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1.
戴启润  李应真 《河南科学》1997,15(2):154-159
B-E关联与F-D关联是研究强子发射源的最有力工具之一。根据非微扰理论提出一种源分布-Q^-v KV(Q)分布,据此研究全同π介子的B-E关联和全同质子的F-D关联。总结了轻子-轻子,核子-核子,介子-核,核-核碰撞时的粒子关联研究结果。  相似文献   

2.
我们用离子团束-飞行时间质谱(ICB-TOFMS)系统制备了金(Au)超微粒子-聚乙烯(PE)薄膜和C60-聚乙烯薄膜。用透射电子显微镜(TEM)分析了所制备的样品。它们的结构是Au超微粒子镶嵌在多晶的PE薄膜中,其中Au原子团呈球形,直径分布在2.0-5.0nm窄范围内,当沉积基底温度为90℃时,Au原子团相互靠近,几乎连接起来,但仍保持原来大小。基底温度为140℃蒸积的C60-PE薄膜具有晶态  相似文献   

3.
我们用离子团束-飞行时间质谱(ICB-ToFMS)系统制备了金(Au)超微粒子-聚乙烯(PE)薄膜和C_(60)-聚乙烯薄膜。用透射电子显微镜(TEM)分析了所制备的样品。它们的结构是Au超徽粒子镶嵌在多晶的PE薄膜中,其中Au原子团呈球形,直径分布在2.0-5.0nm窄范围内,当沉积基底温度为90℃时,Au原子团相互靠近,几乎连接起来,但仍保持原来大小。基底温度为140℃蒸积的C_(60)-pE薄膜具有晶态结构,其晶格常数为1.454nm。  相似文献   

4.
以ELISA检测108例活动性肺结核、39例稳定期肺结核、30例肿瘤、101例非结核性肺部疾病患者及202例正常人血清的抗结核菌纯蛋白衍生物(PPD)IgG抗体(简称抗-PPD)和循环免疫复合物(CIC)中的抗-PPDIgG抗体(简称CIC-PPD)。结果表明,活动性肺结核患者的抗-PPD和CIC-PPD水平明显高于正常人和各疾病组患者的水平(P<0.001),但与其病变范围无关。单一测定活动性肺结核患者的抗-PPD,敏感性为85.2%,特异性为98.5%;测定CIC-PPD,敏感性为86.1%.特异性96.9%。以两者任一项阳性作为诊断活动性肺结核的标准,则敏感性为93.5%。此外,对11例活动性肺结核患者的动态观察表明,随着治疗天数的增加和临床症状的改善,患者的抗-PPD和CIC-PPD水平会逐渐降低,前者于治疗后第20~24周降至正常水平,后者则于治疗后第12~16周降至正常值。研究结果提示测定患者的抗-PPD和CIC-PPD的水平,可用于结核病诊断,对结核病的疗效判定亦有帮助。  相似文献   

5.
用3种不同的加料方法和2种不同的加料顺序,制备了苯乙烯(St)-丙烯酸丁酯(BA)-甲基丙烯酸(MAA)复合聚合物乳液.测定了聚合物乳胶粒子的大小和分布,观测了粒子的形态,测定了羧酸基团在乳胶粒子中的分布及乳液的碱增稠性,还测定了胶膜的溶胀性.探讨了在复合乳化剂下聚合方法-成核机理-粒子微观结构-乳胶性质之间的关系  相似文献   

6.
用群论方法讨论费米子动力学对称模型(FDSM)中k-集体激发模式情形单粒子四极算符P~2(i)约化矩阵元的计算.为heritage混合的计算作准备。  相似文献   

7.
用猝发信号频率分析Doppler测速仪(BSA-LDV)对柴油机高压喷雾碰壁前和碰壁后的粒子速度进行了测量。  相似文献   

8.
纳米Cu—Zn合金粒子结构及催化性能研究   总被引:2,自引:0,他引:2  
利用热蒸发法制备纳米Cu-Zn合金粒子通过透射电子显微镜(TEM)。x射线衍射(XRD)进行结构表征,证实纳米Cu-Zn合金粒子具有立方和六方结构,并利用x射线精炼分析方法对其进行分析。并在苯加氢反应中用做催化剂,发现具有良好的催化活性和高的选择性,对其催化机理做了初步探讨。  相似文献   

9.
CoO纳米粒子的制备及催化性能初探   总被引:6,自引:0,他引:6  
用微乳液法制备了表面经十二烷基苯磺酸钠(DBS)修饰的CoO纳米粒子,初步探讨了合成的最佳条件,利用X射线衍射仪(XRD)、透射电子显微镜(TEM)、红外光谱仪(IR)和X光能谱仪(XPS)研究了样品的性质,并将其用到一氧化碳氧化生成二氧化碳的反应中研究其催化性能。实验结果表明:此法制备的CoO纳米粒子呈球状,属立方多晶结构,粒径可以控制,表面活性剂DBS以SO3^2-形式与Co^2+相结合。对一  相似文献   

