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   45篇
  免费   4篇
林业   3篇
农学   6篇
  17篇
综合类   1篇
农作物   4篇
水产渔业   7篇
畜牧兽医   6篇
园艺   1篇
植物保护   4篇
  2023年   2篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2019年   1篇
  2018年   3篇
  2017年   3篇
  2016年   5篇
  2015年   4篇
  2014年   1篇
  2013年   5篇
  2012年   5篇
  2011年   1篇
  2010年   2篇
  2009年   3篇
  2008年   2篇
  2007年   2篇
  2005年   1篇
  2004年   3篇
  1998年   3篇
排序方式: 共有49条查询结果,搜索用时 15 毫秒
31.
Genome mapping of any organism has become vital and most essential to control the gene related functions and also for the production of new traits of the desired properties. Gene mapping has become a very powerful tool in agriculture sector as well as for terrestrial livestock and going to revolutionize both these sectors from the point of view of enhancing production. However, for aquatic organisms, the information pertaining to gene mapping research is limited and only in recent past few attempts have been made in this direction. The rationale behind genome mapping particularly for aquaculture species is to improve the quality of animals through selective breeding and produce genetically superior traits for commercial production. There is a great potential in this field since most of the aquaculture species have not been subjected to genetic improvement. The advantage of gene mapping tool for any organism is to identify and characterize quantitative trait loci associated with commercial important traits and to use these markers in marker‐assisted selection programmes. Now with advent of gene editing (CRIPSR‐Cas) technology one can modify/repair the gene structure and remove the adverse impact of the gene related characters without replacing the whole genome. Gene mapping of polygenic traits of aquaculture species is also gaining lot of importance because of dominant nature of such additional functional genes with unique predominant character in the species. In the present review, attempts have been made to collect details of information on gene mapping of cultivable penaeid shrimps. Furthermore, how these gene maps can be used to modify the gene structure at the targeted cites using gene editing techniques, has also been discussed.  相似文献   
32.
The impact of fly ash on the biology of the Yamuna River, Delhi, was studied. Effluents come from a 200 MW capacity I.P. thermal power station. Seasonal variations in the biological features in the non-impacted (Y-1) and the impacted (Y-2) segments of the river receiving fly ash effluents were studied. 60 genera of phytoplankton including 29 Chlorophyceae, 19 Bacillariophyceae, 8 Cyanobacteria, and 4 Euglenophyceae were recorded. Phytoplankton diversity was reduced at the impacted site in comparison to the non-impacted site of the river and substantial changes in the composition of various groups inhabiting these areas were observed. Zooplankton were also reduced at Y-2 compared to Y-1, especially rotifers and protozoans, while copepods and nauplii larvae were not affected to the same degree. Species diversity was not significantly different at Y-2 and Y-1 but similarity index varied from low to high between the two stations. Thus, not only was the density, number of genera and diversity reduced, even the generic composition of the plankton was markedly affected in the impacted waters. The observed perturbations could be due to sedimentation of ash particles, pH or elevated metal or salt concentration. A change in the concentration of one or more constituents disturbs the relationship between biota and could be the possible cause of reduced densities in the impacted waters.  相似文献   
33.
The leaves (needles) of eastern red cedar (Juniperus virginiana L.) contain two important natural products: essential oil and podophyllotoxin. The hypothesis of this study was that it may be possible to extract both essential oil and podophyllotoxin from the leaves of the tree, by using a dual extraction method. Podophyllotoxin was obtained from the leaves following steam distillation of the leaves to produce the essential oil, indicating that steam distillation did not degrade podophyllotoxin. Furthermore, a product with 6% purity podophyllotoxin was obtained from the steam-distilled plant material, demonstrating the possibility for the establishment of an industrially economic protocol for dual extraction of these two natural products. Our study demonstrated that J. virginiana leaves, currently a waste-product from the timber industry, could be sequentially extracted for essential oil and podophyllotoxin and utilized as a by-product instead. We also found that the J. virginiana heartwood (a traditional source for cedarwood essential oil) does not contain podophyllotoxin. This is the first study to report both podophyllotoxin and essential oil in J. virginiana, and the first report on the dual extraction of these two natural products from the same biomass samples.  相似文献   
34.
