987 resultados para 555


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Catches of important commercial fish such as red sea bream, flat fish, and yellowtail are decreasing in Japan. In order to sustain these species it is especially important that their distribution and biomass at all life stages are known. However, information on the early life stages of these species is limited because identifying the eggs and larvae of such fish is sometimes extremely difficult.

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第一部分 茎尖分生组织的中央部位是由干细胞组成,维持干细胞的动态平衡对于植物器官启动显得尤为重要。在拟南芥花序分生组织和花分生组织中分别有WUS/CLV和(WUS+LFY)/AG两个负反馈调节环控制着这一平衡,保证了花序分生组织的非决定性和花分生组织的决定性。 本文用T-DNA激活标签技术得到功能增强突变体bre,序列分析表明BRE就是干细胞特征基因WUSCHEL。定量RT-PCR表明在突变体的茎节间WUS大量表达,证实在WUS基因的调控区插入的4个35S增强子使WUS表达增强。突变体bre生长发育缓慢,茎弯曲,花器官数目改变,心皮发育加快。尤为突出的是在茎皮层直接分化出花分生组织。这些表型可能与WUS的表达增强有关。这说明WUS功能是多效的,除了在分生组织中决定干细胞命运、促进CLV和AG的表达外,还可能与生长素极性运输以及花分生组织特征基因的表达有关。 第二部分 春化作用是促进植物从营养生长向生殖生长转变的有效途径之一,作者所在实验室曾经分离到多个小麦春化相关基因。为研究春化期间它们在不同组织或不同细胞内的表达模式,首先建立并完善了RNA组织原位杂交系统。以春化相关基因ver203F为模板,采用地高辛为标记分子,借助体外转录制备RNA探针,分析了小麦胚芽和幼苗中ver203F的表达模式。结果表明:春化前和脱春化的胚芽中不表达ver203F,春化处理14天以上的胚芽幼叶表达ver203F,而且主要定位在叶的边缘分生组织细胞内,叶维管束和表皮组织未检测到转录物,胚芽鞘和茎尖分生组织中不表达。幼苗的侧芽中的幼叶有相同的表达模式。茉莉酸可以诱导ver203F的表达。.说明春化时的低温信号可能由幼叶接收,并有可能涉及到茉莉酸介导的信号转导途径。

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The bastard grunt (Pomadasys incisus) is one of the most abundant coastal demersal fishes inhabiting the Canary Islands. Age and growth were studied from samples collected between October 2000 and September 2001. Growth analysis revealed that this species is a fast growing and moderately short-lived species (ages up to seven years recorded). Length-at-age was described by the von Bertalanffy growth model (L∞=309.58 mm; k=0.220/year; t0=–1.865 year), the Schnute growth model (y1=126.66 mm; y2=293.50 mm; a=–0.426; b= 5.963), and the seasonalized von Bertalanffy growth model (L∞=309.93 mm; k=0.218/ year; t0= –1.896 year; C=0.555; ts=0.652). Individuals grow quickly in their first year, attaining approximately 60% of their maximum length; after the first year, their growth rate drops rapidly as energy is probably diverted to reproduction. The parameters of the von Bertalanffy weight growth curve were W∞=788.22 mm; k=0.1567/year; t0= –1.984 year. Fish total length and otolith radius were closely correlated, r2=0.912. A power relationship was estimated between the total length and the otolith radius (a=49.93; ν=0.851). A year’s growth was represented by an opaque and hyaline (translucent) zone—an annulus. Backcalculated lengths were similar to those predicted by the growth models. Growth parameters estimated from the backcalculated sizes at age were L∞=315.23 mm; k=0.217/year; and t0= –1.73 year.

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In the present study, non-conservative abiotic parameters and biological conditions were utilized to portray the causes, consequences and magnitude of anthropogenic eutrophication in 4 fresh water perennial community ponds at Gangetic West Bengal, India. In order to classify the ponds, a single criterion basis was adopted and more emphasis given to the species of plankton which are biological indicators of eutrophication. Besides this, various abiotic parameters were also studied. On the basis of results obtained, 4 ponds have been classified as "Eutrophic, Tropical Bacillariae".

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This paper reports work exploring the relationship between solid modelling, mesh generating and flow solving in the general context of design optimisation. In particular, the work is interested in the opportunities derived by tightly integrating these traditionally separate activities together within one piece of software. The near term aim is to ask the question: how might a truly virtual, rapid prototyping design system, with a tactile response like sculpting in clay, be constructed? This paper reports the building blocks supporting that ambition.

