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   17篇
  免费   0篇
  3篇
综合类   4篇
农作物   2篇
畜牧兽医   8篇
  2021年   1篇
  2017年   1篇
  2014年   2篇
  2013年   1篇
  2012年   1篇
  2011年   1篇
  2009年   2篇
  2008年   4篇
  2007年   1篇
  2006年   2篇
  2003年   1篇
排序方式: 共有17条查询结果,搜索用时 15 毫秒
1.
Chicken postovulatory follicle (POF) regression occurs via the process of apoptosis. However, the signals and initiator pathways responsible for regression of the POF are unknown. In the current study, we examined gene expression patterns of various caspases (caspase-1, -2 and -3) involved in apoptosis by semi-quantitative RT-PCR. The percentage of apoptotic cells during POF regression was also quantified by flow cytometry. Expression of caspase-3 mRNA was noted in the largest preovulatory follicle (F1). However, the initiator caspases (caspase-1 and -2) were not expressed in F1. During the regression of the POF, caspase-3 was activated during initial stages, whereas the initiator caspases were upregulated at the later stages (POF4 and POF5).The percentage of apoptotic cells was significantly higher during the regression of the POF. It might be possible that levels of caspase-3 mRNA do not necessarily reflect the cell’s potential for facilitating apoptosis, as activation of the caspase-3 by initiator caspases is required for its function. We presume that both caspase-1 and caspase-2 were key initiators in the regression of chicken POF and that the apoptosis-mediated regression of POFs might be similar to mammalian corpus luteum involution.  相似文献   
2.
Even though human and chimpanzee gene sequences are nearly 99% identical, sequence comparisons can nevertheless be highly informative in identifying biologically important changes that have occurred since our ancestral lineages diverged. We analyzed alignments of 7645 chimpanzee gene sequences to their human and mouse orthologs. These three-species sequence alignments allowed us to identify genes undergoing natural selection along the human and chimp lineage by fitting models that include parameters specifying rates of synonymous and nonsynonymous nucleotide substitution. This evolutionary approach revealed an informative set of genes with significantly different patterns of substitution on the human lineage compared with the chimpanzee and mouse lineages. Partitions of genes into inferred biological classes identified accelerated evolution in several functional classes, including olfaction and nuclear transport. In addition to suggesting adaptive physiological differences between chimps and humans, human-accelerated genes are significantly more likely to underlie major known Mendelian disorders.  相似文献   
3.
Giant river catfish (Mystus seenghala) from the Beas river were compared with a population in the Sutlej river of the Indus river system using 28 morphometric characters. Discriminant analyses and a univariate anova were used to explore these data. Allometric transformation of each measurement was done to eliminate correlations with size. The stepwise discriminant analysis retained nine variables that significantly discriminated the Beas samples from the Sutlej samples. Using these variables, 91.2% (original) and 89.0% (cross validated) of fish were classified into their correct samples. Misclassification was higher for the Sutlej samples (12.5%) than for the Beas samples (6.3%). The results of the discriminant analyses showed that variability in the Beas samples was more homogeneous and provided a more characteristic picture of the group than the Sutlej samples. The univariate ANOVA revealed significant differences between the means of the two populations for 12 of the 28 transformed morphometric measurements.  相似文献   
4.
The aim of this study was to examine enzymatic modification of wheat bran, performed in a low-moisture process, and the reduction of bran particle size as means of improving the technological performance of wheat bran in expanded extrudates. Modification of bran by hydrolytic enzymes increased the crispiness and decreased the hardness and piece density of extrudates containing wheat bran and endosperm rye flour in 20:80 ratio. These improvements correlated (P < 0.01 or 0.05) with an increased content of water extractable arabinoxylan and decreased water holding capacity of the bran, as well as with increased longitudinal expansion of the extrudates. Furthermore, bran with a fine average particle size (84 μm) produced extrudates with improved mechanical properties and higher radial expansion than coarse bran (particle size 702 μm). The impact of bran particle size was also observed in the cellular structure of the extrudates as differences in cell size and homogeneity. The bran drying method, oven or freeze drying after enzymatic modification, did not have a major impact on the properties of the extrudates. The study showed that the functionality of wheat bran in extrusion can be improved by enzymatic modification using a low-water process and by reduction of bran particle size.  相似文献   
5.
Traditionally the dispersion of particles in polymeric materials has proven difficult and frequently results in phase separation and agglomeration. We show that thermodynamically stable dispersion of nanoparticles into a polymeric liquid is enhanced for systems where the radius of gyration of the linear polymer is greater than the radius of the nanoparticle. Dispersed nanoparticles swell the linear polymer chains, resulting in a polymer radius of gyration that grows with the nanoparticle volume fraction. It is proposed that this entropically unfavorable process is offset by an enthalpy gain due to an increase in molecular contacts at dispersed nanoparticle surfaces as compared with the surfaces of phase-separated nanoparticles. Even when the dispersed state is thermodynamically stable, it may be inaccessible unless the correct processing strategy is adopted, which is particularly important for the case of fullerene dispersion into linear polymers.  相似文献   
6.