A 60‐day indoor experiment was conducted to study the effect of dietary supplementation of biofloc on metabolic enzyme activities and immune responses in Penaeus monodon juveniles. Biofloc developed in indoor fibreglass‐reinforced plastic (FRP) tanks (1000 L) was used as dietary supplement in P. monodon (2.90 ± 0.10 g) reared in 1000‐L FRP tanks. Graded level of dried biofloc was included in shrimp basal diets, 0% (control, B0), 4% (B4), 8% (B8) and 12% (B12). The level of metabolic enzymes like malate dehydrogenase (MDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was not significantly different with control up to 8% dietary supplementation. A higher level of total haemocyte count (THC) was noticed in B8 (22.16 ± 2.17 × 106 cells mL?1) and B4 (21.11 ± 0.56 × 106 cells mL?1) compared with control, C (14.61 ± 2.74 × 106 cells mL?1). Biofloc‐supplemented groups recorded significantly higher (< 0.05) serum SOD and catalase activity (P < 0.01) in comparison with control. The groups fed with 4% dietary biofloc supplement recorded highest relative percentage survival (RPS), 45% after challenge with Vibrio harveyi followed by 36% and 27% RPS in B8 and B12 groups. Based on these results, it can be concluded that supplementation of biofloc even at 4% level in the feed improves immune responses and metabolic activities in black tiger shrimp juveniles.  相似文献   
35.
The present study aims to evaluate the potential of near-infrared reflectance (NIR) spectroscopy to determine the carbon and nitrogen content in soils and also to assess the effectiveness of NIR spectroscopy to predict carbon and nitrogen content in freshly collected soil samples. Soil samples (n = 179) were collected from different locations in India. Soil carbon and nitrogen contents were successfully predicted (R2 = 0.90 for carbon and R2 = 0.85 for nitrogen) by NIR spectroscopy. The root mean square error (RMSE) and ratio performance deviation (RPD) for the validation of predicted equations for carbon and nitrogen were 0.83 and 2.83 and 0.01 and 6.98, respectively. The efficacy of NIR spectroscopy on the prediction of carbon and nitrogen content in Indian soils is highly reliable. Water content in soil samples could affect the NIR absorbance spectra and in turn affect the quantification of carbon and nitrogen.  相似文献   
36.
The field experiment was conducted on black soil (Vertic Ustropept) at Zonal Agricultural Research Station farm, Solapur, for successive 30 years from 1987–1988 to 2016–2017 under dryland condition in a randomized block design with 10 treatments and 3 replications. The pooled results of seven years (2010–2011 to 2016–2017) revealed that the application of 25 kg N ha?1 through crop residue (CR, byre waste) along with 25 kg N ha-1 through Leucaena lopping (Leucaena leucocephala) to rabi sorghum gave significantly higher grain and stover yield and Sustainable Yield Index (14.61 and 36.11 q ha?1 and 0.47, respectively) which was on par with T7, where 25 kg N ha?1 through farmyard manure (FYM) + 25 kg N ha?1 through urea was applied for grain and stover yield (13.95 and 34.46 q ha?1 and 0.44, respectively). The gross and net monetary returns and benefit–cost ratio were also influenced significantly due to integrated nitrogen management (Rs. 59,796, Rs. 47,353 ha?1, and 3.13, respectively). This was also reflected in residual soil fertility status of soil after harvest of rabi sorghum. The organic carbon content and available nitrogen content of soil, as well as nitrogen uptake and moisture use efficiency for grain, were also increased. The total microbial count of bacteria, fungi, and actinomycetes was more where FYM or CR addition was done. The count of N fixers and P solubilizers was more under Leucaena application either alone or with CR or urea. Application of CR at 4.8 t ha?1 (25 kg N ha?1) along with Leucaena lopping at 3.5 t ha?1 (25 kg N ha?1) as green leaf manure is the best alternative organic source for fertilizer urea (50 kg N ha?1) to increase the production of dryland rabi sorghum.  相似文献   
37.