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A new lupane acid, 2 beta-carboxyl, 3 beta-hydroxyl-norlupA (1)-20 (29)-en-28-oic acid (1), together with five known lupane acid derivatives (2-6), were isolated from the stings of Gleditsia sinensis Lam.. Their structures were elucidated on the basis of

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β_2肾上腺素受体(β_2AR)在哮喘患者中表现出遗传多态性。近年国外已对位点16及27进行了一些临床研究,但是所用基因分型方法不一,此外在中国人群这2个位点的多态性哮喘的关系至今仅有个别报道,我们采用所有样本测序方法,就其多态性与肺功能的关系进行初步探讨。

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In continuation of our program aimed at the discovery and development of compounds with superior anti-human immunodeficiency virus type 1 (HIV-1) activity, 21N-arylsulfonyl-3-acetylindole analogs (2a-u) were synthesized and preliminarily evaluated as HIV-1 inhibitors in vitro. Among of all the analogs, several compounds exhibited significant anti-HIV-1 activity, especially N-phenylsulfonyl-3-acetyl-6-methylindole (2j) and N-(p-ethyl)phenylsulfonyl-3-acetyl-6-methylindole (2n) showed the most potent anti-HIV-1 activity with EC50 values of 0.36 and 0.13 mu g/mL, and TI values of >555.55 and 791.85, respectively. It demonstrated that introduction of the acetyl group at the 3-position of N-arylsulfonyl-6-methylindoles could generally lead to the more potent analogs. (C) 2010 Elsevier Ltd. All rights reserved.

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云南蒙自石榴干腐病助故阮以菌丝体和分生抢子在僵果、干 腐果及其他感病部位越冬。翌年经风雨、昆虫和人为活动在果园广为传播。石榴 花、幼果、果实期均可感病发病, 等筒花丝最易感病。果实发病率达一, 重者达一。采取综合治理措施, 其中重要的是在首次连续降雨前利去干 花丝、套袋和树冠多次喷清水, 提前水解、淡化干花丝、伤口渗出液的微酸性度, 可 控制该病的发生危害, 危害率由原来的一现降为一。

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作者于1989年3月到1990年3月对昆明市284只家鸡进行了住肉孢子虫流行病学调查,在6只家鸡中检到了住肉孢子虫包囊,自然感染率为2.1%。包囊呈梭形,大小为865.5×82.3μm,包囊中充满大小为14.3×2.9μm的梭形缓殖子。鸡颈部、背部和大腿部肌肉中包囊密度较高,心肌无包囊寄生。4只犬和5只猫分别于实验感染包囊后第8d和第13d排出孢子,剖检时小肠粘膜固有层中亦查到孢子。10只15日龄的雏鸡在实验感染来源于犬和猫粪便的孢子后,干不同时间剖杀镜检,除感染后第20d剖杀的2只鸡外,其余8只鸡肌肉中均检到包囊,其形态与自然感染鸡体的包囊相同。实验感染结果表明犬和猫均可充当该住肉孢子虫的终末寄主。虫种鉴定为Sarcocystissp。是国内家鸡住肉孢子虫的首次报告。

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Over the last two or three years, the increasing costs of energy and worsening market conditions have focussed even greater attention within paper mills than before, on considering ways to improve efficiency and reduce the energy used in paper making. Arising from a multivariable understanding of paper machine operation, Advanced Process Control (APC) technology enables paper machine behaviour to be controlled in a more coherent way, using all the variables available for control. Furthermore, with the machine under better regulation and with more variables used in control, there is the opportunity to optimise machine operation, usually providing very striking multi-objective performance improvement benefits of a number of kinds. Traditional three term control technology does not offer this capability. The paper presents results from several different paper machine projects we have undertaken around the world. These projects have been aimed at improving machine stability, optimising chemicals usage and reducing energy use. On a brown paperboard machine in Australasia, APC has reduced specific steam usage by 10%, averaged across the grades; the controller has also provided a significant capacity to increase production. On a North American newsprint machine, the APC system has reduced steam usage by more than 10%, and it provides better control of colour and much improved wet end stability. The paper also outlines early results from two other performance improvement projects, each incorporating a different approach to reducing the energy used in paper making. The first of these two projects is focussed on optimising sheet drainage, aiming to present the dryer with a sheet having higher solids content than before. The second project aims to reduce specific steam usage by optimising the operation of the dryer hood.

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Two near-ultraviolet (UV) sensors based on solution-grown zinc oxide (ZnO) nanowires (NWs) which are only sensitive to photo-excitation at or below 400 nm wavelength have been fabricated and characterized. Both devices keep all processing steps, including nanowire growth, under 100 °C for compatibility with a wide variety of substrates. The first device type uses a single optical lithography step process to allow simultaneous in situ horizontal NW growth from solution and creation of symmetric ohmic contacts to the nanowires. The second device type uses a two-mask optical lithography process to create asymmetric ohmic and Schottky contacts. For the symmetric ohmic contacts, at a voltage bias of 1 V across the device, we observed a 29-fold increase in current in comparison to dark current when the NWs were photo-excited by a 400 nm light-emitting diode (LED) at 0.15 mW cm(-2) with a relaxation time constant (τ) ranging from 50 to 555 s. For the asymmetric ohmic and Schottky contacts under 400 nm excitation, τ is measured between 0.5 and 1.4 s over varying time internals, which is ~2 orders of magnitude faster than the devices using symmetric ohmic contacts.