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   89篇
  免费   7篇
林业   2篇
  6篇
综合类   8篇
农作物   1篇
水产渔业   3篇
畜牧兽医   67篇
园艺   2篇
植物保护   7篇
  2023年   1篇
  2020年   5篇
  2019年   1篇
  2018年   1篇
  2017年   3篇
  2016年   6篇
  2015年   1篇
  2014年   1篇
  2013年   6篇
  2012年   1篇
  2011年   2篇
  2010年   5篇
  2009年   3篇
  2008年   3篇
  2007年   5篇
  2006年   3篇
  2005年   7篇
  2004年   1篇
  2002年   4篇
  2001年   5篇
  1999年   2篇
  1998年   1篇
  1997年   7篇
  1996年   7篇
  1995年   2篇
  1994年   2篇
  1993年   3篇
  1992年   1篇
  1991年   1篇
  1990年   2篇
  1989年   1篇
  1988年   1篇
  1983年   1篇
  1976年   1篇
排序方式: 共有96条查询结果,搜索用时 62 毫秒
51.
The histopathology, immunohistochemistry and ultrastructure of the alimentary canal of chub, Leuciscus cephalus (L.), from the River Brenta, naturally infected with the acanthocephalan Pomphorhynchus laevis Müller, 1776, was studied and described. Of 62 chub examined, 54 (87%) were infected with P. laevis ; the intensity of infection ranged from five to 130 parasites per host, and a density of 8 P. laevis per cm2 was common. Examination of histological material of infected chub revealed that both male and female acanthocephalans deeply penetrated all layers of the gut wall by means of their slender neck, bulb and proboscis. As a result, a capsule was formed around the bulb and proboscis on the external surface of the host intestine. In parasitized chub, four main types of reaction against the body of the acanthocephalan were recognized. Pomphorhynchus laevis caused local damage to the intestinal wall, eliciting catarrhal-erosive enteritis in the lumen and a fibroblastic-collagenous and fibro-epithelioid encapsulation in its thickness with tissue zonation according to the depth of parasite penetration. Furthermore, eosinophilic granular cells (EGC) within the inflammatory tissue were identified by immunohistochemical methods and transmission electron microscopy.  相似文献   
52.
53.
The objective of this study was to evaluate the effect of retinol (RT) and retinoic acid (RA) on the in vitro development of pre‐implantation goat embryos cultured in potassium simplex optimized medium or synthetic oviduct fluid or cocultured in oviductal cells monolayer either in potassium simplex optimized medium or synthetic oviduct fluid. A total of 2407 cumulus‐oocyte complexes were aspirated from 2 to 6 mm ovarian follicles from slaughtered animals. Selected cumulus‐oocyte complexes were subjected to in vitro maturation in TCM 199 for 24 h at 39°C in an atmosphere of 5% (v/v) CO2 in humidified air. In vitro fertilization was performed in modified defined medium. Eighteen hours after in vitro fertilization, cumulus cells were removed and presumptive zygotes were randomly distributed into experimental groups. In Experiment 1, presumptive zygotes were cultured in potassium simplex optimized medium, potassium simplex optimized medium + RT, potassium simplex optimized medium + retinoic acid, synthetic oviduct fluid, synthetic oviduct fluid + RT and synthetic oviduct fluid + RA at 39°C in a humidified atmosphere of 5% (v/v) CO2, 5% (v/v) O2 and 90% (v/v) N2. In Experiment 2, presumptive zygotes were cocultured in potassium simplex optimized medium + oviductal cells monolayer, potassium simplex optimized medium + RT + oviductal cells monolayer, potassium simplex optimized medium + RA + oviductal cells monolayer, synthetic oviduct fluid + oviductal cells monolayer, synthetic oviduct fluid + RT + oviductal cells monolayer and synthetic oviduct fluid + RA + oviductal cells monolayer in an atmosphere of 5% (v/v) CO2 in humidified air. In both experiments, media were partially changed on day 2 after in vitro fertilization and unfertilized oocytes were excluded from the experiment. Embryos were cultured or cocultured for 8 days. In Experiment 1, there was no effect of RT or RA supplementation on the proportion of oocytes that reached the morula or blastocyst stages. By contrast, Experiment 2 demonstrated that the addition of 0.28 μg/ml RT and 0.5 μm RA to the embryo culture media stimulated (p < 0.05) development to the morula and blastocyst stages under the coculture conditions tested. In conclusion, retinoids play an important role in pre‐implantation development of goat embryos and can be used to enhance in vitro embryo production.  相似文献   
54.
