performance with the analytical solution, and also the limiting cases of single fluid MHD flow and two-fluid hydrodynamic flow.  相似文献   
74.
以NBR/CSM为外层胶、NBR/CHR为内层胶、尼龙纤维为骨架材料且内层胶表面贴合聚四氟乙烯薄膜,研制了新型耐油胶布制品。实验证明,该制品能较好地满足贮(运)油类燃料的要求,满足用户需求。  相似文献   
75.
对北京谱仪电磁量能器中晶体的分布、CaI晶体尺寸的测量所用的仪器和方法进行了分析,最后对所有晶体的尺寸进行了统计.  相似文献   
76.
The goals of this study were 1) to compare the effects of transforming growth factor-beta (TGF-beta) and parathyroid hormone-related protein (PTHrP) on mouse blastocyst attachment and outgrowth in vitro, 2) to determine whether TGF-beta acts through a mechanism involving PTHrP, 3) to examine effects of PTHrP on preimplantation mouse embryo development, and 4) to determine the pattern of expression of PTHrP protein in the uterus of the mouse during early gestation. In the first set of experiments, hatched blastocysts were placed in fibronectin-coated wells. Cultures were treated with PTHrP or TGF-beta1 and assessed at 24, 48, and 72 h for attachment and surface area of blastocyst outgrowth. Results showed that both PTHrP and TGF-beta1 increased blastocyst outgrowth significantly. A PTHrP-neutralizing antibody blocked the stimulatory effect of both PTHrP and TGF-beta1, suggesting that TGF-beta1 acts to increase endogenous production of PTHrP by the blastocyst. Immunoassay of conditioned medium from blastocysts treated with either TGF-beta1 or PTHrP 1-34 confirmed a 3- to 4-fold increase in levels of PTHrP 1-141. In the second series of experiments, pronuclear zygotes were cultured in various concentrations of PTHrP for 96 h. Blastocysts then were subjected to differential fluorescent staining of inner cell mass and trophectoderm cells. Treatment of mouse embryos with the various concentrations of PTHrP altered neither the number developing to the blastocyst stage nor the number of inner cell mass or trophectoderm cells in the resulting blastocysts. In the third experiment, pregnant mice were killed at Days 3, 4, 5, 6, and 7 of gestation, and uterine horns were processed for immunohistochemistry. Uterine sections were stained with antibodies to PTHrP, desmin, and laminin. On Days 3, 4, and 5, uterine luminal and glandular epithelial cells stained intensely for PTHrP, while stromal cells were negative. By Days 6 and 7, decidualized stromal cells stained positively for PTHrP, desmin, and laminin. These results support the hypothesis that TGF-beta and PTHrP play an important role in the process of implantation.  相似文献   
77.
In this paper, two methods are presented. One involves the separation of calcipotriol, a new synthetic analogue, from two related compounds, specifically cholecalciferol (Vitamin D3) and calcitriol (1,25-dihydroxyvitamin D3). The other involves the isolation and assay of calcipotriol from a topical ointment. The study was performed with reversed-phase high-performance liquid chromatography using an RP18 column and ultraviolet detection. Applying the method of Snyder, a mobile phase mixture containing methanol-acetonitrile-water (67:23:10, v/v) was found which achieved a total separation within 18 min. A mobile phase of methanol-water (80:20, v/v) attained a slower elution of calcipotriol. For isolation and assay of calcipotriol from an ointment (Daivonex), dissolution in chloroform gave the highest recovery (> 98%). The isolation and assay process can be performed within 2 h.  相似文献   
78.
The beta-crystallins are a major constituent of the mammalian lens, where they associate into dimers, tetramers and higher order aggregates. Appropriate association of lens crystallins is important for lens transparency. To examine the associative properties of betaB2- crystallin, we have expressed mouse betaB2-crystallin using a baculovirus system. Recombinant mouse betaB2-crystallin has an estimated monomer molecular weight of 24 kDa by SDS-PAGE, appropriate immunoreactivity and appropriate secondary structure as assessed by circular dichroism analysis. The recombinant betaB2-crystallin associates into a homodimer with a weight average molecular mass of 39 kDa. The betaB2-crystallin homodimer has an estimated Kd of 5 x 10(-6) M, slightly greater than that of betaA3-crystallin, 0.8 x 10(-6) M. When recombinant betaB2-crystallin is combined with recombinant betaA3- crystallin, a heterodimer is formed within 10 min of incubation at room temperature. When equilibrium is reached in 4-6 h, approximately half of each crystallin associates into heterodimers. Subunit exchange between betaB2-crystallin and betaA3-crystallin occurs readily in the absence of any denaturing agents. Thus, rbetaA3-rbetaB2 heterodimer formation can occur under conditions similar to those found in the eye lens.   相似文献   
79.
A high potential analog of riboflavin with a cyano function at the 8-position was synthesized by employing novel reaction conditions, starting from 8-amino-riboflavin. This was converted to the FAD level with FAD synthetase. The reduced 8-CN-riboflavin, unlike normal reduced flavin, has a distinctive absorption spectrum with two distinctive peaks in the near ultraviolet region. The oxidation-reduction potential of the new flavin was determined to be -50 mV, approximately 160 mV more positive than that of normal riboflavin. The 8-CN-riboflavin and 8-CN-FMN were found to be photoreactive and need to be protected from exposure to light. However such complications were not encountered with protein-bound flavins. The apoproteins of flavodoxin and Old Yellow Enzyme (OYE) were reconstituted with the 8-CN-FMN and apoDAAO was reconstituted with 8-CN-FAD. Spectral properties of the enzyme-bound neutral and anionic semiquinones were determined from these reconstituted proteins. In the case of 8-CN-FMN-OYE I, it was shown that the comproportionation reaction of a mixture of reduced and oxidized enzyme bound flavin is very rapid, compared with the same reaction with native protein, resulting in approximately 100% thermodynamically stable anionic semiquinone. In the case of 8-CN-OYE I, it was shown that the rate of reduction of the enzyme bound flavin by NADPH is approximately 40 times faster, and the rate of reoxidation of reduced enzyme bound flavin by oxygen is an order of magnitude slower than with the normal FMN enzyme. This is in accord with the high oxidation-reduction potential of the flavin, which thermodynamically stabilizes the reduced enzyme.  相似文献   
80.
徐速标  余文腾 《当代化工》2010,39(4):386-388
针对垃圾渗滤液的高浓度、难降解、具有生物毒性的特点,采用混凝沉降法对其进行处理,以处理出水的CODcr为处理程度的表征指标。通过正交实验,确定最佳复合混凝剂的试剂用量,比较不同反应条件对CODcr去除率的影响,优化操作条件。实验结果表明,最佳复合混凝剂:1 250 mg/LPAC+1 500 mg/LPFS+50 mg/L PAM;最佳条件:pH=7.0,搅拌时间为15 min,沉降时间为20 min;CODcr去除率达到66.9%。  相似文献   
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