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1.
Antidromic and orthodromic responses of the projection neurons in the dorsal horn ofthe spinal cord have been recorded by a glass microelectrode in anesthetized and paralyz-ed cats. Furthermore, the effect of cervical segment antidromic stimulation to orthodromicresponse of the projection neurons has been observed by way of conditioning-test stimulation. Among all the spinocervical tract neurons (SCT), the dorsal column postsynaptic neu-rons (DCPS) and the spinocervical tract-dorsal column postsynaptic neurons (SCT-DCPS),which were identified by cervical segment antidromic stimulation, 46% are low-thresholdmechanoreceptive (LTM) and 54% are wide-dynamic-range (WDR) neurons. Most LTMneurons can evoke the same response to both 10 times (10 T) and 50 times (50 T) the thresh-old stimulation on the peroneal nerve. Most WDR neurons to 50 T intensity stimulation arestronger than the 10 T stimulation. Under the antidromic-cervical segment conditioningstimulation, the amount of orthodromic-discharging in most WD  相似文献   

2.
Electrical stimulation of the Zusanli point (ZSL) and solitary tract nucleus (SN) as well as microelectrode recording from the laminae Ⅲ-Ⅴ of the lumbar spinal dorsal horn have been used on the pentobarbital anesthetized rats, finding and identifying 57 spinal neurons responding to the stimulations of both ZSL and SN. Among them, 34 responded antidromically to SN; the others responded orthodromically to SN. Among them, the lowthreshold mechano-receptive(LTM) neurons and wide-dynamic-range (WDR) neurons were 50 percent respectively. The results indicate that (ⅰ) a single spinal dorsal horn neuron receives somatic afferent input and then conveys it to the visceral sensory nucleus-SN; (ⅱ) some spinal dorsal horn neurons receive, in turn, innervation from the SN; (ⅲ) the convergence and integration between somatic and visceral sensory inputs might occur in the spinal dorsal horn neurons and/or SN.  相似文献   

3.
以2种完全相容的多分散的聚合物树脂为研究对象,利用动态流变学手段实现了界面分子链扩散过程的实时检测.研究结果发现,完全相容的聚合物树脂之间的扩散动力学参数α具有相对分子质量差异的依赖性,两者之间相对分子质量差异越大,α值越大.通过流变学参数还可获得另一扩散动力学参数—特征时间tc,从而得以计算出组分之间扩散系数,研究结果表明所获得的扩散系数具有频率依赖性.  相似文献   

4.
9-氨基壬酸系从癸二酸经单酯化、氨化和Hofmann重排制得。该单体以10克规模在玻璃管中和以4公斤量在15升聚合釜中,于260℃聚合成聚壬酰胺。聚合物在288℃纺丝,120℃牵伸,得到尼龙-9纤维。测定了聚合物和纤维的结构和多种性能。  相似文献   

5.
In this paper, the morphology, sedimentary structure, bioherm--building mollusk assem-blages and their growing and piling-up models of modern oyster bioherms in the estuariesof the Zimaigou and Xiaoqing Rivers are described and expounded, the environmentalconditions for the development of oyster bioherms, such as the dynamical geomorphicbackground, water depth, hydrodynamic factors and ecological conditions in the estuaries,are analyzed, the relationship of the successively seaward migrating of oyster biohermswith average annual sea-level changes and the erosion--accretion processes in the estuariesare probed and explained, and the geological significance of oyster bioherms in the studyof Quaternary marine environmental evolution is presented.  相似文献   

6.
本文利用最大重迭方法,在分别考虑卤素配体的杂化及中央原子Si的d轨道杂化的基础上,计算了卤代硅烷系列分子实验构型下的杂化轨道,研究了卤代硅烷分子的NMR自旋偶合常数,IR伸缩频率和基团电负性与轨道成份的关系,较明确地反映了这类分子的化学键性质对分子谱学性质的影响。  相似文献   

