梁子湖鲤鱼鳞片年轮的标志及其形成的时期

<正> 鱼类年龄的测定是渔业生物学上一个重要问题,为了对鱼类资源合理地开发利用,必须广泛展开鱼类的生长、鱼群组成、性成熟的年龄等有关渔业生物学问题的研究。但是这些问题的解决,都以能正确测定鱼类的年龄为先决条件。鲤鱼是梁子湖中最重要的经济鱼类,因此我们就选择鲤鱼作为一个典型来研究测定年龄的方法。我们认为掌握了鲤鱼年龄测定的正确方法以后,可能对其他鲤科鱼类的年龄测定也有所帮助。Hoffbauer 氏(1899)可能是最早研究鲤鱼年龄测定的人,他认为在鱼体生长迅速时,鳞片上环片间距较疏且不规则,而生长较缓慢时,

Observations on two species of phyllodistomes (Trematoda : Gorgoderidae) from fishes of the Hubei Province, central China, with an erection of Neophyllodistomum gen. n.

Two rare trematode species so far reported in the genus Phyllodistomum Braun, 1899, P. pawlovskii (Zmeev, 1936) and P. serrispatula Chin, 1963, were found in the urinary system the yellow catfish Pelteobagrus fulvidraco (Richardson) of Bao'an Lake (prevalence 8 %) and the swamp eel Monopterus albus (Zouiev) of Liangzi Lake (prevalence 6 9/6), respectively, from the Hubei Province, central China. In contrast to the original description, P. pawlovskii showed a considerable morphological variability particularly in the shape, size and topography of testes. A unique morphological feature of P. serrispatula is the presence of many conspicuous lateral outgrowths on the hindbody and, principally based on this character, a new genus Neophyl-lodistomum is erected (type species N. serrispatula (Chin, 1963) comb. n.)) to accommodate this species. Both trematode species are briefly redescribed. P. pawlovskii and N. serrispatula are reported for the first time from the Hubei Province and the former from the Yangtze River drainage system.

Application of plane wave method to the calculation of electronic states of nano-structures

The electronic states of nano-structures are studied in the framework of effective-mass envelope-function theory using the plane wave basis. The barrier width and the number of plane waves are proposed to be 2.5 times the effective Bohr radius and 15(n), respectively, for n-dimensional nano-structures (n = 1,2,3). Our proposals can be widely applied in the design of various nano-structure devices.

An All-E-Beam Lithography Process for the Patterning of 2D Photonic Crystal Waveguide Devices

We present an all-e-beam lithography (EBL) process for the patterning of photonic crystal waveguides.The whole device structures are exposed in two steps. Holes constituting the photonic crystal lattice and defects are first exposed with a small exposure step size (less than 10nm). With the introduction of the additional proximity effect to compensate the original proximity effect, the shape, size, and position of the holes can be well controlled.The second step is the exposure of the access waveguides at a larger step size (about 30nm) to improve the scan speed of the EBL. The influence of write-field stitching error can be alleviated by replacing the original waveguides with tapered waveguides at the joint of adjacent write-fields. It is found experimentally that a higher exposure efficiency is achieved with a larger step size;however,a larger step size requires a higher dose.

Synthesis and electrochemical characteristics of lanthanide complexes with 2-nitro-5,10,15,20-tetraphenylporphyrin and acetylacetonate

Four lanthanide complexes with 2-nitro-5,10,15,20-tetraphenylporphyrin and acetylacetonate were prepared and characterized by elemental analyses, LR, UV-Visible,H-1 NMR, XPS and molar conductance. The redox properties of the lutetium complex with 2-nitro-5,10,15,20-tetraphenylporphyrin and acetylacetonate in dichloromethane were studied by cyclic voltammetry.

Cationic cyclization of styrene-butadiene rubber

Controlled cyclization of styrene-butadiene rubber (SBR) was achieved with the aid of cationic catalyst system based on diethylaluminium chloride (AIEt(2)Cl) and benzyl chloride (C6H5CH2Cl) and by working in xylene solution at high temperature (T > 100 degreesC). The main parameters of the cyclization process were investigated. Elastomers with low intrinsic viscosity, ready solubility, free gel were obtained. The products were characterized with IR H-1-NMR, DSC, GPC. The polycyclic structure was determined. (C) 2001 Published by Elsevier Science Ltd.

Analysis of structural relaxation in a Li(2)O2SiO(2) glass using rate heating approach

The structural relaxation process of an inorganic glass (Li(2)O2SiO(2)) at different cooling rates has been studied by differential scanning calorimetry. A four-parameter model-Tool-Narayanaswamy-Moynihan (TNM) model was applied to simulate the normalized specific heat curve measured. Four parameters, Delta h*/R, beta, In A, and x were obtained and compared with the values obtained from the isothermal approach. (C) 1999 Kluwer Academic Publishers.

Response of the diatom flora in Jiaozhou Bay, China to environmental changes during the last century

The diatom flora in a 164 cm long sediment core obtained from Jiaozhou Bay (Yellow Sea, China) was analyzed in order to trace the response of diatoms to environmental changes over the past 100 years. The sediment core was dated by Pb-210 and Cs-137 and represented approximately 100 years (1899-2001 A.D.). The flora was mainly composed of centric diatoms (59-96%). The concentration of diatoms declined sharply above 30 cm (after similar to 1981 A.D.), while the dominant species changed from Thalassiosira anguste-lineatus, Thalassiosira eccentria, Coscinodiscus excentricus, Coscinodiscus concinnus and Diploneis gorjanovici to Cyclotella stylorum and Paralia sulcata. Species richness decreased slightly, and the cell abundance of warm-water species increased. We argue that these floral changes were probably caused by climate change in combination with eutrophication resulting from aquaculture and sewage discharge. (c) 2007 Elsevier B.V. All rights reserved.

微机控制与管理一体化网络在铝厂的应用

铝厂生产控制和管理一体化系统是一个横向分布,纵向分层的分层分布式集散网络系统。试系统采用集散型结构,实现了负载分散和地域分散,提高了系统的可靠性,而且维护、使用、更换、修理特别方便,具有很大的优越性。