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   50篇
  免费   2篇
农学   1篇
  11篇
综合类   2篇
农作物   6篇
水产渔业   6篇
畜牧兽医   23篇
植物保护   3篇
  2021年   5篇
  2020年   5篇
  2019年   5篇
  2018年   4篇
  2017年   6篇
  2016年   1篇
  2014年   1篇
  2013年   3篇
  2012年   5篇
  2011年   4篇
  2010年   2篇
  2008年   5篇
  2007年   2篇
  2004年   1篇
  2002年   1篇
  1995年   1篇
  1984年   1篇
排序方式: 共有52条查询结果,搜索用时 750 毫秒
1.
This experiment was designed to investigate and compare the egg production, fertility, hatchability and immune responses of some local developed Egyptian chicken strains under high ambient temperatures. A total of 108 (26 weeks old) laying hens of Matrouh, Silver Montazah, Mandarah and Inshas (9 hens × 3 replicates × 4 strains) were used to evaluate the impact of thermal stress (24-34ºC) during summer season (June, July and August) on egg production, fertility, hatchability and immune responses. The obtained results revealed that final body weight (FBW/g) and body weight change (BWC/g) among different chicken strains were not affected. The daily feed consumption (FC/g) and feed conversion ratio (FCR) for Silver Montazah and Inshas strains were significantly (p ≤ .05) higher than those of Matrouh and Mandarah strains. The mean egg production (EP/%) and egg mass (EM) for Silver Montazah and Inshas strains were significantly (p ≤ .05) higher than those of Matrouh and Mandarah strains. The highest percentages of hatchability of total eggs (HTE) and fertile eggs (HFE) were recorded in Inshas chickens, while the lowest value was recorded in Mandarah chickens. Also, the highest embryonic mortalities (p ≤ .05) and lowest chick weight at hatch (CWH/g) were recorded in Mandarah chickens compared with the other strains. The highest values for antibody titres against phytohemagglutinin-P (PHA-P) were recorded in Mandarah chickens, while the least values were recorded in Inshas chickens.  相似文献   
2.
3.
Eimeria dorcadis Mantovani, 1966 is redescribed from dorcas gazelle (Gazella dorcas (L.)) from Saudi Arabia. Oocysts were detected in 7 out of 22 faecal samples (32%) using floatation method. The sporulated oocysts are cylindrical, slightly flattened at the micropylar pole, measure in average 32 x 19 microm (27-36 x 16-24 microm), length/width ratio being 1.7 (1.5-2.1). Oocyst wall is 1.2 microm thick, smooth, double-layered; outer layer is slightly thicker, light blue in colour; inner layer brownish, with micropyle in the inner layer and apparently continual outer one, measures 2.2 microm, but lacks a micropylar cap. The sporocyst elongate-ellipsoidal, measures 14 x 8 microm (12-17 x 6-9 microm), length/width ratio being 1.8, with sporocyst residuum as circular compact, coarse, refractile granules. Stieda body is present, while substieda body is absent. Sporozoites banana-shaped, measure 11 x 2.5 microm, each with a large spheroidal refractile body at the wider pole. Sporulation time is 2-3 days at 25 +/- 2 degrees C.  相似文献   
4.
Hg and As are widespread contaminants globally and particularly in Asia. We conducted a field study in Baiyangdian Lake, the largest lake in the North China Plain, to investigate bioaccumulation and trophic transfer of potentially toxic metals (total mercury and arsenic) in sites differing in proximity from the major point sources of nutrients and metals. Hg concentrations in fish and As concentrations in water are above critical threshold levels (US Environmental Protection Agency based) considered to pose some risk to humans and wildlife. Hg concentrations in biota are within the range of concentrations in lakes in the Northeast US despite the high levels of Hg emission and deposition in China whereas As concentrations are much higher. Dissolved concentrations of both Hg and As decrease with increasing chlorophyll concentrations suggesting that there is significant uptake of metal from water by algae. These results provide evidence for algal blooms controlling dissolved metal concentrations and potentially mitigating the trophic transfer of Hg to fish. This study also underscores the need for further investigation into this contaminated ecosystem and others like it in China that are an important source of fish and drinking water for consumption by local human populations.  相似文献   
5.