7.
聚酯酰胺的合成及表征   总被引:1,自引:0,他引:1  
用两种方法合成了聚酯酰胺(PEA)共聚物.一种是两步法,即先合成对苯二甲酸乙醇酰胺(BAET)单体,然后与对苯二甲酸乙二酯(BHET)共缩聚;另一种是一步法.即在酯交换反应中直接添加乙醇胺(EA).两种方法制得的聚酯酰胺(PEA)共聚物测试证明了为产物,并分析了合成中的化学反应.  相似文献   

8.
丙醛的等离子体聚合以及聚合物的结构与性质初探   总被引:2,自引:1,他引:2  
应用外部电容耦合式等离子体聚合方法,制得了丙醛聚合物,研究了不同的等离子体条件对丙醛的聚合行为的影响。通过元素分析、红外光谱分析、色谱-质谱联合分析、X-射线衍射、润湿性测定等手段研完发现,聚合物为无定形交联结构,表面能为41—45达因/厘米。  相似文献   

9.
本文用(Ph_3P)_2PdCl_2为催化剂,合成了1,4-丁炔二醇(BD)与4,4-二乙炔联苯(DEBP)共聚物。对用不同比例的两种单体得到的共聚物测定了比重(d_4~(25)、溶胀度(θ_D)、最良溶剂及相邻两交联点之间的平均分子量(M_c)。实验表明,在两种单体摩尔比中,DEBP用量越多,共聚物中泡状微孔越多,颜色越淡,溶胀度和比重越小,交联度越大;DEBP/BD(摩尔比)大于1/5时,共聚物的最良溶剂为苯,溶度参数为9.15卡~(0.5)·cm~(-1.5),是1/10时,其最良溶剂为乙醇,溶度参数是12.7卡~0.5·cm~(-1.5)。对共聚物还做了红外光谱表征。  相似文献   

10.
聚酯酰胺的合成及表征   总被引:2,自引:0,他引:2  
 用两种方法合成了聚酯酰胺(PEA)共聚物.一种是两步法,即先合成对苯二甲酸乙醇酰胺(BAET)单体,然后与对苯二甲酸乙二酯(BHET)共缩聚;另一种是一步法.即在酯交换反应中直接添加乙醇胺(EA).两种方法制得的聚酯酰胺(PEA)共聚物测试证明了为产物,并分析了合成中的化学反应.  相似文献   

11.
 本文用(Ph3P)2PdCl2为催化剂,合成了1,4-丁炔二醇(BD)与4,4-二乙炔联苯(DEBP)共聚物。对用不同比例的两种单体得到的共聚物测定了比重(d425、溶胀度(θD)、最良溶剂及相邻两交联点之间的平均分子量(Mc)。实验表明,在两种单体摩尔比中,DEBP用量越多,共聚物中泡状微孔越多,颜色越淡,溶胀度和比重越小,交联度越大;DEBP/BD(摩尔比)大于1/5时,共聚物的最良溶剂为苯,溶度参数为9.15卡0.5·cm-1.5,是1/10时,其最良溶剂为乙醇,溶度参数是12.7卡0.5·cm-1.5。对共聚物还做了红外光谱表征。  相似文献   

12.
李成学  胡之德 《化学学报》1982,40(11):1015-1020
通过对硒和碲的反相薄层色谱和溶剂萃取的研究,及碲在反相薄层色谱和溶剂萃取中的盐析效应,证明在这一体系中,硒和碲的反相薄层色谱过程为分配过程,由反相薄层色谱的实验结果可预测萃取中的分离情况。并得出了碲的Rf值和D值同盐析剂性质间的经验式:Rf=a-b[M]-dz/r D=e+f[M]9z/r较为满意地解释了盐析效应的机制,另外通过加入盐析剂也可改善硒和碲的分离效果,用双对数法确定了碲的萃合物组成为H2TeBr6·2P360,表观萃取平衡常数为Kcx=1.4×10-2。结合氯化亚锡法,萃取法用于二氧化硒样品中对碲的萃取分离和测定,获得良好结果。  相似文献   