10.
研究了测试开发系统(TeDS)中IC测试软件的移植问题,提出并采用了元测试语言的策略.解决了从元测试语言生成IC测试机DIC-8032的测试语言SUMMIT的问题和从SUMMIT语言变换成元语言的问题.  相似文献   

11.
亓宪寅  王胜伟  杨振  付鹏 《科学技术与工程》2022,22(30):13450-13459
为研究层状复合岩石破坏过程和形态,采用相似理论制作出层状复合岩石相似模型,在单轴压缩条件下观测岩石的破坏特征,结合三维数字图像相关技术(3D Digital Image Correlation,以下简称DIC)对试件的整体变形及破坏进行全过程的观测,得到复合岩石三维场的位移和应变,同时基于试件表面应变场的变化,建立了表面损伤程度与损伤因子D之间的量化关系,进而得到基于DIC表征的层状复合岩石损伤演化模型,研究结果表明:(1)层状复合岩石的破坏形态与脆性岩石特征相似,以拉伸劈裂破坏和Y型剪切破坏为主;(2)DIC试验记录的表面应变与损伤因子之间的量化关系可有效反应岩石破坏的全过程,以此为基础建立的损伤演化方程与实验数据拟合效果较好,证明了模型的合理性。  相似文献   

12.
采用数字图像相关技术(digital image correlation,DIC)结合有限元模型修正技术(FEMU),通过2维编织高铝纤维增强多孔气凝胶基复合材料正轴及偏轴拉伸实验,同时识别获得了材料面内多个工程弹性常数.通过力学实验结合有限元数值虚拟实验,研究了识别过程中目标函数构成、优化方法、参数初值、位移场随机误差水平对识别结果和效率的影响.研究表明针对2维编织多孔气凝胶基复合材料,选取DIC实测位移和有限元数值计算位移的方差作为目标函数,通过L-M非线性最小二乘优化方法,计算参数敏感度矩阵,可同时识别获得多个加载面内材料力学性能参数,识别效率高,识别过程对参数初值、位移场随机误差水平不敏感,鲁棒性好.   相似文献   

13.
目的:观察小剂量肝素或低分子肝素治疗弥漫性血管内凝血(19IC)的疗效.方法:对确诊的31例DIC患者中的大部分患者使用小剂量肝素或低分子肝素.结果:31例DIC患者中20例治愈,治愈率为65.500.使用低分子肝素11例,占所有使用低分子肝素7313%,结论:IDC患者使用肝素或低分子肝素,尤其是使用低分子肝素治疗效果较好。  相似文献   

14.
以嘉陵江流域及其梯级开发河段为研究对象, 通过在2008 年8 月(雨季) 及2009 年2 月(旱季) 进行密集采样, 分析测定了河水中溶解无机碳(dissolved inorganic carbon, DIC)含量及其同位素组成, 探讨了河水中DIC的来源及其季节与空间变化特征. 结果表明: 嘉陵江河水DIC 及其同位素13CDIC 组成的平均值, 雨季时为2 018 μmol/L 和−8.6‰, 旱季时为3 150 μmol/L 和−6.0‰, 二者均存在显著的季节变化; 嘉陵江水体13CDIC 的值旱季(枯水期) 高于雨季(丰水期), 与自然河流的季节变化特征相似, 而与水库、湖泊不同, 表明嘉陵江梯级水库群水体“湖沼学反应”并不明显.  相似文献   

15.
Dissolved inorganic carbon (DIC) is a primary constituent of the aquatic geochemistry of terrestrial ecosystems. Changes in DIC concentration and its isotopic composition are closely associated with environmental changes in the drainage basin. Thus, a better understanding of DIC may lead to improved characterization of environmental changes. Corbicula fluminea (Müller 1774), a bivalve native to southeast Asia and a dominant invasive species in many aquatic environments around the world, has the potential to record DIC information, particularly because of its sequential skeletal deposition. Analysis of the stable carbon isotope composition (δ 13C) of the shell and the aquatic DIC in the Xijiang River drainage basins in southern and western China allowed us to determine that changes in δ 13C in the skeleton significantly correlated with those of DIC (P < 0.01, r = 0.63). These results indicate that the isotopic signature of the shell reflects that δ 13C of the DIC in ambient water. The temporal resolution was at the seasonal scale. Metabolic effect does not change the co-variation, even though it makes the shell δ 13C 1.4‰ lower statistically than that of DIC. δ 13C of DIC in creeks of some watershed areas may experience large temporal changes characterization of these changes requires high sampling resolution of the shell. This problem makes the clams in these areas less preferable for reconstruction of environmental changes. The present findings provide the basis for recovering paleoenvironmental changes and carbon cycles in a watershed through analysis of fossil shells of C. fluminea, which are common in some lacustrine and/or riverine sediment sequences.  相似文献   

