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   89篇
  免费   8篇
林业   6篇
农学   6篇
基础科学   1篇
  10篇
综合类   2篇
农作物   2篇
水产渔业   18篇
畜牧兽医   44篇
园艺   1篇
植物保护   7篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2017年   2篇
  2016年   4篇
  2015年   3篇
  2014年   3篇
  2013年   6篇
  2012年   2篇
  2011年   5篇
  2010年   3篇
  2009年   2篇
  2008年   14篇
  2007年   4篇
  2006年   8篇
  2005年   6篇
  2004年   6篇
  2003年   7篇
  2002年   4篇
  2001年   8篇
  2000年   2篇
  1997年   2篇
  1996年   3篇
排序方式: 共有97条查询结果,搜索用时 736 毫秒
31.
ABSTRACT:   Respiratory quinone compositions were analyzed by a high-performance liquid chromatography to characterize the depth-related changes and site-specific differences of microbial communities in marine sediments. Two deep-sea sediment samples and one coastal sediment sample were investigated from three sites on the coast of Japan, Sagami Bay, Suruga Bay and Tokyo Bay. Although depth-related changes in microbial community structures were observed, site-specific differences appeared to have greater influence on overall community structures. A variety of quinone homologs was commonly identified at all sampling sites and depths examined, but a few minor quinone fractions, mainly derived from Actinobacteria , were detected only at specific sampling sites. Methylmenaquinone-7 (MMK-7) was the major component throughout the examined depths in Sagami Bay and Tokyo Bay. Most abundant quinone homologs changed with each depth in Suruga Bay. Menaquinone-6 (MK-6) predominated in the 0 to 2-cm layer (19%). Below 0–2 cm, the most abundant homolog in each sampling depth was phylloquinone (K1; 13%, 4–6 cm), MK-8 (19%, 8–10 cm) and MK-7 (13%, 16–18 cm). The microbial respiratory quinone profiling method shown here, successfully demonstrates the usefulness of this approach to characterize microbial communities in marine sediments.  相似文献   
32.
ABSTRACT:   During the fermentation of mackerel to narezushi , the concentration of peptides required to inhibit 50% of the ACE activity in the assay media (IC50), as an index of the angiotensin  I-converting enzyme (ACE) inhibitory activity, was remarkably decreased with a rapid increase in peptide contents. Systolic blood pressure (SBP) in spontaneously hypertensive rats (SHR) decreased between 2 and 4 h after the single oral administration of greater than 10 mg peptide/kg narezushi extract, and recovered to the initial level by 8 h thereafter. The SBP decreased at seven successive daily doses of 10 mg/kg of narezushi extract and then recovered to the initial level 5 days after stopping a total of 10 daily administrations. The extract was administered to five-week-old SHR rats for 70 days and SBP decreased 21 days after starting and continued for 28 days after the end of administration. The peptide-rich fraction from narezushi extract had a powerful antihypertensive effect, whereas the other fraction had a similar, but weak effect.  相似文献   
33.
Assemblages of vertical migratory mesopelagic fish are described for the nighttime upper 20 m layer of the transitional and adjacent waters in the western North Pacific. Twenty-three mesopelagic fish species belonging to six families and 16 genera were collected during June 1996. Family Myctophidae was most speciose, represented by 17 species, followed by Sternoptychidae (two spp.) and Bathylagidae (one spp.). Six assemblages are recognized based on their species composition: Subarctic, Northern Transition, Southern Transition, Subtropical, Slope Water and Seamount Assemblages. These assemblages are also characterized by size composition and biomass of the catches. The distributions of the Subarctic, Northern Transition, Southern Transition and Subtropical Assemblages are approximately defined by the Kuroshio and Oyashio fronts and the Subarctic Boundary. Slope Water and Seamount Assemblages are closely related to the slope water around the shelf edge off Japan and waters around the Shatsky Rise and the Emperor Seamount chain, respectively. The importance of the Southern Transition Assemblage area between the Kuroshio front and Subarctic Boundary as spawning and nursery grounds of many subarctic, transitional and subtropical fishes is elucidated, based on the geographical distribution patterns of their larvae and juveniles.  相似文献   
34.
In Mongolia, milk production must be improved both quantitatively and qualitatively, and we must find the most desirable method for predicting 305‐day milk yields for cows in Mongolia. Therefore, the predicted 305‐day milk yield from the test interval method (TIM), multiple‐trait prediction (MTP) and the random regression model (RRM) were compared. The daily milk production records during 305 days for cows calving from 1986 to 2007 from the National Livestock Breeding Center in Japan, and the test day records every month for cows calving from 1985 to 2005 from the Hokkaido Dairy Milk Recording and Testing Association were used. Wilmink's model for the average of lactation curve in MTP was adopted. A cubic Legendre polynomials and the parameters of Wilmink's function were used for RRM. The results suggested that RRM was the most desirable method for predicting 305‐day milk yields in Mongolia because estimates by RRM were the most accurate when using over four records. Further analyses will be required to examine the properties of RRM when predicting 305‐day milk yields using test day records in Mongolia.  相似文献   
35.
