首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8篇
  免费   2篇
海洋学   7篇
综合类   3篇
  2018年   1篇
  2015年   1篇
  2013年   1篇
  2008年   1篇
  2007年   1篇
  2005年   1篇
  2003年   2篇
  2002年   2篇
排序方式: 共有10条查询结果,搜索用时 15 毫秒
1
1.
To understand the genetic diversity and population changes in cyanophages in the coastal waters of Shantou,northeast South China Sea,we used the capsid assembly protein gene g 20 as a marker of the abundance and phylogeny of natural cyanomyovirus communities. The abundance of total viruses,heterotrophic bacteria,and picophytoplankton in the coastal waters was monitored with flow cytometry. Hydrological parameters(NO ˉ 3,NO ˉ 2,NH 3,soluble reactive phosphorus,total dissolved nitrogen,total dissolved phosphorus,dissolved oxygen,chemical oxygen demand,temperature,salinity,and chlorophyll a concentration) and microbial abundance(total viruses,total bacteria,P rochlorococcus,Synechococcus,and eukaryotes) were measured in the upper and lower layers at four sampling sites in the research area. In the direct viral counts,cyanomyoviruses accounted for 1.92% to 10% of the total viral community. A phylogenetic analysis showed that the g 20 sequences in the Shantou coastal waters were very diverse,distributed in eight distinct operational taxonomic units,including the newly formed Cluster W. The g 20 gene copies inferred from real time PCR assay indicated that cyanomyoviruses were correlated significantly with the heterotrophic bacteria numbers and the nitrate and chlorophyll a concentrations. These results suggest that cyanomyoviruses are ubiquitous and are an abundant component of the virioplankton in Shantou coastal waters.  相似文献   
2.
以酪蛋白和明胶为蛋白源 ,添加豆油、鱼油、糊精、纤维素以及适量的维生素和矿物质混合剂配制试验饲料 ,饲料配成5个蛋白质水平 ,每个蛋白水平分别包括5个能量级 ,以体质量增长倍数、蛋白质效率和饲料系数为评判依据 ,对体质量为8.73g±0.79g的中华鲟(Acipensersinensis)的适宜蛋白质含量及其蛋白能量比进行了研究。经过为期8周的试验 ,结果表明 :中华鲟幼鲟配合饲料中的适宜蛋白质含量范围为35.7%~41.8% ,饲料的最佳蛋白能量比范围为21.85~30.05ng/J。当试验饲料蛋白质含量为40.3% ,蛋白能量比为27.85ng/J时 ,试验鲟鱼获得最大体质量增长倍数为11.60±1.20,最低的饲料系数为1.68±0.23,以及最高的蛋白质效率为1.58%±0.14%。  相似文献   
3.
中华绒螯蟹仔蟹维生素E营养需求研究   总被引:7,自引:0,他引:7  
以酪蛋白、明胶,糊精和去维生素E的鱼油为原料,配制成等氨等能的半纯化基础饲料,每100g基础饲料中分别添加VE0,10,20,40,60,80mg制成试验饲料,对淡化5d的河蟹大眼幼体和后继仔蟹进行了为期25 d的饲养试验,探讨了VE对大眼幼体和仔蟹生长,存活、蜕皮的影响和适宜需求量,结果表明,每100g饲料中分别添20mgt 40mgVE时,Ⅲ期仔蟹的增重率,存活率和蜕皮频率均较高,分别为436.065,51.17%和2.54和487.61%,61.50%和2.58,而VE缺乏组,同期仔蟹的增重率。存活率和蜕皮频率最低,仅分别是264.94%、26.17%和2.21,但是当每100g饲料中VE的添加量提高到80mg时,仔蟹的上述三项指标,不但没有随之升高,反而明显下降,并与VE缺乏的对照组相接近,表明VE添加过量,也会抑制仔蟹的正常生长,存活和蜕皮。VE对仔蟹的正常生长发育,存活和蜕皮是必需的其适宜添加量为每100g饲料中添加20-40mg.  相似文献   
4.
Fishes represent the highest diversity of vertebrates; however, our understanding of the compositions and functions of their gut microbiota is limited. In this study, we provided the first insight into the gut microbiota of the herbivorous fish Siganus canaliculatus by using three molecular ecology techniques based on the 16 S r RNA genes(denaturing gradient gel electrophoresis, clone library construction, and highthroughput Illumina sequencing), and the Illumina sequencing technique is suggested here due to its higher overall coverage of the total 16 S r RNA genes. A core gut microbiota of 29 bacterial groups, covering 99.9% of the total bacterial community, was found to be dominated by Proteobacteria and Firmicutes in fish fed three dif ferent diets with/without the supplementation of U lva pertusa and non-starch polysaccharide(NSP) enzymes(cellulase, xylanase, and β-glucanase). Diverse potential NSP-degrading bacteria and probiotics(e.g., R uminococcus, Clostridium and Lachnospiraceae) were detected in the intestine of the fish fed U. pertusa, suggesting that these microorganisms likely participated in the degradation of NSPs derived from U. pertusa. This study supports our previous conclusion that U. pertusa-based diets are suitable for the production of S. canaliculatus with lower costs without compromising quality.  相似文献   
5.