A 60‐day indoor trial was conducted to study the effect of periphyton supplementation on metabolic and immune responses in tiger shrimp, Penaeus monodon. Periphyton developed over bamboo substrate in outdoor tanks (15 m2) was used as dietary supplement for P. monodon (2.02 ± 0.04 g) reared in 1000 L FRP tanks. Graded levels of periphyton were included in shrimp basal diets: 0% (P0), 3% (P3), 6% (P6), 9% (P9) and P0 diet with natural periphyton (NP) over bamboo substrate. At the end of the trial, P6 and NP showed significantly higher (P < 0.01) growth rate, 23.9% and 20%, respectively, compared with control, P0. Comparatively, lower level of metabolic enzymes, such as lactate dehydrogenase, malate dehydrogenase, aspartate aminotransferase and alanine aminotransferase, was recorded in treatments P3, P6 and NP compared with control, P0. The periphyton‐supplemented group, P3 had significantly higher (P < 0.05) superoxide dismutase (15.83 ± 0.96) and catalase activity (15.73 ± 0.69) compared to 6.88 ± 2.84 and 9.15 ± 0.67 unit mg?1 protein min?1, respectively, in P0. Similarly, higher total haemocyte counts, 32.58 ± 1.30, 28.51 ± 3.12 and 27.26 ± 4.43 × 106 cells mL?1, were recorded in P6, NP and P3, respectively, compared to P0, 23.57 ± 1.80 × 106 cells mL?1. After challenge with Vibrio harveyi, P3 recorded the highest relative percentage survival 67% followed by NP (58%) and P6 (42%) compared with control. However, treatment with highest periphyton inclusion (P9) did not differ significantly with P0 on growth and immunological parameters. This study indicates that periphyton supplementation at 3–6% level improves growth, immune response and metabolic activities in P. monodon.  相似文献   
38.
A study was conducted to assess comparatively the growth performance of three different indigenous goat breeds during exposure to summer heat stress. The primary objective of the study was to observe the heat stress impact on the growth performance based on the body weight changes, allometric measurements, growth hormone (GH) concentration and peripheral blood mononuclear cell (PBMC) Insulin‐like growth factor‐1 (IGF‐1) mRNA expression pattern during the summer season in comparison with the local breed (Osmanabadi). Thirty‐six ten‐month‐ to one‐year‐old female goats of Osmanabadi, Malabari and Salem Black breeds were randomly divided into six groups, OC (n = 6; Osmanabadi control), OHS (n = 6; Osmanabadi heat stress), MC (n = 6; Malabari control), MHS (n = 6; Malabari heat stress), SBC (n = 6; Salem Black control) and SBHS (n = 6; Salem Black heat stress). Body weight was recorded at weekly intervals, whereas other growth and allometric measurements and blood collection were carried out at fortnightly intervals. Breed factor significantly (p < .05) influenced only few growth variables such as body weight, body mass index (BMI) and body condition score (BCS). However, heat stress treatment significantly (p < .05) reduced all growth parameters expect BMI. Further, the heat stress significantly (p < .01) increased plasma GH concentration in goats with significantly higher (p < .05) concentration recorded in OHS. Among the stress groups, the lower (p < .05) PBMC IGF‐1 mRNA expression was recorded in OHS, while the higher (p < .05) expression was observed in SBHS indicating the extreme adaptive capability of Salem Black breed. Thus, the results indicated that the Salem Black breed performed much better compared to both Osmanabadi and Malabari breeds indicating the superior ability of this breed to adapt to heat stress challenges. The results also indicated that plasma GH and IGF‐1 gene may act as ideal biomarkers for assessing the heat stress impact on growth performance in indigenous goats.  相似文献   
39.
Ocimum tenuiflorum L. (“Holy Basil”/“Tulsi”) is an indigenous Ayurvedic medicinal plant of India, widely distributed in tropical and warm temperate regions. Plant is well known for its enormous therapeutic activities and prevention against diseases. In the present study, thirty-two accessions of O. tenuiflorum germplasm collected from different regions of Northern India were evaluated for their essential oil content and composition. Essential oil obtained by hydrodistillation was analyzed by GC and GC/MS for aroma compounds. Essential oil content in O. tenuiflorum germplasm showed wide range of variation from 0.13 to 0.45 % on FWB. GC and GC/MS profile of O. tenuiflorum oil showed phenylpropanoids, mainly eugenol constituted the major proportion of essential oil. The range of major chemical constituents identified were eugenol (1.94–60.20 %), methyl eugenol (0.87–82.98 %), β-caryophyllene (4.13–44.60 %), β-elemene (0.76–32.41 %). Eugenol and methyl eugenol rich two chemotypes were identified in O. tenuiflorum germplasm. The accessions, IC583281, IC583285 and IC583322 were found to contain high eugenol content (>55 %), while three accessions IC583279, IC583284 and IC583278 were found to possess high methyl eugenol content (>70 %). Eugenol has been reported to be largely responsible for the therapeutic potentials of tulsi, while methyl eugenol is a high value aroma chemical used as flavouring agent. The results suggest holy basil have a potential as a new essential oil crops and can provide oil yields and composition typical for the respective species.  相似文献   
40.
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