猫视皮层神经元对光栅反应最优方位在视网膜上分布特性的研究

用金属微电极记录了114个猫皮层17、18区细胞对不同方位光栅图象刺激的反应。细胞最优方位与其感受野中心在视网膜的位置间有系统性关系,即最优方位总是倾向于垂直于各感受野中心与视网膜中心区(area centralis)的连线。这一规律对在18区或17、18区全体记录到的细胞而言,有统计意义。 在17、18区内,仅对于感受野位于视网膜离心度(eccentricity)大于9°视角的细胞、具有较窄感受野(宽度小于2.5°)的细胞以及感受野处于视网膜垂直经线附近的细胞,上述规律才有统计意义,而对感受野离心度小于9°的细胞、感受野宽度大于2.5°的细胞以及感受野在倾斜经线附近的细胞,上述规律不明显。     

猫外膝体神经元对光栅刺激方位倾向性的一种分布特性

我们检测了猫外膝体(LGN)神经元对闪烁方波光栅的反应与光栅方位的关系。对一定对比度和空间频率的光栅,26个记录到的神经元的反应均随方位不同而变化,其最大反应和最小反应的比值平均为3.0±0.3(S.E.)。神经元的最优方位(即引起最大反应的光栅方位)随其感受野中心在视网膜上的位置而异,具有平行于其各自感受野中心与视网膜中央区(area cen-sralis)的连接线的倾向。     

Torsional Tribological Behavior and Torsional Friction Model of Polytetrafluoroethylene against 1045 Steel

In this work, the plane-on-plane torsional fretting tribological behavior of polytetrafluoroethylene (PTFE) was studied. A model of a rigid, flat-ended punch acting on an elastic half-space was built according to the experimental conditions. The results indicate that the shape of T–θ curves was influenced by both the torsional angle and the normal load. The torsion friction torque and wear rate of PTFE exponentially decreased when the torsion angle rose. The torsional torque increased from 0.025 N·m under a normal load of 43 N to 0.082 N·m under a normal load of 123 N. With sequentially increasing normal load, the value of torque was maintained. With rising normal load, the wear mass loss of PTFE disks was increased and the wear rate was decreased. Good agreement was found with the calculated torque according to the model and the experimental torque except for that under a normal load of 163 N. The difference under a normal load of 163 N was caused by the coefficient of friction. Usually the coefficient of friction of a polymer decreases with increasing normal load, whereas a constant coefficient of friction was applied in the model.     

Isolation of 24 novel cDNA fragments from microdis—sected human chromosome band

INTRODUCTIONTheprocedure0fhu1nangenecl0ningandidentificationhasbeengreatlypro-pelledbytherapidprogress0fhumangen0memappingandsequencing[1].P0sitionalcloningisthemainstrategyusedinhumangenecl0ning,especiallyindiseaJse-relatedgenecloning.Is0latillggenesfr0l…     

嵊泗海岛不同底质潮间带春秋季大型底栖动物的群落格局

于2006年9月(秋季)和2007年4月(春季)对嵊泗海岛的不同底质潮间带断面设立的8个取样站采集的调查资料,采用ABC曲线方法和大型多元统计分析软件PRIMER5对嵊泗海岛大型底栖动物进行Bray-Curtis相似性聚类分析和非度量MDS标序,研究群落结构格局以及用物种多样性指数、物种均匀度和物种丰富度指数分析潮间带大型底栖动物物种多样性和群落种类组成,并对大型底栖动物的群落结构进行了初步研究。调查获得嵊泗海岛的不同底质潮间带大型底栖动物130种,其中多毛类31种,软体动物57种,节肢动物32种,棘皮动物4种,其它类6种。春、秋季嵊泗潮间带大型底栖动物多样性指数(H′)(F1,13=0.10,P=0.75)、物种丰富度(D)(F1,13=0.66,P=0.43)和均匀度指数(J)(F1,13=0.33,P=0.58)均无显著差异;不同底质嵊泗潮间带大型底栖动物多样性指数(H′)(F1,13=14.28,P<0.01)、物种丰富度(D)(F1,13=14.07,P<0.01)存在显著差异,而均匀度指数(J)(F1,13=1.62,P=0.23)无显著差异。群落结构聚类分析和MDS标序表明,8个取样站的群落可分为3组(Ⅰ、Ⅱ和Ⅲ组)。根据所调查嵊泗海岛潮间带的丰度和生物量资料做的ABC曲线分析表明,底栖动物群落受到了中等程度的污染或者扰动。     

海洋桡足类的热耐受性

为了探明热排放对近海生态的影响,选用我国东海近海主要桡足类,采用热升温实验方法对其半致死温度进行研究.结果表明,不同生物在相同适温条件下和同种生物在不同适温条件下的热耐受能力均存在差异.自然适应水温为13.5 ℃,中华哲水蚤(Calanus sinicus)和细巧华哲水蚤(Sinocalanus tenellus)的24 h半致死温度值分别为26.9 ℃和25.4 ℃;自然适应水温为14.2 ℃,中华异水蚤(Acartiella sinensis)和近缘大眼剑水蚤(Corycaeus affinis)的24 h半致死温度值分别为26.7 ℃和30.5 ℃;自然适应水温为28.0 ℃,背针胸刺水蚤(Centropages dorsispinatus)、强额拟哲水蚤(Paracalanus crassirostris)、刺尾纺锤水蚤(Acartia spinicauda)和尖额真猛水蚤(Euterpina acutifrons)的24 h半致死温度值分别为34.0 ℃、34.3 ℃、35.7 ℃和36.0 ℃.细巧华哲水蚤在自然适应水温分别为13.5 ℃和23.5 ℃下的24 h半致死温度值为25.4 ℃和33.0 ℃.     

A Preliminary Study on Alien Invasive Plants in Jiangsu,China

From 1985 to 2013, there were only 9 literatures reports on alien invasive plants in Jiangsu, less than 025% of total 3665 similar reports during the same period in China, and it was much disproportionate with the development level of social, economic, cultural and other aspects of the province. Through field investigation, literature review and specimen inspection, the preliminary statistics, analysis and discussion of 47 families 128 genera and 209 species of alien invasive plants in Jiangsu have been made, including their composition, origin, and the life form. All alien invasive plants were ranked into 5 grades according to the damage to ecosystem and economy: twenty two malignant invasive species; forty one serious invasive species; thirty two local invasive species; fifty one general invasive species; a left 63 species with unknown damage wait for further observation. The characteristics of alien invasive plants in Jiangsu have been discussed, and the proposals of suggestion have been made.     

我国藏鼠兔一新亚种

青海省地方病防治研究所动物病调查队于1983年5-9月在青海东部进行动物病调查时,采到一些藏鼠兔(Qchotona thibetana)标本,鉴定后,发现系一新亚种,现报道如下。     

视网膜神经节细胞感受野的一种新模型 II.神经节细胞方位选择性中心周边相互作用机制

在前文建立的二维视网膜神经节细胞含大周边感受野模型基础上 ,结合生理实验结果模拟了神经节细胞的方位选择性特性。文中采用椭圆感受野的观点解释了方位选择性的成因。并通过中心区以外区域对中心区方位选择性的复杂调制组合 ,展示了感受野不同亚单元对方位选择性的影响作用 ;指出方位选择性的成因是感受野椭圆亚单元的存在;感受野复杂的方位选择性是由于中心和周边在不同刺激条件下竞争的不同结果造成的;同时指出对椭圆感受野 ,倍频反应也会有相应的方位选择性。