The efficacy of two broad spectrum anthelmintics (Ivermectin and Levamisole) against the nematode Nematodirus spathiger in the reem (Arabian sand gazelle) and idmi (Arabian mountain gazelle) at King Khalid Wildlife Research Centre (KKWRC) was determined. Gazelles of both species naturally infected with N. spathiger were each divided into 3 groups. One group was treated with Ivermectin, the other group with Levamisole and the last group was left as untreated control. Faecal egg counts were employed to determine the efficacy of the two drugs against N. spathiger infection in both gazelle species. Reduction in arithmetic mean faecal egg counts achieved by Ivermectin and Levamisole in the reem gazelles was 94% and 89.3%, respectively. The reduction in the idmi gazelles was 97.2% and 96.4%, respectively. Hence, both anthelmintics appeared to be more effective in the idmi gazelles than in the reem gazelles, however, there was no significant difference in the faecal egg reduction tests in both animal species.  相似文献   
6.
Purpose: The purposes of this study were to determine the effect of matrine on the migration and the colonization dynamics of the two fluorescent-tagged rhizobia in Gannong No.5 alfalfa (Medicago sativa L. Gannong No. 5) tissues, and also to determine the effect of the combination treatments on alfalfa seedlings’ growth.

Materials and methods: 0, 100, 200, 300 and 400 mg L?1 matrine levels were added into two cyan fluorescent protein (CFP)-tagged rhizobia; Ensifer meliloti LZgn5f (gn5f) and Ensifer meliloti 12531f (12531f), respectively; and drenched the alfalfa root with the inoculants. Then the migration and colonization of the two rhizobia in alfalfa on D7, D14, D21 and D28, and subsequently seedling growth were investigated.

Results: The results showed that the optimum matrine level enhanced the colonization of both fluorescent-tagged rhizobia in alfalfa roots and the highest colonization densities of log 6.31 cfu g?1 and log 5.87 cfu g?1 were achieved by adding 300 mg L?1 matrine into 12531f and adding 100 mg L?1 matrine into gn5f, respectively. They could migrate to the aerial tissues and most colonize stems through the application of adding 300 mg L?1 matrine into 12531f and 100 mg L?1 matrine into gn5f, respectively. No fluorescent-tagged rhizobia were detected in the control treatment. Alfalfa seedling growth parameters like leaf chlorophyll content, seedling growth rate, root length, seedling biomass and total N percentage also increased the most when 300 mg L?1 matrine was added into 12531f and 100 mg L?1 matrine added into gn5f treatments.

Conclusions: Our results suggest that 300 mg L?1 matrine added into 12531f and 100 mg L?1 matrine added into gn5f might be exploited to promote the colonization of rhizobia in alfalfa tissue and positively impact growth and yield, indicating possible benefits for plant cultivation.  相似文献   
7.
Effects of sodium nitroprusside (SNP; nitric oxide donor) treatments on enhancement of secondary metabolites production, oxidative stress mediators (\(\mathrm{O}_{2}^{-}\)) accumulation and antioxidant defense enzymes of Potato Spunta Sp. suspension culture cells elicited by a fungal extract from phytophthora infestans mycelium. The obtained data confirmed the significant increase in various oxidative burst (super oxide anion, hydrogen peroxide and total glutathione) contents. The administration of various NO concentrations strongly decreased hydrogen peroxide concentration and superoxide anion levels. Moreover, the SNP treatments regulate elicitor-induced activation of phenylalanine ammonium-lyase and total soluble phenols accumulation. The highest concentrations of NO donor sodium nitroprusside potentiated elicitor-induced H2O2 production. On the other hand, the lowest H2O2 contents coincided with elicitation regulated various activities of enzymes superoxide-dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and Phenyl alanine ammonia lyase (PAL) activity, the decrease in H2O2 concentration was probably due to a direct reduction interaction of NO-H2O2. On the other hand, the addition of these previous NO treatments affects mRNA peroxidase gene expression using RT-PCR techniques. In general, the addition of lower concentrations of nitric oxide reduce the mRNA peroxidase activity on contrary, the higher concentrations induced the mRNA peroxidase activity, which induce the hypersensitive reactions against fungus infection.  相似文献   
8.
