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   14篇
  免费   2篇
农学   1篇
  3篇
综合类   1篇
农作物   2篇
水产渔业   1篇
畜牧兽医   5篇
植物保护   3篇
  2021年   2篇
  2020年   1篇
  2019年   1篇
  2016年   1篇
  2015年   2篇
  2011年   1篇
  2010年   1篇
  2009年   1篇
  2008年   1篇
  2006年   1篇
  2005年   1篇
  2003年   1篇
  1998年   1篇
  1980年   1篇
排序方式: 共有16条查询结果,搜索用时 15 毫秒
1.
A 43 yr-old female African elephant (Loxodonta africana) collapsed acutely and died. Necropsy revealed an enlarged right adrenal medulla. Histologic appearance was typical of pheochromocytoma. Special stains and electron microscopy demonstrated chromaffin granules, suggesting that the tumor was derived from catecholamine secreting cells of the adrenal medulla, and may have been functionally secretory. Serum levels of both norepinephrine and epinephrine were elevated at time of death, supporting the functional nature of the tumor. Histologic findings of arteriolar sclerosis and smooth muscle hyperplasia suggested that the animal may have suffered from chronic systemic hypertension. Pheochromocytoma should be considered as a differential diagnosis in cases of suspected hypertension and acute death in elephants.  相似文献   
2.
This study analyses the role of variability induced by climate and soil properties (texture and total available soil water in the root zone, TAW) on the “corn deficit irrigation–water use efficiency” relation over a 25-year period, between 1981 and 2005, in three different sites located in the South of Italy. The analysis of water use efficiency was carried out by means of three indexes: crops water use efficiency (WUEET and WUET) and irrigation water use efficiency (IWUE). These indexes can be obtained by calculating the ratio between the yield and the seasonal values of evapotranspiration (ET), transpiration (T) and irrigation volume (I). After its validation, the STICS model was retained to simulate the variables required to determine these indexes.Climatic variability affected the three indexes in different ways during the 25-year period studied. The dispersion around the mean values of the water use efficiency is 17% on average for the WUE (ET or T) indexes, whereas it could reach 54% for the IWUE index. This last index is only poorly reliable due to the high variability of rainfall during the corn growing season in the Mediterranean region.For the same level of soil water deficit, TAW led to an improvement (the case of the site with a high TAW and loam–clay soil texture), a stabilisation (the case of the site with a high TAW and clay soil texture) or a decrease (the case of the site with a poor TAW and clay soil texture) in WUEET and WUET values. For the same conditions of soil water deficit and TAW, crops water use efficiency was higher in loam textured soil than in clay soil.The results derived by analyzing three indexes (WUEET, WUET and IWUE) converge to the same conclusions on the “corn deficit irrigation–water use efficiency” relation observed at the three different sites.The hypotheses which may explain the differences observed in the different sites studied in terms of water use efficiency are discussed, with the presentation of some suggestions devised for corn irrigation practices.  相似文献   
3.
Tropical Animal Health and Production - A cross-sectional study was conducted to determine the seroprevalence and the risk factors associated with C. burnetii infection in cattle in the state of...  相似文献   
4.
Tropical Animal Health and Production - The objective of this work was to study the effect of the incorporation of argane by-products (meal and pulp) in ewe’s diet on the production and...  相似文献   
5.
Studies were conducted on the properties of seeds and oil extracted from Maclura pomifera seeds. The following values (on a dry-weight basis) were obtained for M. pomifera seed, respectively: moisture 5.88%, ash 6.72%, oil 32.75% and the high protein content 33.89%. The carbohydrate content (20.76%) can be regarded as a source of energy for animals if included in their diets. The major nutrients (mg/100 g oil) were: potassium (421.65), calcium (218.56) and magnesium (185.00). The physicochemical properties of the oil include: the saponification number 174.57; the iodine value 141.43; the p-anisidine value 1.86; the peroxide value 2.33 meq O2/kg; the acid value 0.66; the carotenoid content 0.59 mg/100 g oil; the chlorophyll content 0.02 (mg/100 g oil) and the refractive index 1.45. Polymorphic changes were observed in thermal properties of M. pomifera seed oil. This showed absorbency in the UV-B and UV-C ranges with a potential for use as a broad spectrum UV protectant. The main fatty acids of the crude oil were linoleic (76.19%), oleic (13.87%), stearic (6.76%) and palmitic acid (2.40%). The polyunsaturated triacylglycerols (TAGs) LLL, PLL, POL + SLL, OLL, OOL (L: linoleic acid, O: oleic, P: palmitic acid and S: stearic acid) acids were the major TAGs found in M. pomifera seed oil. A relatively high level of sterols making up 852.93 mg/100 g seed oil was present. The sterol marker, β-sitosterol, accounted for 81% of the total sterol content in the seed oil and is followed by campesterol (7.4%), stigmasterol (4.2%), lupeol (4.1%) and Δ5-avenesterol (3.2%). The seed oil was rich in tocopherols with the following composition (mg/100 g): α-tocopherol 18.92; γ-tocopherol 10.80; β-tocopherol 6.02 and δ-tocopherol 6.29. The results showed that M. pomifera seed oil could be used in cosmetic, pharmaceutical and food products.  相似文献   
6.