16.
To determine the impact of damming on the geochemical behavior of dissolved inorganic carbon (DIC) in the Wujiang River basin, field measurements and samples were collected semimonthly for a year. The surface waters of the reservoirs contained concentrations of chlo- rophyll a up to 5.6 times higher than the upstream river. Compared with the entering waters, the contributions of HCO3- and dissolved CO2 to DIC decreased, and the contribution of CO32- to DIC and the carbon isotopic composition of DIC (δ13CDIc) increased in the surface waters of the reservoirs, while in the waters released, the DIC species showed reverse geochemical behaviors. The δ13CDIc ranged from -10.2 %o to 2.5 %0, indicating that significant contributions were from carbonate weathering, photosynthesis, and respiration. After the damming of a river, the bioactivity of phytoplankton was enhanced, and this affected the geochemistry of DIC compared to an unimpacted river and δ13CDIC can be used to discern these changes. High-frequency monitoring of river-reservoir systems is necessary to evaluate the efflux of CO2 and provide a better understanding of the carbon sinks and sources in the impounded river.  相似文献   

17.
研究了南昌市内7个主要湖泊和赣江水体春秋季可溶解无机碳(DIC)浓度和碳同位素组成.结果表明,各湖泊水体可溶解无机碳浓度与碳同位素与赣江水体差别较大;湖泊水体DIC浓度春季高于秋季,而DIC碳同位素则相反,而赣江水体DIC浓度和碳同位素值几乎不随季节变化.南昌市湖泊内水生植物繁盛,而市内赣江段水体清澈,水生植物较少,反映湖泊水体中DIC浓度和碳同位素组成受水生植物的影响,而赣江水体DIC浓度与碳同位素组成更多取决于水体与大气中CO2的收支平衡.  相似文献   

18.
国际热核聚变试验堆(ITER)所希冀的是由管内电缆导体(CICC)绕制的超导磁体产生强磁场约束高温等离子体的运动,进而实现可控的热核聚变. CICC导体结构复杂,通常是由上千根NbTi/Cu或Nb3Sn/Cu经四级或五级绞缆加工而成,运行在极低温、大电流、强磁场复杂环境,承受的电磁力将引起股线间产生接触挤压变形,甚至引起股线的断裂,给装置安全性带来隐患.传统的CICC导体横截面股线接触力研究实验上多采用非实体的光弹模型,数值上采用不含颗粒变形的离散单元法(Discrete Element Method, DEM),均难以给出真实的CICC导体截面股线接触力特征.本文实验中采用真实的CICC导体,通过在横截面喷涂散斑的方式,采用数字图像相关法(Digital Image Correlation, DIC),给出了股线间的变形特征.理论上采用颗粒单元法(Granular Element Method, GEM),将DIC获得的股线变形作为输入参数,直接给出了CICC导体在横向压力作用下的横截面股线接触力的分布特征,并对接触力链大小和方向进行了统计分析.  相似文献   

19.
针对电测方法需在试件表面粘贴应变片及单点测量局限,将数字图像相关方法(Digital Image Correlation,DIC)引入到材料力学性能测试分析中。设计二维DIC系统,并将其应用于三点弯曲沥青混凝土梁的变形和应变全场测试。根据应变云图,可以直观地观察到弯曲正应变沿梁横截面线性分布的特点。实验结果表明,DIC方法可以实现变形和应变分布的全场非接触和准确测量,可为土木工程试验提供可靠的测试手段。  相似文献   

20.
Digital image correlation (DIC) is an experimental stress analysis technique used in nondestructive tests. The accuracy of DIC in crack detection depends on various factors such as the sizes of speckles and pixels. In the current study, a speckle pattern based on the spreading of nanoparticles with small speckles is compared with a conventional sprayed pattern to understand whether crack detection via DIC is improved by reducing the sizes of speckles and pixels. Owing to the small size of nanoparticles, an optical microscope is used for magnification. The spreading method for crack detection is first investigated experimentally. Results show that cracks can be detected easily when a 250 nm opening appears in the crack edges. Subsequently, the spreading method is compared with the conventional DIC, in which the spraying method is used for patterning, in terms of crack detection. Results show that by reducing the speckle size and closely analyzing the speckle pattern, the DIC technique is considerably better than the conventional technique in detecting small cracks. Moreover, the conventional method is more suitable for detecting large cracks.  相似文献   

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