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   365篇
  免费   39篇
林业   19篇
农学   9篇
基础科学   3篇
  86篇
综合类   34篇
农作物   20篇
水产渔业   25篇
畜牧兽医   167篇
园艺   4篇
植物保护   37篇
  2024年   2篇
  2023年   8篇
  2022年   10篇
  2021年   13篇
  2020年   7篇
  2019年   16篇
  2018年   15篇
  2017年   8篇
  2016年   15篇
  2015年   8篇
  2014年   13篇
  2013年   11篇
  2012年   14篇
  2011年   28篇
  2010年   26篇
  2009年   22篇
  2008年   34篇
  2007年   28篇
  2006年   18篇
  2005年   18篇
  2004年   18篇
  2003年   15篇
  2002年   12篇
  2001年   3篇
  2000年   3篇
  1999年   3篇
  1998年   2篇
  1997年   3篇
  1995年   3篇
  1994年   1篇
  1992年   3篇
  1991年   3篇
  1990年   2篇
  1988年   1篇
  1985年   4篇
  1982年   3篇
  1981年   1篇
  1980年   2篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1965年   1篇
  1957年   1篇
  1955年   3篇
排序方式: 共有404条查询结果,搜索用时 15 毫秒
71.
72.
A subpalpebral lavage catheter is commonly used to administer medications in the treatment of infectious keratitis in horses. Drugs may mix in the subpalpebral lavage catheter, potentially affecting antimicrobial efficacy. The objective of this study was to determine the in vitro antimicrobial efficacy of combinations of commonly used ophthalmic preparations. An agar gel diffusion bioassay was used to determine the antibiotic activity of a number of antimicrobial, antifungal, mydriatic, and antiproteinase drug combinations. Drug mixtures were allowed to sit in a syringe at ambient temperatures and room lighting, for 1 (T1) and 6 hours (T2). The antibacterial efficacy was determined by measuring the zone of inhibition around wells containing the drug combinations after overnight incubation at 37°C and comparing them with the zone of inhibition around the antimicrobial alone. Combinations were tested against Pseudomonas aeruginosa and Streptococcus zooepidemicus. There was no significant decrease in the zone of inhibition, compared with controls, for the majority of combinations tested. Significantly smaller zones of inhibition were identified for the following combinations: (1) tobramycin, cefazolin, natamycin, and serum (T1) and (2) tobramycin, cefazolin, natamycin, serum, and atropine (T1) compared with tobramycin alone; (3) ciprofloxacin, cefazolin, natamycin (T1) compared with ciprofloxacin alone; (4) triple antibiotic ophthalmic solution (TAB) and natamycin (T6); (5) TAB, natamycin, and serum (T6); and (6) TAB, natamycin, serum, and atropine (T6) compared with TAB alone. Admixture does not affect in vitro antibacterial efficacy for the majority of ophthalmic preparations, although efficacy of TAB may be decreased compared with the drug alone.  相似文献   
73.
Objective To compare the incidence of anesthetic complications in diabetic and nondiabetic dogs undergoing general anesthesia and phacoemulsification cataract surgery. Procedure The medical and anesthetic records of all dogs undergoing phacoemulsification cataract surgery at Davies Veterinary Specialists between 2005 and 2008 were reviewed. Anesthetic records were evaluated by an ECVAA Diplomate. Dogs for which records were incomplete were excluded. The anesthetic technique, including all drugs administered in the perioperative period, was recorded. The anesthetic complications investigated included hypotension (MAP (mmHg): ≥55 none/mild; ≤54 moderate/severe), bradycardia (<60 bpm associated with hypotension) and hypothermia (esophageal temperature <36.7 °C). Where hypotension was present, the method of and response to treatment was recorded. The incidence of severe hyperglycemia (blood glucose >13.75 mmol/L (250 mg/dL)) in the diabetic group was also assessed. Results 66 diabetic and 64 nondiabetic dogs were included in the study. Diabetic dogs were more likely to develop moderate and severe intraoperative hypotension than nondiabetic dogs. Forty‐four percent of diabetic dogs had at least one episode of severe hyperglycemia whilst anesthetized. Conclusions Diabetic dogs undergoing phacoemulsification are more likely to suffer the anesthetic complications of moderate and severe hypotension than nondiabetic dogs. The increased incidence and severity of hypotension in diabetic dogs may be explained by hypovolemia secondary to hyperglycemia and resultant osmotic diuresis.  相似文献   
74.
