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   49篇
  免费   0篇
  国内免费   1篇
林业   11篇
农学   4篇
基础科学   1篇
  14篇
综合类   1篇
农作物   3篇
畜牧兽医   12篇
植物保护   4篇
  2023年   1篇
  2022年   1篇
  2021年   3篇
  2020年   3篇
  2019年   3篇
  2018年   2篇
  2016年   3篇
  2015年   1篇
  2013年   3篇
  2012年   7篇
  2011年   5篇
  2010年   4篇
  2009年   1篇
  2008年   3篇
  2006年   1篇
  2005年   1篇
  2001年   1篇
  2000年   2篇
  1999年   1篇
  1997年   1篇
  1984年   1篇
  1977年   1篇
  1971年   1篇
排序方式: 共有50条查询结果,搜索用时 0 毫秒
1.
Jhinuwa is an aromatic rice (Oryza sativa L.) landrace from the Pokhara Valley of Nepal. A total of 210 accessions comprising seven types of Jhinuwa rice landraces were randomly collected from the rice fields to evaluate inter- and intra-population variability based on agro-morphological traits. The experiment was conducted in factorial randomized complete block design with three replicates in 2005. The first six principal components (PCs) accounted for 76.6 % variation for agro-morphological traits. Major traits that accounted for the variation by six PCs includes days to heading, days to maturity, total grain panicle?1, fertile grain panicle?1, culm length, panicle length, milling recovery, head rice recovery, aroma, 1,000 grain weight, sterile grain panicle?1, grain sterility %, and leaf characteristics. Both principal coordinate analysis and cluster analyses revealed four phenotypic groups, two of which represent Bayarni, Jhinuwa, and Biramphul while the other two account for Tunde and Pakho Tunde. Tunde, Pakho Tunde, Kalo Bayarni, and Seto Bayarni showed higher intra- as well as inter-population variation compared to other populations. The phenotypic and genotypic coefficients of variation, broad sense heritability (h 2B) and genetic advance (GA) as a percent of the mean assessed for 210 accessions revealed high h 2B and GA estimates for leaf width, leaf length breadth ratio, ligule length, sterile grain panicle?1, grain sterility % and 1,000 grain weight. The current study demonstrates that improvement in Jhinuwa rice landrace is possible by selecting superior accessions from existing natural populations while selection should be focussed to market traits with higher h 2B and GA estimates.  相似文献   
2.
Poultry is an integral part of the rural livelihoods in Cambodia, with more than half of the households keeping poultry in their small-scale, traditional, and extensive backyards. More than 20 highly pathogenic avian influenza (HPAI) outbreaks have been reported since 2004 with deaths of over 21,000 birds. During the HPAI outbreaks, some of the flocks in the rural areas were culled without compensation and producers were not allowed to sell outside of the community. Heifer International worked with 2,000 rural families through local project partners in the target communities to develop an effective intervention mechanism to mitigate the impact of the HPAI crisis. Heifer International provided training, public education, and networking as well as promoting model farms based on improved scavenging poultry management. Each community selected one farm family to serve as a model farm. They were trained in Heifer's working approach and committed to practicing integrated farming systems based on scavenging poultry management. One Village Animal Health Worker (VAHW) in each community participated during the project implementation, playing a key role in the information exchange and the interaction between the communities and the avian influenza experts. Formal and informal trainings were conducted for all project partners and project recipients through experts and VAHWs, respectively. There have been no outbreaks reported in the communities in the project areas. Farmers have started using appropriate techniques to maintain biosecurity. They are passing on the knowledge and the skills to the surrounding communities. This participatory approach in educating rural farmers can serve as a model to mitigate HPAI in the developing countries around the world.  相似文献   
3.