The distinct patterns of cytokine expression in CD4+ and CD8+ T cells are well understood in mice and humans. However, little information is available about cytokine expression in bovine CD4+ and CD8+ T cells. In this study, mRNA expression of 19 different cytokines was analyzed in CD4+ and CD8+ T cells of calves with or without Concanavalin A (Con A) stimulation. CD4+ and CD8+ T cell populations were enriched to 98% purity by positive selection using magnetic cell sorting (MACS). CD4+ T cells spontaneously expressed the mRNAs of interleukin-1alpha (IL-1alpha), IL-1beta, IL-2, IL-6, IL-7, IL-8, IL-10, IL-18, IFN-gamma, TNF-alpha, TNF-beta and TGF-beta, and augmented the mRNA expression of IL-10, IFN-gamma and TNF-beta after Con A stimulation. The mRNAs of IL-3, IL-4, IL-5, IL-13 and GM-CSF were newly expressed in Con A-stimulated CD4+ T cells. CD8+ T cells displayed spontaneous mRNA expression of IL-6, IL-18, TNF-alpha, TNF-beta and TGF-beta, and newly expressed the mRNA of IL-2, IL-7, interferon-gamma (IFN-gamma) and GM-CSF after Con A stimulation. It was found that CD4+ T cells expressed the mRNA of 17 cytokines except for IL-12 and IL-15, while CD8+ T cells expressed only the mRNA of 9 cytokines after Con A stimulation. The profile of cytokine mRNA expression was substantially different in the CD4+ and CD8+ T cells of calves, indicating that CD4+ T cells can be distinguished from CD8+ T cells by the cytokine gene expression of IL-1alpha, IL-1beta, IL-3, IL-4, IL-5, IL-8, IL-10 and IL-13. Differential cytokine expression between CD4+ and CD8+ T cells serve to interpret an individual function of T cell subsets in the immune system of calves.  相似文献   
36.
M cells play a central role in the initiation of mucosal immune responses. However, a primary source of difficulty for investigations of this is the lack of an available specific marker for bovine M cells. As M cells possess irregular and short microvilli, we investigated the distribution and localization of the microvillar proteins actin and villin by immunohistochemistry of the gut of calves. In ileum of the calf, actin and villin were clearly and continuously immunostained in the brush border of the villous epithelia, however, discontinuous immunostaining with patches of no staining were observed in follicle-associated epithelium (FAE). Electron microscopy revealed that M cells had irregular microvilli and lacked the typical brush border, and it was inferred that these patches of no staining might be the intercellular crevices of M cells. As the microvilli of M cells were very sparse, there were several areas of weak immunostaining in calf jejunal FAE. These results suggest that M cells in calf FAE are detectable by the absence of staining for actin and villin.  相似文献   
37.
Recently, the analysis of the microbial community structure in soil has received a great deal of attention. Various analytical methods based on biomarkers have been developed: 16S-rDNA, total DNA, phospholipid fatty acids, ergosterols, muramic acids, etc. (Tunlid and White 1992; Carter and Lynch 1993). In a previous paper, we reported that respiratory quinones are useful biomarkers to characterize the microbial community structure in soil (Fujie et al. 1998). In these analyses, only fresh moist soils or frozen soils had been used as samples. However, the soil samples are generally stored in the dark after air drying in many research institutes and experimental stations. It was considered that the analysis of microbial communities in dried soil samples was not possible.

In this paper, we observed that the drying of soils did not affect the proportions of quinone species in soil although the treatment decreased the amount of extracted quinones. These findings suggest that the analysis of the respiratory quinone profile of dried soils reflects the micro biota present in fresh moist soils before drying.  相似文献   
38.
Viruses were isolated from leaves of plants of Aconitum species with symptoms such as mottling and yellowing in Hokkaido and Gunma prefectures in Japan. These viruses were identified as Cucumber mosaic virus (subgroup II) based on particle morphology, host range, aphid transmission, and serology.  相似文献   
39.
ABSTRACT:   For bioremediation of organically enriched sediment deposited below fish farms, the extremely high potential for population growth of a deposit-feeding polychaete, Capitella sp. I, in the organically enriched sediment, and the effect on decomposition of organic matter in the sediment, were examined. A mass-culturing technique was conducted for this species. Bioremediation experiments were conducted on the organically enriched sediment in a fish farm in Kusuura Bay, Japan in 2003–2006. Approximately 1.7 million individuals of the worms were placed on the sediment below one net pen in December 2003, 9.3 million individuals in November 2004, and 2.2 million individuals in November 2005. After the worms were spread on the sediment, they rapidly increased in number and reached the highest densities of approximately 134 000 inds/m2 in February 2004, 527 000 inds/m2 in March 2005 and 103 000 inds/m2 in January 2006. In the process of rapid population growth, the decomposition of the organic matter of the sediment was enhanced markedly. Our results demonstrate that the promotion of population growth by spreading cultured colonies of Capitella can enhance the decomposition rate of organic matter markedly in organically enriched sediment below fish farms. This method is promising for minimization of the negative effects of fish farms.  相似文献   
40.
Solutions of sucrose, glucose and fructose were artificially injected into the stems of sweet potato plants. The effects of solution injection on both dry matter production and the activity of adenosine 5'-diphosphate glucose pyrophosphorylase (AGPase) in tuberous roots were investigated and compared. The total weight of carbon (TC) artificially and photosynthetically supplied to a plant during the treatment period of 40 days was 0.987–1.869 times the weight of photosynthetically assimilated carbon alone. At the final sampling time, the dry matter weight of tuberous roots in the plants injected with sugar solutions showed a 2.73–9.13-fold increase over that of the control plant. The root weight linearly increased with TC. The activity of AGPase was also enhanced by solution injections, with 27–63 % increases compared to the control, but was not significantly related to TC. The injection of sugar solutions is concluded to have a dual effect on root production in sweet potato. One effect is that the increased sugar concentration in the plant increases AGPase and sink activities, and the other effect is that the increased carbon supply quantitatively promotes starch synthesis and accumulation in roots.  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