This investigation was carried out to study the susceptibility of Saudi Biomphalaria arabica to Egyptian Schistosoma mansoni in comparison with the susceptibility of Egyptian Biomphalaria alexandrina to the same parasite. This was in order to know the possibility that the parasite might be able to spread into Saudi Arabia and to determine the genetic variability between Egyptian B. alexandrina and Saudi Biomphalaria arabica snails. Lab bred Egyptian B. alexandrina and Saudi B. arabica snails were exposed individually to 10 freshly hatched Egyptian S. mansoni miracidia/snail. The mortality rate, infection rate, prepatent period, duration of cercarial shedding and cercariae production per snail were recorded in both the sympatric couple (Egyptian B. alexandrina and Egyptian S. mansoni) and in the allopatric combination (Saudi B. arabica and Egyptian S. mansoni). The results revealed that, the survival rate of snails exposed to Egyptian S. mansoni miracidia at 34th day post-exposure (at first cercarial shedding) was higher in B. arabica than in B. alexandrina. After shedding, the mortality rate was higher in the B. arabica, compared to B. alexandrina. The infection rate was higher in B. arabica than B. alexandrina; the mean of prepatent period was shorter in the B. arabica than in the B. alexandrina. However, the duration of cercarial shedding was longer in the Egyptian snails and the cercarial production per snail was higher in B. alexandrina snails than in B. arabica. To study the genetic variability between B. alexandrina and B. arabica, RAPD-PCR on the genomic DNA of snails was done. RAPD-PCR revealed significant variation between the two snail species. In conclusion, the results suggest that B. arabica can play a role in the transmission of Egyptian S. mansoni in Saudi Arabia and therefore this parasite might be able to spread into the Kingdom. In addition, the RAPD-PCR results demonstrated genetic variability between the two species which may be related to the differences in susceptibility of both Saudi and Egyptian Biomphalaria snails to Egyptian S. mansoni infection.  相似文献   
9.
Tropical Animal Health and Production - Contagious caprine pleuropneumonia (CCPP) is one of the most fatal and contagious diseases of goats. To date, the occurrence of CCPP in Egypt has not been...  相似文献   
10.
Deficit irrigation has been widely investigated as a valuable strategy for dry regions where water is the limiting factor in crop cultivation. Soil moisture can be one of the important factors that influence root-knot nematode (RKN) disease development. To determine how different levels of irrigation can affect disease development, irrigation regimes ranging from 20% to full field capacity (FC) were applied to tomato and eggplant plants inoculated with Meloidogyne javanica (M. javanica) under controlled conditions. In addition, in vitro bioassays were done to evaluate the effect of water potential and soil moisture content on M. javanica viability in the soil and reproduction on plant hosts. The relative egg hatching percentage decreased significantly with decreasing water potential from –0.1 to –1 MPa. The use of 80% irrigation level caused minor reductions in growth but significantly reduced nematode infection load. Nematode infection was reduced even further at lower levels of irrigation, however this also led to marked reductions in fresh and dry weights of the tomato and eggplants. Therefore, deficit irrigation could be used at a rate of 80% or 60% of FC to increase water use efficiency and reduce the level of RKN (M. javanica) infection without greatly reducing the growth performance of tomato and eggplant crops.  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