Agricultural intensification has led to dramatic losses in biodiversity over the past several decades. Many studies have shown the effects of intensification on vegetation or soil communities at field or local scales. However, the functional significance of biodiversity may only appear at larger spatial and temporal scales, due to exchanges among local ecosystems throughout a landscape. To examine how patterns of biodiversity loss are reflected at larger spatial scales, plant and soil biodiversity and associated indicators of ecosystem functions were assessed in riparian areas over a 150 km2 agricultural landscape in the Sacramento Valley of California. Publicly-available GIS data were first used to classify and select sites over the range of soils, topography and plant community types. Representative sites from the landscape were sampled for soil physiochemical properties, as well as microbial, nematode, and plant communities. Higher agricultural intensification, based on field and landscape indices, was negatively correlated with richness and diversity of plant and soil taxa, and was related to indicators of ecosystem functions, such as increased soil nitrate and phosphorus loading, decreased riparian health ratings, and lower soil carbon, soil microbial biomass and soil food web structure. Both field- and landscape-scale factors played important roles in the measured losses. The study area was composed of a wide array of soils, vegetation, and land management, indicating that the observed trends transcended site-specific conditions.  相似文献   
75.
In common with much of the Western world, agrarianism—valuing farmers and agricultural activity as intrinsically worthwhile, noble, and contributing to the strength of the national character—runs through Australian culture and politics. Agrarian sentiments and attitudes have been identified through empirical research and by inference from analysis of political debate, policy content, and studies of media and popular culture. Empirical studies have, however, been largely confined to the US, with little in the way of recent re-evaluations of, or developments from, early work. This paper reports on research that seeks quantitative empirical evidence for the existence of agrarianism in the Australian community and seeks to identify its core characteristics. Using a purpose-designed sub-set of items within a large, omnibus-style survey of regional and rural Australia, we demonstrate that agrarianism exists as a scientifically quantifiable concept identifiable through responses to four key propositions: that Australians should support policies aimed at improving the position of the agricultural industries; that working in agriculture and associated industries brings out the best in people; that agricultural producers make a major contribution to environmental protection and biodiversity conservation; and that the development of agriculture in Australia contributed to the development of the national character. We found very little variation in the degree to which different demographic groupings agree with agrarianism. Older people, farmers, and non-Indigenous Australian-born respondents were among those who were statistically significantly more likely to agree with the defining propositions of agrarianism, but their scores were only very slightly higher than those of other sub-populations in the sample.  相似文献   
76.
77.
78.
To date Cryptosporidium muris has been identified by microscopy and genotyping in cats in two studies. We report morphological and genetic evidence of a mixed C. muris and C. felis infection in a cat and provide the first histological, immunohistochemical, in situ hybridisation and genetic confirmation of a C. muris infection in the stomach of a cat. The cat suffered persistent diarrhoea after the initial consultation, which remained unresolved, despite several medical interventions. Further studies are required to determine the range, prevalence and clinical impact of Cryptosporidium species infecting cats.  相似文献   
79.
European Journal of Plant Pathology - The formal honeybush tea industry in South Africa is relatively new, and has tremendous growth potential. However, as with other cultivated crops, production...  相似文献   
80.
Summary Of 250 isolates ofPhytophthora infestans obtained from Northern Ireland potato crops between 1981 and 1993, only six proved to be of the A2 mating type, the remainder being A1. The first A2 isolate was obtained from a tuber in 1987. The frequency of A2 isolates from 1987 onwards was 3%, a lower incidence than has been reported for England and Wales and the Republic of Ireland. There was no association between phenylamide resistance and mating type.  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