13.
The scientific and technical history of polymerization can be divided into three periods, which will be illustratedfor emulsion polymerization. The first period was when emulsion polymers were originally produced, and was developed asan attempt to copy natural rubber latex. Indeed, the natural process is quite different from the synthetic process of emulsionpolymerization, which in fact does not even need an emulsion to be present: the term is a misnomer! The results werefunctional but limited. In the second period, the first theories appeared, and a huge range of products was madefor surface coatings, adhesives, commodity polymers such as SBR, neoprene, etc. The work of the outstanding pioneers wasbased on limited types of experimental data, and some suppositions are now seen to be incorrect. Nevertheless, manyexcellent products were made and have evolved to many materials currently in everyday use. The third period of emulsionpolymerization is now dawning. The scientific efforts of many teams over previous decades, aided by the advent of newphysical techniques for investigation, have resulted in better understanding of the fundamentals of emulsion polymerizations.Some examples from the author's group involve creating novel materials using controlled seeded emulsion polymerizationfrom natural rubber latex and other polyenes. Latex topology and controlled free-radical chemistry can be combined toproduce a) a comb polymer with hydrophobic backbone and hydrophilic "teeth", or b) with sufficient in situ compatibilizerbetween two otherwise incompatible polymers to yield a spatially uniform material down to the nanostructure level, and c) toproduce controlled nanostructures.  相似文献   

14.
纳米刚性微粒与橡胶弹性微粒同时增强增韧聚丙烯的研究   总被引:83,自引:0,他引:83  
通过力学性能测试、动态力学试验、DSC 分析以及材料断面形貌与结构分析等手段,对以纳米二氧化硅(SiO2) 为刚性微粒、以三元乙丙橡胶(EPDM) 为弹性微粒组成的聚丙烯(PP)/ 纳米SiO2/EPDM 的同时增强增韧效果进行了研究.结果显示,上述两种微粒可同时大幅度提高PP 的韧性、强度和模量,当PP/ 纳米SiO2/EPDM 为80/3/20 时,两种微粒体现较明显的协同增韧效应.纳米SiO2 可提高PP 的结晶温度和结晶速度,并使球晶细化.纳米SiO2 刚性微粒在PP连续相中以微粒团聚体形态分布,构成团聚体的平均微粒数约为6 ~7 ,其与PP基体表现出较强的结合牢度.PP/ 纳米SiO2/EPDM 的综合性能已接近或达到工程塑料的性能.  相似文献   

15.
Conchostracans, with a laterally compressed body enclosed between two symmetric valves, live swimming in fresh or brackish water. The carapace valve has a number of growth bands with various sculptures. The general trend of sculptural evolution is from smooth to punctate-minute polygon-medium reticulation-large reticulation, while these punctate, polygonal and various reticulate patterns may separately develop into various radial ridges. The development of sculpture can be well explained by mechanical principle. Functional morphology of carapace is discussed in the light of mechanics in this paper.  相似文献   

16.
本文给出了多分形的动态描述,讨论了多分形的一级、二级相变以及广义熵Kq在多分形中的应用。  相似文献   

17.
通过介绍军事计量学的概念、作用和特点并结合美国军事最新导弹防御系统、近代局部战争中显现的信息化先进武器装备等实例,简要分析了军事计量工作的发展动态、方向和前景.  相似文献   

18.
实验室质量体系和体系文件的策划   总被引:3,自引:2,他引:1  
简述了实验室质量体系所含的要素和建立质量体系的一般过程,以及质量体系文件的组成和编写、编辑文件的要点。  相似文献   

19.
20.
本文研究了单磺化酞菁镓(SPcGa)在水、微乳液(TritonX-100-壬烷-正戊醇-水)中的二聚现象和解聚反应动力学,测定了二聚平衡常数KD和解聚速率常数k。结果表明:SPcGa的解聚反应速率与SPcGa的单体浓度CM和双体浓度CD的关系为:V=k1CD-k2CM2  相似文献   

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