This study tested the effect of melatonin treatment, initiated in late February on reproductive traits of young rams. A total of 14 young Barbarine rams were used. Seven animals were treated with three melatonin subcutaneous implants (Melatonin) on 28 February while the remaining rams remained untreated (Control). After 60 days of melatonin administration, scrotal circumference reached average values of 32.1 ± 1.54 and 29.5 ± 1.0 cm for Melatonin and Control animals, respectively (P < 0.05). Semen characteristics did not differ between groups; melatonin treatment tended (P = 0.091) to increase sperm concentration 60 days after implantation when means reached 5.87 ± 0.703 and 4.61 ± 0.654 × 109 spermatozoa/mL for Melatonin and Control rams, respectively. Melatonin treatment significantly affected total activity time, number of lateral approaches and mount attempts in comparison to controls. During a 6‐h sampling period, mean plasma testosterone concentrations increased as a result of melatonin treatment (P < 0.001) and testosterone pulse frequency averaged 3.45 ± 2.24 and 1.25 ± 1.0 (P = 0.086) for Melatonin and Control rams. Data clearly suggest that abrupt treatment of young rams with melatonin implants in winter is sufficient to improve reproductive traits.  相似文献   
7.
海岛棉品种资源研究现状与展望   总被引:1,自引:0,他引:1  
文中概速了新疆吐鲁番棉区海岛棉品种资源研究的现状.其内客包含海岛棉品种资源的收集,整理,保存.研究方法.性状与品质鉴定.在育种工作上的利用.井提出了今后研宄的主要方向等同题.  相似文献   
8.

The family Botryosphaeriaceae is one of the most widespread and cosmopolitan endophytic group of fungi. Every year, species of this family cause severe damages on table and wine grape production, worldwide. However, this threat is still poorly known in Algeria. In this study, a large number of Botryosphaeriaceae-like isolates were obtained from symptomatic grapevines collected from eight regions with different ecological conditions, namely: Boumerdès, Médéa, Algiers, Tipaza, El Taref, Sidi Bel Abbes, Biskra and Adrar. The isolates were identified using DNA sequences of the translation elongation factor (tef1-α) and internal transcribed spacer (ITS) regions. Eleven species belonging to six genera, including Neofusicoccum parvum, N. algeriense, N. vitifusiforme, N. stellenboschiana, N. luteum, Diplodia seriata, D. olivarum, Lasiodiplodia theobromae, Dothiorella sarmentorum, Botryosphaeria dothidea and Neoscytalidium dimidiatum were identified. The spatial distribution of the Botryosphaeriaceae showed that D. seriata and N. stellenboschiana were the most widespread in the Algerian vineyards, while L. theobromae was recorded in the desert region of Biskra. Pathogenicity trials showed that all species were pathogenic on detached green shoots of grapevine, with N. parvum and L. theobromae being the most aggressive.

  相似文献   
9.
10.
We report the impact of human-induced desertification on the species richness, abundance, and composition of sand dune flora and herpetofauna of North Sinai, Egypt. Our hypothesis was that degraded habitats would have reduced vegetation complexity, richness, and abundance, and consequently lower reptile species richness and abundance. We also hypothesized that desert lizards would not follow the typical generalist/specialist responses to habitat degradation found in other biomes. Instead, we predicted that because vegetation loss intensifies the environmental extremity of deserts, those species specialized for open and sandy environments would be more likely to persist in desertified habitats than would desert generalists. Our results showed that areas protected from vegetation loss did not have significantly higher vegetation richness or abundance except for only a few species. However, protected sites did have significantly higher percent vegetation cover and height. Habitat protection clearly had strong effects on the reptile community as species richness and abundances were significantly higher in protected sites. The composition of the reptile community between protected and unprotected sites differed significantly. Contrary to past studies in other environments, desert generalist species were not able to persist in degraded sites and were only found in protected sites. Specialist species were ubiquitous in that they occurred in both areas protected and unprotected from vegetation loss. We propose that the effects of disturbance on species composition (specialists or generalists) depends on whether the disturbance exacerbates or reduces environmental harshness and the conditions that favor specialization. In extreme environments, specialist and generalist responses to habitat degradation are opposite to that of more productive environments.  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