The effect of starvation on physiological and biochemical indicators of body, muscle and hepatopancreas were investigated for juvenile red swamp crawfish (Procambarus clarkii), and the results showed the effect was obvious. In a 70-day starvation experiment, mean body weight, exuvial rate, ab- dominal muscle ratio and hepatosomatic index decreased significantly. The percentage of protein, fat, ash and moisture were also significantly affected. The protein content decreased sharply at Day 30 onward and the percentage of fat decreased rapidly from Day 50 and on. The percentages of ash and moisture started to increase significantly at Day 40 and 30 respectively. After the starvation experiment, the hepa- topancreatic total and neutral lipid content decreased slightly from 23.90% to 20.39% and 73.75% to 70.35%, while the hepatopancreatic polar lipid content increased from 23.81% to 27.32%. On the other hand, all the muscular total, neutral and polar lipid contents, and the muscular fatty acid compositions did not change significantly except for the hepatopancreatic fatty acid composition. The relative percentages of 14:0, 16:0, 16:1n-7 and 18:1n-9 were decreased by 55.17%, 11.11%, 8.5% and 6.70% from the initial values, and the relative percentages of 18:2n-6, 18:3n-3, 20:4n-6, 20:5n-3 and 22:6n-3 increased obvi- ously from 5.2%, 3.9%, 2.4%, 10.6%, and 13.7% to 7.1%, 5.0%, 2.8%, 11.5%, and 14.4% respectively. Preference of utilization of fatty acids from hepatopancreas during starvation was as follows: 14:0>16:0>16:1n-7>18:1n-9, and the conservation of highly unsaturated fatty acids was in the order of: 18:2n-6 >18:3n-3>20:4n-6>20:5n-3>22:6n-3.  相似文献   
6.
中华绒螯蟹幼蟹维生素C营养需求研究   总被引:9,自引:0,他引:9  
在每100g等氮、等能纯化饲料中分别添加0,100,200,400,800,1 000mg维生素C(Vc)多聚磷酸酯(LAPP),用这样配制成的试验饲料饲喂已淡化5d的河蟹大眼幼体及后续幼蟹25d,探讨Vc对大眼幼体和幼蟹生长、存活、蜕壳频率及抗逆性的影响,同时探明幼蟹对Vc的适宜需求量,结果表明,饲料Vc添加量为100~400mg/100g时,可以保证幼蟹正常生长、存活和蜕皮,尤其以投喂添加Vc200mg/100g(C2组)和400mg/100g(C3组)饲料的Ⅲ期幼蟹增重率、存活率和平均蜕皮频率较高,其中C2组(上述各指标值)分别为516.18%,62.83%,2.58,C3组分别为458.89%,66.17%,2.61;饲料中缺少Vc时(如C0组),Ⅲ期幼蟹的增重率、存活率和平均蜕皮频率最低,分别为265.31%,26.67%和2.26.饲料中Vc的添加量达到800mg/100g(C4)和1 000mg/100g(C5)时,幼蟹的蜕皮反而受到抑制,平均蜕皮频率降低,蜕皮周期延长,且存活率降低,到Ⅲ期幼蟹的增重率、存活率和平均蜕皮频率在C4组分别为355.7%,31.33%,2.39,在C5组分别为307.53%,28.56%,2.19.此外,各处理组幼蟹对抗逆性影响的试验表明,在一定的范围内,饲料中添加Vc能提高幼蟹的耐低氧能力和耐pH突变能力,而对耐盐度突变能力没有明显的影响.综合上述结果可以得出,为保持幼蟹良好生产性能,饲料中添加的Vc?  相似文献   
7.