Designing superoleophobic surfaces   总被引:1,自引:0,他引:1  
Understanding the complementary roles of surface energy and roughness on natural nonwetting surfaces has led to the development of a number of biomimetic superhydrophobic surfaces, which exhibit apparent contact angles with water greater than 150 degrees and low contact angle hysteresis. However, superoleophobic surfaces-those that display contact angles greater than 150 degrees with organic liquids having appreciably lower surface tensions than that of water-are extremely rare. Calculations suggest that creating such a surface would require a surface energy lower than that of any known material. We show how a third factor, re-entrant surface curvature, in conjunction with chemical composition and roughened texture, can be used to design surfaces that display extreme resistance to wetting from a number of liquids with low surface tension, including alkanes such as decane and octane.  相似文献   
7.
There is often a conservation need to estimate population abundances of elusive, low-density, wide-ranging carnivore species. Because of logistical constraints, investigators often employ non-invasive ‘captures’ that may involve ‘genetic’ or ‘photographic’ sampling in such cases. Established capture–recapture (CR) methods offer a powerful analytical tool for such data. In this paper, we developed a rigorous combination of captive, laboratory and field-based protocols for identifying individual tigers (Panthera tigris) from fecal DNA. We explored trade-offs between numbers of microsatellite loci used for reliable individual identifications and the need for higher capture rates for robust analyses. Our field surveys of scats were also specifically designed for CR analyses, enabling us to test for population closure, estimate capture probabilities and tiger abundance. Consequently, we could compare genetic capture estimates to results of a ‘photographic capture’ study of tigers at the same site. The estimates using the heterogeneity model (Mh-Jackknife) for fecal DNA survey were [Mt+1 = 26; and ()=66 (12.98)] in close agreement with those from the photographic survey [(Mt+1 = 29; and () = 66 (13.8)]. Our results revealed that designing field surveys of scats explicitly for CR data analyses generate reliable estimates of capture probability and abundance for elusive, low density species such as tigers. The study also highlights the importance of rigorous field survey and laboratory protocols for reliable abundance estimation in contexts where other approaches such as camera-trapping or physical tagging of animals may not be practical options.  相似文献   
8.
Economic losses incurred by Przhevalskiana silenus in goats of Jammu province of Jammu and Kashmir (North India) were assessed from July 2005 to June 2006. Abattoir studies revealed holes in hides for 112 days (mid-December 2005 to first week of April 2006) and trimming of carcass for 243 days (July 2005 to February 2006) during a lifecycle, leading to annual losses of Rs. 7,391,432 and Rs. 10,510,837, respectively. An effect on production traits (weight gain and milk) was assessed on naturally P. silenus-infested Beetal goats. The mean body weight loss of warbled goats was 2.40 kg (equal to 1.096 kg of meat, assuming 45.7% dressing percentage of goat) leading to an annual loss of Rs. 35,473,265. The mean milk yield loss per warbled goat per day was 101.7 g resulting in losses to the tune of Rs. 19,879,012. It can be concluded that P. silenus infestation resulted in an overall loss of Rs. 73,254,547, i.e. 73.26 million annually (equivalent to US 1.62 million; US1.62 million; US 1 = Rs. 45.24), where reduced growth alone contributed 49% of the total losses. A study recommends that a control scheme against P. silenus infestation in goats using an effective insecticide should be followed to prevent huge economic losses in hide, milk and meat production. Economic losses associated with P. silenus infestation in goats were estimated for the first time from India.  相似文献   
9.
Type 1 diabetes mellitus results from the autoimmune destruction of the beta cells of the pancreatic islets of Langerhans and is recapitulated in the nonobese diabetic strain of mice. In an attempt to rescue islet loss, diabetic mice were made normoglycemic by islet transplantation and immunization with Freund's complete adjuvant along with multiple injections of allogeneic male splenocytes. This treatment allowed for survival of transplanted islets and recovery of endogenous beta cell function in a proportion of mice, but with no evidence for allogeneic splenocyte-derived differentiation of new islet beta cells. Control of the autoimmune disease at a crucial time in diabetogenesis can result in recovery of beta cell function.  相似文献   
10.
The efficacy of minidose of pour-on ivermectin and eprinomectin formulations against first instar larvae of Przhevalskiana silenus was observed in naturally infested goats in the Jammu region, North India. The study was performed in mid August 2011. A total of 280 goats were randomly divided in to 7 groups of 40 each. Goats of the first three groups were treated with pour-on ivermectin at dosage of 2, 5, and 200 μg/kg body weight, respectively, whereas animals of the fourth to sixth groups were treated with pour-on eprinomectin at 25, 50, and 500 μg/kg body weight, respectively. Group VII animals were kept as untreated control. The results indicated that no warbles were recorded between December 2011 and March 2012 on back of animals treated with pour-on preparations of ivermectin at dosage of 5 and 200 μg/kg body weight, respectively, and eprinomectin at dosage of 50 and 500 μg/kg body weight, respectively. Thus, it is concluded that administration of minidose of pour-on ivermectin (5 μg/kg body weight) and eprinomectin (50 μg/kg body weight) is cost effective and so can be used for warble fly control campaign in Jammu region.  相似文献   
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