Objective To perform in vivo analysis of retinal functional and structural parameters in healthy mouse eyes. Animal Studied Adult C57BL/6 male mice (n?=?37). Procedures Retinal function was evaluated using pattern electroretinography (pERG) and the chromatic pupil light reflex (cPLR). Structural properties of the retina and nerve fiber layer (NFL) were evaluated using spectral-domain optical coherence tomography (SD-OCT). Results The average pERG amplitudes were found to be 11.2?±?0.7?μV (P50-N95, mean?±?SEM), with an implicit time for P50-N95 interval of 90.4?±?5.4?ms. Total retinal thickness was 229.5?±?1.7?μm (mean?±?SEM) in the area centralis region. The thickness of the retinal nerve fiber layer (mean?±?SEM) using a circular peripapillary retinal scan centered on the optic nerve was 46.7?±?0.9?μm (temporal), 46.1?±?0.9?μm (superior), 45.8?±?0.9?μm (nasal), and 48.4?±?1?μm (inferior). The baseline pupil diameter was 2.1?±?0.05?mm in darkness, and 1.1?±?0.05 and 0.56?±?0.03?mm after stimulation with red (630?nm, luminance 200?kcd/m(2) ) or blue (480?nm, luminance 200?kcd/m(2) ) light illumination, respectively. Conclusions Pattern electroretinography, cPLR and SD-OCT analysis are reproducible techniques, which can provide important information about retinal and optic nerve function and structure in mice.  相似文献   
55.
Congenital portosystemic shunts in Maltese and Australian Cattle Dogs   总被引:2,自引:0,他引:2  
SUMMARY Congenital portosystemic shunts were definitively diagnosed in 62 dogs over a period of 15 years. Maltese and Australian Cattle Dogs were significantly over-represented, accounting for 14 and 13 cases, respectively. Maltese invariably had a single extrahepatic shunt derived from the left gastric or gastrosplenic vein, whereas Cattle Dogs usually had large intrahepatic shunts involving the right liver lobes. The clinical syndromes resulting from anomalous portosystemic communications were indistinguishable in the 2 breeds. Fasting blood ammonia concentration was elevated in 20 of 22 dogs tested, providing a minimally invasive and effective means of diagnosis. Complete or partial shunt attenuation was performed successfully in all 9 Maltese and in 2 of 6 Cattle Dogs in which it was attempted.  相似文献   
56.
57.
The effects of the botanical insecticides Biopiren plus, Piresan plus and Neemazal T/S on the predatory mite Amblyseius andersoni (Chant) were tested under laboratory, semi-field, and field conditions. The tests carried out in the laboratory allowed detection of the direct toxicity on eggs and females as well as the effects on fecundity, whereas semi-field trials assessed their residual toxicity. In laboratory and semi-field tests, pyrethrins, particularly Piresan plus, proved to have the highest toxicity with E value, concerning both female mortality and fecundity, of 100% and 45%, respectively. The same product tested in the field only caused a significant reduction in the phytoseiid population shortly after the treatment. The relevant escape rate registered in semi-field tests could explain the lack of phytoseiid eradication in the field after treatment with pyrethrins.  相似文献   
58.
The effects of the botanical insecticides Biopiren plus, Piresan plus and Neemazal T/S on the predatory mite Amblyseius andersoni (Chant) were tested under laboratory, semi-field, and field conditions. The tests carried out in the laboratory allowed detection of the direct toxicity on eggs and females as well as the effects on fecundity, whereas semi-field trials assessed their residual toxicity. In laboratory and semi-field tests, pyrethrins, particularly Piresan plus, proved to have the highest toxicity with E value, concerning both female mortality and fecundity, of 100% and 45%, respectively. The same product tested in the field only caused a significant reduction in the phytoseiid population shortly after the treatment. The relevant escape rate registered in semi-field tests could explain the lack of phytoseiid eradication in the field after treatment with pyrethrins.  相似文献   
59.
响应面法优化姬松茸液体发酵培养基中红糖和酵母膏浓度   总被引:6,自引:0,他引:6  
运用响应面分析法优化姬松茸液体发酵培养基中红糖和酵母膏浓度.结果表明,红糖浓度为20.24g/L、酵母膏浓度为2.055g/L时,菌丝体生物量最高,达2.279g/L;红糖浓度为20.8g/L、酵母膏浓度为2.23g/L时,胞外多糖产量最高,达0.749g/L.  相似文献   
60.
A free-living mouflon (Ovis musimon) was presented with a mass on the left shoulder. At necropsy, multifocal, slightly protruding whitish spots were noted on the kidneys, and several lymph nodes were abnormal. Histologically, the mass was composed of epithelial cells arranged in tubular and tubulopapillary structures. The cytoplasm of the epithelial cells had numerous periodic acid-Schiff-positive and diastase-resistant granules. Ultrastructurally, the cytoplasm of the neoplastic cells contained numerous pleomorphic secretory granules and microvilli, which partially covered the luminal surface of the tumor cells. Metastatic foci were present in prescapular and mediastinal lymph nodes and kidneys. On the basis of histological and ultrastructural findings, this tumor was diagnosed as a tubulopapillary adenocarcinoma, arising from apocrine sweat glands of the skin.  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