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排序方式: 共有1725条查询结果,搜索用时 15 毫秒
81.
Carmen Murcia Laura Coello Rogelio Fernández María Jesús Martín Fernando Reyes Andrés Francesch Simon Munt Carmen Cuevas 《Marine drugs》2014,12(2):1116-1130
Tanjungides A (1) (Z isomer) and B (2) (E isomer), two novel dibrominated indole enamides, have been isolated from the tunicate Diazona cf formosa. Their structures were determined by spectroscopic methods including HRMS, and extensive 1D and 2D NMR. The stereochemistry of the cyclised cystine present in both compounds was determined by Marfey’s analysis after chemical degradation and hydrolysis. We also report the first total synthesis of these compounds using methyl 1H-indole-3-carboxylate as starting material and a linear sequence of 11 chemical steps. Tanjungides A and B exhibit significant cytotoxicity against human tumor cell lines. 相似文献
82.
Naití A. Morales Maike Heidemeyer Robert Bauer Sebastian Hernández Enzo Acuña Simon Jan van Gennip Alan M. Friedlander Carlos F. Gaymer 《水产资源保护:海洋与淡水生态系统》2021,31(2):340-355
- Marine protected areas (MPAs) are becoming a widely used tool for the conservation of biodiversity and for fishery management; however, most of these areas are designed without prior knowledge of the basic ecological aspects of the species that they are trying to protect.
- This study investigated the movement of two top predators: the Galapagos shark, Carcharhinus galapagensis, and the yellowtail amberjack, Seriola lalandi, in and around the Motu Motiro Hiva Marine Park (MMHMP) using MiniPAT satellite tags to determine the effectiveness of this MPA for the protection of these species.
- The Galapagos sharks (n = 4) spent most of their tag deployment periods inside the MMHMP. However, high intraspecific variability was observed in their movement dynamics. Daily individual maximum movements ranged from 17 to 58 km and the maximum distance from Salas y Gómez Island, the only emergent island within the MMHMP, ranged from 31 to 139 km.
- The maximum linear distance travelled for a female juvenile Galapagos shark (152 cm total length) was 236 km, which is greater than the maximum distance previously documented for juveniles of this species (<50 km).
- For the yellowtail amberjack (n = 1), 91% of the satellite geolocations were within the MMHMP, with a maximum daily distance travelled of 6 km. The maximum distance travelled between points was 111 km and the maximum distance from Salas y Gómez Island was 62 km.
- All archival tagged fish spent most of their time at depths of <50 m and never left the epipelagic zone. Daytime versus night-time differences were pronounced in all individuals but showed high interindividual variability.
- This study provides a baseline on the movement of these two top predators in the MMHMP and provides valuable insights for the creation of MPAs in the region and elsewhere.
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84.
The influence of the simultaneous administration of monensin and tiamulin on the motor nerve conduction velocity and the refractory periods of the N. ischiadicus was studied on 4-week old cockerels. The combined administration of the two substances resulted in significant decrease of the conduction velocities of the peripheral nerve, while the relative and absolute refractory periods were seen to increase significantly as a result of the medications. The observed alteration of the peripheral nerve function in the early phase can already attribute to the development of the serious clinical signs of the toxic interaction. The simultaneous application of monensin and tiamulin caused also changes in the electrocardiogram which was expressed in a prolongation of the RS interval and the ST segment. At the same time the heart rate was reduced. 相似文献
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A feeding trial was carried out with turkey poults, which were fed a diet containing 10(10) viable probiotic E. faecium NCIB 10415 cells/kg feed. Samples of the intestinal tract were analyzed for lactate, colony forming units of total anaerobic bacteria, lactic acid bacteria, enterobacteria and enterococci. Furthermore, metabolic activity of total eubacterial, lactobacilli and enterococci was recorded in selected RNA-extracts with specific ribosomal RNA oligonucleotide probes. Animals fed the probiotic diet showed continously increasing lactate concentrations throughout the sampling period up to day 42 of life. No correlation was found for colony forming units (cfu) of lactic acid bacteria, but metabolic activity of lactobacilli showed very close relation to continously increasing lactate concentrations. Throughout the feeding trial, enterococci in the control group continously increased to a maximum of 10(4) cfu/g wet weight, but 10-fold higher enterococci cfu were generally found in the treated group. However, rRNA content as measure for metabolic activity showed a drastic decline in both groups after high metabolic activities on day 7. This study shows that E. faecium NCIB 10415 (E. faecium SF68) stimulates other lactic acid bacteria in the small intestine, especially lactobacilli. 相似文献
87.
疫病是世界养禽生产效率的主要限制因素。尽管分子生物学方面的基础研究导致了新型疫苗的出现,但集约化生产体系仍受到新的和变异疫病的危害,这常常是多因子感染造成的。本文综述了一些重要疫病复合症的研究进展并对商品蛋鸡群和肉鸡生产效益的影响作一评述。 相似文献
88.
Wade O. Watanabe Eileen P. Ellis Simon C. Ellis Juan Chaves Christine Manfredi Randolph W. Hagood Maria Sparsis Steven Arneson 《Journal of the World Aquaculture Society》1998,29(2):176-187
Abstract Wild-caught mutton snapper Lutjanus analis , a high-value marine food fish species, matured in flow-through seawater (36 g/L) tanks after 3 yr in captivity. On 31 May 1995, a female with a mean oocyte diameter of 382 μm was injected with human chorionic gonadotropin (HCG) (500 IU/kg body wt.) followed 24 h later by a second injection (1,000 IU/kg body wt.). At the time of the second injection, three males were injected with HCG (500 IU/ kg body wt.). Voluntary spawning occurred 33 h after the first injection, with a total of 534, 781 eggs released. Fertilization rate was 75.7%, while average diameter of fertilized eggs was 783 μm. Embryos were stocked in a 30-m3 outdoor tank at a density of 10.5/L. On day 2 post-hatching (d2ph), larval density was 8.61 larvae/L, and average notochord length was 2.6 mm. Larvae were fed ss-type rotifers from dl-d28ph, Artemia nauplii from 0–08ph, and artificial diets (52–48% protein) from d24-d38ph. On d38ph, fish averaged 0.308 g and 22.2 mm standard length. Survival (from d2ph) was 14.3%, with a total of 36,900 post-metamorphic juveniles produced. On d97ph, 1,390 hatchery-reared juveniles (avg. wt. = 10.5 g) were stocked into two 14.5-m3 recirculating seawater tanks (695 fish/tank; 48 fish/m3 ) and fed a 56% protein pellet. After 168 d, fish averaged 140.8 g, with a survival rate of 97.8% and a feed conversion ratio (dry wt./wet wt.) of 1.2. These preliminary results reveal the mutton snapper to be a prime, new candidate species for commercial cultivation. 相似文献
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90.
Transposable elements are presents in all known genomes so far, and have the faculty of changing their genomic location and/or number of copies within the genome. They are mobile endogenous genetic elements, with a large variety of structure and transposition mechanism. In crops, they compose the major part of the nucleic DNA, up to 80% in some cereals like maize and wheat. Despite their omnipresence, they are largely unknown and uncharacterized within the Poaceae family. In this review, we describe a possible classification of the elements present in this family, some of their known transposition mechanism, their known activity and possible action in crops, and their possible origin. 相似文献