黑眉锦蛇的有丝分裂染色体和减数分裂联会复合体的观察

黑眉锦蛇的二倍体染色体数目为2n=36, 核型组成为16(8m+6sm+2t)大染色体 +20微小染色体 。C带显现于几乎所有染色体的着丝粒区, 有一对插入型C带位 于第6对端着丝粒染色体。黑 眉锦蛇减数分裂精母细胞联会复合体(SC)的结构与 其他动物的SC相似, 是由两股平行的侧线组成, SC组型与有丝分裂染色体组型 有较好的一致性。图版2图2表1参16

长江中下游湖泊软体动物的多样性及分布现状(英文)

长江中下游流域是我国淡水贝类多样性最为集中的地区,然而由于人类活动的影响,淡水贝类已成为高度濒危的类群。为有效保护淡水贝类的多样性,我们于 2003 年 6 月-2005 年 5 月对长江中下游流域 13 个水体软体动物的多样性及分布进行了调查。共采集到软体动物 69 种(中国特有种 42 种),隶属于腹足类 9 科 14 属 29 种和瓣鳃类 5 科 17 属 40 种。其中,蚌科和田螺科是种类数最多的两个科,分别占总种类数的 50.7%和 14.5%。不同类型湖泊软体动物种类数的差别较大。通江湖泊所占

八种不同工艺组合人工湿地系统除磷效果研究

传统的人工湿地系统除磷效能的提高方式主要集中在基质填料的选择、湿地植物的筛选等方面,本试验从调整湿地的组合工艺着手探索提高磷去除效率的优化组合,在为期两年的研究中考察了推流床—下行流—上行流、下行流—上行流—推流床、好氧塘—下行流、下行流—兼性塘、推流床—下行流、下行流—上行流、推流床等8种不同工艺组合人工湿地系统对富营养化湖泊水体中磷的去除规律,比较了这些湿地组合所构建的生物学效应。试验结果显示,如果采用塘系统作组合单元在湿地系统中前置比较理想,而在不同的季节,不同水力负荷下的冲击试验结果表明,复合垂直

孤雌生殖累积世代数和雌体年龄对萼花臂尾轮虫繁殖的影响

采用单个体培养方法,研究了孤雌生殖的累积世代数和雌体年龄对萼花臂尾轮虫混交雌体形成和产卵量的影响.结果表明,随着轮虫孤雌生殖累积世代数的增加,各代中的总混交雌体百分率呈减小的趋势;年幼的雌体可产生较多的混交雌体;非混交雌体所产后代中的总混交雌体百分率具有随其祖母年龄的增大而增大的趋势.孤雌生殖的累积世代数对轮虫非混交雌体的平均产卵量无显著的影响,非混交雌体的年龄对其后代的平均产卵量亦无显著的影响.

免疫组化法检测美国青蛙组织中的蛙虹彩病毒

分不同时间 ,收集经人工感染了蛙病毒的样蛙 ,取其心、肺、肾、肠、脾、肝六种组织 ,并通过免疫组化方法进行检测。结果分别在感染了病毒 3d、9d、1 1d后的幼蛙这六种组织中 ,由表及里观察到了深色的阳性信号 ,从而测定了病毒在入侵组织中的存在部位。其中 ,肺和肠组织中阳性信号最强 ,呈灶性分布 ,其余四种组织中的阳性信号则呈散在分布。在未注射病毒的幼蛙阴性对照组六种组织中没有检测到阳性信号。

武汉东湖表层沉积物有机物污染状况

2 0 0 0年 12月在武汉东湖采集了 5个表层沉积物样品 ,采用气 -质联用分析了其中的有机污染物 ,以探讨东湖沉积物受有机物污染的程度 .共检出有机物 180种 ,其中环境优先控制污染物和美国EPA筛选的内分泌干扰物 35种 .有机污染严重程度为 :水果湖区 >郭郑湖南湖区 >郭郑湖北湖区 .

池养条件下中华绒螯蟹的若干生物学特征(英文)

开展中华绒螯蟹 (Eriocheirsinensis)生物学研究 ,对指导养殖具有重要意义。 1 993年 6月 2 0日购于上海市崇明县的仔蟹放养于湖北省保安湖渔场的一个试验塘 (2 3 3 0m2 ) ,每天投喂小杂鱼和螺蚌肉。在试验期间 ,河蟹成活率为 1 8.6 %。协方差分析表明 ,性别对各月体重与壳长、体重与壳宽及壳宽与壳长回归方程的截距和斜率均无显著影响 (p >0 .0 5) ;但是 ,两性数据混合后的不同月份间回归方程的截距却有显著差异 (p <0 .0 1 )。在每次取样时 ,雄蟹与雌

保安湖沉积物和间隙水中氮和磷的含量及其分布

保安湖沉积物中氮(N)的含量平均为5.20mg/g，平面分布以桥墩湖区含量最高。沉积物中磷(P)的含量平均为0.75mg/g，平面分布以扁担塘湖区含量最高。沉积物间隙水中总氮的平均含量为3.63mg/L，无机氮中以氨氮的含量最高，占总氮的57.2%；间隙水中总磷的含量平均为0.098mg/L，磷酸盐占总磷的50.0%。间隙水中氮和磷含量的平面分布差异不明显。间隙水中氮和磷的含量比湖水中含量高，但除氨氮外，一般不超过5倍，表明湖水和沉积物间隙水之间营养交换十分强烈。

Rank-preserving geometric means of positive semi-definite matrices

The generalization of the geometric mean of positive scalars to positive definite matrices has attracted considerable attention since the seminal work of Ando. The paper generalizes this framework of matrix means by proposing the definition of a rank-preserving mean for two or an arbitrary number of positive semi-definite matrices of fixed rank. The proposed mean is shown to be geometric in that it satisfies all the expected properties of a rank-preserving geometric mean. The work is motivated by operations on low-rank approximations of positive definite matrices in high-dimensional spaces.© 2012 Elsevier Inc. All rights reserved.

