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   123篇
  免费   2篇
林业   1篇
农学   4篇
  11篇
综合类   2篇
农作物   5篇
水产渔业   7篇
畜牧兽医   92篇
园艺   1篇
植物保护   2篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2018年   1篇
  2017年   1篇
  2016年   3篇
  2015年   2篇
  2013年   4篇
  2011年   3篇
  2010年   1篇
  2009年   1篇
  2008年   1篇
  2006年   3篇
  2005年   7篇
  2004年   4篇
  2003年   3篇
  2002年   2篇
  2001年   2篇
  2000年   4篇
  1999年   3篇
  1998年   1篇
  1996年   2篇
  1992年   7篇
  1991年   3篇
  1990年   4篇
  1989年   1篇
  1988年   7篇
  1987年   8篇
  1986年   4篇
  1985年   4篇
  1984年   4篇
  1983年   3篇
  1982年   1篇
  1981年   2篇
  1979年   4篇
  1978年   1篇
  1977年   5篇
  1975年   1篇
  1974年   1篇
  1972年   1篇
  1971年   1篇
  1970年   4篇
  1969年   2篇
  1968年   2篇
  1966年   3篇
排序方式: 共有125条查询结果,搜索用时 31 毫秒
21.
22.
Paecilomycosis in a dog   总被引:1,自引:0,他引:1  
  相似文献   
23.
24.
Mounting evidence has revealed pathological interactions between HIV and malaria in dually infected patients, but the public health implications of the interplay have remained unclear. A transient almost one-log elevation in HIV viral load occurs during febrile malaria episodes; in addition, susceptibility to malaria is enhanced in HIV-infected patients. A mathematical model applied to a setting in Kenya with an adult population of roughly 200,000 estimated that, since 1980, the disease interaction may have been responsible for 8,500 excess HIV infections and 980,000 excess malaria episodes. Co-infection might also have facilitated the geographic expansion of malaria in areas where HIV prevalence is high. Hence, transient and repeated increases in HIV viral load resulting from recurrent co-infection with malaria may be an important factor in promoting the spread of HIV in sub-Saharan Africa.  相似文献   
25.
Cystic thymoma was diagnosed in 14 cats in a period of 6 years. The most common clinical sign was laboured breathing. The tumours were characterized by various-sized cystic spaces with central vessels. The epithelial cells varied from oval to spindle to polygonal cells enclosing cystic spaces or in pure epithelial cell components. The nuclei of the neoplastic cells had scattered chromatin and small nucleoli. The cytoplasm was pale eosinophilic. The concentration of mature lymphocytes varied from area to area with rare germinal centres. Immunohistochemically, the epithelial cells stained only with AE(1)/AE(3). The central vessels were positive for vimentin, smooth muscle actin, and factor VIII antigen. Electron microscopy revealed that the cyst walls were lined by epithelial cells that were joined by desmosomes, and the walls were well separated from the cystic spaces by a well-defined basement membrane. The neoplastic epithelial cells contained scattered tonofilaments. Three of the cats had metastasis to the lymph nodes and lungs. Two novel cases of ectopic cystic thymoma have also been described. Results of this study reveal that cystic thymoma is uncommon in cats, and that the histomorphologic, immunohistochemical, and electron microscopic features are similar to those of cystic thymoma in humans.  相似文献   
26.
Dietary acidifiers have been recognized as beneficial in animal production including aquacultural production of fish where they confer such benefits as improved feed utilization, growth, and resistance to bacterial pathogens. If improvements in growth and immune responses by acidifier supplementation can be confirmed in shrimp, then mortalities due to diseases could be minimized, limiting the emergence of disease‐resistant bacterial pathogens as a potential result of antibiotic misuse. With this in mind, a 35‐d feeding trial was conducted to evaluate growth, enteric microbiota populations, and nonspecific immune responses of Litopenaeus vannamei fed diets containing the commercial acidifier Vitoxal, based on acidic calcium sulfate in an indoor temperature‐controlled, recirculating culture system without any natural productivity. Experimental diets were formulated to contain 0 (basal), 0.4, 1.2, 1.6, or 2.0% acidic calcium sulfate (ACS) by weight. Shrimp fed in excess, 15 times a day using automatic feeders. Weight gain and survival among treatments were excellent, but not significantly different (P > 0.05). Denaturing gradient gel electrophoresis analysis revealed that the enteric microbial community of shrimp fed the basal diet differed markedly from those fed the acidifier on the basis of 64.9% similarity coefficient. Shrimp fed the commercial acidifier at 1.2 and 2.0% responded significantly (P < 0.05) better to reduced stress and displayed enhanced immune responses including hemocyte phagocytic capacity, hemolymph protein concentration, hyaline cell counts, and hemolymph glucose, compared with shrimp fed the basal diet. These results point to an enhanced performance in terms of positive shifts in the composition of enteric microbial communities as well as improved immune performance, with no changes in growth or survival.  相似文献   
27.
