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   75篇
  免费   0篇
林业   6篇
农学   4篇
  44篇
综合类   1篇
农作物   3篇
水产渔业   5篇
畜牧兽医   7篇
植物保护   5篇
  2018年   1篇
  2017年   1篇
  2016年   3篇
  2014年   1篇
  2013年   31篇
  2011年   3篇
  2010年   2篇
  2009年   1篇
  2008年   2篇
  2007年   5篇
  2006年   8篇
  2005年   2篇
  2004年   7篇
  2003年   1篇
  2002年   4篇
  2000年   2篇
  1999年   1篇
排序方式: 共有75条查询结果,搜索用时 31 毫秒
61.
ABSTRACT:   The barfin flounder has been recently declared to be rare, as the number of wild individuals in Japan has greatly reduced since 1975. The Japanese National Center for Stock Enhancement started the stocking program for this species on 1987. In the present study, microsatellite DNA loci were applied in order to determine the pedigree of the hatchery-produced juveniles for stock enhancement. Additionally, using six polymorphic microsatellite markers, the accuracy to assign dyads to categories of kinship was estimated using the relatedness estimator ( R XY), similarity indexes (individual genetic identity [GI] and proportion of shared alleles [ P S]), identification of kin groups using unweighted pair group method with arithmetic mean (UPGMA) clustering based on interindividual genetic distances (1- R XY, 1- P S, and 1-GI), a likelihood ratio approach, and partition methods to separate individuals into cohorts. The results were compared with the pedigree relationship previously obtained from parentage analysis. Estimation of the kinship relationship between individuals could be better inferred by means of UPGMA dendrogram clustering based on 1-GI or 1- P S as interindividual genetic distances, or using computer software to perform partitioning of set of individuals.  相似文献   
62.
Field experiments were conducted to analyze the relationship between the settled soil volume in water (SSVW) and the growth of Monochoria vaginalis (Burm. f.) Kunth under organic farming conditions. SSVW corresponds to the mud volume per dry matter weight. Soil was sampled from the superficial layer of the topsoil (<10 mm), which was of a finer texture than the rest of the topsoil. Without the application of rice bran, there was a negative correlation between SSVW and the number of individuals of M. vaginalis. This finding suggests that SSVW is useful as a physical indicator for the growth suppression of M. vaginalis. The application of rice bran dramatically reduced the number of M. vaginalis. The values of SSVW with rice bran were greater than those without rice bran. The analysis of SSVW indicates that the change in soil physical properties following the application of rice bran was one of the factors responsible for the suppression of M. vaginalis growth.  相似文献   
63.
In the course of chemical weathering, rockforming minerals release constituent ions changing into secondary minerals by alteration or recrystallization. Minerals formed in this way are primarily of colloidal nature, and are the most active portion in soils together with humus. The chemical weathering has dual meaning for soil fertility, that is, it provides soils with nutrients released and inorganic colloids formed, namely clay minerals. It has been well established that climate, vegetation, parent material, topography and time influence the formation of soils. Generally speaking, Japanese soils have developed under a warm and humid climate which causes leaching of released bases resulting in acid reactions, and a predominance of kaolin in soils. Accumulated information pertaining to Japanese soils, however, has disclosed that physical, chemical, and mineralogical properties of parent rocks are still obviously reflected in the clay minerals of soils.  相似文献   
64.
Studies of the constituents of Uruguayan propolis   总被引:4,自引:0,他引:4  
Eighteen flavonoids including two new compounds, four aromatic carboxylic acids, and eleven phenolic acid esters including one new compound were isolated and identified from the ethyl acetate soluble fraction of the 70% ethanol extract of Uruguayan propolis. The new compounds were elucidated as pinobanksin 3-(2-methyl)butyrate (1; recently reported in Usia, T.; Banskota, A. H.; Tezuka, Y.; Midorikawa, K.; Matsushige, K.; Kadota, S. J. Nat. Prod. 2002, 65, 673-676) pinobanksin 3-isobutyrate (2), and 2-methyl-2-butenyl ferulate (24). The constituents isolated from Uruguayan propolis in this study were similar to those of propolis of European and Chinese origin. Thus, it is suggested that the Uruguayan propolis has a plant origin similar to those of propolis from Europe and China.  相似文献   
65.
The production of cellulosic bioethanol from non-edible plants is a potential countermeasure against global warming. Erianthus species provide cellulosic raw material for bioethanol because they have high biomass productivity and high tolerance to environmental stress, associated with their large, deep root systems. However, it is difficult to select Erianthus species for breeding by direct observation of their root systems because the roots are widely dispersed in the soil. Instead, we examined shoot morphological traits that could be closely related to root morphology to find effective reference indices for selection. The potential to evaluate root structure and function in Erianthus according to bleeding rate was also examined. An analysis of root–shoot relationships in seedlings indicated that root number and mean length were closely related to stem number and diameter, respectively. These results suggest that root–shoot relationships may provide useful criteria for selective breeding of root systems in Erianthus.  相似文献   
66.
中日合作水稻品质·食味研究的现状和展望   总被引:5,自引:0,他引:5  
介绍了中国水稻食味研究取得的成果和正在开展的研究工作,对今后水稻食味研究的发展做了展望。随着中国社会经济的迅速发展,人们的饮食结构发生了变化,对主食稻米的需求正在由数量型向品质食味型转变。影响水稻食味的三大因素包括遗传特性、产地特点和生产技术,其中,首选遗传特性。中国水稻食味育种工作已经展开,优质食味米配套生产技术的研...  相似文献   
67.
The potential of microsatellite markers for use in genetic studies has been evaluated in Allium cultivated species (Allium cepa, A. fistulosum) and its allied species (A. altaicum, A. galanthum, A. roylei, A. vavilovii). A total of 77 polymerase chain reaction (PCR) primer pairs were employed, 76 of which amplified a single product or several products in either of the species. The 29 AMS primer pairs derived from A. cepa and 46 microsatellites primer pairs from A. fistulosum revealed a lot of polymorphic amplicons between seven Allium species. Some of the microsatellite markers were effective not only for identifying an intraspecific F1 hybrid between shallot and bulb onion but also for applying to segregation analyses in its F2 population. All of the microsatellite markers can be used for interspecific taxonomic analyses among two cultivated and four wild species of sections Cepa and Phyllodolon in Allium. Generally, our data support the results obtained from recently performed analyses using molecular and morphological markers. However, the phylogeny of A. roylei, a threatened species with several favorable genes, was still ambiguous due to its different positions in each dendrogram generated from the two primer sets originated from A. cepa and A. fistulosum.  相似文献   
68.
ABSTRACT