The effect of Ln(III)/An(III) separation on TRU multi-recycling in CONFU assembly

This work examines the basic feasibility of the net-zero-balance TRU multi-recycling concept in which trivalent lanthanide fission products (Ln(III) ) are not separated from trivalent actinides (An(III)). The TRU together with Eu and Gd isotopes are recycled in a standard PWR using Combined Non-Fertile and UO2 (CONFU) assembly design. The assembly assumes a heterogeneous structure where about 20% of U02 fuel pins on the assembly periphery are replaced with Inert Matrix Fuel (IMF) pins hosting TRU, Gd, and Eu generated in the previous cycles. The 2-D neutronic analysis show potential feasibility of Ln / An recycling in PWR using CONFU assembly. Recycling of Ln reduces the fuel cycle length by about 30 effective full power days (EFPD) and TRU destruction efficiency by about 5%. Power peaking factors and reactivity feedback coefficients are close to those of CONFU assembly without Ln recycling.

Application of polyurethane foam units and calorimetry to microbial monitoring in Lake Donghu

Combined with the national standard biomonitoring method (polyurethane foam units method), calorimetry was applied to study the metabolic activities of PFU microbial communities in fresh water to determine the effects of anthropotgenic stresses on the activity of the microbial community. Comparisons were made at four sampling stations with different eutrophic status in Lake Donghu. Water quality variables, species number of protozoa, abundances of microorganisms, biomass, heterotrophy indexes and diversity indexes are reported. The heat rate-time curves of the native and concentrated PFU microbial communities were determined at 28 degrees C. Growth rate, measured maximum power output and total heat were calculated from the heat rate-time curves. The values of metabolic variables are higher at the more eutrophic stations, which suggests that organic pollution increases the activity of PFU microbial communities. The metabolic variables are in good agreement with chemical and biotic variables. And calorimetry will be useful for biomonitoring of the PFU microbial community. (C) 2005 Elsevier B.V. All rights reserved.

Diving behaviour of freshwater finless porpoises (Neophocaena phocaenoides) in an oxbow of the Yangtze River, China

Dive-depth and swim-speed of a juvenile and an adult free-ranging, Yangtze finless porpoises (Neophocaena phocaenoides) were observed using velocity-time-depth recorders in an oxbow of the Yangtze River. In total, 8222 individual dives were recorded over 59 hours. Two dive types, deep-dive (greater than or equal to 2.7 m) and shallow-dive. were recognized. Horizontal travel distances of two finless pot-poises in a day were 94.4 km and 90.3 km, which were longer than those of oceanic relative species (harbor porpoises, Phocoena phocoena). Although the shallow water limited the maximum dive-depth, dive-duration, and bottom-time of finless porpoises were similar to the harbor porpoises. A sudden drop of swim-speed below 0.25 m s(-1) was frequently observed nearby the maximum dive-depth. This seemed to indicate "turning, around" behaviour, possibly during prey pursuit. (C) 2002 Published by Elsevier science Ltd on behalf of International Council for the Exploration of the Sea.

Taxonomic re-evaluation of Aphanizomenon flos-aquae NH-5 based on morphology and 16S rRNA gene sequences

The taxonomy of Aphanizomenon flos-aquae strain NH-5, a producer of cyanotoxins, was re-evaluated by comparison with six other Aphanizomenon strains using morphological characteristics and 16S rRNA gene sequences. Strain NH-5 was concluded to be improperly identified as Aph. flos-aquae based upon (1) lack of bundle formation in the trichomes, (2) location of akinetes next to heterocytes, (3) lower similarities (less than 97.5%) in the 16S rRNA gene sequences relative to Aph. flos-aquae strains, and (4) comparison within a phylogenetic tree constructed from 16S rRNA gene sequences. The Aphanizomenon strains investigated in this study are classified to four morphological groups as described by the classical taxonomy of Komarek & Kovacik (1989). This classification was supported from the phylogenetic results of 16S rRNA gene sequences. This study also discusses the generic boundaries between Aphanizomenon and Anabaena.

Optical modulator based on a Si0.75Ge0.25/Si/Si0.5Ge0.5 asymmetric superlattice structure

An optical modulator is designed and fabricated based on a Si0.75Ge0.25/Si/Si0.5Ge0.5 asymmetrical superlattice structure. The device comprises a p-i-n diode made on the asymmetrical superlattice integrated with a 920-mu m-long Fabry-Perot (F-P) cavity. Parameters of the rib waveguide are designed to satisfy only the fundamental-TE mode transmission. Here, 65 and 40-pm red shifts of the peak resonant were measured under the applied bias of 2.5 and -32.0 V, respectively. The analysis shows that, besides the thermal-optical and plasma dispersion effects, the Pockels effect also contributes to such a peak shift. The corresponding calculated effective Pockels coefficient is about 0.158 pm/V.