    
We investigated the effects of Arbuscular Mycorrhiza (AM) fungi and various phosphorus (P) levels on the distribution and availability of P in dominant soils of Bihar, India. Potassium chloride (KCl)-P (labile P), sodium hydroxide (NaOH)-P (Fe-Al-bound P), hydrochloric acid (HCl)-P (Ca-bound P), and residual P (Res-P) fractions were analyzed in the soils under maize plant. Ca-bound P was the most abundant P fraction in the alkaline soils (65% of the total P) followed by neutral soil (35% of the total P), whereas it was less abundant (<4%) in the acidic soil type. Fe-Al-bound P was found to be highest for acidic soil (65% of the total P). Soils under the inoculation with Glomus mossae and control gave the highest and lowest values (15.63 mg kg?1 and 10.74 mg kg?1 respectively) for the labile fraction which was similar to the organically bound residual fractions of P (200.17 mg kg?1 and 193.66 mg kg?1 respectively. Inoculation of the soils with AM fungi leads to the redistribution of P fractions in different soils which consequently helps in improvement of available P in soil conducive for plant uptake.  相似文献   
4.
The present study was conducted to evaluate two Indian native chicken breeds, namely, Aseel and Kadaknath for fertility, hatchability, genetic parameters of juvenile growth traits, and semen quality traits at the onset of sexual maturity. The fertility was similar in Aseel (86.96%) and Kadaknath (85.15%); however, a relatively higher hatchability was observed in Kadaknath (77.94%) than Aseel (70.74%). Heritability estimates of body weights at 4 weeks of age were almost similar in Aseel (0.37) and Kadaknath (0.39), while the estimate of body weight at 6 weeks of age was higher in Aseel (0.42) than Kadaknath (0.31). The heritability estimate of shank length at 6 weeks of age was lower in Aseel (0.16) compared to Kadaknath (0.35). The age at first egg in the flock was comparable in Aseel (148 days) and Kadaknath (150 days). Aseel breed with significantly (P ≤ 0.001) higher body weight, absolute and relative testes weights had significantly higher semen volume (P ≤ 0.05) and sperm motility (P ≤ 0.01) but had lower seminal plasma cholesterol level (P ≤ 0.05) as compared to Kadaknath. It can be concluded that there is a scope for genetic improvement of these two native breeds for juvenile growth traits since heritability estimates of these traits were relatively high.  相似文献   
5.
    
Genetic Resources and Crop Evolution - The wild Malus germplasm is considered as a gene reservoir for various biotic and abiotic stresses tolerance/resistance genes, including important novel...  相似文献   
6.
An in vitro propagation method for female plants of Momordica dioica (Roxb.) has been established. The nodal segments were harvested and the cut ends of the explants were sealed with wax and then surface sterilized and cultured. Bud breaking occurred on Murashige and Skoog’s (MS) agar-gelled medium + 2.0 mg L−1 6-Benzylaminopurine (BAP) + 0.1 mg L−1 Indole-3 acetic acid (IAA). The cultures were amplified by passages on MS medium supplemented with 1.0 mg L−1 BAP + 0.1 mg L−1 IAA. Further, shoot amplification (29.2 shoots per vessel) was achieved by subculturing of in vitro regenerated shoot clump on MS medium + 0.5 mg L−1 BAP + 0.1 mg L−1 IAA. The micropropagated shoots were subsequently transferred for root formation on half-strength MS medium + 2.0 mg L−1 Indole-3 butyric acid (IBA) with 89% success rate. The in vitro-regenerated shoots were also rooted ex vitro with 34% success. These plantlets were hardened in the greenhouse and transferred to the field. The established protocol is suitable for true to type cloning of mature female plant of M. dioica.  相似文献   
7.
The chemical composition of essential oils isolated from aerial parts of native populations of Origanum vulgare L. from northwestern Himalaya was investigated by enantioselective gas chromatography (enantio-GC), capillary-gas chromatography (capillary-GC) and GC–MS. Seventy compounds, which accounted for 84.9–97% of the oil composition, have been identified. The oils were allotted to two main groups; the first group had a high percentage of components belonging to the thymol/carvacrol biosynthetic pathway and the second was characterized by a different sesquiterpene composition and a high linalool and bornyl acetate percentage. Essential oils of O. vulgare populations from Rilkot and Dhanachuli areas in northwestern Himalaya were characterized by high monoterpenoids proportions as compared to Nainital and Bhowali populations, which were dominated by sesquiterpenoids. High proportions of thymol (29.2–82%) were found only in two populations. Composition of the samples collected from Dhanachuli area differed from Nainital and Bhowali collections by a unique presence of carvacrol. Notably, there were significant differences in the concentration of rest of the terpenes in all the collections. On enantio-GC, enantiomeric excess for (3R) (−)- and (3S) (+)-linalool, (S) (+)- and (R) (−)-terpinen-4-ol, (S) (−)- and (R) (+)-α-terpineol, (1S) (−)-bornyl acetate and (1S) (−)-borneol were established in populations from Bhowali and Dhanachuli area. Moreover, linalool type oregano may be useful in promoting wider commercial utilization of the biodiversity of this species.  相似文献   
8.