Aquaculture International - Lectin protein families are diverse and multi-functional in crustaceans. The carbohydrate-binding domains (CRDs) of lectins recognize the molecular patterns associated...  相似文献   
28.
A 35‐day feeding trial was conducted to evaluate growth, bacterial populations of the gastrointestinal tract (GIT) and immune responses of Litopenaeus vannamei fed diets containing the commercial prebiotic Previda®. Diets were formulated to contain Previda® at 0, 0.2, 0.5, 1.0 or 1.6 g kg?1 by weight. At the end of the study, differences in weight gain and survival among treatments were not significant (> 0.05), but denaturing gradient gel electrophoresis analysis revealed that the microbial communities in the GIT changed significantly with the inclusion of dietary Previda® at different levels. Previda® was therefore able to selectively modify the microbial communities in the shrimp's GIT. Although individual bacterial species were not identified, enteric populations in shrimp fed the prebiotic at similar levels of inclusion were genetically similar. In addition, shrimp fed Previda® at 1.6 g kg?1 responded significantly (< 0.05) better immunologically with respect to hemocyte phagocytic capacity, haemolymph protein, hyaline cell counts and haemolymph glucose compared with shrimp fed the basal diet. Although shrimp were not exposed to virulent pathogens in this study, the observed upregulation of some of imm‐une responses upon prebiotic supplementation indicates that an improved outcome of such challenges may be anticipated in Previda®‐fed shrimp under commercial conditions.  相似文献   
29.
Reclamation of saline soils involves heavy leaching with water, with or without the addition of gypsum, depending upon the calcium content of the soil. Many a time, flushing the soil becomes difficult because of its low permeability due to high clay content, as obtained in most of the coastal saline soils of India. There is also the danger of hydrolysis under conditions of prolonged leaching, which may result in raising the pH, dispersion of the soil, impeded drainage, root penetration and aeration. Reclamation of such soils, therefore, calls for the improvement of physical conditions for better permeability and addition of calcium rich substances. Indigenous materials like basic slag, lime sludge, calcareous soil and iron rich mineral soil, in addition to gypsum, may serve as useful amendments for improving the soil's physical conditions. It was, therefore, thought worth-while to study the effect of addition of these materials on the improvement of saline soils.  相似文献   
30.
Feline melanoma: a comparative study of ocular, oral, and dermal neoplasms   总被引:2,自引:0,他引:2  
Melanomas diagnosed in 29 cats over an 11 year period included 19 ocular (16 intraocular, three palpebral), five oral, and five dermal melanomas. Intraocular melanomas involved the ciliary body and iris in 12; the whole eye was involved in four. The average age of cats with intraocular melanomas was 11 years; the female : male ratio was 9 : 7. Histologically, eight intraocular tumors were mixed, six were epithelioid, and two were spindle cell. Ten of 16 cats (62.5%) with intraocular melanomas were killed because of the tumor at a mean of 156 days; four are living with no evidence of disease (average, 255 days). The mean time of death in cats with palpebral melanoma was 409 days. Metastasis occurred in 63% of cats with intraocular melanoma and all cats with palpebral melanoma. Four cats with oral melanoma were killed at a mean of 61 days; all had metastasis. Of five cats with cutaneous melanoma, one was killed with metastasis at 90 days; three cats were alive without evidence of recurrence or metastasis greater than 365 days after surgery. Results of this study indicate that in the cat, ocular melanomas are more common than oral and dermal melanomas, and ocular and oral melanomas are more malignant than dermal melanomas, with higher rates of mortality and metastasis.  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