Growth of the weed Monochoria vaginalis (Burm. f.) Kunth under the conditions of organic rice production is a serious problem. The reason for the growth of M. vaginalis being dominant, especially in organic rice production, is not fully understood. In this study, laboratory experiments were conducted to analyze soil and seed factors in relation to the promotion of germination. (1) After incubation of flooded soil with or without the addition of rice bran (0.3%, 0.6%, and 0.9% in an air-dried soil basis), soil solutions were recovered and seeds of M. vaginalis were incubated in the soil solutions. Germination in the soils solutions without and with 0.3% rice bran was greater than that in distilled water. However, germination was suppressed in the presence of 0.6% and 0.9% of rice bran. These findings indicate that the solution from the soils with rice bran has different effects that may either increase or decrease germination. (2) A mixture of air-dried soil and distilled water was filtered to obtain a soil solution. Seeds were incubated in the soil solution (same as above). Environmental and physiological factors affected germination: exposure of seeds to light was an environmental factor and high germination activity and shallow dormancy of seed were physiological. The recovered soil solution promoted germination when these factors were not optimized. (3) There was a negative and significant correlation between dissolved oxygen (DO) in the soil solution and germination, indicating that a low content of DO was a promotive factor for germination. (4) Based on an experiment using pH buffers, germination increased with decrease in pH of soil solution, as long as the pH ranged from 4.0 to 7.0. This finding indicates that pH is also a factor that promotes germination.  相似文献   
69.
Gastrin-releasing peptide (GRP) has been suggested as a novel regulatory peptide in the female reproductive tract but the presence of GRP and GRP mRNA in the non-neurogenic tissue of the cervix has not yet been clarified. In the present study, immunohistochemistry and in situ hybridization were used to reveal the distribution of GRP immunoreactivity and expression of GRP mRNA in the bovine cervix. The cervixes from 21 non-pregnant and 20 pregnant cows, and 6 fetuses were used in the study. In the fetus, adult non-pregnant and pregnant specimens, GRP and GRP mRNA were predominantly detected in the luminal epithelial cells of basal areas of peripheral regions of the cervix. Positive staining of GRP in the epithelial cells of the cervix was first detected in the CRL 37 cm of the fetus. During the estrous cycles, the staining intensity of GRP in the epithelial cells was stronger in the follicular phase than in the luteal phase. During the early gestational period, GRP immunoreactivity was detected at relatively similar intensity to the follicular phase. In situ hybridization results ascertained the expression of GRP mRNA in the superficial epithelial cells of the cervix of non-pregnant and pregnant cows. The results suggest that GRP may be important both in the development of the fetal cervix and secretory activity of the epithelial cells of the cervix.  相似文献   
70.
A contrasting occurrence of clay minerals was found within a soil profile which was derived from volcanic materials in the suburbs of Fukuoka-city, Northern Kyushu. The soil profile is located on an isolated terrace, and the morphological characteristics of the soil correspond exactly to Andosols, so-called Kuroboku soils or Humic Allophane soils.

The clay fraction of upper horizons of the soil consists largely of alumina-rich gel-like materials, gibbsite, and layer silicates such as chlorite and chloritevermiculite intergrades, while that of lower horizons is composed of allophane and gibbsite or halloysite. There was no positive indication of allophane in the upper horizons. Corresponding with the clay mineralogical composition, quartz is abundant in the fine sand fraction of the upper horizons, while the mineral is very scarce or none in the lower horizons, suggesting a close relation between the petrological nature of parent volcanic materials and the mineralogical composition of weathering products. The dominant clay mineral in the volcanic 1.10il might be dependent on the petrological nature of parent materials, and allophane is mostly formed from andesitic materials, and alumina-rich gel-like materials and layer silicates have come from quartz andesitic materials. Allophane would transform to gibbsite or halloysite according to weathering conditions, and aluminarich gel-like materials change to gibbsite under a well-drained condition.

The soil materials have been so greatly weathered that some horizons contain gibbsite of even more than 40 per cent or halloysite over 70 per cent. The morphology and mineralogy are quite similar to so-cailed “non-volcanic Kuroboku soils.”  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