119 resultados para 14-138


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The authors thank the anonymous reviewer for helpful comments on the early version of the manuscript. This work was financially supported by the earmarked fund for Modern Agro-industry Technology Research System, the Science Fund for Young Scholars in Sichuan Province (Grant No: ZQ 026-017), and the National 863 Project of China (No. 2008AA101001).

Relevância:

20.00% 20.00%

Publicador:

Resumo:

中国树qu动脉系的主要特征与树qu科中的其他种类如笔尾树qu、普通树qu和 地树qu等的动脉系极为相似,而与灵长类中的猿猴类有较大差异。图4参14

Relevância:

20.00% 20.00%

Publicador:

Resumo:

用胜红蓟、黄花蒿、青蒿、艾蒿、鬼针草、三叶鬼针草、鱼眼草、小鱼眼草、紫茎泽兰、千里光、希莶草、万寿菊、肿柄菊、苍耳等14种菊科植物的石油醚、氯仿、丙酮、乙醇、甲醇和水提取物对菜青虫5龄幼虫的生测结果表明,黄花蒿、青蒿、艾蒿、鱼眼草、小鱼眼草、紫茎泽兰、万寿菊等7种菊科植物甲醇和乙醇提取物具有较高的杀虫活性。此结果为进一步从菊科植物中提取、分离和筛选高活性杀虫活性成分奠定了基础。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

1999年6月至2000年5月对武汉东湖铜锈环棱螺的种群生态学进行了周年研究.铜锈环棱螺年均密度和生物量分别为92.2ind./m2和142.83g/m2,密度和生物量的高峰分别出现在6月(157ind./m2)和11月(205.78g/m2);东湖铜锈环棱螺为一年一代,其一年中种群含有5个年龄组,其中1998年龄组占绝对优势.利用瞬时增长率法计算东湖铜锈环棱螺的周年生产量带壳湿重为91.56g/m2,去壳干重为5.32g/m2,P/B系数为0.64.同时研究了铜锈环棱螺的生产力动态变化,其生产量累积多数

Relevância:

20.00% 20.00%

Publicador:

Resumo:

利用14C标记1,2,7,8-四氯代二苯并二噁英(1,2,7,8Tetrachloro[U—14C]dibenzodioxin,14C1,2,7,8TCDD)初步研究了其在鲤体内的分布和代谢规律。14C1,2,7,8-TCDD溶解于丙酮/植物油中,腹腔暴露。暴露1、2、4、8、12d后取样,肝脏、胆汁、腹腔脂肪等消化制样后用液闪仪测量放射性活度。肝脏和胆汁内的放射性活度同步变化,都是第8d达到峰值后下降。腹腔脂肪内1—2d放射性明显高于随后取样的样品。肝和腹腔脂肪的分布量之比呈现“S”型变化趋势。暴露4d

Relevância:

20.00% 20.00%

Publicador:

Resumo:

对淡水生态系统的重要性及生态系统服务的内涵进行了阐述 ,指出了当前淡水生态系统服务研究的不足 ;认为淡水生态系统服务的正常发挥离不开一个健康的生态系统 ,但少有将两者结合的综合研究 ,而这样的研究又是必要的 .水资源应明确包括水量、水质、水能和水生生物四大要素 ,以此为基础 ,对淡水生态系统服务及其评价指标体系进行了论述 ,并简要介绍其评价方法 .文章还对国内相关研究的思路及其技术路线进行了探讨 .

Relevância:

20.00% 20.00%

Publicador:

Resumo:

本文讨论了种植菹草 (PotamogetoncrispusL .)、水花生 (AlternanthearphiloxeroidesGriseb .)、紫背浮萍 (Spirodelapolyrhiza(L .)Schleid .)以及对照实验池 (12 .5m× 9.5m)过滤 (小于0 4 5 μm)与未过滤水样和沉积物中碱性磷酸酶的动力学特征及其分布 .水生植被能降低水样和表层沉积物酶的催化效率 ,抑制作用因植物的种类而异 ,且在未过滤水中表现得尤为突出 .因此 ,受抑制者多与较大的颗粒相联系 ,这一结

Relevância:

20.00% 20.00%

Publicador:

Resumo:

武汉东湖的沉积物中氮(N)的平均含量上层(0—10厘米)为14.2毫克/克(干重,下同),下层(10—40厘米)为12.0毫克/克。磷(P)的平均含量上层为0.87毫克/克,下层为0.62毫克/克。沉积物中氮和磷的含量均有明显的垂直和平面分布上的差异,上层高于下层,水果湖区高于其它湖区。沉积物间隙水中总溶解氮的浓度高,平均为11.52毫克/升,主要以氨氮的形态存在,占总溶解氮的61.3%。总溶解磷的浓度较低,平均为0.113毫克/升,其中正磷酸盐占55.8%。间隙水中氮和磷的浓度均有明显的季节变动,夏季和

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Apo-14 is a fish-specific apolipoprotein and its biological function remains unknown. In this study, CagApo-14 was cloned from gibel carp (Carassius auratus gibelio) and its expression pattern was investigated during embryogenesis and early larval development. The CagApo-14 transcript and its protein product were firstly localized in the yolk syncytial layer at a high level during embryogenesis, and then found to be restricted to the digestive system including liver and intestine in later embryos and early larvae. Immunofluorescence staining in larvae and adults indicated that CagApo-14 protein was predominantly synthesized in and excreted from sinusoidal endothelial cells of liver tissue. Morpholino knockdown of CagApo-14 resulted in severe disruption of digestive organs including liver, intestine, pancreas and swim bladder. Moreover, yolk lipid transportation and utilization were severely affected in the CagApo-14 morphants. Overall, this data indicates that CagApo-14 is required for digestive system organogenesis during fish embryogenesis and larval development.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A novel fish-specific apolipoprotein (apo-14 kDa) has been recently cloned from eel and pufferfish. However, its expression pattern has not been elucidated. in this study, EcApo-14 has been screened from hypothalamic cDNA library of male orange-spotted grouper, which shows 62.9%, 51%, 46.9%, 43.2%, and 31.9% identities to Apo-14 of European flounder, pufferfish, Japanese eel, gibel carp, and grass carp, respectively. RT-PCR analysis reveals that this gene is first transcribed in neurula embryos and maintains a relatively stable expression level during the following embryogenesis. EcApo-14 transcripts are at a very high level during embryonic and early larval development in the yolk syncytial layer (YSL), and decrease in YSL and form intense staining in liver at 3 days after hatching. In adult tissues, EcApo-14 is predominantly expressed in liver and brain. The data suggested that EcApo-14 might play an important role in liver and brain morphogenesis and growth. (c) 2005 Elsevier Inc. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The photosynthetic performances of Porphyra haitanensis thalli were investigated in order to understand its mechanisms for exogenous carbon acquisition during emersion at low tide. The emersed photosynthesis was studied by altering the pH value in the water film on the thalli surface, treating them with carbonic anhydarase inhibitors (acetazolamide and 6-ethoxyzolamide), adjusting the CO2 concentrations in the air, and comparing the theoretical maximum CO2 supply rates within the adherent water film with the observed photosynthetic CO2 uptake rates. It was found that the principal exogenous inorganic carbon source for the photosynthesis of P. haitanensis during emersion was atmospheric CO2. The driving force of CO2 flux across the water film was the CO2 concentration gradient within it. Carbonic anhydrase accelerated both extracellular and intracellular CO2 transport. The emersed photosynthesis of P. haitanensis was limited by the present atmospheric CO2 level, and would be enhanced by atmospheric CO2 rise that would trigger global warming.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Resting metabolism was measured in immature mandarin fish Siniperca chuatsi weighing 42.1-510.2 g and Chinese snakehead Channa argus weighing 41.5-510.3 g at 10, 15, 20, 25, 30 and 35 degreesC. Heat increment of feeding was measured in mandarin fish weighing 202.0 (+/-14.0) g and snakehead weighing 200.8 (+/-19.3) g fed swamp leach Misgurnus anguillicaudatus at 1% body weight per day at 28 degreesC. In both species, weight exponent in the power relationship between resting metabolism and body weight was not affected by temperature. The relationship between resting metabolism and temperature could be described by a power function. The temperature exponent was 1.39 in mandarin fish and 2.10 in snakehead (P < 0.05), indicating that resting metabolism in snakehead increased with temperature at a faster rate than in mandarin fish. Multiple regression models were used to describe the effects of body weight (W, g) and temperature (T, C) on the resting metabolism (R-s, mg O-2/h): In R-s = - 5.343 + 0.772 In W + 1.387 In T for the mandarin fish and In R-s = -7.863 + 0.801 ln W + 2.104 In T for the Chinese snakehead. The proportion of food energy channelled to heat increment was 8.7% in mandarin fish and 6.8% in snakehead. (C) 2000 Elsevier Science Inc. All rights reserved.