VC对河蟹血清和组织中超氧化物歧化酶及磷酸酶活性的影响   总被引:38,自引:2,他引:36  
研究了饲料中添加不同含量VC 对河蟹体内超氧化物歧化酶 (SOD)、碱性磷酸酶 (ALP)和酸性磷酸酶 (ACP)活性的影响 .结果表明 ,饲料中不添加VC 时 ,河蟹肝胰腺、卵巢、血清和肌肉各组织中SOD、ALP和ACP活性各异 ,其中SOD活性大小顺序为肝胰腺 >卵巢 >血清 >肌肉 ,ALP活性顺序为肝胰腺 >血清 >卵巢 >肌肉 ,而ACP活性则为肝胰腺 >血清 >肌肉 >卵巢 .饲料中VC 添加量分别 2 .5× 1 0 - 3 、5.0×1 0 - 3 、1 0 .0× 1 0 - 3 和 1 5.0× 1 0 - 3 (m m)时 ,与对照组相比 ,河蟹不同组织中SOD活性显著下降 (p <0 .0 5或 p <0 .0 1 ) ,而ALP、ACP这两种酶的活性却显著升高 (p <0 .0 5或 p <0 .0 1 ) .但它们的变化幅度不同 ,其中就肝胰腺、卵巢、血清和肌肉中SOD活性而言 ,VC 添加量为 1 5.0× 1 0 - 3 (m m )饲料组分别比对照组的低1 41 .3 4 %、1 2 5.94%、1 1 6.67%和 1 1 5.79%;ALP活性 ,VC 添加量为 1 0 .0× 1 0 - 3(m m)饲料组分别比对照组高 93 .0 %、77.5%、1 66.3 %和 2 66.4%;ACP活性 ,VC的添加量为 1 5.0× 1 0 - 3 (m m)饲料组分别比对照组高 1 3 0 .7%、2 3 7.4%、43 7.6%和 2 65.5%.饲料中VC 添加量为 (5.0~ 1 0 .0 )× 1 0 - 3 (m m )时 ,可有效地增强河蟹非特异性免疫能力 .此外 ,本实验还就VC  相似文献   
8.
浅色黄姑鱼的高密度养殖一直受到病害的困扰,导致成鱼养殖成活率低,直接影响了浅色黄姑鱼养殖业的发展.以汕头南澳岛患皮肤溃烂症的养殖浅色黄姑鱼为材料,从其溃烂头部组织中分离得到优势菌KLg,人工感染实验证实菌株KLg为浅色黄姑鱼的致病菌.药敏试验表明菌株KLg对头孢哌酮、红霉素、头孢曲松、先锋霉素V、复达欣、头孢呋辛和氧哌嗪青霉素等7种抗生素敏感,革兰氏染色、生理生化测定等手段初步确定菌株KLg为哈维氏弧菌(Vibrio harveyi),这一结果通过16S rDNA基因序列及进化树分析得到进一步确认.哈维氏弧菌是海水养殖鱼类的常见致病菌,但在浅色黄姑鱼养殖中尚属首次报道.实验结果可为我国沿海地区浅色黄姑鱼养殖中弧菌病害的防治提供重要参考.  相似文献   
9.
在以鱼粉、豆粕、玉米粉和麦麸为主要原料配制而成的每kg基础饲料中分别添加VE0、100、200、400、600mg配制成五种试验饲料,对均重为(37.52±2.19)g的中华绒螯蟹进行为期60天的饲养试验,以酚氧化酶(PO)、抗菌力(Ua)、溶菌酶活性(UL)等指标为依据,探讨VE对中华绒螯蟹非特异性免疫的影响。结果表明,VE对中华绒螯蟹各组织、器官中PO、Ua、UL等活性有显著或极显著的影响(P<0.05或P<0.01),在适宜范围内,随着VE添加量的增加,PO、Ua和UL活性显著增强,从而增强中华绒螯蟹的非特异性免疫力。综上所述,VE作为免疫刺激剂能有效地增强中华绒螯蟹的非特异性免疫能力,增强中华绒螯蟹免疫功能的VE适宜添加量为200—400mg/kg饲料。  相似文献   
10.
VE对河蟹血清和组织中超氧化物歧化酶及磷酸酶活性的影响   总被引:12,自引:0,他引:12  
通过投喂添加VE 量分别为 0、0 .1× 1 0 - 3 、0 .2× 1 0 - 3 、0 .4× 1 0 - 3 、0 .6× 1 0 - 3(m m)的 5种实验饲料饲养河蟹 6 0d ,以探讨VE 对其体内SOD、ALP和ACP等酶活性的影响 .结果表明 ,饲料中未添加VE 时 ,河蟹血清、肝胰腺、卵巢和肌肉各组织中SOD、ALP和ACP活性各异 ,其中SOD的活性从高到低依次为肝胰腺 >卵巢 >血清 >肌肉 ,ALP活性的为肝胰腺 >血清 >卵巢 >肌肉 ,而ACP活性则是肝胰腺 >血清 >肌肉 >卵巢 .饲料中添加VE 时 ,与对照组相比 ,各组织中SOD活性随着VE添加量的升高而显著降低 ( p <0 .0 5或 p <0 .0 1 ) ;ALP和ACP活性则随着VE 添加量的增加而显著升高 ( p <0 .0 5或 p <0 .0 1 ) .这表明VE 作为天然抗氧化剂在河蟹体内发挥了很大的作用 ,并促进机体的新陈代谢 ,从而增强机体的非特异性免疫力 .VE 作为免疫刺激剂能有效地增强河蟹的非特异性免疫能力 ,能有效发挥其增强河蟹免疫功能的VE 适宜添加量为 ( 0 .2~ 0 .4)× 1 0 - 3(m m) .  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号