Phytoparasitica - Thrips are economically important pests of crops and vectors of viral diseases worldwide. Invasion and outbreak of thrips have recently caused havoc in agricultural and...  相似文献   
9.
To evaluate different crosses and purebreds ducks in respect to various economic traits and to estimate different crossbreeding genetic parameters, a 3?×?3 complete diallel cross involving indigenous duck (DD), Khaki Campbell (KK) and White Pekin (WW) were used to produce three purebreds (DD, KK, WW) three crossbreds (DK, DW, KW) and three reciprocals (KD, WD, WK). A total of 609 ducklings produced were reared on deep litter and the females (316 in number) were evaluated for growing and laying period body weight along with the production performance traits. Different crossbreeding genetic parameters were estimated for different traits. All the traits in respect to body weight gain during growing and laying period and different production traits including laying house mortality rate showed significant (p?≤?0.05) difference between different genetic groups. In general, crossbreds perform better than the purebreds for most of the traits studied. General combining ability (GCA), specific combining ability (SCA) and reciprocal effect (RE) were significant (p?≤?0.01) for body weight and production traits. Egg weight showed significant (p?≤?0.01) difference in respect to GCA, SCA and RE for all the ages of measurement except RE for 30th week egg weight. Laying period mortality rate was only significant (p?≤?0.05) for SCA. Most of the crossbreds recorded heterosis rate in desirable direction for majority of the traits. Overall results revealed that the crossbreds perform well in respect to different traits than the purebreds and may be used to take advantage of heterosis. DW performs well in respect to majority of the traits measured and is of importance for commercial exploitation. Further, pure line selection with development of specialised sire and dam line followed by crossing may be of importance to enhance the performances in the crosses.  相似文献   
10.
    
There is evidence to suggest that poultry may have a dietary requirement for metabolically available chromium (Cr) that exceeds the amount provided through wheat soybean meal diets. The objective of the present study was to investigate the effects of dietary supplemental organic Cr from Cr propionate at different dose levels (control = 0 μg/kg, T1 = 200 μg/kg, T2 = 400 μg/kg) on the growth performance, carcass traits, and meat quality of broilers. Weight gain and feed intake of each treatment were recorded at the start and after 14, 28 and 35 d, and feed conversion ratios (FCR) were calculated accordingly. At 35 d of age, birds were randomly selected and euthanized for carcass evaluation. Results of the first trial indicate that both Cr propionate treatments increased final body weight (P < 0.05), feed efficiency (P < 0.05) and body weight gain (P < 0.0001). Furthermore, Cr propionate supplementation improved (P < 0.0001) all carcass characteristics. Interestingly, with increased Cr dosage, carcass yield, dressing percentage and breast meat yield increased linearly (P < 0.0001). The second study reveals that the feed intake in the control group was significantly higher compared to both Cr propionate supplemented groups (T1 & T2). Furthermore, the Cr propionate supplemented T2 group displayed a significantly lower FCR than the control and T1 group (P = 0.027). Finally, Cr propionate supplementation increased the dressing percentage compared to control birds (P < 0.0001). In the third experiment, Cr propionate supplementation (T1 & T2) increased final body weight and decreased FCR compared with the control treatment. These effects were highly significant (P < 0.0001) throughout all feeding phases of the trial. Cr propionate supplementation also increased (P < 0.0001) carcass yield, dressing percentage, breast meat yield, leg and thigh weights compared with the control treatment. In conclusion, growth performance, feed conversion, carcass yield, breast and leg meats of broiler birds can be significantly improved by dietary inclusion of Cr propionate. Cr propionate can be supplemented to broiler birds from 1 d old of age at a level that provides 200 or 400 μg/kg organic Cr and can increase the efficiency of broiler production.  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